Fluid density fluid displacement for storing or generating electricity

Abstract

The system involves a first storage reservoir near the surface of a body of water and configured to store a first fluid. A second storage reservoir is located below the surface of the body of water and configured to store a second fluid having a higher density than the first fluid. The pump, generator, and first and second reservoirs are operatively connected to store electricity by pumping the less dense fluid in the first storage reservoir into the second storage reservoir, thereby displacing the more dense fluid in the second storage reservoir. Electricity is generated or discharged by allowing the less dense fluid in the second storage reservoir to return to the first storage reservoir. The more dense fluid can be in liquid form or in solid-liquid mixture form. The less dense fluid can be in liquid form or in solid-liquid mixture form.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Application No. 17 / 214,100, filed March 26, 2021, which is a continuation-in-part of U.S. Application No. 16 / 932,429, filed July 17, 2021. This application also claims priority to U.S. Application No. 63 / 117,355, filed November 23, 2020, U.S. Application No. 63 / 132,778, filed December 31, 2020, and U.S. Application No. 63 / 139,157, filed January 19, 2021. All of the foregoing applications are incorporated by reference herein in their entirety. [Background technology]

[0002] Solar, wind, and other intermittent energy sources account for an increasingly large proportion of the world's power generation capacity. Due to the intermittency of solar and wind energy, power grids and other infrastructure that can quickly be dominated by high proportions of wind and solar power generation will require storage to match power supply with power demand. The required storage capacity will generally increase with the increasing penetration of intermittent renewable energy sources, particularly solar- or wind-dominated power grids and power grids with limited geographic distribution. The required duration of storage capacity also generally increases with the increasing penetration of intermittent renewable energy. For example, power grids with a large proportion of solar-generated power may have insufficient power generation at night, and therefore may require storage with a duration of 10 to 16 hours to support nighttime grid power needs. In the United States, 80% solar and wind energy penetration may be feasible with a duration of 12 hours of storage. In particular, 100% solar and wind energy penetration is only feasible with storage durations of at least three weeks due to wind and / or solar events tending to occur at less than expected rates at least once a year and / or due to seasonal variations in solar and / or wind energy. Prior art energy storage technologies are too expensive and / or geographically limited to meet the large number of terawatt-hours of long-duration storage required for high penetration rates of solar and wind power worldwide.

[0003] Energy storage technologies are compared with respect to various factors. Levelized cost, i.e., levelized cost of generation (LCOE) or levelized cost of storage (LCOS), is generally considered the primary or most important factor. Energy storage customers, such as project developers, electric utilities, and other customers, typically employ levelized cost as their primary metric for comparing energy storage technologies, where the lower the levelized cost, the more economically desirable the energy storage technology is compared to other options. A levelized cost calculation may include values ​​including, but not limited to, one or more of the following variables or combinations: capital cost, or cost of capital, or discount rate, or capacity utilization rate, or round-trip energy efficiency, or cost of land, or power capacity degradation rate, or energy storage capacity degradation rate, or balance of plant, or land use, or geographic limitations, or end-of-life cost, or cost per MW of power capacity, or cost per MWh of storage capacity. Prior art energy storage technologies generally have high levelized costs due to shortcomings of one or more of the aforementioned variables or a combination of these variables. For example, lithium-ion batteries have high capital costs, significant power capacity degradation, significant energy capacity degradation, land use, and high end-of-life costs. For example, compressed air energy storage has low round-trip energy efficiency and geographic limitations. For example, pumped hydro storage has high land use and geographic limitations. For example, hydrogen energy storage has low round-trip energy efficiency, a high cost per MW of power capacity, and a high power capacity degradation rate.

[0004] Other factors may include, but are not limited to, one or more or a combination of the following: environmental impact of manufacturing, environmental impact of land use, material constraints, end-of-life disposal, recyclability, labor use, local labor values, local economic impact, and required maintenance. For example, lithium-ion batteries have the following drawbacks related to the factors mentioned above: - The adverse environmental impact of manufacturing, including the production of material inputs ○Lithium, cobalt, nickel, and graphite material constraints Short life and end-of-life disposal issues. Lithium-ion batteries are not currently recyclable Local labor values ​​are generally minimal, especially for high-cost material inputs, including lithium, nickel, and cobalt. Unethical labor practices and downstream environmental impacts, particularly in the mining and refining of needed metals and materials, including cobalt and graphite. Local job creation and associated economic impacts are minimal because the majority of costs and labor occur at large manufacturing and mining operations, which are generally located far from the renewable energy or energy storage project site. Maintenance needs are high due to the need for thermal regulation, balance of plant, and expansion. Expansion is the installation of additional new lithium-ion batteries to compensate for the loss of energy storage and / or power capacity that naturally occurs in lithium-ion battery energy storage facilities over time. At large lithium-ion battery energy storage sites, significant "expansion" typically occurs at least once every five years.

[0005] For example, conventional pumped storage hydropower generation has the following drawbacks related to the factors mentioned above: Large-scale land use and significant geographical constraints Serious environmental damage and permanent environmental alteration • earthquake risk and landslide risk, including the risk of significant economic and / or human disaster in the event of a significant earthquake or landslide, or both;

[0006] Another challenge in the renewable energy industry is the availability of land for the development of renewable energy and / or energy storage projects. In many cases, local, regional, national, and international stakeholders strongly oppose the development of undeveloped or "pristine" land, including the development of renewable energy sources such as wind and solar. Stakeholders often oppose such development due to environmental, visual, or noise pollution during the construction and / or operation of wind and / or solar projects. Such opposition makes it increasingly difficult to explore new land, obtain permits, and develop solar and wind projects, significantly increasing development timelines. As a result, renewable energy developers have become increasingly interested in developing offshore renewable energy projects in oceans and other large bodies of water. The visual impact of near-shore wind farms has also led developers to look increasingly far out to sea and deeper underwater. Interconnecting power transmission from offshore wind to the onshore power grid presents significant challenges due to the intermittency of wind power and the large volume of wind power that requires interconnection. One potential solution is long-duration energy storage. Most prior art energy storage technologies are not suitable for the marine environment. For example, lithium-ion batteries are considered unsuitable or undesirable for the marine environment due to the corrosive nature of the marine environment and the flammability of lithium in water, even in the absence of air or oxygen. There is a significant need for low-cost, scalable, environmentally friendly, low land or water use, long-duration, high round-trip energy efficiency, long-duration energy storage technology suitable for the offshore environment.

[0007] Additionally, due to the increasingly common occurrence of extreme and abnormal weather events resulting from climate change, the need for power generation and storage technologies to reliably, consistently, and long-termly generate electricity when needed is becoming increasingly critical. Prior art energy storage technologies are unable to provide additional power beyond their nameplate storage capacity in the event of an emergency, which contributed to the high-profile power outages in California and across the United States in recent years. For example, if a lithium-ion battery or pumped hydroelectric power plant is rated for 1,000 MWh and the 1,000 MWh is fully used or fully discharged, the lithium-ion battery or pumped hydroelectric power plant will be unable to provide more power, even if more power is needed.

[0008] There is a significant need for energy storage technology that can function as both a high round trip efficiency (>70%) short, medium or long duration energy storage system and as a multi-day, multi-week or multi-month energy storage system, as needed.There is a significant need for energy storage technology that can function as both a high round trip efficiency (>70%) greater than 8 hour duration energy storage system and as a multi-day, multi-week or multi-month energy storage system, as needed.There is a significant need for energy storage technology that can function as both a high round trip efficiency (>70%) greater than 8 hour duration energy storage system and as a multi-day, multi-week or multi-month energy storage system, as needed. Summary of the Invention

[0009] The present invention relates to systems and methods for energy storage, or energy generation, or a combination thereof.

[0010] Some embodiments may be applicable to energy storage devices, for example. Some embodiments may include a storage area below the surface of a body of water or liquid and a storage area near or above the surface of the body of water or liquid. To "charge" the energy storage device, a lower-density fluid, such as a relatively lower-density liquid or gas, may be pumped into the storage area to displace a higher-density fluid, such as water. To discharge the energy storage device, the higher-density fluid may be allowed to displace the lower-density fluid, generating electricity due to the flow of the lower-density fluid through a generator.

[0011] Some embodiments may address one or more or all of the shortcomings of prior art energy storage systems. For example, some embodiments include one or more or a combination of the following: Low capital costs relative to the cost per MWh of energy storage capacity and the cost per MW of power generation capacity High round trip efficiency, such as a round trip efficiency of one or more or a combination of the following: 60%, or 65%, or 70%, or 75%, or 80%, or 85%, or 90%, or 95%, or 99%. No power capacity degradation over each charge-discharge cycle No degradation of energy storage capacity over each charge-discharge cycle No land use ●Minimum water surface area usage Minimal geographical limitations, as 40% of the world's population lives within 100km of the coast ● A long lifespan such as 20, 25, 30, 35, 40, 45, 50, 55, or 60 years, or any combination thereof. - Recyclability of most or all components at "end of life" • Reusability of most or all components at "end of life", which may include, but is not limited to, extending life or reusing for other uses. Minimal environmental impact of manufacturing and building materials Minimal environmental impact of construction, installation, and operation Significant positive impact on the local economy Oil and gas workers can transition to the renewable energy industry. For example, some embodiments employ much the same equipment, such as pipes, vessels, and pumps, and materials, such as steel and cement, and skills, except for, for example, energy storage systems to store renewable electricity. Designed for and / or applicable to aquatic, marine, or offshore environments

[0012] Some embodiments may be applicable to systems that provide high round-trip efficiency power storage and can supply fuel and / or electricity for days, weeks, months, or years, or any combination thereof, as needed. For example, some embodiments may store energy by displacing a high-density liquid with a low-density liquid, where the low-density liquid or the high-density liquid, or both, may contain chemicals that can alternatively be employed as fuel. For example, some embodiments may involve storing power by displacing a high-density liquid with a low-density liquid, where the displacing energy storage mechanism may store enough energy to provide power at maximum system power capacity for 1 hour, or 2 hours, or 4 hours, or 6 hours, or 8 hours, or 10 hours, or 14 hours, or 16 hours, or 18 hours, or 20 hours, or 25 hours, or 30 hours, or 35 hours, or 40 hours, or 45 hours, or 50 hours, or 75 hours, or 100 hours, or any combination thereof, or more. For example, some embodiments may involve storing electricity by displacing a high-density liquid with a low-density liquid, where the displacing energy storage mechanism may store enough energy to provide power at maximum system power capacity for less than 50 hours, and the low-density liquid, the high-density liquid, or both, may include fuel and may be capable of providing power for more than 50 hours, or more than 75 hours, or more than 100 hours, or more than a week, or more than a month, as needed. For example, some embodiments may involve storing electricity by displacing a high-density liquid with a low-density liquid, where the displacing energy storage mechanism may store enough energy to provide power at maximum system power capacity for a first duration, and the low-density liquid, the high-density liquid, or both, may include fuel and may be capable of providing power for a second duration, as needed.For example, some embodiments may involve storing electricity by displacing a high density liquid with a low density liquid, where the displacing energy storage mechanism may store enough energy to provide power at maximum system power capacity for a first duration, and where the low density liquid, or the high density liquid, or both, may include fuel and may be capable of providing power as needed for a second duration, the second duration being greater than the first duration.

[0013] Some embodiments may be applicable to ensure that a submersible tank is in pressure equilibrium with seawater adjacent to, surrounding, or at the same elevation as the submersible tank. Some embodiments may be applicable to minimize the pressure difference between the pressure of a fluid inside a submersible tank and the pressure of external water or other fluid adjacent to, surrounding, or at the same elevation as the submersible tank. For example, some embodiments may relate to the use of a pressure or power exchanger to extract excess pressure or power from one fluid and transfer the excess pressure or power to another fluid. For example, some embodiments may relate to the use of a pressure or power exchanger to extract excess pressure or power from a less dense fluid and transfer the excess pressure or power to a more dense fluid. For example, some embodiments may relate to the use of a pressure or power exchanger to extract excess pressure or power from a more dense fluid and transfer the excess pressure or power to a less dense fluid. For example, some embodiments may relate to the use of a pressure or power exchanger to extract excess pressure or power from a higher density fluid and transfer the excess pressure or power to a lower density fluid. For example, some embodiments may relate to the use of a pressure or power exchanger to extract excess pressure or power from a higher pressure fluid and transfer the excess pressure or power to a lower pressure fluid. For example, some embodiments may relate to the use of a pressure or power exchanger to extract excess pressure or power from a higher pressure fluid and transfer the excess pressure or power to a lower pressure fluid, where the excess pressure may be less than or equal to the pressure difference between the higher pressure fluid and water adjacent to, surrounding, outside of, or at least a portion of the submersible tank.For example, some embodiments may relate to the use of a pressure or power exchanger to extract excess pressure or power from a first fluid and transfer the excess pressure or power to a second fluid, where the excess pressure may be less than or equal to the pressure difference between the first fluid and water or other fluid adjacent to, surrounding, outside of, or level with at least a portion of the submersible tank. For example, some embodiments may relate to the use of a pressure or power exchanger to extract excess pressure or power from a second fluid and transfer the excess pressure or power to the first fluid, where the excess pressure may be less than or equal to the pressure difference between the second fluid and water or other fluid adjacent to, surrounding, outside of, or level with at least a portion of the submersible tank. For example, some embodiments may relate to a pressure balancing device for enabling or ensuring pressure equilibrium with water or other fluid adjacent to, surrounding, outside of, or at the same elevation as at least a portion of a submersible tank. For example, some embodiments may relate to a pressure sensor, or a valve, or any combination thereof. For example, some embodiments may relate to systems and methods for minimizing or preventing hydraulic rams or minimizing or preventing the potential adverse effects of hydraulic rams. Some embodiments may include an energy storage system in which the denser liquid has a density greater than water or seawater. Some embodiments may include an energy storage system in which at least one reservoir is located at an elevation above the elevation of the surface of a body of water, or sea level, or both.

[0014] Some embodiments may be applicable to energy storage systems where the lower density liquid, the higher density liquid, or both, are volatile or have a low boiling point. For example, some embodiments may be applicable to using pressurized tanks or tanks that are resilient to pressure differences. For example, some embodiments may be applicable to locating tanks at depths or hydrostatic pressures where the pressure difference between the pressurized fluid inside the tank and the fluid outside, surrounding, or adjacent to the tank is less than if the tank were on land or surrounded by atmospheric pressure, or both. For example, some embodiments may be applicable to refrigerating, semi-refrigerating, cooling, passive cooling, active cooling, thermal management, or any combination thereof, lower density liquids, higher density liquids, or both. For example, some embodiments may relate to ensuring that the lower density liquid, the higher density liquid, or both, are stored in a liquid state. For example, some embodiments may relate to ensuring that low-density liquids, high-density liquids, or both are stored in a liquid state, a supercritical state, a slurry state, or any combination thereof. For example, some embodiments may relate to systems and methods for heat exchange and / or heat storage to minimize energy use and / or maximize energy efficiency and / or utility of lower-density liquids, higher-density liquids, or both for refrigeration, semi-refrigeration, cooling, passive cooling, active cooling, thermal management, or any combination thereof. For example, some embodiments may be applicable to enabling the use of cryogenic liquids. For example, some embodiments may be applicable to enabling simultaneous storage of energy and power generation from ocean thermal energy conversion, or from the temperature difference of an ocean or body of water temperature gradient, or the temperature difference between air and water, or any combination thereof.

[0015] Some embodiments may relate to a tank applicable to storing low-density fluids underwater. For example, some embodiments may relate to a rigid structure or a flexible structure. For example, some embodiments may relate to a tank or storage area containing a porous solid medium, where a low-density fluid may be stored in the pores of the porous medium. For example, some embodiments may relate to a tank or storage area containing a porous solid medium, where a low-density fluid is stored in the porous medium by pumping or otherwise directing the low-density fluid into the porous medium to displace a higher-density fluid stored in the porous medium. For example, some embodiments may employ a storage reservoir including a porous medium, where the density or weight of the porous medium may reduce the buoyancy of the storage reservoir. For example, some embodiments may employ a storage reservoir including a porous medium, the presence of which prevents the reservoir from substantially collapsing, for example, when the pressure inside the reservoir is less than the pressure outside, adjacent to, surrounding, or at the same elevation as the reservoir. For example, some embodiments may employ a storage reservoir including a porous medium, the presence of which prevents the reservoir from substantially collapsing, for example, when fluid is pumped out of or removed from the storage reservoir at a volumetric rate greater than the volumetric rate at which fluid is added to or pumped into the storage reservoir. For example, some embodiments may employ a storage reservoir including a porous medium, the presence of which prevents the reservoir from substantially collapsing, for example, when fluid is pumped out of or removed from the storage reservoir without the simultaneous addition of another fluid to the reservoir.Substantial collapse can include the storage reservoir decreasing in total volume by the following or more, one or more of the following, or a combination of the following: 1 percent, or 5 percent, or 10 percent, or 15 percent, or 20 percent, or 25 percent, or 30 percent, or 35 percent, or 40 percent, or 45 percent, or 50 percent, or 55 percent, or 60 percent, or 65 percent, or 70 percent, or 75 percent, or 80 percent, or 85 percent, or 90 percent, or 95 percent.

[0016] Some embodiments may be applicable to simultaneous energy storage systems and tidal power systems. For example, some embodiments may enable storage of electricity while generating power from tidal changes in water level within the same system. Some embodiments may be applicable, for example, to tidal power energy generation systems that generate energy from tidal changes in water level. Some embodiments may involve generating energy, such as electricity, using displacement of air or other fluid from a storage area due to tidal increases in water level. Some embodiments may involve generating power using displacement of air or other fluid into a storage area due to tidal decreases in water level. If desired, moving parts for such tidal power systems, such as pumps and generators, may be located entirely above the surface of the body of water or liquid.

[0017] Some embodiments may be applicable to inhibiting or preventing growth or fouling buildup on structures in a liquid environment on marine structures, which may include, but are not limited to, marine structures designed for energy storage, or tidal power generation, or a combination thereof. Some embodiments may be applicable to inhibiting or preventing growth or fouling buildup on structures in a liquid environment, which may include aqueous and / or non-aqueous environments. Some embodiments described herein may inhibit, eliminate, or prevent growth or fouling buildup without the need for coatings, painting, manual cleaning / scrubbing, or other methods described in the art. Growth may include, but is not limited to, one or more, or a combination of marine growths, fouling buildup, marine organisms, marine animals, inorganic scaling, organic scaling, barnacles, mussels, bivalves, oysters, worms, shrimp, crustaceans, biofilms, algae, bacteria, fungi, or amoebas. Moving parts of the embodiments related to inhibiting or preventing growth or fouling or corrosion of structures in a liquid environment, such as pumps and generators, may be located entirely above the surface of the body of water or liquid, if desired.

[0018] Some embodiments may be applicable to increasing or decreasing the height of a floating structure, such as a dock. Some embodiments described herein may involve increasing the height of a floating structure above the surface of a liquid by pumping air into the floating structure or into a recessed area below the floating structure such that the air or other gas or other low-density fluid at least partially replaces a portion of the water in the recessed area. Similarly, the height of a floating structure above the surface of a liquid may be decreased by allowing gas to escape from the recessed area or by pumping gas out of the recessed area. Air or other gas may be transported into or out of the recessed area using one or more tubes. The recessed area may be open to water or other liquid. Where advantageous, the pumping or release of gas may be performed entirely outside the body of water or liquid using moving parts. By having moving parts outside of and not in contact with the water or liquid, the moving parts (e.g., air pump) may comprise lower cost equipment, may be less susceptible to fouling, and may have a longer lifespan.

[0019] It is important to note that the embodiments described herein may be combined, and the systems and methods described herein may overlap or have multiple simultaneous applications. [Brief explanation of the drawings]

[0020] [Figure 1] An exemplary structure having a recessed area "gas pocket" ("3") under each floating body or pontoon. [Figure 2] (Above): An exemplary structure having a recessed area "gas pocket" ("3") under each float or pontoon with interconnected air pumps and tubes. [Figure 3] An exemplary embodiment having an extended "wall" that may be employed to prevent air or gas loss in the event of, for example, waves, turbulent water, or a significant change in the angle of the dock. [Figure 4]An exemplary embodiment in which varying the volume of gas in the gas pocket adjusts the height and / or angle above the liquid surface of a floating structure, such as a dock. Figure 4 may show an increase in height. [Figure 5] In an exemplary embodiment, varying the volume of gas in the gas pocket adjusts the height and / or angle above the liquid surface of a floating structure, such as a dock. Figure 5 may show the height decreasing. [Figure 6] 1 is an exemplary simplified setup of an embodiment employing a lower density liquid and a higher density liquid. [Figure 7] Step 1: FIG. 7 may show an energy storage embodiment in the process of charging. [Figure 8] Step 2: FIG. 8 may show the energy storage embodiment in a relatively charged state. [Figure 9] Step 3: FIG. 9 may show an energy storage embodiment during discharge. [Figure 10] Step 4: FIG. 10 may show the energy storage embodiment in a relatively discharged state. [Figure 11] FIG. 11 may show an exemplary embodiment in which the LDL and / or HDL storage area above the high side head elevation or surface is located on a platform or floating platform. [Figure 12] FIG. 12 may show an exemplary embodiment in which the LDL and / or HDL storage area above the high side head elevation or surface is located on land. [Figure 13] FIG. 13 may illustrate an exemplary embodiment in which multiple subsurface storage regions are employed for energy and / or chemical storage. [Figure 14] Step 1 FIG. 14 may show an embodiment during power generation. [Figure 15] Step 2 Figure 15 may show an embodiment in which the storage area is nearly filled with water. [Figure 16] Step 3 FIG. 16 may illustrate an embodiment in which power generation is occurring when the water level of the surrounding body of water is relatively low compared to the water level inside the storage area. [Figure 17] Step 4 Figure 17 may show an embodiment in which the storage area has been nearly emptied of water. [Figure 18] Step 4 Alternative: Figure 18 may show an embodiment in which the storage area has been completely emptied of water. [Figure 19] Step 5 (Undertow, pump residual water out): Figure 19 may show an embodiment in which air is pumped into the storage area to remove or replace residual water. [Figure 20] Step 1 (Upwelling, Filling, Power Generation): Figure 20 shows an exemplary embodiment in which the water / air cavity or storage area contains a porous material. [Figure 21] Step 2 (High Tide, Cavity Full): Figure 21 shows an exemplary embodiment in which the water / air cavity or storage area contains a porous material. [Figure 22] Step 3 (Unload, Empty, Generate Power): Figure 22 shows an exemplary embodiment in which the water / air cavity or storage area contains a porous material. [Figure 23] Step 4 (Undertide, Empty): Figure 23 shows an exemplary embodiment in which the water / air cavity or storage area contains a porous material. [Figure 24] Step 1 (Rise, Fill, Generate Power): Figure 24 shows an exemplary embodiment where the water / air cavity or storage area is located on or within a body of water. [Figure 25] Step 2 (High Tide, High Water): Figure 25 shows an exemplary embodiment where the water / air cavity or storage area is located on or within a body of water. [Figure 26] Step 3 (Undertide, Empty): Figure 26 shows an exemplary embodiment where the water / air cavity or storage area is located on or within the body of water. [Figure 27] Alternative Step 3 (low tide, empty, depending on tide and location): Figure 27 shows an exemplary embodiment where the water / air cavity or storage area is located on or within the body of water. [Figure 28]Step 4 (Undertide, Empty): Figure 28 shows an exemplary embodiment where the water / air cavity or storage area is located on or within a body of water. [Figure 29] FIG. 29 shows an exemplary embodiment with a floating pump or floating generator station. [Figure 30] FIG. 30 shows an energy storage system in which the first storage reservoir is located on land and the pump and / or generator is located on land. [Figure 31] FIG. 31 shows an energy storage system in which the first storage reservoir is located on land and the pump and / or generator is located on land. [Figure 32] FIG. 32 illustrates an energy storage system in which the first storage reservoir is located near, at, or below the surface of the body of water, and / or the pump and / or generator is located near, at, or below the surface of the body of water. [Figure 33] FIG. 33 illustrates an energy storage system in which the first storage reservoir is located near, at, or below the surface of the body of water, and / or the pump and / or generator is located near, at, or below the surface of the body of water. [Figure 34] 1 is an embodiment of a low density fluid displacement. [Figure 35] 1 is an embodiment of a low density fluid displacement. [Figure 36] 1 is an embodiment of a low density fluid displacement. [Figure 37] 1 is an embodiment of a low density fluid displacement. [Figure 38] 1 is an embodiment of a low density fluid displacement. [Figure 39] 1 is an embodiment of a low density fluid displacement. [Figure 40] 1 is an embodiment of a low density fluid displacement. [Figure 41] 1 is an embodiment of a low density fluid displacement. [Figure 42] 1 is an embodiment of a low density fluid displacement. [Figure 43] 1 is an embodiment of a low density fluid displacement. [Figure 44] 1 is an embodiment of a low density fluid displacement. [Figure 45] 1 is an embodiment of a low density fluid displacement. [Figure 46] 1 is an embodiment of a low density fluid displacement. [Figure 47] 1 is an embodiment of a low density fluid displacement. [Figure 48] 1 is an embodiment of a low density fluid displacement. [Figure 49] 1 is an embodiment of a low density fluid displacement. [Figure 50] 1 is an embodiment of a low density fluid displacement. [Figure 51] 1 is an embodiment of a low density fluid displacement. [Figure 52] 1 is an embodiment of a low density fluid displacement. [Figure 53] 1 is an embodiment of a low density fluid displacement. [Figure 54] 1 is an embodiment of a low density fluid displacement. [Figure 55] 1 is an embodiment of a low density fluid displacement. [Figure 56] 1 is an embodiment of a low density fluid displacement. [Figure 57] 1 is an embodiment of a low density fluid displacement. [Figure 58] 1 is an embodiment of a low density fluid displacement. [Figure 59] 1 is an embodiment of a low density fluid displacement. [Figure 60] 1 is an embodiment of a low density fluid displacement. [Figure 61] 1 is an embodiment of a low density fluid displacement. [Figure 62] 1 is an embodiment of a low density fluid displacement. [Figure 63] 1 is an embodiment of a low density fluid displacement. [Figure 64] 1 is an embodiment of a low density fluid displacement. [Figure 65] 1 is an embodiment of a low density fluid displacement. [Figure 66] 1 is an embodiment of a low density fluid displacement. [Figure 67]1 is an embodiment of a low density fluid displacement. [Figure 68] 1 is an embodiment of a low density fluid displacement. [Figure 69] 1 is an embodiment of a low density fluid displacement. [Figure 70] 1 is an embodiment of a low density fluid displacement. [Figure 71] 1 is an embodiment of a low density fluid displacement. [Figure 72] 1 is an embodiment of a low density fluid displacement. [Figure 73] 1 is an embodiment of a low density fluid displacement. [Figure 74] 1 is an embodiment of a low density fluid displacement. [Figure 75] 1 is an embodiment of a low density fluid displacement. [Figure 76] 1 is an embodiment of a low density fluid displacement. [Figure 77] 1 is an embodiment of a low density fluid displacement. [Figure 78] 1 is an embodiment of a low density fluid displacement. [Figure 79] 1 is an embodiment of a low density fluid displacement. [Figure 80] 1 is an embodiment of a low density fluid displacement. [Figure 81] 1 is an embodiment of a low density fluid displacement. [Figure 82] 1 is an embodiment of a low density fluid displacement. [Figure 83] 1 is an embodiment of a low density fluid displacement. [Figure 84] 1 is an embodiment of a low density fluid displacement. [Figure 85] 1 is an embodiment of a low density fluid displacement. [Figure 86] 1 is an embodiment of a low density fluid displacement. [Figure 87] 1 is an embodiment of a low density fluid displacement. [Figure 88] A process for energy storage that stores electricity by replacing a high density liquid with a low density liquid and employing auxiliary cold and warm thermal storage. [Figure 89]A process for energy storage that generates electricity by displacing a low density liquid with a high density liquid and employing auxiliary cold and warm thermal storage. [Figure 90] A process for energy storage that stores electricity by replacing a high density liquid with a low density liquid and employing cold and warm auxiliary thermal storage and refrigeration systems. [Figure 91] A process for energy storage that generates electricity by displacing a low density liquid with a high density liquid and employing cold and warm auxiliary thermal storage and cooling systems. [Figure 92] A process for energy storage that stores electricity by replacing a high density liquid with a low density liquid and employing a heat storage and cooling system. [Figure 93] A process for energy storage that generates electricity by displacing a low density liquid with a high density liquid and employing a heat storage and cooling system. [Figure 94] A process for energy storage that stores electricity by replacing a high density liquid with a low density liquid and employing a heat storage and cooling system. [Figure 95] A process for energy storage that generates electricity by displacing a low density liquid with a high density liquid and employing a heat storage and cooling system. [Figure 96] A process for energy storage that stores electricity by replacing a high density liquid with a low density liquid and employing a heat storage and cooling system. [Figure 97] A process for energy storage that generates electricity by displacing a low density liquid with a high density liquid and employing a heat storage and cooling system. [Figure 98] A process for energy storage that generates electricity by displacing a low density liquid with a high density liquid and employing a heat storage and cooling system. [Figure 99] A process for energy storage that stores electricity by replacing a high density liquid with a low density liquid and employing a heat storage and cooling system. [Figure 100]A process for energy storage using a higher elevation reservoir located on land and a lower elevation reservoir located underwater. [Figure 101] A process for energy storage using a higher elevation reservoir located on land and a lower elevation reservoir located underwater. [Figure 102] A process for energy storage using a higher elevation reservoir located underwater near or on the seabed and a lower elevation reservoir located underwater near or on the seabed. [Figure 103] A process for energy storage using a higher elevation reservoir located underwater near or on the seabed and a lower elevation reservoir located underwater near or on the seabed. [Figure 104] A process for energy storage using a higher elevation reservoir located above water as a semi-submersible or fully submersible or combination thereof vessel and a lower elevation reservoir located underwater near or on the seabed. [Figure 105] A process for energy storage using a higher elevation reservoir located above water as a semi-submersible or fully submersible or combination thereof vessel and a lower elevation reservoir located underwater near or on the seabed. [Figure 106] A process for energy storage using a higher elevation reservoir including a floating vessel and a lower elevation reservoir located underwater near or on the seabed. [Figure 107] A process for energy storage using a higher elevation reservoir including a floating vessel and a lower elevation reservoir located underwater near or on the seabed. [Figure 108] A process for energy storage using underwater and / or lower elevation reservoirs above and / or on the seabed. [Figure 109] A process for energy storage using underwater and / or lower elevation reservoirs above and / or on the seabed. [Figure 110]A process for energy storage using underwater and / or lower elevation reservoirs above and / or on the seabed. [Figure 111] A process for energy storage using underwater and / or lower elevation reservoirs above and / or on the seabed. [Figure 112] A process for energy storage using lower elevation reservoirs that are underwater and / or underground below the seabed, or buried, or a combination thereof. [Figure 113] A process for energy storage using lower elevation reservoirs that are underwater and / or underground below the seabed, or buried, or a combination thereof. [Figure 114] A process for energy storage using lower elevation reservoirs that are underwater and / or underground below the seabed, or buried, or a combination thereof. [Figure 115] A process for energy storage using lower elevation reservoirs that are underwater and / or underground below the seabed, or buried, or a combination thereof. [Figure 116] A process for energy storage using underground lower elevation reservoirs. [Figure 117] A process for energy storage using underground lower elevation reservoirs. [Figure 118] A process for energy storage using underground lower elevation reservoirs. [Figure 119] A process for energy storage using underground lower elevation reservoirs. [Figure 120] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation. [Figure 121] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation. [Figure 122]A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation. [Figure 123] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation. [Figure 124] A process for energy storage configured to store both a low density liquid and a high density liquid in a higher elevation reservoir, the higher elevation reservoir being a floating structure. [Figure 125] A process for energy storage configured to store both a low density liquid and a high density liquid in a higher elevation reservoir, the higher elevation reservoir being a floating structure. [Figure 126] A process for energy storage configured to store both a low density liquid and a high density liquid in a higher elevation reservoir, the higher elevation reservoir being a floating structure. [Figure 127] A process for energy storage configured to store both a low density liquid and a high density liquid in a higher elevation reservoir, the higher elevation reservoir being a floating structure. [Figure 128] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing thermal storage. [Figure 129] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing thermal storage. [Figure 130] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing thermal storage. [Figure 131] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing thermal storage. [Figure 132] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing thermal storage. [Figure 133] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing thermal storage. [Figure 134] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing a thermal storage and thermal management system. [Figure 135] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing a thermal storage and thermal management system. [Figure 136] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation at exemplary flow rates. [Figure 137] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation at exemplary flow rates. [Figure 138] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing cooling from chilled water or seawater or deep seawater. [Figure 139] A process for energy storage configured to store both low density and high density liquids in a reservoir at a higher elevation and employing cooling from chilled water or seawater or deep seawater. [Figure 140A] A process for energy storage using a pressure exchanger that uses heat management, or cooling, or refrigeration. [Figure 140B] A process for energy storage using a pressure exchanger that uses heat management, or cooling, or refrigeration. [Figure 140C]A process for energy storage using a pressure exchanger without thermal management, cooling, or refrigeration. [Figure 141A] A process for energy storage using a pressure exchanger that uses heat management, or cooling, or refrigeration. [Figure 141B] A process for energy storage using a pressure exchanger that uses heat management, or cooling, or refrigeration. [Figure 141C] A process for energy storage using a pressure exchanger without thermal management, cooling, or refrigeration. [Figure 142A] A process for energy storage using a pressure exchanger housed in one unit that uses thermal management, or cooling, or refrigeration. [Figure 142B] A process for energy storage using a pressure exchanger housed in one unit without the use of thermal management, cooling, or refrigeration. [Figure 143A] A process for energy storage using a pressure exchanger housed in one unit that uses thermal management, or cooling, or refrigeration. [Figure 143B] A process for energy storage using a pressure exchanger housed in one unit without the use of thermal management, cooling, or refrigeration. [Figure 144] A process for energy storage that employs a mechanism for removing or separating a portion of a lower density liquid present in a higher density liquid. [Figure 145] A process for energy storage using a countercurrent heat exchanger. [Figure 146] A process for energy storage using a countercurrent heat exchanger. [Figure 147] A process for energy storage using a countercurrent heat exchanger and additional auxiliary cooling. [Figure 148] A process for energy storage using a first reservoir, a second reservoir, and a third reservoir, wherein the elevations of the first reservoir and the third reservoir are greater than the elevation of the second reservoir, and the elevation of the first reservoir is different from the elevation of the third reservoir. [Figure 149]A process for energy storage using a first reservoir, a second reservoir, and a third reservoir, wherein the elevations of the first reservoir and the third reservoir are greater than the elevation of the second reservoir, and the elevation of the first reservoir is different from the elevation of the third reservoir. [Figure 150] A process for energy storage using a first reservoir, a second reservoir, and a third reservoir, wherein the elevations of the first reservoir and the third reservoir are greater than the elevation of the second reservoir, and the elevation of the first reservoir is different from the elevation of the third reservoir. [Figure 151] A process for energy storage using a first reservoir, a second reservoir, and a third reservoir, wherein the elevations of the first reservoir and the third reservoir are greater than the elevation of the second reservoir, and the elevation of the first reservoir is different from the elevation of the third reservoir. [Figure 152] Subsea, underwater or submerged tanks, including rigid tanks and pressure balancing devices. [Figure 153] Subsea, underwater or submerged tanks, including rigid tanks and pressure balancing devices. [Fig. 154] A process for energy storage using a pressure exchanger. [Figure 155] A process for energy storage using a pressure exchanger. [Figure 156] A process for energy storage using a pressure exchanger. [Figure 157] A process for energy storage using a pressure exchanger. [Figure 158] A process for energy storage that uses a pump to provide auxiliary pressure. [Figure 159] A process for energy storage that uses a pump to provide auxiliary pressure. [Figure 160] A process for energy storage using a pressure exchanger. [Figure 161] A process for energy storage using a pressure exchanger. [Figure 162]A process for energy storage using a pressure exchanger and a second reservoir at a different elevation than a third reservoir. [Figure 163] A process for energy storage using a pressure exchanger and a second reservoir at a different elevation than a third reservoir. [Fig. 164] A process for energy storage using a lower elevation reservoir that includes separate storage for a higher density liquid in addition to a lower density liquid, where at least a portion of the displacement is provided by a pressure exchanger. [Figure 165] A process for energy storage using a lower elevation reservoir that includes separate storage for a higher density liquid in addition to a lower density liquid, where at least a portion of the displacement is provided by a pressure exchanger. DETAILED DESCRIPTION OF THE INVENTION

[0021] Overview of Exemplary Energy Storage Embodiments: Systems and methods for energy storage and / or simultaneous oil or chemical storage are introduced. In some embodiments, energy is stored via a hydrostatic pressure difference between one or more insoluble or sparingly soluble fluids, which may be driven by a density difference between the one or more fluids. This technology may, for example, employ the depth of a body of water to enable this hydrostatic pressure. An embodiment may, for example, include a relatively high-density liquid and a relatively low-density liquid or fluid, which may have a lower density than the relatively high-density liquid. The end-to-end technology may be a closed system, or may be closed at least below the surface of the body of water. In some embodiments, all or nearly all moving parts are above the surface of a body of water, such as an ocean or lake, or advantageously have no moving parts underwater or deep water, or have no substantial moving parts, or have no relatively expensive moving parts, or have no moving parts at depths greater than 250 feet underwater, or have no moving parts at depths greater than 1000 feet underwater. It may be beneficial for the system to be a closed system, with the internal fluids, e.g., high-density and low-density liquids, in direct contact with each other. The internal fluids may be isolated from the surrounding body of water or may not be in substantial contact with the surrounding body of water. Simply employing water in a body of water may ensure that pressure, e.g., liquid pressure, is balanced between the internal fluid and the surrounding or external body of water. Equilibrating pressure between the outside and inside of the container may, for example, allow for the use of lower-cost materials, for example, because at least a portion of the material may not require a pressure differential or substantial resistance. Energy may be stored in a hydrostatic pressure difference between media (e.g., liquids) inside the container, e.g., where one or more media have a higher hydrostatic pressure than another one or more media. The hydrostatic pressure difference may be driven by the difference in hydrostatic pressure of liquids of different densities at the same head height. Embodiments may include a medium containing two or more immiscible or low-solubility liquids with different densities. The density difference between two or more liquids at the same or similar height may drive the hydrostatic pressure difference. Advantageously, the process can operate at reciprocating efficiencies in excess of 70% or 80% due to the incompressibility of liquids and the high efficiency of hydroelectric generators.

[0022] Embodiments may use liquid, solid, gas, supercritical fluid, or other medium phases. One or more phases may be advantageously employed, for example, because the integrated system may be a closed system. For example, in a closed system, contamination by surrounding bodies of water may not be an issue, unless there is a leak, for example.

[0023] In one embodiment, a liquid reservoir of a higher density liquid (e.g., water) and a liquid reservoir of a lower density liquid (e.g., butane) are positioned at a relatively higher head height than one or more separate liquid-liquid interface vessels. The relatively higher head height may include, but is not limited to, one or more of the following combinations: located at a smaller depth within the surface of the body of water, located at the surface of the body of water, located above the surface of the body of water, floating on the surface of the body of water, located on land adjacent to the body of water, or located on another body of water, or located on land. It may be desirable for the higher density liquid to have the same or similar density as the surrounding body of water at the same depth. For example, if a pipe or container containing high-density and low-density liquids is in the ocean, the higher density liquid may include a liquid with the same, similar, or relatively close density as the surrounding body of water or other surrounding medium. Alternatively, the higher density liquid may have a significantly different density than the surrounding body of water or other surrounding medium, as a pressure differential resistant material may be required in such embodiments. The separate liquid-liquid interface storage vessel(s) may be located at a lower head elevation than the liquid storage vessel(s). The liquid-liquid interface storage vessel(s) may be connected to the liquid storage vessel(s) at a higher head elevation using one or more tubes. The tubes may be employed to transport a lower density liquid, a higher density liquid, or a combination thereof. The one or more tubes may be connected to one or more valves or pumps or sealed connection joints. For example, the lower density liquid may be connected to one or more liquid tubes, which may be connected to one or more pumps or generators, or a reservoir of the lower density liquid, or a combination thereof. For example, the higher density liquid may be connected to one or more liquid tubes, which may be connected to one or more pumps or generators, or a reservoir of the higher density liquid, or a combination thereof.

[0024] Storing energy may involve, for example, pumping a lower density liquid into one or more tubes and transferring at least a portion of a higher density liquid from the one or more tubes and one or more submerged containers to a reservoir of higher density liquid, or alternatively, transferring the higher density liquid to a surrounding body of water. For example, when the lower density is pumped into the tubes or storage container, it overcomes the hydrostatic pressure of the higher density liquid and develops a head, so that energy may be stored due to the difference in hydrostatic pressure between the lower density liquid and the higher density liquid at the same head height. When the storage device stops charging, a valve may be employed to prevent one or more liquids from undesirably reversing flow direction.

[0025] Check valves may be employed during pump operation to prevent the low-density liquid from reversing the pumping direction. In the absence of leaks, the energy storage period may be infinite. During discharge, one or more valves may open to allow the pressurized low-density liquid to be at least partially displaced, allowing the low-density liquid to power a generator. The valves, pumps, generators, and other moving parts may be located at the surface, just below the surface, on land, or a combination thereof, as this may reduce capital, operating, and / or maintenance costs.

[0026] In another embodiment, the process may be an open system, with the denser fluid comprising one or more liquids or fluids in a body of water, such as water, saltwater, oils, or relatively inexpensive liquids. For charging, a lower-density liquid may be pumped into one or more vessels to replace the denser water or liquid in the vessels. The process may contaminate the water in the bay, but this may be minimized by, but not limited to, minimizing mixing, preventing contaminant levels, such as low-density liquid levels, from approaching or exceeding the edges of the vessels, using a combination of liquids or media with low solubility or insolubility, using non-hazardous or inexpensive low-density liquids, or combinations thereof. In this embodiment, a storage vessel for the dense liquid is not required, potentially reducing capital costs and complexity. A version of this embodiment may include an upside-down barrel with a tube opening inside the closed, upward-facing face of the barrel and a port open to the surrounding body of liquid (e.g., a body of water, ocean, or lake) on the downward-facing face of the barrel. A version of this embodiment may include an inverted barrel with tubing connected to a liquid-tight port connected to the upward-facing surface of the barrel and a port on the downward-facing surface of the barrel that is open to a surrounding body of liquid (e.g., a body of water, ocean, or lake). A version of this embodiment may not include a liquid-tight port, and the tubing may be routed to the open side of the inverted container or barrel and attached to the lower portion of the container or barrel's interior (inside the upper portion of the barrel, since it is inverted). Advantages of this alternative embodiment include, but are not limited to, a simplified configuration, higher pressure resistance, reduced chance of leaks or contamination, and lower cost. One or more containers or barrels may be further connected to a weight or anchor, and the upper region of the barrel may be connected to buoyancy to maintain the one or more containers or barrels in a desired position (e.g., in an upside-down position). One or more tubes may be further connected to a pump or generator, which may be further connected to one or more low-density fluid storage containers. The one or more lower density liquid (or other fluid, such as gas) storage vessels may be located at a higher head elevation, for example, near, at, or above the surface of the body of water.During charging, a less dense liquid (or other fluid such as a gas) may be pumped into the container to displace the more dense liquid. During discharging, a less dense liquid may be pumped into the container to displace the more dense liquid.

[0027] Pressure of low density liquid: The pressure of the lower-density liquid when displacing the higher-density liquid may be higher than the surrounding body of water, as in the case of energy storage, and the pressure difference between the lower-density liquid and the surrounding body of water increases as depth decreases. At the interface between the lower-density liquid and the higher-density liquid, the pressures of the two liquids may be equal or nearly equal. As the depth of the lower-density liquid decreases (or the lower-density liquid is higher above the liquid-liquid interface), the lower-density liquid deviates more in pressure from the higher-density liquid, or the net pressure of the lower-density liquid is greater. As a result, tubes or other containers that transport the lower-density liquid over depths or head heights may need to be pressure-resistant, and the pressure-resistant requirements may increase as the depth decreases (or the head height from the liquid-liquid interface or deepest point increases). The pump or point of production may contain the highest pressure in an embodiment. One way to explain this phenomenon is as follows:

[0028] When an open tube is placed vertically within a body of water, the water inside the tube, even though isolated, is primarily at the same pressure as the surrounding body of water at any given depth because the water pressure exerted by the water inside the tube above a given point in the tube is the same as the water surrounding the tube. Similarly, when liquids of different densities, such as lower or higher density, are placed in a closed lower vessel outdoors, the liquid pressure at any given point may be equivalent to the liquid pressure exerted by the liquid above the point within the liquid. At the same height or depth, the lower density liquid may have a significantly lower gravity-induced pressure than the higher density liquid. When the lower density liquid is displacing the higher density liquid where it is subjected to gravity (e.g., due to the application of an external force), the net pressure or pressure differential experienced by the lower density liquid at any given height above the liquid-liquid interface or deepest point of the lower density liquid is: P Net =P HD -P LD During the ceremony, ● "P Net " may be the net pressure of the less dense liquid at a given height above the minimum depth of the less dense liquid or liquid-liquid interface. ● "P HD " may be the hydrostatic head of a less dense liquid or a more dense liquid at an elevation above the minimum depth of the liquid-liquid interface ● "P LD " may be the hydrostatic head of a less dense liquid at a height above the minimum depth of the less dense liquid or liquid-liquid interface

[0029] Figure 6: Figure 6 shows an exemplary simplified configuration of an embodiment employing a lower-density liquid and a higher-density liquid. The two boxes with black text are storage vessels for the higher-head height liquid. The higher-head height liquid storage area is connected to one or more separate storage vessels via tubing or piping. In Figure 6, the tubing is connected to a single storage vessel at a head height below the surface of the body of liquid (such as a body of water), located at a head height below the higher-head height liquid storage vessel, which may be referred to as the lower-head height storage vessel. The higher-density liquid tubing or piping is connected to one or more ports at the bottom of the lower-head height storage vessel. The lower-density liquid tubing or piping is connected to one or more ports at the top of the lower-head height storage vessel. The location of the port placement on the lower head height storage vessel may not be important, and the ports may be arranged, including, but not limited to, adjacent to each other, vertically opposite each other, horizontally opposite each other, randomly, or in another configuration, or combinations thereof. It may be important that the ports be liquid-tight. An exception may be, for example, when a heavy liquid port is open to the surrounding water basin, potentially eliminating the need for a liquid-tight port for the denser liquid and potentially eliminating the need for a pipe or storage vessel for the denser liquid. The region within the lower head height vessel where the denser liquid and the less dense liquid meet may be referred to as a fluid-fluid interface or liquid-liquid interface. The liquids may be in direct contact, in which case it may be desirable for the liquids to be immiscible. The liquids may also be spaced apart, separated, or constitute discontinuous liquids by separators, or drums, including, but not limited to, drums or floating drums. When a floating drum is employed to separate a more dense liquid from a less dense liquid, it may be desirable for the floating drum to be less dense than the more dense liquid and more dense than the less dense liquid. A liquid-liquid separator or drum may be employed, for example, to reduce liquid-liquid mixing (particularly important for soluble liquids) or to reduce environmental contamination when open water is a more dense liquid than the more dense liquid.Energy can be stored by pumping a less dense liquid into a tube or pipe of the less dense liquid, thereby displacing a more dense liquid from a storage vessel at a lower head level. The stored energy can be released by allowing the displaced water to enter the vessel at the lower head level, thereby displacing the liquid at the lower head level and generating electricity. In the configuration shown in FIG. 1, a pump / generator is shown connected to the pipe or tube of the less dense liquid, which can allow for high pump efficiency. The pump can be above the water surface, allowing for no moving parts to be submerged. The less dense liquid can be pressurized during charging and discharging.

[0030] A pump / generator may be connected to the denser liquid. One potential challenge with directly pumping a denser liquid is that charging may require the creation of a partial vacuum, which may be less efficient, and even a pure vacuum may not be enough driving force to remove enough denser liquid from a vessel at a lower head height. For example, if the pump or generator is in direct contact with or pumping a denser liquid, it may be desirable for the pump or generator to be below the water line.

[0031] The liquid storage area may include a tank or reservoir that stores a less dense liquid or a more dense liquid. Substantially immiscible or insoluble may mean a liquid that is less than 50 weight percent (wt%), or less than 40 wt%, or less than 30 wt%, or less than 20 wt% soluble in another liquid.

[0032] It may be advantageous for the storage area of ​​the denser liquid to be below the water line or at a depth equal to, similar to, or lower than the liquid-liquid interface or lowest point of the liquid. This may be advantageous, for example, when the denser liquid has the same density as the body of liquid, such as a body of water, surrounding the energy storage device. The storage area of ​​the denser liquid may include, for example, a storage device such as a floatation bladder that is in pressure equilibrium with the surrounding body of liquid, such as a body of water. The storage area of ​​the denser liquid may include, for example, a storage device with a floating or retractable roof that is in pressure equilibrium with the surrounding body of liquid, such as a body of water.

[0033] The lower head height vessel may be pressure differential resistant. The pressure resistance required by the lower head height vessel may increase with the vertical distance from the liquid-liquid interface or the lowest point of the lower density liquid. It may be advantageous to minimize the vertical height of the vessel and minimize the pressure differential experienced by the lower head height vessel compared to the lower head height vessel. This may allow more or most of the pressure differential of the lower density liquid to be transferred to the pipe / tube. It may be advantageous to gradually increase the reinforcement of the lower head height vessel with increasing vertical distance from the liquid-liquid interface or the lowest point of the lower density liquid. For example, a structure with gradually increasing reinforcement of the lower head height vessel may be similar to a water tower, with the vessels being gradually more pressure resistant and reinforced with higher hydrostatic pressures.

[0034] The higher density liquid reservoir and the lower density liquid reservoir may be located below the surface, floating above the surface, or on land, for example. In some embodiments, the higher density liquid reservoir may include the surrounding body of water. In some embodiments, the higher density liquid reservoir may be in a different location than the lower density liquid reservoir. For example, the higher density liquid reservoir may be a swim bladder-like expandable and contractible volumetric storage area below the surface of the body of water, while the lower density liquid storage area may be located on land.

[0035] An energy storage device may undergo charging or discharging of its storage capacity at any time. For example, if the device is at least partially charged, the device may be discharged. For example, if the device is at least partially discharged, the device may be charged. For example, if the device is fully charged, the device may not have the capacity to charge further. For example, if the device is fully discharged, the device may not have the capacity to discharge further.

[0036] Exemplary step-by-step instructions: Figure 7: Step 1: Figure 7 may show an energy storage device in the process of charging. A liquid pump may pressurize and pump a lower-density liquid (LDL) into a pipe connected to a lower-head height storage area, allowing the LDL to displace a higher-density liquid (HDL) in the lower-head height storage. As the HDL is displaced by the LDL, gravitational potential energy may be stored. Figure 7 may show the HDL being transferred to an HDL storage area above the lower-head height storage area. The HDL storage area may be located elsewhere, for example, below the surface of the liquid body, at the same height or depth as the lower-head region, or below the depth of the liquid-liquid interface, for example, if the HDL storage area contains a fluid that is in hydrostatic equilibrium with the surrounding liquid or a liquid of the same density as the surrounding liquid. One or more pumps may be powered by work, such as electrical work, hydraulic work, or mechanical work.

[0037] The LDL may be a volatile liquid (such as propane or butane), and the LDL storage area may be closed. Whether the LDL is volatile or not, the LDL storage area may be closed to the atmosphere. If the LDL is sufficiently volatile, the headspace gas within the LDL may contain LDL in the gas phase. If the LDL has a sufficiently high partial pressure (e.g., propane or butane), the LDL storage area may be pressure-resistant, and appropriate safety precautions may be taken.

[0038] The HDL may be a volatile liquid. The HDL may include water. It may be desirable for the HDL storage area not to be open to the atmosphere, as biofouling agents and other contaminants may enter. Instead, the headspace of the HDL storage area may contain, for example, filtered or treated air.

[0039] Figure 8: Step 2: Figure 8 may show the energy storage device in a relatively charged state. A check valve may be employed to prevent liquid from entering the LDL tank in a charged or discharged state, or during charging, or at steady state.

[0040] For example, during overcharge when the HDL storage region is at a higher elevation relative to the LDL, it may not be advantageous to allow the LDL to enter the denser liquid region. If this were to occur, for example, when the HDL storage region is at a higher elevation relative to the LDL liquid-liquid interface, the LDL may float to the surface of the HDL storage region. This can be remedied, for example, by removing the LDL from the HDL, for example, using one or more or a combination of the following: decanting, cyclones, coalescers, filters, or other means of phase or liquid-liquid separation. If the LDL forms a gas phase at the conditions in the HDL storage region, the LDL can be separated, for example, by one or more or a combination of the following, including, but not limited to, removing the LDL gas from the head space, compressing the head space gas, cooling the head space gas, gas separation methods, pressure swing adsorption, pressure swing absorption, membranes, distillation, combustion, absorption, or adsorption.

[0041] Figure 9: Step 3: Figure 9 may show the energy storage device discharging. HDL may displace LDL in the subsurface storage area, which may result in high pressure LDL passing through a generator to generate electricity and entering an LDL storage tank, for example.

[0042] Figure 10: Step 4: Figure 10 may show the energy storage device in a relatively discharged state. A check valve may be employed to prevent liquid from entering the LDL tank when in a discharged or charged state, or when charging, or at steady state.

[0043] Figure 11: Figure 11 may show an exemplary embodiment in which the LDL and / or HDL storage area above the high-side head elevation or surface is located on a platform or floating platform. If desired, the only direct interconnection between the energy storage device and land may be a medium for transporting electricity, such as an electric cable.

[0044] FIG. 12: FIG. 12 may show an exemplary embodiment in which the LDL and / or HDL storage area, at head height or above the surface on the higher side, is located on land, for example on a beach or island.

[0045] Figure 13: Figure 13 may show an exemplary embodiment in which multiple subsurface storage areas are employed for energy storage. If there are two or more subsurface storage areas, the subsurface storage areas may be interconnected, which may minimize the number of pipes between one or more storage areas at higher head elevations and one or more storage areas at lower head elevations or subsurface. Exemplary installation of exemplary embodiments: 1. Connect the tubing (lower density liquid tubing and higher density liquid tubing) to two ports of a liquid-tight container. The tubing can be wound in a roll or another storage configuration. a. The location of the ports can be important, e.g., they can be located to minimize mixing. For example, the ports can be located near the top of the vessel for tubing connections of lower density liquids and near the bottom of the vessel for tubing of higher density liquids. b. The tubing may be connected to one or more rolls of tubing. c. The tubes or containers may need to be pressure resistant, although in some embodiments, only the tubes transporting the less dense liquids need to be able to withstand substantial pressure differences. 2. Fill the container or tube, or both, with a liquid of the same or similar density as the surrounding body of water (e.g., in the ocean, a density similar to that of seawater could be salt water or an aqueous solution containing a high density organic additive such as glycerol or ethylene glycol or propylene glycol. It may be desirable for the liquid to be free of biofouling deposits, scaling agents, or agents that cause corrosion or degradation). Alternatively, the liquid may contain biofouling deposits, scaling agents, or agents that cause corrosion or degradation, such as raw seawater or lake water, or crude oil storage liquid, or raw wastewater or other raw liquid. The liquid filling the container or tube, or both, in this step may be considered a denser liquid. 3. Attach tubing to desired storage tank and generator / pump 4. To ensure that the vessel remains in a desired position (e.g., upright, etc.) and to prevent tubing tangling, implementations may include attaching one or more weights or anchors near the bottom of the vessel and attaching one or more buoyant floating objects near the top of the vessel. The vessel float or near the top of the vessel, or a combination thereof, may be further attached to a line that may be connected by a detachable mechanism such as a clip, or a connector with a remotely detachable clip. 5. Allow the vessel to sink to the desired depth, e.g., near or at the bottom of the body of water. As the vessel sinks, unwind the tubes and lines (e.g., float lines and guide lines). 6. Once the vessel reaches its desired depth (eg, the depth at which the weight or anchor reaches the bottom), the guide line can be removed or attached to a float that designates the location. 7. To charge, a lower density liquid is pumped into the liquid tube or container, displacing the higher density liquid, which then travels through adjacent tubing to the storage container. During charging, the lower density liquid may displace the higher density liquid in the tube or container, or a combination thereof. 8. To discharge, open the valve to provide the pressurized low-density liquid (e.g., from step 8) to a generator (e.g., which may be another generator or a pump that can be reversibly used as a generator). Potential benefits of the energy storage technologies described herein: ●>80% round trip efficiency Liquid pumps and generators achieve high efficiency and low thermodynamic losses Unlimited usable land area (located under a body of water or ocean) ●Unlimited storage time Unlimited charge / discharge cycles ○No moving parts in the ocean ○No deterioration or corrosion The reagents do not come into contact with the ocean (oceans and other bodies of water are simply used to create depths / heads with the same ambient hydrostatic pressure) Not affected by marine or aquatic growths (e.g. barnacles, sludge) ·Completely closed system Cost per kWh - butane is 1m 3 The cost is about $300 per liquid. Energy density (1m at 1000m 3 of butane-water is about 1 kWh of electricity) ●No impact on the environment ○Closed system Non-toxic reagents (in case of leaks) Abundant, non-toxic, non-volatile reagents and building materials Simple, low-cost structures The hydrostatic pressure inside the technology can be the same as its surroundings, allowing for the use of low-cost, low-pressure-resistant construction materials. (Note: Tubes connected to low-density liquids may require higher pressure resistance.) ○No moving parts underwater o An embodiment may include three tanks (two on the surface and one on the seabed), two pipes, and one pump / generator.

[0046] It may be desirable for the high density liquid (HDL) to have a density similar to that of the liquid in the surrounding body of water, which may allow for similar hydrostatic pressures within the vessel(s) and / or pipe as those surrounding the vessel(s) and / or pipe, potentially allowing for the use of lower cost, less pressure resistant materials.

[0047] To maximize the energy density of the storage device implemented, potentially desirable properties include, but are not limited to, a large net density difference (i.e., density of the high density liquid minus density of the "low density liquid") and low pressure or low temperature driven liquid compression (e.g., water compresses minimally under high pressure). Examples of this include, but are not limited to, propane (LDL) and water (HDL).

[0048] To enable effective functionality of the introduced storage device, potentially desirable properties include, but are not limited to, two or more reagents being substantially insoluble or immiscible. It may be desirable for a high density liquid and a low density liquid to be substantially insoluble or immiscible with each other.

[0049] To minimize capital costs, potentially desirable properties include, but are not limited to, low-cost reagents, low density liquids, and / or low-corrosion or non-corrosive reagents. For example, butane and propane are low-cost, liquids that operate at higher pressures.

[0050] To minimize capital costs, potentially desirable features include, but are not limited to, employing materials that are compatible with the internal reagents of the integrated process. For example, polypropylene or HDPE is inexpensive, abundant, corrosion resistant, and compatible with water, seawater, butane, and propane.

[0051] The energy storage device may also be a means for storing hydrocarbon liquids or chemicals or volatile hydrocarbons. For example, LDL storage areas and lower head height storage areas may include hydrocarbon reservoirs, such as, but not limited to, crude oil, gasoline, diesel, kerosene, ethane, propane, butane, hexane, octane, cyclopropane, or decane, or combinations thereof. The hydrocarbon liquids are stored in small, medium, or large quantities before being used or transported for various applications, such as polymer production, fuel, or other uses. By employing the energy storage device as a concurrent storage device for relatively low-density liquids, capital costs for hydrocarbon liquids can be avoided. For example, oil and gas companies, hydrocarbon transportation companies, oil traders, commodity traders, chemical companies, and other users of hydrocarbons or other relatively low-density liquids may employ the energy storage device as a hydrocarbon liquid storage device. For example, the owner or operator of the energy storage device may receive compensation for storing, servicing, or storing relatively low-density liquids. Although relatively low density liquids may be purchased, in this embodiment, the relatively low density liquids may not be advantageously purchased by the owner or operator of the energy storage device. Instead, the owner or operator of the energy storage device may be compensated for accurately storing the relatively low density liquids. This may eliminate the need to incur capital expenses for purchasing hydrocarbon liquids and may also develop new revenue streams for storing hydrocarbon liquids.

[0052] High density liquids may include higher density liquids with limited solubility in water, such as propylene carbonate (density of about 1.2 g / cm3) or ethylene glycol diacetate (density of about 1.128 g / cm3). With such higher density liquids with limited solubility in water, water may be employed as the low density liquid. Such high density liquids may be low cost, non-volatile, and relatively non-toxic, allowing for the use of large quantities of such high density liquids in aquatic or marine environments. Aquatic and marine are used interchangeably herein. Ridged storage areas or containers may be employed for one or more storage areas located below the surface of water. Such storage areas may include, but are not limited to, storage containers employed herein for storing crude oil or chemicals below the surface of the ocean or other body of water. Storage areas, including non-ridged or ridged storage areas or containers, may be located outside a body of water or liquid. Alternatively or additionally, the storage area may be located in a strategic petroleum reserve, oil reservoir, natural gas reservoir, liquid reservoir, saline aquifer, geological system, or oil and gas well. One or more storage areas subject to hydrostatic pressures greater than atmospheric pressure may be desirable in an environment that exerts similar or supporting pressures to minimize the strength requirements and potential costs of the storage area or container. In the case of solid environments, such as geological systems like salt caverns, the geological system or an artificially constructed geological system may function to directly contain or store the liquids and may itself function as a storage area. Illustrative exemplary embodiments: An energy storage device, ○Contains two or more storage areas, at least one storage area has a greater pressure than another storage area; An energy storage device in which energy is stored using the pressure difference between a less dense liquid and a more dense liquid at the same head height or depth An energy storage device, ○Contains two or more storage areas, at least one storage area has a greater pressure than another storage area; the energy storage device is charged by pumping a relatively less dense liquid into the storage area to displace a relatively more dense liquid; an energy storage device that is discharged by allowing a relatively more dense liquid to displace a relatively less dense liquid and allowing the flow of the less dense liquid to power an electrical generator or a hydraulic turbine; - Subsea oil or chemical storage facilities that simultaneously function as large-scale energy storage devices, ○Contains two or more storage areas, at least one storage area has a greater pressure than another storage area; An energy storage device in which energy is stored using the pressure difference between a less dense liquid and a more dense liquid at the same head height or depth - Subsea oil or chemical storage facilities that simultaneously function as large-scale energy storage devices, ○Contains two or more storage areas, at least one storage area has a greater pressure than another storage area; the energy storage device is charged by pumping a relatively less dense liquid into the storage area to displace a relatively more dense liquid; an energy storage device that is discharged by allowing a relatively more dense liquid to displace a relatively less dense liquid and allowing the flow of the less dense liquid to power an electrical generator or a hydraulic turbine; A process for storing energy / electricity while simultaneously storing natural gas, comprising: storing natural gas in gas bags or storage areas below the surface of a body of water; compressing or pumping natural gas into the gas bag or storage area, which may expand the volume of the storage area; discharging or generating electricity by allowing the natural gas to leave the gas bag or storage area and pass through a generator or turbine; The storage area is connected to a surface natural gas pipeline or LNG facility or natural gas facility through one or more tubes or pipes; Illustrative exemplary sub-embodiments: • Energy is stored in the displacement of a denser liquid with a less dense liquid under conditions where the pressure head due to gravity of the denser liquid exceeds the hydrostatic head of the less dense liquid ● The pump can reversibly function as a generator One storage area is located below the surface of the body of water, and another storage area is located near or above the surface of the body of water. The storage area acts as a reservoir for oils or chemicals The low density liquid or high density liquid or both are oils or chemicals that require storage. The storage area below the surface of the body of water constitutes a higher pressure, lower head height storage area, while the storage area above the surface of the body of water constitutes a lower pressure, higher head height area. The pump or generator is located near or above the surface of the body of water. The storage area below the surface of the body of water includes a recessed area having an opening near the bottom of the recessed area that is open to the surrounding body of water. A drum or separator separates or is located between a low density liquid and water from a surrounding body of water. The storage area below the surface of the body of water comprises an inflatable, or contractible, or flexible structure such as a swim bladder or bag or balloon, which can expand and fill with a low density liquid during charging, or can deflate or contract or empty during discharging. - The storage area includes an expandable or contractible or flexible structure that can displace water around the storage area. • The dense liquid comprises the water or body of water surrounding the storage area. The storage area below the surface of the body of water may be moored or anchored to the ground near the bottom of the body of water. The pump or generator comes into contact with a low-density liquid. The pump or generator comes into contact with a high-density liquid. The pump or generator is located below the water surface. Pumps or generators are in contact with high-density liquids and are located at low head heights, near higher-pressure storage areas. During filling, the denser liquid is pumped out of the storage area and the less dense liquid replaces the denser liquid. • One or more storage areas are employed for the storage of one or more chemicals. • The low density liquid or the high density liquid or both contain the chemicals being stored. - Low density liquid or high density liquid or both can be added to or removed from the system. The storage facility or energy storage device is located near an oil platform or chemical facility. A treatment unit is employed to separate the remaining high density liquid from the low density liquid, or vice versa, before using one or more of said liquids or before transporting said liquids after removal from said storage area. Storage units can be employed for oil or chemical storage when excess storage is required. The storage unit may contain, be filled with, be nearly completely filled with, or be filled with more low density liquids, employed temporarily, semi-permanently, or permanently for oil storage or chemical storage, for example, when such storage is required. The storage unit may contain, be filled with, be nearly completely filled with, or be filled with more dense liquids, employed temporarily, semi-permanently, or permanently for oil storage or chemical storage, for example, when such storage is required. ●The system may be optimized to prioritize or balance energy storage or oil storage or chemical storage or a combination thereof, for example, depending on one or more or a combination of the following, including but not limited to: Amount of chemicals or oils that require storage ○Market rates / prices for chemical or oil storage Market rates / prices for energy storage in the power grid Arbitrage value available for energy storage Arbitrage value available for chemical storage ●Low density liquids are low density fluids The low-density fluid contains gas. The low density fluid or gas may include natural gas. The natural gas may be employed in the system for power generation and oil and natural gas storage. Natural gas can be stored in the form of compressed natural gas (CNG) or liquid natural gas (LNG). The storage area is connected to a surface natural gas pipeline or LNG facility or natural gas facility through one or more tubes or pipes; A process for storing energy / electricity while simultaneously storing natural gas, comprising: storing natural gas in gas bags or storage areas below the surface of a body of water; compressing or pumping natural gas into the gas bag or storage area, which may expand the volume of the storage area; discharging or generating electricity by allowing the natural gas to leave the gas bag or storage area and pass through a generator or turbine; The storage area is connected to a surface natural gas pipeline or LNG facility or natural gas facility through one or more tubes or pipes;

[0053] The lower head height, the higher pressure storage area, can be equivalent to the storage area below the surface of the body of water. [Table 1]

[0054] liquid density The table below shows the densities of various exemplary liquids that may be employed in the technology introduced herein. [Table 2-1] [Table 2-2] [Table 2-3] [Table 2-4] [Table 2-5] [Table 2-6]

[0055] The low density liquid or the high density liquid may be sourced from, for example, a waste product, including, but not limited to, one or more or a combination of the following: waste cooking oil, waste plastic, waste plastic converted to a liquid, waste plastic converted to fuel oil, waste glycerol, waste alcohol, waste refrigerant, waste antifreeze, waste lubricant, waste fuel, contaminated oils, contaminated chemicals, or expired goods.

[0056] Further discussion of the second description of the embodiment Overview of Additional Energy Storage Embodiments The present invention relates to a system for storing energy, which stores energy in the hydrostatic pressure difference between a less dense liquid and a more dense liquid over the same head or depth.

[0057] The present invention may involve storing energy by displacing water or other more dense liquid with a less dense liquid. The displacing water with the less dense liquid may involve pumping the less dense liquid to a greater depth below the surface of the body of water or other liquid. The pumping may consume power, such as electricity, which may be converted into energy stored in gravitational potential energy and / or hydrostatic pressure differentials. The stored energy may be converted back into power by allowing the less dense liquid to be released from the greater depth below the surface of the body of water or other liquid to a lesser depth below the surface of the body of water or other liquid, passing through a generator in the process.

[0058] Text description of the illustration image022.gif. Figure 30: Figure 30 may illustrate an energy storage system in which a first storage reservoir is located on land and a pump and / or generator is located on land. The second storage reservoir is located below the surface of the body of water at a greater hydrostatic pressure and / or a greater depth below the surface of the body of water than the first storage reservoir. The first storage reservoir, pump and / or generator, and second storage reservoir may be connected using pipes. Figure 30 may illustrate an energy storage system in the process of charging. Charging may involve storing power by pumping a low-density liquid from the first storage reservoir to the second storage reservoir. The storage reservoir may include an expandable and / or collapsible or collapsible tank. For example, during charging, the first storage reservoir may contract or collapse to a smaller volume as liquid is pumped from the first storage reservoir to the second storage reservoir. For example, during charging, the second storage reservoir may expand to a larger volume as liquid is pumped from the first storage reservoir to the second storage reservoir.

[0059] FIG. 31 may illustrate an energy storage system in which a first storage reservoir is located on land and a pump and / or generator is located on land. The second storage reservoir is located below the surface of the body of water at a greater hydrostatic pressure and / or a greater depth below the surface of the body of water than the first storage reservoir. The first storage reservoir, pump and / or generator, and second storage reservoir may be connected using pipes. FIG. 31 may illustrate an energy storage system in the process of discharging. Discharging may involve releasing stored energy by allowing a less dense liquid to be released from the first storage reservoir to the second storage reservoir, and in the process generating electricity by allowing the less dense liquid to pass through a generator. The storage reservoir may include an expandable and / or contractible or collapsible tank. For example, during discharging, the first storage reservoir may expand to a larger volume as liquid is released from the second storage reservoir into the first storage reservoir. For example, during discharge, the second storage reservoir may contract or collapse to a smaller volume as liquid is released from the second storage reservoir into the first storage reservoir.

[0060] Figure 32: Figure 32 may show an energy storage system in which a first storage reservoir is located near, at, or below the surface of the body of water, and / or a pump and / or generator is located near, at, or below the surface of the body of water. The second storage reservoir is located below the surface of the body of water, at a greater hydrostatic pressure and / or at a greater depth below the surface of the body of water than the first storage reservoir. The first storage reservoir, pump and / or generator, and second storage reservoir may be connected using pipes. Figure 32 may show the energy storage system in the process of charging.

[0061] Figure 33: Figure 33 may show an energy storage system in which a first storage reservoir is located near, at, or below the surface of the body of water, and / or a pump and / or generator is located near, at, or below the surface of the body of water. The second storage reservoir is located below the surface of the body of water at a greater hydrostatic pressure and / or at a greater depth below the surface of the body of water than the first storage reservoir. The first storage reservoir, pump and / or generator, and second storage reservoir may be connected using pipes. Figure 33 may show the energy storage system in the process of discharging.

[0062] Illustrative figure legend [Table 3-1] [Table 3-2] [Table 3-3] [Table 4-1] [Table 4-2] [Table 4-3] [Table 5-1] [Table 5-2] [Table 5-3] [Table 6-1] [Table 6-2] [Table 6-3]

[0063] Illustrative Step-by-Step Instructions Charging: Pump low density liquid from reservoir "1" to reservoir "2" using pump "3". Electricity is stored in the gravitational potential energy and / or hydrostatic pressure difference of the low density liquid stored in reservoir "2" relative to reservoir "1".

[0064] Discharge: The low density liquid is released from reservoir "2" and transferred to reservoir "1" to generate electricity using generator "3". Power is generated by releasing the gravitational potential energy of the low density liquid stored in reservoir "2" and / or the energy stored in the hydrostatic pressure difference relative to reservoir "1".

[0065] Example Calculations The following table shows key metrics regarding the energy density and cost of butane in the present gravitational potential energy storage device. The cost figures use an exemplary butane commodity price of $0.60 USD per gallon. [Table 7]

[0066] Note Note: Electricity can be transferred between power grids or applications that require or provide electricity.

[0067] Note: Electricity may be transported using, for example, subsea or underground or above ground power lines, or a combination thereof.

[0068] Note: The lines / arrows between "1" and "3" and between "3" and "2" may represent the transfer of low density liquid between these process elements. The liquid may be transferred using, for example, a pipe or a transport vehicle. If the liquid is transferred using a pipe, it may be desirable for the pipe to be one or more or a combination of, but not limited to, located on the surface of the ground, or suspended above the surface of the ground, or located below the ground, or including an underwater pipeline, or including an underground pipeline, or including a pipeline below the water and above the ground, or including a pipeline below the ground and below the water, or including a pipeline above the water and above the ground.

[0069] Note: An expandable or collapsible reservoir may include a liquid storage container that can expand or contract in volume to allow for the storage of more or less liquid, respectively. The pressure inside the reservoir may be close to or equal to the pressure surrounding the reservoir. The reservoir may include, but is not limited to, an expandable or collapsible liquid storage device, including, but not limited to, one or more or combinations of the following: a pillow tank, or an onion tank, or a balloon tank, or a bladder tank, or a fabric tank, or a swim bladder tank, or a collapsible tank, or a flexible tank, or a bellows tank, or an accordion tank, or a liner tank.

[0070] Note: The present invention may include an LPG storage facility, or an oil storage facility, or a strategic LPG reserve, or a strategic petroleum reserve.

[0071] Note: The present invention may be employed to store fuels or other commodity chemicals while simultaneously employing the fuels or other commodity chemicals as gravity storage media. This may allow the facility owner or operator to have an additional revenue stream (storage or discharge) in addition to revenue from the storage of fuels or other commodity chemicals. By employing the present invention as a storage facility, instead of purchasing or leasing low-density liquids, the facility owner may be paid a storage fee for storing low-density liquids, which may further improve the economics of the facility. A portion of the low-density liquid storage within the facility may be available for "commodity storage," while a portion of the low-density liquid storage within the facility may be intended for permanent or semi-permanent storage. The portion of the low-density liquid storage available for "commodity storage" versus the portion of the low-density liquid storage intended to be permanent or semi-permanent within the facility may vary by facility and may depend on multiple economic factors and facility priorities.

[0072] Note: "Commodity storage" may include flexible or semi-flexible storage and may include a portion of a storage facility's stored low-density liquids that may be periodically removed or added for market needs, such as those of commodity traders or other entities involved in commodity markets. If desired, the corresponding low-density liquid storage capacity devoted to "commodity storage" may include a portion of low-density liquids that may be added or removed without substantially affecting the performance, capacity, or capability of the storage. The threshold for "substantially affecting" may vary from facility to facility based on economic factors and facility priorities. "Semi-permanent storage" may include long-term storage or storage that may be utilized periodically or infrequently. For example, semi-permanent storage uses may include, but are not limited to, storage for commodity asset-backed funds, commodity asset-backed ETFs or ETNs, or strategic reserves. Permanent storage may encompass low-density liquids intended to remain within the facility and / or may be necessary for the proper operation of the facility.

[0073] Note: Stored low-density liquids may be employed as stored assets or physical assets backing a commodity-tracking ETF or other fund. The owner or operator of a low-density liquid storage facility may generate revenue from the electricity market as an energy storage service and from management fees generated by the ETF for storing the low-density liquids backing the ETF. The ability to have these two revenue streams may allow the facility owner or operator to generate more revenue from the facility, or may allow for lower CAPEX for the facility, or may allow for lower management fees for the ETF, or a combination thereof. To ensure that the assets backing the ETF or ETN are sufficiently readily available or transferable, a portion of the low-density liquid may be stored in storage reservoir "1" at all times to meet short-term needs for low-density liquids.

[0074] Note: The temperature of ocean water below a certain depth may be relatively stable. The liquid in storage reservoir "2" is cooled or heated by the ambient seawater temperature, depending on the ambient temperature conditions surrounding reservoir "1" and the ambient conditions surrounding reservoir "2." For example, the ambient conditions surrounding reservoir "2" may be cooler than the ambient conditions surrounding reservoir "1." In such an embodiment, the relatively cooler temperature of the liquid transferred from reservoir "2" to reservoir "1" may be utilized to provide cooling to one or more applications requiring cooling. Exemplary applications requiring cooling may be a pump or generator "3." For example, the ambient conditions surrounding reservoir "2" may be warmer than the ambient conditions surrounding reservoir "1." In such an embodiment, the relatively warmer temperature of the liquid transferred from reservoir "2" to reservoir "1" may be utilized to provide heat or enthalpy to one or more applications requiring heat or enthalpy. The specified depth may include less than, greater than, one or more of, or a combination of: 300 meters, or 400 meters, or 500 meters, or 600 meters, or 700 meters, or 800 meters, or 900 meters, or 1000 meters, or 1100 meters, or 1200 meters, or 1300 meters, or 1400 meters, or 1500 meters, or 1750 meters, or 2000 meters.

[0075] Note: Due to the low density liquid being a liquid and the liquid being essentially incompressible compared to gas, the round trip efficiency of the present pressure and / or gravity energy storage devices can have significantly greater round trip efficiencies than energy storage devices employing pressurized gas. For example, the round trip efficiency of the present invention can be 40% or greater, or 50% or greater, or 60% or greater, or 70% or greater, or 75% or greater, or 80% or greater, or 85% or greater, or 90% or greater, or 95% or greater.

[0076] NOTE: A low density liquid may have a low viscosity, e.g., a viscosity close to, equal to, or less than that of water. For example, butane has a kinematic viscosity of about 0.2 cP at 1°C, compared to water's kinematic viscosity of 1.73 cP at 1°C. Other low density liquids other than, or in addition to, butane may have a viscosity less than that of water. Low viscosity may be advantageous because, for example, a lower viscosity liquid may allow for smaller pipe diameters, lower CAPEX, lower pump energy losses, greater shuttle efficiency, and greater distances between reservoir "1" and reservoir "2."

[0077] Notes: compatibility with low density liquids, compatibility with water or seawater, biofouling, pressure compatibility. For pipes transporting low density liquids, the pressure difference between the low density liquid in the pipe and the water surrounding the pipe increases with decreasing depth below the water surface. For example, to minimize CAPEX, the pressure rating of the pipes may be increased with a larger pressure difference. For example, pipes near reservoir "2" may have a lower pressure rating (and / or may be lower cost) and pipes near reservoir "1" may have a higher pressure rating (and / or may be higher cost).

[0078] Note: Reservoir "2" and / or reservoir "1" may be moored or connected or secured or anchored to land above an underlying body of liquid (e.g., a body of water).

[0079] Note: The storage reservoir or tank may include one or more or combinations of the following, but is not limited to: pillow tank, or onion tank, or balloon tank, or bladder tank, or fabric tank, or swim bladder tank, or collapsible tank, or flexible tank, or bellows tank, or accordion tank, or liner tank, or rigid tank, or piston tank, or actuator tank, or valve tank, or basin tank, or cement tank, or wooden tank, or plastic tank, or ceramic tank, or fiber tank, or composite tank, or rubber tank, or flexible tank.

[0080] Note: Pipe materials may include, but are not limited to, one or more or combinations of the following: plastic pipe, composite pipe, metal pipe, fiber pipe, resin pipe, wooden pipe, cement pipe, flexible pipe, rubber pipe, rigid pipe.

[0081] Note: It may be desirable to attach the first and / or second reservoirs to a denser material to reduce the buoyancy of the reservoirs. In the case of the first reservoir, the distance between the reservoir and land below the body of water is large enough to justify attaching a denser material to the first reservoir to reduce the cost of the tether cable. A tether cable may be employed to counteract the buoyancy of the reservoir and / or ensure that the reservoir is in the appropriate location relative to the other reservoir(s). In some embodiments, the distance between the first reservoir and land below the body of water may be large enough that attaching a denser material to the first reservoir is less costly than reducing the cost of the tether cable.

[0082] Note: In some embodiments, the location of the first reservoir may be maintained using a dynamic positioning system. The dynamic positioning system may employ various sensors, GPS, radar, or other positioning equipment to notify the operating system of changes in current location and / or changes in the position of the first reservoir and / or external thrust vectors such as currents. If the position of the first reservoir changes and / or a thrust vector is detected, aquatic or marine engines may be employed to offset the external thrust vector and / or position change to ensure the first reservoir maintains a desired position. If desired, attachment of a denser material to the first reservoir may make it similar or neutral in density relative to the surrounding body of water. If desired, the first reservoir may employ a mechanism for dynamically adjusting the density of the first reservoir, for example, using the addition of a higher density material, the addition of a lower density material (e.g., a low density liquid or a gas such as air), the release of a higher density material, or the release of a lower density material. Such mechanism(s) for dynamically adjusting density may also be incorporated into a dynamic positioning system. A dynamic positioning system may also be employed for the second reservoir.

[0083] Note: Collapsible or collapsible may include a structure or container or tank whose occupied volume or storage capacity can be reversibly reduced.

[0084] Note: Inflatable may include a structure or vessel or tank that can reversibly increase its occupied volume or storage capacity.

[0085] Note: The less dense liquid may be soluble or partially soluble in the more dense liquid. Advantageously, the less dense liquid may be separated from the more dense liquid by a physical barrier, which may prevent dissolution of the less dense liquid into the more dense liquid. For example, the physical barrier may include a storage tank liner, or a wall, or a pipe, or a combination thereof.

[0086] Note: In some cases, one or more low-density liquids having a density less than that of water may have a boiling point close to or below the temperature of ambient air or water and / or may have a large vapor pressure at the temperature of ambient air or water. In such cases, it may be desirable for the first reservoir to be a pressurized or rigid tank. For example, the pressurized or rigid storage tank may allow the low-density liquid to remain in the liquid phase while the low-density liquid is at a temperature above the atmospheric boiling point of the low-density liquid. In such cases where a rigid or pressurized tank is employed in the first storage reservoir, when a liquid, such as a low-density liquid, is removed from the first storage reservoir, the total volume of the rigid or pressurized tank may remain the same. The volume within the tank previously occupied by the low-density liquid in the liquid phase may instead be occupied by the low-density liquid in the vapor phase. The low-density liquid in the vapor phase may reside in a headspace above a liquid phase within the tank, such as the low-density liquid in the liquid phase. When a liquid, such as a low-density liquid, is added to the first storage reservoir, the total volume of the rigid or pressurized tank may remain the same. The volume in the tank previously occupied by the low-density liquid in its gas phase may instead be occupied by the low-density liquid in its liquid phase. Exemplary low-density liquids that may be applicable may include, but are not limited to, liquefied petroleum gas (LPG), propane, butane, diethyl ether, dimethyl ether, methoxypropane, methanol, acetone, pentane, hexane, petroleum ether, methoxyethane, liquid natural gas (LNG), gasoline, diisopropyl ether, an alkane, an alkene, an alkyne, a cycloalkane, or a combination thereof.

[0087] Note: The present invention may employ devices for leak detection and / or leak prevention. Additionally, the present invention may employ methods for minimizing loss or damage caused by leaks. For example, a containment mechanism, including but not limited to a liner, blanket, tarp, fabric, funnel, floating object, or other containment mechanism, or combinations thereof, may be placed or suspended above the second reservoir and / or pipe and / or pipe connection. In the event of a leak, low-density liquid may rise from the leak and be captured or received by the containment mechanism. The containment mechanism may be effective because low-density liquids tend to float and may cover a portion or the entire surface area of ​​the second reservoir and / or pipe and / or pipe connection above the second reservoir and / or pipe and / or pipe connection. The low-density liquid captured by the containment mechanism may be funneled into the containment mechanism, if desired, or may be transported to the surface using a return pipe, where the low-density liquid may be collected. Contact of the low-density liquid with a portion of the containment vessel or pipe may trigger one or more sensors that alert a system operator to the need to repair the leak. For example, the sensors may include a mechanism for measuring the increased buoyancy of the containment mechanism due to the capture or containment of the leaked low-density liquid. For example, the sensors may include a mechanism for measuring the flow rate of liquid in the return pipe, and the presence of at least a certain liquid flow rate may indicate the presence of a low-density liquid leak. For example, the sensors may include a mechanism for detecting the low-density liquid using spectroscopy, or density or molecular weight measurements, or a combination thereof. For example, the sensors may include measuring changes in mass, pressure, or volume within a container connected to the return pipe. For example, the sensor may include measuring a change in mass or volume of the first or second reservoir, which may include a change in mass or energy storage capacity when the process is at steady state, or an unexplained change in mass or energy storage capacity. The first reservoir may employ the containment mechanism and / or sensor.For example, the first reservoir and / or pump and / or generator may employ such containment mechanisms and / or sensors, for example, if the first reservoir and / or pump and / or generator is located below the surface of the body of water.

[0088] Note: The low density liquid or the pipe or the container or the reservoir or combination thereof may contain a medium that reacts when or at the site of a leak. For example, if the low density liquid begins to leak, a material in the wall of the pipe or the container or the reservoir may react with the low density liquid. The reaction may inhibit, block or prevent the leak. The reaction may include, but is not limited to, one or more or a combination of the following: an absorption reaction, or a swelling reaction, or a foaming reaction, or an expansion reaction, a reaction to form a solid, a reaction to form a viscous liquid, or a combination thereof. Alternatively or additionally, the low density liquid or the walls of the pipe or the container or the reservoir or combination thereof may contain a reagent that, upon exposure to water or air, reacts with water, air, or salts in the water. The reaction may inhibit, block or prevent the leak. The reaction may include one or more or a combination of the following, including, but not limited to, an absorption reaction, or a swelling reaction, or a foaming reaction, or an expansion reaction, a reaction that forms a solid, a reaction that forms a viscous liquid, or a combination thereof. The reaction may include forming a material that is more easily or readily trapped, or a more environmentally friendly material, or a material that may prevent further leaks, or a material that may simplify or facilitate the process of leak detection, or a material that may reduce the cost or damage associated with leaks. For example, the reaction may include forming a liquid of a particular color, or the reaction may include a tracing reagent.

[0089] Note: The low density liquid or pipe or vessel or reservoir, or combinations thereof, may contain a tracer chemical or reagent that can facilitate leak detection. For example, a part or component of the pipe or vessel or reservoir may contain a material that, when exposed to water, saltwater, low density liquid, air, or combinations thereof, can change one or more properties to facilitate detection of leaks, wear, or other forms of damage or exposure. For example, such properties may include, but are not limited to, color, electrical conductivity, electrical resistivity, thermal conductivity, surface texture, surface morphology, absorbance spectrum, vibration frequency, flexibility, temperature, density, stiffness, or combinations thereof.

[0090] Note: The temperature below a body of water may be different from the temperature above it. In addition, the body of water itself may have various temperature ranges that may correlate with depth. The temperature of a body of water relative to its depth may be known as the body of water's thermocline. In very deep bodies of water, such as oceans or lakes, water is generally most dense at about 4°C, so temperatures below about 1000 meters, or below about 1250 meters, or below about 1500 meters, range from about 3-8°C. For example, in the ocean, even if the temperature of the water at the surface is warm, e.g., above 15°C or above 20°C, the temperature of the water below 1500 meters is generally near 4°C. In the present invention, the second reservoir may be located at a different depth than the first reservoir. The temperature of the water surrounding the second reservoir may be relatively constant or stable, for example, if the second reservoir is located at a depth greater than 100 meters, 200 meters, 300 meters, 500 meters, 700 meters, 900 meters, 1000 meters, 1250 meters, or 1500 meters below a body of water. The temperature of the air or water adjacent to the first reservoir or surrounding the second reservoir may differ from the temperature of the water surrounding the second reservoir. The temperature difference between the second reservoir and the first reservoir may be beneficially utilized or may be put to use. For example, if the temperature of the second reservoir is less than the temperature of the first reservoir or an object adjacent to the first reservoir, electricity may be generated from the temperature difference between the liquid returning from the second reservoir and the ambient temperature around the first reservoir, or the temperature inside the first reservoir, or another heat or warm source or enthalpy source. For example, if the temperature of the second reservoir exceeds the temperature of the first reservoir or an object adjacent to the first reservoir, electricity may be generated from the temperature difference between the liquid returning from the second reservoir and the ambient temperature around the first reservoir, or the temperature inside the first reservoir, or another cold or warm source or heat or enthalpy sink. For example, if the temperature of the second reservoir is less than the temperature of the first reservoir or an object adjacent to the first reservoir, the liquid from the second reservoir may be employed as a cooling medium or source, or in district cooling to provide valuable or useful cooling to one or more applications requiring cooling.For example, if the temperature of the second reservoir exceeds the temperature of the first reservoir or objects adjacent to the first reservoir, liquid from the second reservoir may be employed as a heating medium or heat source, or in district heating to provide valuable or useful heating for one or more applications requiring heating. For example, if the temperature of the second reservoir is less than the temperature of the first reservoir or objects adjacent to the first reservoir, liquid from the second reservoir may be employed as a cooling source to power or facilitate a desalination process or a process for removing water from a gas stream or air. For example, if the temperature of the second reservoir is less than the temperature of the first reservoir or objects adjacent to the first reservoir, it may be desirable to insulate the first reservoir or one or more pipes. The insulator may allow the first reservoir to remain cooler, which may be advantageous, for example, if the low-density liquid has a low boiling point or is volatile, and minimizing the temperature in the first reservoir minimizes the pressure in the first reservoir. The insulator may also prevent condensation from forming on the tank.

[0091] Note: The present invention may also be employed as a means for Ocean Thermal Energy Conversion (OTEC).

[0092] o Note: If desired, one or more components of the present invention may be heated or cooled, temperature controlled, or a combination thereof.

[0093] Note: The low-density liquid may have a freezing point below that of water, which may be advantageously utilized. For example, the first reservoir may be employed as a cold or heat storage unit, e.g., to provide cooling for a refrigeration or freezer storage facility. Such cold storage may be employed, e.g., to optimize energy consumption or for grid load shifting or load reduction. For example, the first reservoir may be employed as a cryogenic cold or heat storage unit. Alternatively or additionally, the cold, low-density liquid may be employed as a low-temperature heat transfer fluid and / or a low-temperature heat storage medium. For example, the low-density liquid may be employed in applications requiring cooling, which may include, but are not limited to, district cooling, or cooling for a desalination facility, or cooling for a power plant, or cooling for an air separation unit, or cooling for a liquefaction facility, or cooling for an HVAC system. For example, an LNG gasification facility may generate large amounts of waste cooling. An LNG gasification facility may employ a low-density liquid in or from the first reservoir as a heat or enthalpy source, cooling the low-density liquid in the process. Due to its potentially lower freezing point, the low-density liquid may be cooled to a lower temperature than water while remaining in the liquid phase, enabling heat transfer or large-scale heat storage, or both, at temperatures near, at, or below the freezing point of water. Additionally, because the first reservoir is interconnected to a second reservoir and the second reservoir may be at a relatively consistent "cold" temperature, the "warm" low-density liquid may be near 4°C or otherwise below ambient temperature. Advantageously, because the "warm" low-density liquid may be significantly below ambient temperature, more energy may be recovered from the "cold source" than if the low-density liquid were near or at ambient temperature.

[0094] Note: Low density liquids or high density liquids or both may be employed as heat transfer fluids or as heat storage fluids in ocean thermal energy conversion.

[0095] Illustrative exemplary embodiments: 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water adjacent to the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; Water and a fluid having a density lower than that of water are both in liquid form in the system. 2. The system of embodiment 1, wherein the second storage reservoir is expandable, contractible, or collapsible. 3. The system of embodiment 1, wherein the second storage reservoir is a pillow tank, an onion tank, a balloon tank, a bag tank, a fabric tank, a swim bladder tank, a collapsible tank, a flexible tank, a bellows tank, an accordion tank, or a liner tank. 4. The system of embodiment 1, wherein the second storage reservoir includes a recessed area having an opening near a bottom of the recessed area, the opening being open to a body of water. 5. A system for storing and generating electricity, comprising: a first storage reservoir configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water, the second storage reservoir being at a greater depth below the surface of the body of water than the first storage reservoir; A pump and a generator; The pump, the generator, and the first and second reservoirs (1) storing electricity by pumping a low density fluid in a first storage reservoir into a second storage reservoir to displace water; or (2) generating or discharging electricity by allowing the lower density fluid in the second storage reservoir to return to the first storage reservoir; or (3) operatively connected so that both (1) and (2) are true; Water and a fluid having a density lower than that of water are both in liquid form in the system. 6. The system of embodiment 5, wherein the displaced water is in a second storage reservoir. 7. The system of embodiment 5, wherein the displaced water is water within a body of water, and the displaced water is adjacent to the second storage reservoir. 8. The system of embodiment 5, wherein the water pump and the generator are the same unit. 9. The system of embodiment 5, wherein the first storage reservoir, the second storage reservoir, or both, comprise an expandable, contractable, or collapsible structure. 10. The system of embodiment 5, wherein the first storage reservoir, the second storage reservoir, or both comprise a pillow tank, an onion tank, a balloon tank, a bag tank, a fabric tank, a swim bladder tank, a collapsible tank, a flexible tank, a bellows tank, an accordion tank, or a liner tank. 11. The system of embodiment 5, wherein the second storage reservoir includes a recessed area having an opening near a bottom of the recessed area that is open to the body of water. 12. The system of embodiment 5, wherein the second storage reservoir is anchored beneath the body of water. 13. The system of embodiment 5, wherein the fluid having a density lower than that of water comprises a hydrocarbon liquid. 14. The system of embodiment 5, further comprising a dynamic positioning system for maintaining or adjusting the position of the first reservoir, the second reservoir, or both. 15. The system of embodiment 5, further comprising an operable connection to a power grid or power transmission infrastructure. 16. The system of embodiment 5, wherein the second storage reservoir is configured to store a fluid having a density lower than that of water. 17. The system of embodiment 5, wherein the first and second reservoirs are connected by one or more pipes. 18. The system of embodiment 5, wherein the pump and generator comprise a single unit. 19. The system of embodiment 5, wherein the first reservoir is configured to be located below the surface of the body of water. 20. The system of embodiment 5, wherein the fluid having a density lower than water comprises propane, butane, LPG, pentane, hexane, or a mixture thereof. 21. The system of embodiment 5, wherein the fluid having a density lower than that of water comprises an alcohol, an ether, an ester, or a mixture thereof. 22. The system of embodiment 5, wherein the fluid having a density lower than that of water comprises methanol, ethanol, propanol, acetone, dimethyl ether, diethyl ether, or a mixture thereof. 23. The system of embodiment 9, wherein the second reservoir is configured to collapse or contract during discharge. 24. The system of embodiment 26, wherein the collapse or contraction is due to water adjacent to the second reservoir displacing a fluid having a lower density than water. 25. The system of embodiment 9, wherein the second reservoir expands during charging. 26. The system of embodiment 25, wherein the expansion is due to the fluid having a lower density than the water entering the second reservoir and displacing water adjacent to the second reservoir. 27. The system of embodiment 19, wherein the first reservoir is configured to be retained at the bottom of a body of water. 28. The system of embodiment 19, wherein the first reservoir is configured to be attached to a material having a density greater than water to reduce buoyancy. 29. The system of embodiment 19, wherein the first reservoir is attached to a material having a density greater than water and is configured to be neutrally buoyant, and wherein the position of the first reservoir is configured to be maintained or adjusted by a dynamic positioning system. 30. The system of embodiment 5, wherein the second reservoir is attached to a material having a density greater than water to reduce buoyancy.

[0096] Summary of Additional Liquid Displacement Embodiments The present invention relates to systems and methods for storing or generating electricity. Some embodiments relate to systems or methods for storing energy by displacing a higher density liquid with a lower density liquid. Some embodiments relate to systems or methods for facilitating electricity storage or generation. Some embodiments relate to environmental, health, and safety mechanisms. Some embodiments relate to systems and configurations for enabling energy storage in specific geographic types. Some embodiments relate to systems and configurations for enabling energy storage using low density liquid working fluids with various levels of volatilization or vapor pressure. Some embodiments relate to ensuring optimal energy storage performance.

[0097] Exemplary definition: Condensable gas: A chemical or mixture of chemicals that undergoes a reversible phase transition from liquid to gas, or gas to vapor, or both, or has a boiling point, or a combination of these, under the following conditions: ○ Vapor pressure of less than 2.5 atmospheres, or less than 5 atmospheres, or less than 10 atmospheres, or less than 15 atmospheres, or less than 20 atmospheres A vapor pressure of more than 0.1 atmospheres, or more than 0.2 atmospheres, or more than 0.3 atmospheres, or more than 0.4 atmospheres, or more than 0.5 atmospheres, or more than 0.6 atmospheres, or more than 0.7 atmospheres, or more than 0.8 atmospheres, or more than 0.9 atmospheres, or more than 1.0 atmospheres ○Temperature range of 230 Kelvin to 380 Kelvin Partially Discharged or Partially Charged: A state in which the energy storage system contains stored energy, but the stored energy is less than the total energy storage capacity of the energy storage system. For example, when a surface LDL storage tank contains an amount of LDL that is above its minimum capacity and below its maximum capacity. For example, when a submerged LDL storage tank contains an amount of LDL that is above its minimum capacity and below its maximum capacity. ● Maximum capacity: Maximum capacity may include the maximum amount of HDL or water, and / or the maximum amount of LDL, or both, that can be stored in a given storage tank, or in a region of an energy storage device, or in general. For example, the maximum capacity of LDL in a subsea tank may include the maximum amount of LDL that can be stored in the subsea tank before the LDL is compromised or can or enters a pipeline designed to transfer water. For example, the maximum capacity of HDL in a subsea tank may include the maximum amount of water or HDL that can be stored in the subsea tank before the HDL is compromised or can or enters a pipeline designed to transfer LDL. For example, the maximum capacity of LDL in a subsea tank may include the maximum amount of LDL that can be stored in the subsea tank before the LDL is compromised or can or enters a surface HDL or water tank. For example, the maximum capacity of HDL in a subsea tank may include the maximum amount of HDL that can be stored in the subsea tank before the HDL is compromised or can or enters a surface LDL tank. Minimum Capacity: Minimum capacity may include the minimum amount of HDL or water, and / or the maximum amount of LDL, or both, that can be stored in a given storage tank, or in a region of an energy storage device, or in general. For example, the minimum capacity of a tank of LDL or HDL may include the tank containing no LDL or HDL, or containing very little LDL or HDL. For example, the minimum capacity of LDL in a subsea tank may include the minimum amount of LDL that can be stored in the subsea tank before the HDL is compromised or can or enters a pipeline designed to transport the LDL. For example, the minimum capacity of HDL in a subsea tank may include the minimum amount of water or HDL that can be stored in the subsea tank before the LDL is compromised or can or enters a pipeline designed to transport the HDL. For example, the minimum capacity of LDL in a subsea tank may include the minimum amount of LDL that can be stored in the subsea tank before the HDL is compromised or can or enters a surface LDL or water tank. For example, the minimum volume of HDL in a subsea tank may include the minimum amount of water or HDL that can be stored in the subsea tank before the LDL is endangered or can or enters a surface HDL or water tank. The minimum volume or amount of LDL in a floating submersible tank may include the minimum amount of LDL needed to ensure the floating submersible tank is buoyant. Pump and Generator, or Pump and Generator: The pump and generator may include a combined pump / generator unit, which may include, but is not limited to, a Hydro Power Recovery Turbine (HPRT). Alternatively or additionally, some embodiments may employ a separate pump and a separate generator. ● First reservoir: The first reservoir may include one or more or a combination of tanks configured to store a low density liquid and may be located at a higher elevation than the second reservoir or at an elevation greater than the second reservoir. ● Second reservoir: The second reservoir may include one or more or a combination of tanks configured to store a low-density liquid and may be located at a lower elevation than the first reservoir or at a lower elevation than the first reservoir. The second reservoir may be configured to store both the low-density liquid and water. The second reservoir may be configured to store both the low-density liquid and water in a manner where the low-density liquid and the water exchange volume or pressure while preventing mixing or direct physical contact between the water and the low-density liquid. ● Third reservoir: The third reservoir may be interconnected to or may include the ocean. The third reservoir may include a water tank or storage vessel. The water tank or storage device may be on the surface, above water, underwater, or a combination thereof. The submersible water reservoir may include a tank or storage vessel or reservoir or body of water containing water interconnected to the second reservoir via a pipe. If desired, at least a portion of the water tank or storage vessel, the third reservoir, or the water interconnected to the third reservoir may have a pressure similar to or equilibrium with the hydrostatic pressure of the ocean. If the density of the liquid inside the third reservoir is the same as seawater, the third reservoir may be located at any elevation between the elevations of the first and second storage reservoirs, or at any elevation underwater. Storage vessel: A storage vessel or tank may comprise a barrier for containing a material such as a liquid, solid, or gas. The storage vessel or tank may comprise a variety of configurations or materials and may include, but is not limited to, storage tanks, or vessels adapted to store liquids or multiphase media, or combinations thereof, as known in the art. Treated Seawater: Treated seawater may include water or aqueous solutions derived from seawater that are less corrosive than seawater, or have a lower dissolved oxygen concentration than seawater, or are less susceptible to the formation of biofouling or scaling than seawater, or a combination thereof. It may be desirable for the treated seawater to have a density similar to seawater. Tether: A tether may include a cable or line or connector connecting a floating or buoyant structure to another structure, which may include, but is not limited to, the seabed, a mooring, a vessel, another tank, or an anchor, or any combination thereof. Configured to store water and fluids having a lower density than water: This term may describe a reservoir or storage designed for the storage of water and lower density liquids. This term may include configuring storage that prevents water and lower density liquids from reacting, dissolving, or forming new phases. This term may include configuring storage that ensures that water and lower density liquids are physically separated while being stored in the same storage vessel. ●Low density liquid: A liquid that is less dense than a more dense liquid. A liquid that is less dense than the density of water. A liquid that is less dense than liquid water at temperatures above 3°C and / or below 50°C. ●Substantial low density liquid-water hydrates: "Substantial" may mean an amount or location or combination thereof of low density liquid-water hydrates such that the low density liquid-water hydrates interfere with or disrupt the operation of the energy storage system. ● Close to or approximately the same as: "Close to or approximately the same as" can describe a value that is within 10% of another value. Sub-tank: A sub-tank may include a tank located within another tank, or within an enclosed structure, or within a recessed structure, or a combination thereof, or a tank located inside any of the above. Rigid Containment Structure: A rigid containment structure may include an enclosure or cover that holds a subtank or one or more other structures. The rigid containment structure may capture or collect low-density liquids and / or debris in the event of a failure of the subtank or one or more other structures. Mechanically Isolated: A submersible tank that is mechanically isolated from surrounding or adjacent seawater may include a tank in which the contents within the tank are isolated from or operate under a pressure independent of the pressure of the contents surrounding the tank. A mechanically isolated tank may be a tank that does not exchange pressure with fluids or materials outside or surrounding the tank. For example, a submersible tank may have a pressure within the tank that is different from the pressure of the water surrounding the submersible tank, and the shape and / or volume of the tank may remain unchanged. In some embodiments herein, the pressure within the submersible tank may be close to or approximately equal to the hydrostatic pressure of water at the same depth as the tank, but the contents within the tank may not exchange pressure with seawater adjacent to or surrounding the tank. Achieving a pressure within the tank similar to the pressure outside the tank without exchanging pressure between the interior and exterior of the tank may involve one or more or a combination of engineering design systems and / or methods. For example, the engineered head space gas or condensable head space gas may be engineered to have a vapor pressure in the hydrostatic pressure range of seawater at the same depth as the tank at temperatures within the range of the temperature inside the tank and / or the temperature of the water surrounding or adjacent to the tank. By achieving a pressure inside the tank similar to that outside the tank without exchanging pressure between the inside and outside of the tank, the submersible tank or submersible rigid tank may be manufactured, for example, from fewer or less expensive materials or a combination thereof. Defects: Defects may include breaks, or leaks, or disconnections, or accidental releases that may result in the release of internal liquids, which may include, but are not limited to, low density liquids and / or water.

[0098] Detailed Figures and Description of Exemplary Embodiments Figure 34: This diagram may illustrate an energy storage system that stores electricity by pumping a lower density liquid from a tank at a higher elevation to a tank at a lower elevation to displace water in the tank at the lower elevation. This diagram may illustrate charging or storing electricity in this embodiment. The tank with the lower density liquid at the higher elevation may include a first reservoir. The tank with the lower density liquid and water at the lower elevation may include a second reservoir. The tank with water at the higher elevation may include a third reservoir or surface water tank. The density of the water in the surface water tank may be close to or equal to the density of seawater. The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the depth of the second reservoir.

[0099] Figure 35: This figure may include the same embodiment as Figure 34. This figure may show the embodiment in a nearly fully charged state.

[0100] Figure 36: This figure may include the same embodiment as Figure 34. This figure may show that this embodiment discharges or generates electricity.

[0101] Figure 37: This figure may include the same embodiment as Figure 34. This figure may show this embodiment in a nearly fully discharged state.

[0102] Figure 38: Legend for figures 34, 35, 36, and 37.

[0103] Figure 39: An energy storage system that charges by pumping a low-density liquid from a first reservoir (“1”) near the surface to a second reservoir (“2”) underwater, displacing the seawater surrounding the second reservoir. This diagram shows an energy storage system that charges by pumping a low-density liquid from the first reservoir to the second reservoir, displacing the water surrounding the second reservoir. The first reservoir (“1”) near the surface can be at an elevation greater than the elevation of the second reservoir (“2”). The first reservoir can be above water on land, or can remain floating on water, or can be underwater. In this diagram, the second reservoir is floating above the seabed. In this diagram, the second reservoir may be suspended above the seabed and may be buoyant. In this diagram, the second reservoir may be anchored and / or moored to the seabed. In this illustration, the second reservoir may be surrounded by seawater. The second reservoir may include a piston tank. The second reservoir may include an inflatable or collapsible structure such as an onion tank, swim bladder tank, pillow tank, or storage bag. In this illustration, the internal pressure of the second reservoir may be close to or approximately equal to the hydrostatic pressure of the water in contact with the bottom of the second reservoir.

[0104] Figure 40: An energy storage system that stores electricity by pumping a low-density liquid from a first reservoir (“1”) near the surface to a second reservoir (“2”) underwater, displacing the seawater surrounding the second reservoir. This diagram shows the energy storage system fully charged at steady state. The first reservoir (“1”) near the surface may be at an elevation greater than the elevation of the second reservoir (“2”). The first reservoir may be above water on land, may remain afloat on the water, or may be submerged. In this diagram, the second reservoir is floating above the seabed. In this diagram, the second reservoir may be suspended above the seabed and may be buoyant. In this diagram, the second reservoir may be anchored and / or moored to the seabed. In this diagram, the second reservoir may be surrounded by seawater. The second reservoir may include a piston tank. The second reservoir may comprise an inflatable or collapsible structure such as an onion tank, swim bladder tank, pillow tank, storage bag, etc. In this illustration, the internal pressure of the second reservoir may be close to or approximately equal to the hydrostatic pressure of the water in contact with the bottom of the second reservoir.

[0105] Figure 41: An energy storage system that stores electricity by pumping a low-density liquid from a first reservoir ("1") near the surface to a second reservoir ("2") underwater, displacing the seawater surrounding the second reservoir. This diagram shows the energy storage system discharging or generating electricity by displacing the low-density liquid inside the second reservoir with the water surrounding the second reservoir ("2"), passing it through a pipe to a generator, generating electricity, and transferring it back into the first reservoir ("1"). The first reservoir ("1") near the surface can be at an elevation greater than the elevation of the second reservoir ("2"). The first reservoir can be above water on land, floating on water, or underwater. In this diagram, the second reservoir is floating above the seabed. In this diagram, the second reservoir may be suspended above the seabed and may be buoyant. In this illustration, the second reservoir may be anchored and / or moored to the seabed. In this illustration, the second reservoir may be surrounded by seawater. The second reservoir may include a piston tank. The second reservoir may include an inflatable or collapsible structure such as an onion tank, swim bladder tank, pillow tank, or storage bag. In this illustration, the internal pressure of the second reservoir may be close to or approximately equal to the hydrostatic pressure of the water in contact with the bottom of the second reservoir.

[0106] Figure 42: An energy storage system that stores electricity by pumping a low-density liquid from a first reservoir (“1”) near the surface to a second reservoir (“2”) underwater, displacing the seawater surrounding the second reservoir. This diagram shows the energy storage system in a fully discharged state. The first reservoir (“1”) near the surface may be at an elevation greater than the elevation of the second reservoir (“2”). The first reservoir may be above water on land, may remain afloat on the water, or may be submerged. In this diagram, the second reservoir is floating above the seabed. In this diagram, the second reservoir may be suspended above the seabed and may be buoyant. In this diagram, the second reservoir may be anchored and / or moored to the seabed. In this diagram, the second reservoir may be surrounded by seawater. The second reservoir may include a piston tank. The second reservoir may comprise an inflatable or collapsible structure such as an onion tank, or swim bladder tank, or pillow tank, or storage bag, etc. In this illustration, the internal pressure of the second reservoir may be close to or approximately equal to the hydrostatic pressure of the water in contact with the bottom of the second reservoir.

[0107] Figure 43: Figure 43 is an energy storage system with a labeled tether or anchor or tie-down tether. "C" is the labeling of the tether or anchor or tie-down. The tether or anchor or tie-down may be employed to connect a submersible tank (e.g., "2") to the seabed, which may allow the submersible tank (e.g., "2") to float above the seabed.

[0108] Figure 44: Figure 44 shows a water or HDL storage tank with a condensable gas in the head space. The storage tank can be rigid in construction. "A" is the labeling designation for the yellow layer (lighter in black and white). "A" represents a practically insoluble condensed liquid that contains the condensable gas in a condensed (i.e., liquid) state. The insoluble condensed liquid can have the same composition as at least a portion of the gas in head space "B" and / or the vapor pressure of the insoluble condensed liquid can be in equilibrium or equilibrium with the head space gas. "B" represents the gas occupying the head space. "A" contains less liquid in Figure 44 than in Figure 45 because more condensable gas is in the condensed liquid state in Figure 45 compared to Figure 44. "6" can represent a third reservoir. The condensable head space gas can allow the water tank to drain water while maintaining a relatively stable pressure within the tank or without substantially reducing the pressure within the water tank. The condensable head space gas may enable the interior of the submerged rigid water tank to have an internal pressure that approaches the hydrostatic pressure of seawater at the depth of the submerged rigid tank while remaining mechanically isolated from seawater at the depth of the submerged rigid tank. The condensable head space gas may have an engineered vapor pressure or boiling point to fit a design pressure range within a design temperature range.

[0109] Figure 45: Figure 45 shows a water or HDL storage tank with condensable gas in the head space. The storage tank can be rigid in construction. "A" is the labeling designation for the yellow layer (lighter in black and white). "A" represents a practically insoluble condensed liquid that contains the condensable gas in a condensed (i.e., liquid) state. The insoluble condensed liquid can have the same composition as at least a portion of the gas in the head space "B" and / or the vapor pressure of the insoluble condensed liquid can be in equilibrium or equilibrium with the head space gas. "B" represents the gas occupying the head space. "A" contains more liquid in Figure 45 compared to Figure 44 because more condensable gas is in the condensed liquid state, which can be due to the water occupying a larger percentage of the volume in Figure 45. "6" can represent a third reservoir. The condensable head space gas may allow the water tank to evacuate water while maintaining a relatively stable pressure inside the tank or without substantially reducing the pressure inside the water tank. The condensable head space gas may allow the interior of the submerged rigid water tank to have an internal pressure that approaches the hydrostatic pressure of seawater at the submerged rigid tank's depth while remaining mechanically isolated from seawater at the submerged rigid tank's depth. The condensable head space gas may have an engineered vapor pressure or boiling point to fit a design pressure range within a design temperature range.

[0110] Figure 46: An energy storage system that stores electricity by pumping a low-density liquid into a rigid submersible tank to displace water inside the rigid tank, which is then transferred to an external submerged water reservoir. This figure shows, for example, this embodiment in a charging state, e.g., powering a pump ("4") to transfer low-density liquid from a near-surface reservoir ("1") to a submerged reservoir ("2"), whereby the low-density liquid displaces water inside the submerged reservoir. The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the submerged depth of the second reservoir.

[0111] Figure 46: An energy storage system that stores electricity by pumping a low-density liquid into a rigid underwater tank to displace water inside the rigid tank, which is then transferred to an external underwater water reservoir. This figure shows the embodiment at a fully charged steady state. The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0112] Figure 48: An energy storage system that stores electricity by pumping a low-density liquid into a rigid, underwater tank to displace water inside the rigid tank, which is then transferred to an external underwater water reservoir. This diagram shows this embodiment in a power generation or discharge state. For example, a valve ("5") may be opened to allow water inside the underwater reservoir ("2") to displace the low-density liquid from the underwater reservoir through a pipe ("3") to generate electricity through a generator ("4") or discharge stored electricity into the near-surface reservoir ("1"). The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0113] Figure 49: An energy storage system that stores electricity by pumping a low-density liquid into a rigid submersible tank to displace water inside the rigid tank, which is then transferred to an external submersible water reservoir. This figure shows the embodiment in a fully discharged steady state. The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the submerged depth of the second reservoir.

[0114] Figure 50: An energy storage system that stores electricity by pumping a low-density liquid into a submersible tank (second reservoir) to displace water inside the second reservoir, which is then transferred to an external submersible water reservoir (third reservoir). This figure shows the embodiment in a fully discharged steady state. "2" may represent a rigid submersible tank that may include the second reservoir. "S" may represent a separator or barrier that may be located between the low-density liquid and the water, or that may physically separate, prevent, or minimize direct contact between the low-density liquid and the water. The separator or barrier may prevent direct contact between the low-density liquid and the water and / or provide physical separation between the low-density liquid and the water. The separator or barrier may, for example, allow the low-density liquid to displace the water while preventing or minimizing direct contact between the water and the low-density liquid. "8" may represent an external water reservoir or a third reservoir. In this diagram, the external reservoir may be located underwater. In this diagram, the external reservoir may be underwater at a depth similar to the second reservoir. "9" may represent a water pipe interconnecting the external reservoir to the second reservoir. In this diagram, the external water reservoir, or the pipe interconnecting the external water reservoir to the second reservoir, or a combination thereof, may have an internal pressure that is close to the hydrostatic pressure of seawater at or near the depth of the second reservoir. The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0115] Figure 51: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank (second reservoir) to displace water within the second reservoir, which is then transferred to an external submerged water reservoir (third reservoir). This figure shows, for example, this embodiment in a charging state, e.g., powering a pump ("4") to transfer low-density liquid from a near-surface reservoir ("1") to a submerged reservoir ("2"), whereby the low-density liquid displaces water within the submerged reservoir. "2" may represent a rigid submerged tank that may contain the second reservoir. "S" may represent a separator or barrier that may be located between the low-density liquid and the water, or that may physically separate or prevent or minimize direct contact between the low-density liquid and the water. The separator or barrier may prevent direct contact between the low-density liquid and water and / or may provide physical separation between the low-density liquid and water. The separator or barrier may, for example, allow the low-density liquid to displace water while preventing or minimizing direct contact between the water and the low-density liquid. "8" may represent an external water reservoir or a third reservoir. In this diagram, the external reservoir may be located underwater. In this diagram, the external reservoir may be underwater at a depth similar to that of the second reservoir. "9" may represent a water pipe interconnecting the external reservoir to the second reservoir. In this diagram, the external water reservoir, or the pipe interconnecting the external water reservoir to the second reservoir, or a combination thereof, may have an internal pressure approximating the hydrostatic pressure of seawater at or near the depth of the second reservoir. The pressure within the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0116] Figure 52: An energy storage system that stores electricity by pumping a low-density liquid into a submersible tank (second reservoir) to displace water inside the second reservoir, which is then transferred to an external submersible water reservoir (third reservoir). This figure shows the embodiment in a fully charged steady state. "2" may represent a rigid submersible tank that may include the second reservoir. "S" may represent a separator or barrier that may be located between the low-density liquid and the water, or that may physically separate, prevent, or minimize direct contact between the low-density liquid and the water. The separator or barrier may prevent direct contact between the low-density liquid and the water and / or provide physical separation between the low-density liquid and the water. The separator or barrier may, for example, allow the low-density liquid to displace the water while preventing or minimizing direct contact between the water and the low-density liquid. "8" may represent an external water reservoir or a third reservoir. The physical separation or barrier may include a membrane. In this illustration, the external reservoir may be located underwater. In this illustration, the external reservoir may be underwater at a similar depth as the second reservoir. "9" may represent a water pipe interconnecting the external reservoir to the second reservoir. In this illustration, the external water reservoir, or the pipe interconnecting the external water reservoir to the second reservoir, or a combination thereof, may have an internal pressure that is close to the hydrostatic pressure of seawater at or near the depth of the second reservoir. The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0117] Figure 53: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank (second reservoir) to displace water inside the second reservoir, which is then transferred to an external submerged water reservoir (third reservoir). This figure shows this embodiment in a power generation or discharge state. For example, a valve ("5") may be opened to allow water inside the submerged reservoir ("2") to displace the low-density liquid from the submerged reservoir through a pipe ("3") to generate electricity through a generator ("4") or discharge stored electricity into a reservoir near the surface ("1"). "2" may represent a rigid submerged tank that may contain the second reservoir. "S" may represent a separator or barrier that may be located between the low-density liquid and the water or that may physically separate, prevent, or minimize direct contact between the low-density liquid and the water. The separator or barrier may prevent direct contact between the low-density liquid and water and / or may provide physical separation between the low-density liquid and water. The separator or barrier may, for example, allow the low-density liquid to displace water while preventing or minimizing direct contact between the water and the low-density liquid. "8" may represent an external water reservoir or a third reservoir. In this diagram, the external reservoir may be located underwater. In this diagram, the external reservoir may be underwater at a depth similar to that of the second reservoir. "9" may represent a water pipe interconnecting the external reservoir to the second reservoir. In this diagram, the external water reservoir, or the pipe interconnecting the external water reservoir to the second reservoir, or a combination thereof, may have an internal pressure approximating the hydrostatic pressure of seawater at or near the depth of the second reservoir. The pressure within the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0118] Figure 54: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank (second reservoir) and displacing the water within the second reservoir into a separate water reservoir. The third reservoir may include a tank at a higher elevation than the second reservoir, and / or a tank at a lower elevation than the second reservoir, and / or a rigid tank mechanically isolated from the water submerging the tank, and / or a tank on or above the surface of a body of water, and / or a tank located on land. This figure shows the embodiment at or near a fully discharged steady state. "2" may include a submerged second reservoir that may contain a low-density liquid and water within the submerged tank. Within the second reservoir, the low-density liquid may be physically separated from the water by a physical barrier or separator ("S"). The physical barrier or separator may allow the low-density liquid to exchange pressure with the water while ensuring that the water and the low-density liquid are physically separated or do not come into direct contact. The physical barrier or separator may be rigid, flexible, or a combination thereof. The physical separation or barrier may include a membrane. The physical barrier or separator may be removable, replaceable, adjustable, or a combination thereof, which may facilitate operation, maintenance, efficiency, system life, cost, or a combination thereof. The separator or barrier may prevent direct contact between the low-density liquid and the water and / or provide physical separation between the low-density liquid and the water. The separator or barrier may, for example, allow the low-density liquid to displace the water while preventing or minimizing direct contact between the water and the low-density liquid. "6" may include a third reservoir, which in this illustration includes a reservoir for displaced water and may be located on land. "1" may include a first reservoir, which may contain a store of low density liquid and may be located at an elevation above the second reservoir. Electricity may be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to a second reservoir ("2") and by transferring water from the second reservoir through a pipe ("7") to a third reservoir ("6").Electricity may be generated or discharged by allowing the lower density liquid in the second reservoir to be replaced by water from a third reservoir, which passes the lower density liquid from the second reservoir through a pipe ("3") to a generator ("4"), generating electricity and transferring it back into the first reservoir. The pump and generator may include the same unit(s) that may reversibly function as a pump and generator, which may include a hydraulic power recovery turbine (HPRT). The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0119] Figure 55: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank (second reservoir) and displacing the water therein into a separate water reservoir. The third reservoir may include a tank at a higher elevation than the second reservoir, and / or a tank at a lower elevation than the second reservoir, and / or a rigid tank mechanically isolated from the water submerging the tank, and / or a tank on or above the surface of a body of water, and / or a tank located on land. This figure shows the embodiment in a storage or charging state, where electricity may be stored by powering a pump to transfer the low-density liquid from the first reservoir to the second reservoir and displacing the water in the second reservoir. "2" may include a submerged second reservoir that may contain a low-density liquid and water within the submerged tank. Within the second reservoir, the low-density liquid may be physically separated from the water by a physical barrier or separator (“S”). The physical barrier or separator may allow the low-density liquid to exchange pressure with the water while ensuring that the water and the low-density liquid are physically separated or do not come into direct contact. The physical barrier or separator may be rigid, flexible, or a combination thereof. The physical barrier or separator may be removable, replaceable, adjustable, or a combination thereof, which may facilitate operation, maintenance, efficiency, system life, cost, or a combination thereof. The separator or barrier may prevent direct contact between the low-density liquid and the water and / or may provide physical separation between the low-density liquid and the water. The separator or barrier may, for example, allow the low-density liquid to displace the water while preventing or minimizing direct contact between the water and the low-density liquid. "6" may include a third reservoir, which in this illustration includes a reservoir for displaced water and may be located on land. "1" may include a first reservoir, which may include a reservoir of low density liquid and may be located at an elevation above the second reservoir.Electricity may be stored by powering a pump ("4") to pump low density liquid from a first reservoir through a pipe ("3") to a second reservoir ("2") and transferring water from the second reservoir through a pipe ("7") to a third reservoir ("6"). Electricity may be generated or discharged by allowing the low density liquid in the second reservoir to be replaced by water from a third reservoir, which passes the low density liquid from the second reservoir through a pipe ("3") to a generator ("4"), generating electricity and transferring it into the first reservoir. The pump and generator may comprise the same unit(s) that may function reversibly as a pump and generator, which may include a hydropower recovery turbine (HPRT). The pressure within the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0120] Figure 56: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank (second reservoir) and displacing the water within the second reservoir into a separate water reservoir. The third reservoir may include a tank at a higher elevation than the second reservoir, and / or a tank at a lower elevation than the second reservoir, and / or a rigid tank mechanically isolated from the water submerging the tank, and / or a tank on or above the surface of a body of water, and / or a tank located on land. This figure shows the embodiment at or near a fully charged steady state. "2" may include a submerged second reservoir that may contain a low-density liquid and water within the submerged tank. Within the second reservoir, the low-density liquid may be physically separated from the water by a physical barrier or separator ("S"). The physical barrier or separator may allow the low-density liquid to exchange pressure with the water while ensuring that the water and the low-density liquid are physically separated or do not come into direct contact. The physical barrier or separator may be rigid, flexible, or a combination thereof. The physical barrier or separator may be removable, replaceable, adjustable, or a combination thereof, which may facilitate operation, maintenance, efficiency, system life, cost, or a combination thereof. The separator or barrier may prevent direct contact between the low-density liquid and the water and / or provide physical separation between the low-density liquid and the water. The separator or barrier may, for example, allow the low-density liquid to displace the water while preventing or minimizing direct contact between the water and the low-density liquid. "6" may include a third reservoir, which in this illustration includes a reservoir for displaced water and may be located on land. "1" may include a first reservoir, which may contain a store of low density liquid and may be located at an elevation above the second reservoir. Electricity may be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to a second reservoir ("2") and by transferring water from the second reservoir through a pipe ("7") to a third reservoir ("6").Electricity may be generated or discharged by allowing the lower density liquid in the second reservoir to be replaced by water from a third reservoir, which passes the lower density liquid from the second reservoir through a pipe ("3") to a generator ("4"), generating electricity and transferring it back into the first reservoir. The pump and generator may include the same unit(s) that may reversibly function as a pump and generator, which may include a hydraulic power recovery turbine (HPRT). The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0121] Figure 57: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank (second reservoir) and displacing the water therein into a separate water reservoir. The third reservoir may include a tank at a higher elevation than the second reservoir, and / or a tank at a lower elevation than the second reservoir, and / or a rigid tank mechanically isolated from the submerged water, and / or a tank on or above the surface of a body of water, and / or a tank located on land. This figure shows the embodiment in a generating or discharging state. Electricity may be generated by allowing the low-density liquid to be transferred from the second reservoir through a pipe into a generating generator and into the first reservoir. The low-density liquid in the second reservoir may be allowed to be replaced by water. This allowing may include opening a valve ("5") on the low-density liquid pipe. "2" may include a submerged second reservoir that may contain a low-density liquid and water within the submerged tank. Within the second reservoir, the low-density liquid may be physically separated from the water by a physical barrier or separator ("S"). The physical barrier or separator may allow the low-density liquid to exchange pressure with the water while ensuring that the water and the low-density liquid are physically separated or do not come into direct contact. The physical barrier or separator may be rigid, flexible, or a combination thereof. The physical barrier or separator may be removable, replaceable, adjustable, or a combination thereof, which may facilitate operation, maintenance, efficiency, system life, cost, or a combination thereof. The separator or barrier may prevent direct contact between the low-density liquid and the water and / or provide physical separation between the low-density liquid and the water. The separator or barrier may, for example, allow the lower density liquid to displace the water while preventing or minimizing direct contact between the water and the lower density liquid. "6" may include a third reservoir, which in this illustration includes a reservoir for the displaced water and may be located on land."1" may include a first reservoir, which may contain a store of low-density liquid and may be located at an elevation above the second reservoir. Electricity may be stored by powering a pump ("4") to pump the low-density liquid from the first reservoir through a pipe ("3") to a second reservoir ("2") and transferring water from the second reservoir through a pipe ("7") to a third reservoir ("6"). Electricity may be generated or discharged by allowing the low-density liquid in the second reservoir to be replaced by water from a third reservoir, which passes the low-density liquid from the second reservoir through a pipe ("3") to a generator ("4"), generating electricity and transferring it into the first reservoir. The pump and generator may include the same unit(s) that may reversibly function as a pump and generator, which may include a hydraulic power recovery turbine (HPRT). The pressure within the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0122] Figure 58: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank ("2") (second reservoir) and displacing the water within the second reservoir into a separate water reservoir. The second reservoir may include a submerged rigid tank that can contain both the low-density liquid and water. Within the second reservoir, the low-density liquid may be stored in a sub-reservoir or sub-tank ("10") that may include an inflatable or collapsible structure such as a bladder tank or a piston or combination thereof. The sub-tank may be employed to prevent direct contact between the low-density liquid and the water in the second reservoir. In the event of a breach or leak of the internal sub-tank, the leaked low-density liquid may remain within this rigid tank or rigid containment structure, preventing exposure of the low-density liquid to the surrounding environment. The sub-tank may be considered a physical barrier or separator and may be removable, replaceable, adjustable, or a combination thereof, which may facilitate operation, maintenance, efficiency, system life, cost, or a combination thereof. This figure shows this embodiment in a nearly fully discharged state. A third reservoir, which may be connected to the second reservoir using a pipe, may include nearby seawater, a water tank in pressure equilibrium with the ocean, a rigid water tank mechanically isolated from the nearby ocean and at a pressure similar to the hydrostatic pressure of the nearby ocean, a water tank on or near the ocean surface, or a land-based water tank. The third reservoir may be located at any elevation relative to the second reservoir, provided that it is in pressure equilibrium with the surrounding ocean and / or the density of the liquid within the third reservoir is close to that of seawater. For example, the third reservoir may be located at the same or a similar elevation as the second reservoir, as shown in this figure. For example, the third reservoir may be located at a greater depth or at a lower elevation than the second reservoir. For example, the third reservoir may be located at a shallower depth or at a higher elevation than the second reservoir. For example, the third reservoir may be located on land.Electricity can be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to the second reservoir ("2") and to transfer water from the second reservoir through a pipe ("7") to the third reservoir ("6"). Electricity can be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to the second reservoir ("2"), specifically to the low density liquid second reservoir sub-tank ("10"), and to transfer water from the second reservoir through a pipe ("9") to the third reservoir ("8"). Electricity may be generated or discharged by allowing the low density liquid in the second reservoir, specifically in the low density liquid second reservoir sub-tank ("10"), to be replaced by water from the third reservoir, which passes the low density liquid from the second reservoir through a pipe ("3") to a generator ("4"), generating electricity and transferring it into the first reservoir ("1"). The pump and generator may include the same unit(s) that may reversibly function as a pump and generator, which may include a hydraulic power recovery turbine (HPRT). The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0123] An energy storage system having a surface tank ("1"), a submerged rigid tank ("2"), a float bladder sub-tank ("10") configured to store a low density liquid, and an interconnected external float bladder tank ("8") configured to store water.

[0124] This embodiment is in a nearly fully discharged state.

[0125] Figure 59: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank ("2") (second reservoir) and displacing the water within the second reservoir into a separate water reservoir. The second reservoir may include a submerged rigid tank that can contain both the low-density liquid and water. Within the second reservoir, the low-density liquid may be stored in a sub-reservoir or sub-tank ("10") that may include an inflatable or collapsible structure such as a bladder tank or a piston or combination thereof. The sub-tank may be employed to prevent direct contact between the low-density liquid and the water in the second reservoir. In the event of a breach or leak of the internal sub-tank, the leaked low-density liquid may remain within this rigid tank or rigid containment structure, preventing exposure of the low-density liquid to the surrounding environment. The sub-tank may be considered a physical barrier or separator and may be removable, replaceable, adjustable, or a combination thereof, which may facilitate operation, maintenance, efficiency, system life, cost, or a combination thereof. This diagram shows this embodiment storing or "charging" electricity, where a low-density liquid is pumped from a first reservoir to a second reservoir, displacing water from the second reservoir to a third reservoir. The third reservoir, which may be connected to the second reservoir using a pipe, may include nearby seawater, or a water tank in pressure equilibrium with the ocean, or a rigid water tank mechanically isolated from the nearby ocean and at a pressure similar to the hydrostatic pressure of the nearby ocean, or a water tank on or near the ocean surface, or a water tank on land. The third reservoir may be located at any elevation relative to the second reservoir, provided that the third reservoir is in pressure equilibrium with the surrounding ocean and / or the density of the liquid within the third reservoir is close to that of seawater. For example, the third reservoir may be located at the same elevation or a similar elevation as the second reservoir, as shown in this figure. For example, the third reservoir may be located at a greater depth or at a lower elevation than the second reservoir. For example, the third reservoir may be located at a shallower depth or at a higher elevation than the second reservoir. For example, the third reservoir may be located on land.Electricity can be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to the second reservoir ("2") and to transfer water from the second reservoir through a pipe ("7") to the third reservoir ("6"). Electricity can be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to the second reservoir ("2"), specifically to the low density liquid second reservoir sub-tank ("10"), and to transfer water from the second reservoir through a pipe ("9") to the third reservoir ("8"). Electricity may be generated or discharged by allowing the low density liquid in the second reservoir, specifically in the low density liquid second reservoir sub-tank ("10"), to be replaced by water from the third reservoir, which passes the low density liquid from the second reservoir through a pipe ("3") to a generator ("4"), generating electricity and transferring it into the first reservoir ("1"). The pump and generator may include the same unit(s) that may reversibly function as a pump and generator, which may include a hydraulic power recovery turbine (HPRT). The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0126] Electricity storage ("charging") in this embodiment: Low density liquid is pumped ("4") from the surface tank ("1") through a pipe ("3") into the submerged rigid tank ("2"), displacing the water in the submerged rigid tank ("2"). The displaced water travels through a pipe ("9") into the external swim bladder tank ("8").

[0127] Figure 60: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank ("2") (second reservoir) and displacing the water within the second reservoir into a separate water reservoir. The second reservoir may include a submerged rigid tank that can contain both the low-density liquid and water. Within the second reservoir, the low-density liquid may be stored in a sub-reservoir or sub-tank ("10") that may include an inflatable or collapsible structure such as a bladder tank or a piston or combination thereof. The sub-tank may be employed to prevent direct contact between the low-density liquid and the water in the second reservoir. In the event of a breach or leak of the internal sub-tank, the leaked low-density liquid may remain within this rigid tank or rigid containment structure, preventing exposure of the low-density liquid to the surrounding environment. The sub-tank may be considered a physical barrier or separator and may be removable, replaceable, adjustable, or a combination thereof, which may facilitate operation, maintenance, efficiency, system life, cost, or a combination thereof. This figure shows this embodiment in a nearly fully charged state. A third reservoir, which may be connected to the second reservoir using a pipe, may include nearby seawater, a water tank in pressure equilibrium with the ocean, a rigid water tank mechanically isolated from the nearby ocean and at a pressure similar to the hydrostatic pressure of the nearby ocean, a water tank on or near the ocean surface, or a land-based water tank. The third reservoir may be located at any elevation relative to the second reservoir, provided that it is in pressure equilibrium with the surrounding ocean and / or the density of the liquid within the third reservoir is close to that of seawater. For example, the third reservoir may be located at the same or a similar elevation as the second reservoir, as shown in this figure. For example, the third reservoir may be located at a greater depth or at a lower elevation than the second reservoir. For example, the third reservoir may be located at a shallower depth or at a higher elevation than the second reservoir. For example, the third reservoir may be located on land.Electricity can be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to the second reservoir ("2") and to transfer water from the second reservoir through a pipe ("7") to the third reservoir ("6"). Electricity can be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to the second reservoir ("2"), specifically to the low density liquid second reservoir sub-tank ("10"), and to transfer water from the second reservoir through a pipe ("9") to the third reservoir ("8"). Electricity may be generated or discharged by allowing the low density liquid in the second reservoir, specifically in the low density liquid second reservoir sub-tank ("10"), to be replaced by water from the third reservoir, which passes the low density liquid from the second reservoir through a pipe ("3") to a generator ("4"), generating electricity and transferring it into the first reservoir ("1"). The pump and generator may include the same unit(s) that may reversibly function as a pump and generator, which may include a hydraulic power recovery turbine (HPRT). The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0128] This embodiment is in a nearly fully charged state.

[0129] Figure 61: An energy storage system that stores electricity by pumping a low-density liquid into a submerged tank ("2") (second reservoir) and displacing the water within the second reservoir into a separate water reservoir. The second reservoir may include a submerged rigid tank that can contain both the low-density liquid and water. Within the second reservoir, the low-density liquid may be stored in a sub-reservoir or sub-tank ("10") that may include an inflatable or collapsible structure such as a bladder tank or a piston or combination thereof. The sub-tank may be employed to prevent direct contact between the low-density liquid and the water in the second reservoir. In the event of a breach or leak of the internal sub-tank, the leaked low-density liquid may remain within this rigid tank or rigid containment structure, preventing exposure of the low-density liquid to the surrounding environment. The sub-tank may be considered a physical barrier or separator and may be removable, replaceable, adjustable, or a combination thereof, which may facilitate operation, maintenance, efficiency, system life, cost, or a combination thereof. This figure illustrates this embodiment generating or "discharging" power. For example, discharging may include allowing a low-density liquid in the second reservoir to be replaced by water in a third reservoir, which enters a pipe, enters a generator, generates power, and is transferred back into the first reservoir. The third reservoir, which may be connected to the second reservoir using a pipe, may include nearby seawater, or a water tank in pressure equilibrium with the ocean, or a rigid water tank mechanically isolated from the nearby ocean and at a pressure similar to the hydrostatic pressure of the nearby ocean, or a water tank on or near the ocean surface, or a water tank on land. The third reservoir may be located at any elevation relative to the second reservoir, provided that the third reservoir is in pressure equilibrium with the surrounding ocean and / or the density of the liquid within the third reservoir is close to that of seawater. For example, the third reservoir may be located at the same elevation or a similar elevation as the second reservoir, as shown in this figure. For example, the third reservoir may be located at a greater depth or at a lower elevation than the second reservoir. For example, the third reservoir may be located at a shallower depth or at a higher elevation than the second reservoir. For example, the third reservoir may be located on land.Electricity can be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to the second reservoir ("2") and to transfer water from the second reservoir through a pipe ("7") to the third reservoir ("6"). Electricity can be stored by powering a pump ("4") to pump low density liquid from the first reservoir through a pipe ("3") to the second reservoir ("2"), specifically to the low density liquid second reservoir sub-tank ("10"), and to transfer water from the second reservoir through a pipe ("9") to the third reservoir ("8"). Electricity may be generated or discharged by allowing the low density liquid in the second reservoir, specifically in the low density liquid second reservoir sub-tank ("10"), to be replaced by water from the third reservoir, which passes the low density liquid from the second reservoir through a pipe ("3") to a generator ("4"), generating electricity and transferring it into the first reservoir ("1"). The pump and generator may include the same unit(s) that may reversibly function as a pump and generator, which may include a hydraulic power recovery turbine (HPRT). The pressure inside the second reservoir may be close to or approximately equal to the hydrostatic pressure of the ocean at the underwater depth of the second reservoir.

[0130] Power generation ("discharge") in this embodiment: Water in the external swim bladder tank ("8") is allowed to displace the low density liquid in the submerged rigid tank ("2"). The displaced low density liquid travels through a pipe ("3"), through a generator ("4"), and to the surface tank ("1").

[0131] Figure 62: This figure may include an embodiment similar to Figures 58-61. This figure may show this embodiment in a nearly fully discharged state. This figure may employ a third reservoir containing nearby seawater or open ocean water. The sub-tank within the second reservoir ("10"), the second reservoir, and an external water pipe ("11") connected to the second reservoir may be configured so that when a low-density liquid is pumped into "10," displaced water from the second reservoir exits the second reservoir in a manner that prevents the low-density liquid from exiting the second reservoir in the event of a release or leak of the low-density liquid. For example, this configuration may include configuring the pipes and / or tank such that the liquid or material exiting the tank must have a density equal to or greater than that of water, or close to that of water. For example, the configuration may include the external water pipes "11" having an outlet or external outlet facing towards the seabed or a downward bend. For example, the configuration may include the external water pipes "11" having an upward bend and / or a pipe facing upward and / or towards the sea surface and / or away from the seabed and / or with an upward opening inside the submersible tank. For example, the configuration may include the external water pipe containing a chemical or reagent or material that, when present with or in contact with the low-density liquid, will swell, absorb, or react with the low-density liquid, which may occur, for example, in the event of a leak or release of the low-density liquid from the sub-tank, which may cause a valve inside the pipe to close, or the pipe to be passively blocked or closed, or a combination thereof, in the event of a leak or release of the low-density liquid from the sub-tank. "11" may be removable or replaceable. The sub-tank inside the second reservoir, or the external water pipe, or the third reservoir (if including a tank), or a combination thereof, may be removable or replicable.For example, while the second storage reservoir continues to operate, a sub-tank within the second reservoir, or an external water pipe, or a third reservoir (if it includes a tank), or a combination thereof, can be removed or replaced. For example, a sub-tank within the second reservoir, or an external water pipe, or a third reservoir (if it includes a tank), or a combination thereof can be removed or replaced while the second storage reservoir continues to be installed. For example, a sub-tank within the second reservoir, or an external water pipe, or a third reservoir (if it includes a tank), or a combination thereof can be removed, replaced, or maintained while one or more components continue to be installed and / or operating, which may include one or more of the components described herein or other parts of the invention.

[0132] An electrical energy storage system having a surface tank ("1"), a submerged rigid tank ("2"), and a float bladder sub-tank configured to store a low density liquid ("10"), the submerged rigid tank ("2") being in direct fluid communication with adjacent deep seawater by a pipe ("11").

[0133] This embodiment is in a nearly fully discharged state.

[0134] Figure 63: This diagram may include the embodiment described in the legend to Figure 62. This diagram shows the embodiment in a "charging" or energy storage or charge accumulation state. Charging may involve pumping a low-density liquid from a first reservoir to a second reservoir to replace water in the second reservoir. Water may exit the second reservoir during the replacement such that the low-density liquid may remain in the second reservoir even if the low-density liquid leaks from an internal sub-tank within the second reservoir.

[0135] Electricity storage ("charging") in this embodiment: A low density liquid is pumped ("4") from the surface tank ("1") through a pipe ("3") into the submerged rigid tank ("2"), displacing seawater from the submerged rigid tank ("2"). The displaced seawater travels through a pipe ("11") into the ocean adjacent to the submerged rigid tank ("2").

[0136] Figure 64: This figure may include the embodiment described in the legend to Figure 62. This figure shows this embodiment in a nearly fully charged state.

[0137] Figure 65: This diagram may include the embodiment described in the legend to Figure 62. This diagram shows the embodiment in a "discharging" or energy or power generation state. Discharging may involve allowing a lower density liquid to be transferred from a second reservoir into a pipe, through a generator generating electricity, and into the first reservoir. The displacement may involve seawater passing through a pipe ("11") into the second reservoir. Water may exit the second reservoir during the displacement such that the lower density liquid may remain in the second reservoir even if the lower density liquid leaks from an internal sub-tank within the second reservoir.

[0138] Power generation ("discharge") in this embodiment. Seawater adjacent to the submerged rigid tank ("2"), which is in direct fluid communication with the submerged rigid tank ("2") through pipe ("11"), allows the displaced low-density liquid in the submerged rigid tank ("2"). The displaced low-density liquid travels through pipe ("3"), through the generator ("4"), and to the surface tank ("1").

[0139] Figure 66: Energy storage embodiments having a second and / or third reservoir with a containment cover or containment barrier ("CB" or "CCB"). The CB may include a cover positioned over or above one or more components of the system. The CB may include a cover positioned over or above a component of the system that may hold or contain a low density liquid. If the low density liquid flows out of the second reservoir, the low density liquid may float and be captured by the CB, for example, due to the low density liquid being less dense than water.

[0140] Figure 67: Energy storage embodiments having a second and / or third reservoir with a containment cover or barrier ("CB" or "CCB"). The CB may include a cover positioned over or above one or more components of the system. The CB may include a cover positioned over or above a component of the system that may hold or contain a low density liquid. If the low density liquid flows out of the second reservoir, the low density liquid may float and be captured by the CB, for example, due to the low density liquid being less dense than water.

[0141] Figure 68: Energy storage embodiments having a second and / or third reservoir with a containment cover or containment barrier ("CB" or "CCB"). The CB may include a cover positioned over or above one or more components of the system. The CB may include a cover positioned over or above a component of the system that may hold or contain a low density liquid. If the low density liquid flows out of the second reservoir, the low density liquid may float and be captured by the CB, for example, due to the low density liquid being less dense than water.

[0142] Figure 69: Energy storage embodiment having a second and / or third reservoir with a containment cover or containment barrier ("CB" or "CCB"). The CB may include a cover positioned over or above one or more components of the system. The CB may include a cover positioned over or above a component of the system that may hold or contain a low density liquid. If the low density liquid flows out of the second reservoir, the low density liquid may float and be captured by the CB, for example, due to the low density liquid being less dense than water. In this figure, the "S" may include a separator or barrier that may prevent or minimize physical or direct contact between the low density liquid and the water in the second reservoir.

[0143] Figure 70: An energy storage system that stores electricity by pumping a low-density liquid into a sub-tank ("5") in a second reservoir ("2") to displace water therein. The second reservoir may comprise a rigid tank or rigid containment structure that may surround or house a sub-tank ("5") configured to store the low-density liquid. The sub-tank may include an expandable or collapsible tank. The sub-tank may be located over a water port or hole or water pipe or outlet or combination thereof to ensure that the low-density liquid remains within the second reservoir in the event of, for example, a leak or accidental release of the low-density liquid. The water port or hole or water pipe or outlet or combination thereof may be employed to allow displaced water to exit the second reservoir during "storage" of electricity and / or to allow water to enter the second reservoir to displace the low-density liquid during discharge or generation. The subtank may include a membrane or membrane-like structure. A rigid tank or rigid containment structure may surround the subtank and / or cover an upper portion of the subtank. Exemplary characteristics of the rigid tank or rigid containment structure may include the ability to control the ingress or egress of water or other liquids or substances to or from the second reservoir, including, but not limited to, the ability to open or close valves or ports that may enable or disable, or both, the inflow or egress of water or other liquids or other substances to or from the second reservoir. This figure illustrates the "charging" of this embodiment. The charging may involve pumping a lower density liquid from the first reservoir to the second reservoir to replace water from the second reservoir with the lower density liquid.

[0144] Figure 71: An energy storage system that stores electricity by pumping a low-density liquid into a sub-tank ("5") in a second reservoir ("2") to displace water therein. The second reservoir may comprise a rigid tank or rigid containment structure that may surround or house a sub-tank ("5") configured to store the low-density liquid. The sub-tank may include an expandable or collapsible tank. The sub-tank may be located over a water port or hole or water pipe or outlet or combination thereof to ensure that the low-density liquid remains within the second reservoir, for example, in the event of a leak or accidental release of the low-density liquid. The water port or hole or water pipe or outlet or combination thereof may be employed to allow displaced water to exit the second reservoir during "storage" of electricity and / or to allow water to enter the second reservoir to displace the low-density liquid during discharge or generation. A rigid tank or rigid containment structure may surround the sub-tank and / or cover an upper portion of the sub-tank. Exemplary characteristics of the rigid tank or rigid containment structure may include the ability to control the ingress or egress of water or other liquids or substances to or from the second reservoir, including, but not limited to, the ability to open or close valves or ports that may enable or disable, or both, the inflow or egress of water or other liquids or other substances to or from the second reservoir. This figure shows this embodiment in a nearly fully charged state.

[0145] Figure 72: An energy storage system that stores electricity by pumping a low-density liquid into a sub-tank ("5") in a second reservoir ("2") to displace water therein. The second reservoir may comprise a rigid tank or rigid containment structure that may surround or house a sub-tank ("5") configured to store the low-density liquid. The sub-tank may include an expandable or collapsible tank. The sub-tank may be located over a water port or hole or water pipe or outlet or combination thereof to ensure that the low-density liquid remains within the second reservoir, for example, in the event of a leak or accidental release of the low-density liquid. The water port or hole or water pipe or outlet or combination thereof may be employed to allow displaced water to exit the second reservoir during "storage" of electricity and / or to allow water to enter the second reservoir to displace the low-density liquid during discharge or generation. The rigid tank or rigid containment structure may surround the sub-tank and / or cover an upper portion of the sub-tank. Exemplary characteristics of the rigid tank or rigid containment structure may include the ability to control the ingress or egress of water or other liquids or substances to or from the second reservoir, including, but not limited to, the ability to open or close valves or ports that may enable or disable, or both, the inflow or egress of water or other liquids or other substances to or from the second reservoir. This figure illustrates discharge or power generation in this embodiment. Discharge or power generation may involve transferring a low-density liquid from the second reservoir into the first reservoir by piping it through a generator to generate electricity. Transfer of the low-density liquid from the second reservoir may be enabled by opening a valve near or within the pump or generator, or a valve near or within the second reservoir tank, or a combination thereof. Displacing the less dense liquid in the second reservoir may include water entering the second reservoir and displacing the less dense liquid in the second reservoir.

[0146] Figure 73: An energy storage system that stores electricity by pumping a low-density liquid into a sub-tank ("5") in a second reservoir ("2") to displace water therein. The second reservoir may comprise a rigid tank or rigid containment structure that may surround or house a sub-tank ("5") configured to store the low-density liquid. The sub-tank may include an expandable or collapsible tank. The sub-tank may be located over a water port or hole or water pipe or outlet or combination thereof to ensure that the low-density liquid remains within the second reservoir in the event of, for example, a leak or accidental release of the low-density liquid. The water port or hole or water pipe or outlet or combination thereof may be employed to allow displaced water to exit the second reservoir during "storage" of electricity and / or to allow water to enter the second reservoir to displace the low-density liquid during discharge or generation. A rigid tank or rigid containment structure may surround the sub-tank and / or cover an upper portion of the sub-tank. Exemplary characteristics of the rigid tank or rigid containment structure may include the ability to control the ingress or egress of water or other liquids or substances to or from the second reservoir, including, but not limited to, the ability to open or close valves or ports that may enable or disable, or both, the inflow or egress of water or other liquids or other substances to or from the second reservoir. This figure shows this embodiment in a nearly fully discharged state.

[0147] Figure 74: This diagram illustrates charging or storing power in this embodiment. This diagram illustrates an embodiment in which a first reservoir ("1") and / or pump ("4") and / or generator ("4") are located underwater at a higher elevation or less depth than the second reservoir. The first reservoir may include a rigid tank or a swim bladder tank. In this diagram, the first reservoir is shown as a rigid tank. In this embodiment shown in this diagram, a subsea power cable ("15") connects the pump and / or generator ("4") to a power source and / or power demand source and / or power grid. The power source and / or power demand source and / or power grid, which may include transmission infrastructure, may be represented in this diagram by "13" and "14" and may be located on land or underwater. The subsea power cable may interconnect the energy storage system with offshore power sources, including, but not limited to, offshore wind, offshore solar, and offshore rigs, offshore power plants, or other power sources. The subsea power cable may interconnect the energy storage system with offshore demand sources, including, but not limited to, offshore pipelines, offshore power transmission stations, offshore compression stations, offshore drilling, heated flowlines, offshore oil rigs, offshore production systems, hydrogen production, ammonia production, CO2 conversion, gas processing facilities, and / or other energy consumption sources. Subsea power cables may interconnect the energy storage system with onshore energy demands and onshore power sources, including industrial electricity demands, commercial electricity demands, residential electricity demands, transportation electricity demands, renewable power sources, residential power sources, power grid load balancing, power grid services, onshore solar power plants, onshore wind power, onshore hydroelectric power, onshore combustion power generation, hydrogen production, storage of excess renewable power, and discharge during peak demand or when intermittent renewable energy is short of power production. The diagram may show an energy storage system that stores electricity by pumping a low-density liquid into a sub-tank ("5") in a second reservoir ("2") to replace the water inside the second reservoir.

[0148] The present embodiment takes advantage of several aspects of the technical limitations of offshore technology and the geography of many offshore regions. • The offshore seafloor in most of the world is relatively shallow within 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 miles of the coast, or any combination thereof. Relatively shallow depths can include water depths of less than 1,000 meters, less than 900 meters, less than 800 meters, less than 700 meters, less than 600 meters, less than 500 meters, less than 400 meters, less than 300 meters, less than 200 meters, or less than 100 meters, or any combination thereof. Furthermore, in most terrains, the relatively shallow waters ultimately meet on a steep rocky or continental shelf that descends to depths of 1,500 meters, 2,000 meters, 2,500 meters, or 3,000 meters, or even greater. This embodiment places the first reservoir and / or the pump and generator near the rock or continental shelf, which may minimize the length of the pipeline from the first reservoir to the second reservoir. Minimizing the pipeline length improves round trip energy efficiency and reduces capital costs. In this embodiment, the pump and / or generator may be interconnected to a power source, a power demand, a power grid, or a combination thereof, by a subsea power cable. Subsea power cables are cheapest and / or easiest to install in relatively shallow and / or relatively flat terrain. The subsea cable herein may be installed in relatively shallow and / or relatively flat undersea terrain. Modern offshore wind farms require relatively shallow water depths, typically less than 1,000 meters, to be economically viable. This embodiment allows the present invention to be integrated with current offshore wind farms by being located relatively close to shallow waters ideal for offshore wind farms. Also, by being able to coexist with offshore wind, offshore solar, offshore rigs, or a combination thereof, the present invention may be integrated with existing or pre-planned subsea power cables or transmission infrastructure. Alternatively or additionally, by being able to coexist with offshore wind, offshore solar, offshore rigs, or other offshore technologies, the present invention may improve the economics of those and other technologies, facilitating the construction of subsea power infrastructure and / or the present invention. For example, Virginia, North Carolina, Delaware, and Maryland (all locations where offshore wind farms are proposed) have shallow water and nearby steep rock shelves and / or continental shelves. ● Due to the first reservoir and / or generation being located "offshore," the only "cross-shore infrastructure" in this embodiment may be subsea power cables and associated transmission interconnections and infrastructure. The minimal "cross-shore" and "onshore" infrastructure of this embodiment may reduce required permits and / or approvals and / or timelines and / or regulatory agencies. Additionally, the lack of tanks or generators onshore may allow this embodiment to occupy less land area onshore and / or allow this embodiment to be less visually obtrusive and / or may make this embodiment more visually appealing. In this embodiment, the first reservoir and / or pump and / or generator may be located at a depth deep enough to minimize exposure to ocean waves and / or marine weather. In this embodiment, the first reservoir and / or pump and / or generator may be located at a depth shallow enough to allow a significant elevation difference between the first and second reservoirs. For example, a significant elevation difference may include an elevation or depth difference of 500 meters or more, or 1,000 meters or more, or 1,500 meters or more, or 2,000 meters or more. In this embodiment, it may be advantageous for the first reservoir and / or pump and / or generator to be located at a depth shallow enough to allow access or convenient access for professional divers and / or professional diving vessels for monitoring and / or maintenance. This embodiment has a virtually unlimited land area and / or geographic region for energy storage. The amount of undersea seabed with suitable geographic conditions far exceeds the land area of ​​seabed required for multi-hour, multi-day, or even multi-month storage using this embodiment.

[0149] Figure 75: This figure includes the same embodiment as Figure 74. This figure shows this embodiment in a nearly fully charged state.

[0150] Figure 76: This figure includes the same embodiment as Figure 74. This figure shows the discharge or generation of electricity in this embodiment.

[0151] Figure 77: This figure includes the same embodiment as Figure 74. This figure shows this embodiment in an almost fully discharged state.

[0152] Figure 78: This diagram illustrates charging or storage of this embodiment. This diagram illustrates an embodiment in which the first reservoir ("1") and / or pump ("4") and / or generator ("4") are located within a floating vessel ("16"). The floating vessel may include a carrier, a carrier modified to allow for greater offloading or loading flow rates than conventional carriers, or a specially designed carrier, or a combination thereof. The carrier may include, for example, a ship such as an LPG carrier. The floating vessel may be interconnected to a subsea power cable and / or a subsea low-density liquid pipeline using, or facilitated by, one or more buoys. For example, this diagram may illustrate a low-density liquid pipeline interconnection buoy as an "L" and a subsea cable electrical interconnection buoy as an "X." One or more, or a combination of, a subsea pipeline, a floating vessel, a buoy, a subsea tank, or a subsea tank may be employed.

[0153] Floating vessels may be connectable or disconnectable, or both. Floating vessels may be connectable or disconnectable to each other. Floating vessels may be connectable to a floating buoy or disconnectable from a floating buoy. For example, floating vessels may be added or removed (connected or disconnected) if more or less energy storage or power capacity or both are needed. Floating vessels may be transferred between one or more facilities or businesses to, for example, optimize needed resources. For example, some areas may need more storage or power capacity during certain periods or seasons, and / or less storage or power capacity may be needed during certain other periods or seasons. Floating vessels may be transferred or added to some areas during periods of greater demand. Floating vessels may be disconnected and / or transferred during periods of less demand. Floating vessels may be transferred from areas of less demand to areas of greater demand as needed. For example, a futures market or a spot market, or both, may be created to lease the floating vessel. The floating vessel may be employed as an LPG carrier or other form of carrier when demand for energy storage is low. In some cases, it may be desirable for one or more of the floating vessel and / or the low density liquid and / or a portion of the low density liquid to be leased by the utility operator or owner, for example, instead of being owned outright.

[0154] Floating vessels may be disconnected to avoid severe weather such as hurricanes. Floating vessels may be disconnected for maintenance. Floating vessels may be updated or replaced over time. For example, new technological advances or application or performance needs may be integrated into the floating vessel as a retrofit, or a new floating vessel may be constructed, or both. Floating vessels may be disconnected or connected due to changes in demand.

[0155] A floating vessel may exist in multiple forms. For example, a floating vessel may include a storage unit for a low-density liquid. For example, a floating vessel may include both a storage unit for a low-density liquid and a pump and / or a generator. For example, a floating vessel may include a pump and / or a generator. Multiple forms of floating vessels may be combined or integrated as needed. A floating vessel may be variously modified, replaced, or integrated, or may have an updated configuration, or a combination thereof, which may be easy to implement, for example, in response to changing needs from one or more applications.

[0156] The floating vessel attachment buoy may include an anchor attachment or similar device to allow the floating vessel to remain in a general location without or with minimal need for a dynamic positioning system.

[0157] The use of floating vessels may allow for virtually unlimited energy storage capacity. For example, floating vessels may be interconnected to increase energy storage capacity or power capacity or both. This embodiment may benefit from the current global capability to construct and ship large floating carriers for LPG and other hydrocarbons and / or the availability of floating carriers currently used to transport hydrocarbons or offshore floating storage or both, for example.

[0158] The use of a floating vessel for the first reservoir and / or pump and / or generator may minimize permits and / or approvals required due to, for example, existing permits for the carrier vessel.

[0159] The floating vessel may be connected to the buoy by a turret and swivel stack that may be located on the floating vessel and may allow the vessel to rotate into the wind or otherwise move while interconnecting low density liquid pipelines and / or subsea electrical cables.

[0160] Figure 79: This figure includes the embodiment of Figure 78. This figure shows this embodiment in a nearly fully charged state.

[0161] Figure 80: This figure includes the embodiment of Figure 78. This figure shows the discharge or generation of electricity of this embodiment.

[0162] Figure 81: This figure includes the embodiment of Figure 78. This figure shows this embodiment in an almost fully discharged state.

[0163] Figure 82: This figure shows an embodiment in which the first reservoir ("1") and / or pump ("4") and / or generator ("4") are located within the floating vessel ("16"). This figure may show an embodiment in which the floating vessel can be connected to a subsea low density liquid pipeline ("3") and a subsea electrical cable ("15") by means of an associated buoy ("LX"). The associated buoy may be able to connect to and / or disconnect from the floating vessel. The associated buoy may simplify the connection and / or disconnection process between the floating vessel and the associated buoy. In this figure, the associated buoy may be shown disconnected from the floating carrier.

[0164] Figure 83: This figure may include the same embodiment as Figure 82. In this figure, the combined buoy may be shown connected to a floating carrier.

[0165] Figure 84: Energy storage system having a surface low density liquid tank ("1"), a submerged rigid tank ("2"), a float bladder sub-tank ("10") configured to store low density liquid, and a surface water tank ("6").

[0166] This embodiment is in a nearly fully discharged state.

[0167] FIG. 85: This embodiment includes the embodiment of FIG.

[0168] Electricity storage ("charging") in this embodiment: Low density liquid is pumped ("4") from the surface low density liquid tank ("1") through pipes ("3") to the submerged rigid tank ("2"), displacing water from the submerged rigid tank ("2"). The displaced water travels through pipes ("7") to the surface water tank ("6").

[0169] Figure 86: This embodiment includes the embodiment of Figure 84. This embodiment is in an almost fully discharged state.

[0170] FIG. 87: This embodiment includes the embodiment of FIG.

[0171] Electricity storage system power generation ("discharge"). Water in the surface water tank ("6") is transferred through a pipe ("7") to the submerged rigid tank ("2"), where it is allowed to displace the low-density liquid in the submerged rigid tank ("2"). The displaced low-density liquid travels through a pipe ("3"), through a generator ("4"), and to the surface tank ("1").

[0172] Figure legend Please note: the drawings or figures are not drawn to scale. [Table 8-1] [Table 8-2] [Table 9-1] [Table 9-2] [Table 10-1] [Table 10-2] [Table 10-3]

Table 11-1

Table 11-2

Table 11-3

Table 12-1

Table 12-2

Table 12-3

Table 13-1

Table 13-2

Table 13-3

Table 14-1

Table 14-2

Table 15-1

Table 15-2

Table 15-3

Table 16-1

Table 16-2

Table 16-3

[0173] Additional explanation A first reservoir of high vapor pressure, low density liquid and / or underwater Locating the first reservoir underwater may have key advantages. For example, by locating the first reservoir underwater, a low-density liquid with a high vapor pressure may be employed as the low-density liquid working fluid. The system may be designed such that the underwater first reservoir is located at a depth where the hydrostatic pressure of water is close to the vapor pressure of the low-density liquid at seawater temperature. By locating the tank at a depth where the vapor pressure inside the underwater first reservoir is similar to the pressure of the water surrounding the first reservoir, the installed tank may require a smaller pressure differential resistance and may have relatively thin walls or be less expensive than a tank storing the same liquid on the surface. Also, advantageously, the temperature of water below the ocean may be relatively consistent depending on climate and location, which may allow for easier prediction of the vapor pressure of the low-density liquid and / or design of tank pressure requirements and / or design depth. Also, advantageously, the temperature of the water below the ocean may be relatively consistently below a certain temperature range, which may allow for easier prediction of vapor pressure of low density liquids and / or design of tank pressure requirements and / or design depth.

[0174] As an example, liquid ethane has a vapor pressure of 2807 kPa at 280°K and 4357 kPa at 300°K, which is equivalent to the hydrostatic pressure of water at depths of approximately 286 meters and 445 meters, respectively. The first reservoir and / or pump and / or generator may be located, for example, at a depth greater than 150 meters and less than 500 meters. The ethane remains in a liquid phase rather than a supercritical phase, which is below ethane's critical point of 305.322°K. Advantageously, even in equatorial regions, the temperature of ocean water at depths greater than 150 meters is generally consistently below 300°C, which may ensure that the ethane remains in a liquid phase rather than a supercritical phase. In the liquid phase of ethane, ethane has a vapor pressure of 304 kg / m at 300°K. 3 , 383 kg / m at 280°K 3 This embodiment may be configured similarly to the configuration of FIG. 74. Alternatively or additionally, this embodiment may be configured similarly to FIG. 55, except that "1," "6," and / or "4" are located underwater, albeit at a higher elevation than "2." Alternatively or additionally, this embodiment may be configured similarly to other figures herein, but the first reservoir, or the third reservoir, or the pump / generator, or a combination thereof, may be located below the ocean, in figures where the first reservoir, or the third reservoir, or the pump / generator, or a combination thereof may be shown above the ocean or on land adjacent to the ocean. Advantageously, liquid ethane may be more abundant and / or less expensive than other low-density liquid options. Advantageously, liquid ethane may have a lower density than other low-density liquid options.

[0175] liquid-liquid displacement The present embodiments relate to an energy storage device employing a low-density liquid and a high-density liquid. Electricity is stored by displacing a high-density liquid with a low-density liquid, and electricity is generated by allowing a high-density liquid to displace the low-density liquid. In the present embodiments, the displacement occurs within a submerged storage reservoir configured to store both the low-density liquid and the high-density liquid. An exemplary high-density liquid may include, but is not limited to, water. An exemplary low-density liquid may include, but is not limited to, propane, butane, ethane, or LPG. In some embodiments, the submerged storage reservoir may include a rigid storage tank. In some embodiments, the low-density liquid includes hydraulic fluid employed in pumps and generators to generate electricity.

[0176] In some embodiments, a lower density liquid floats above a higher density liquid within the underwater storage reservoir. The lower density liquid may include hydraulic or working fluids employed in pumps or generators. There are several advantages that result from allowing the lower density liquid to float or sit above the higher density liquid within the underwater storage reservoir. Such advantages may include, but are not limited to: By allowing the lower density liquid to float above the higher density liquid, the present invention may employ a rigid submersible tank. A rigid submersible tank or structure may be employed to contain or store at least a portion of the lower density liquid. A rigid submersible tank may have numerous advantages, which may include, but are not limited to, a longer lifespan, reduced risk of leaks or breakage, and resilience to the elements. In the event of a catastrophic failure or leak or rupture of the underwater storage area, one or more or a combination of the following beneficial outcomes may occur: Energy storage systems can continue to operate The low density liquid may be safely removed and / or recoverable by allowing the low density liquid to be transported from an underwater reservoir to a reservoir near the surface, thereby allowing the storage system to generate power or "discharge." Low density liquids can remain in underwater storage areas Low density liquids may not leak or flow out of underwater storage areas • Low density liquids can be contained within rigid regions of the underwater storage tank, which may have longer term or safer storage characteristics. Low density liquids and water can directly replace each other while being physically separated The present embodiment may employ density-based methods for passive risk mitigation, error correction, and emergency response, which may include, but are not limited to: For example, this embodiment may employ a floating plug having a density greater than that of the low-density liquid and less than that of water. The plug may stop the flow of liquid into the low-density liquid pipe when the water level in the second reservoir exceeds a predefined level. The plug may prevent water from entering the low-density liquid pipe. The plug may be employed to ensure that a predefined minimum volume of low-density liquid is present in the underwater storage reservoir. ○If the barrier or separator is damaged, During filling, the less dense liquid may displace the water downwards and out of the submersible tank through the lower port in the submersible tank.

[0177] In some embodiments, the lower density liquid may be prevented from direct contact with the higher density liquid by physical separation. - The physical separation may involve a liquid that is insoluble in both the low density liquid and the high density liquid, but has a density greater than the low density liquid and less than the high density liquid. - The physical separation may include solids. - The physical separation may include a barrier having a density greater than the low density liquid and less than the high density liquid. - The physical separation may include an impermeable material such as a synthetic fabric or liner. - Such physical separation may be employed to prevent hydrate formation. - The physical separation can be below a low density liquid and above water in a submersible storage reservoir or rigid submersible storage tank. - The physical separation may be located in an underwater storage reservoir. - The physical separation may be in a tank that includes a rigid structure that may include an underwater storage reservoir.

[0178] Containment Cover or Containment Barrier or Containment Boundary ("CB" or "CCB") The present invention may include a containment cover, boundary, or barrier (CB or CBB) over an underwater storage reservoir. The CB may capture low-density liquids in the event of a leak or accidental release of the low-density liquid. The CB may be located on or above the underwater storage reservoir. The CB may include a liner, fabric, or solid, or sheet, or a combination thereof. The CB may be configured to funnel low-density liquids (if captured) into specific areas of the CB, for example, to facilitate recovery of LDL. In the event of an accidental release or leak of LDL, the LDL or LDL hydrate or LDL composition may rise to the top of the underwater reservoir and be captured by the CB or float within the CB. The CB may float above the underwater reservoir or be moored to the seabed. The CB may be less dense than seawater, which may facilitate floating. Alternatively or additionally, the CB itself may be suspended or floating due to float(s) attached to the CB. In some embodiments, the CB may cover or be above a surface area equal to or greater than the surface area of ​​the underwater reservoir and / or underwater valve or connection. In some embodiments, the CB may cover or be above only a specific section of the underwater reservoir, e.g., covering only the surface area above a connection or port. There may be more than one CB. For example, there may be a CB above a specific connection or port. In some embodiments, there may be redundant CBs. For example, a CB may cover a specific port while another CB may cover the entire port and / or section of the underwater reservoir.

[0179] The CB may include a material that has an affinity for water and / or LDL. The CB may include a material that repels both water and LDL. The CB may include a hydrophobic material that absorbs LDL.

[0180] The CB may include a sensor, system, or mechanism for determining whether there is an LDL leak or whether LDL is being captured by the CB. For example, the sensor may include measuring buoyancy acting on the CB. As LDL is released and floats within the CB, the buoyancy acting on the CB increases, which may be measured by one or more sensors. For example, the sensor or indicator may include a hydrophobic material that absorbs LDL. When LDL contacts the hydrophobic material, the LDL may be absorbed, which may trigger the sensor and / or provide an indication of the occurrence of an LDL leak or accidental release. For example, the sensor may include spectroscopy, which may provide an indication of the presence of a new liquid other than seawater, such as LDL. For example, the sensor may include a float that is less dense than water but greater in density than LDL. If a sufficient amount of LDL leaks and collects within the CB, the float may begin to sink into the LDL layer that may form. Other mechanisms of the sensor may include, but are not limited to, conductivity, spectroscopy, spectrophotometry, visible color, absorbance, viscosity, pH, solubility, polarity, dielectric constant, or combinations thereof.

[0181] Systems may be employed to notify a system operator of the occurrence of an LDL release, employing passive and / or active systems to correct the problem, shut down the system, undergo predefined procedures, undergo new procedures, or combinations thereof, autonomously, semi-autonomously, or in the presence of a human system operator, or combinations thereof.

[0182] Rigid tank with interconnected water reservoirs An exemplary embodiment or configuration may include a rigid tank with an internal swim bladder tank for storing an LDL. The remaining storage volume not occupied by the LDL swim bladder tank may be occupied by water. The water may be interconnected to or may include the surrounding or adjacent ocean. The water may include water from an interconnection to a water reservoir. The reservoir may include a surface water reservoir or a submerged reservoir. The submerged water reservoir may include a tank containing water interconnected to the rigid tank via a pipe. The water reservoir may have a pressure similar to or in equilibrium with the hydrostatic pressure of the ocean.

[0183] The following are some characteristics and attributes of exemplary embodiments: The LDL port in the rigid tank and / or the LDL swim bladder in the rigid tank may be located in the upper portion of the rigid tank and / or away from the water port. The water port may be located at the bottom or bottom portion of the rigid tank and / or separate from the LDL and / or LDL port. The water tank may contain fresh water or deionized water if desired, which may be advantageous to prevent corrosion on the inside of the submersible rigid tank. In the event of a break or rupture of one or all of the inflatable / swim bladder containment devices, the LDL will remain within the rigid tank and may be safely removed through the LDL port, which may involve the same procedure typically employed for electrical discharge / power generation in the present invention. Because the LDL port is near the top of the rigid tank and / or the LDL is stored near the top of the tank, the LDL may rise to the top of the rigid tank, which may prevent the LDL from leaking and / or spilling into surrounding bodies of water, or may ensure that the LDL is contained within the system, or may ensure that the LDL is salvageable to the system. If LDL were to mix with water inside the underwater rigid tank, LDL hydrates could form, which could be significantly denser than LDL. When the underwater tank is filled with LDL, the underwater reservoir could be designed to ensure that the rigid tank water port is blocked by LDL hydrates, preventing LDL from exiting the water port. Such designs could include, but are not limited to, filters or screens within the port that could intentionally block or collect solids if LDL hydrates form. • When LDL hydrates form, they may sink to the bottom of the tank or float at the interface between the water and the LDL. In the event of a leak or rupture or detection of hydrate formation, one or more valves may close. For example, a water pipe or water port may have a valve that closes. Similarly, an LDL port or LDL pipe may have a valve that closes. This embodiment has multiple redundancies. This embodiment may allow the LDL to remain contained within a rigid structural object or tank, which may ensure that if one or more swim bladders or barriers fail, rupture, or break, the LDL will not be released into the surrounding ocean and / or that the LDL will be salvageable and recoverable and / or that the process will be functional. Additionally, this embodiment may allow the interior of the rigid tank to come into contact with water that has less corrosive species than seawater.

[0184] Floating bladder tank: The present invention may relate to a gravity energy storage system involving the displacement of water with a low density liquid, where a submersible storage tank floats above the seabed. The floating submersible storage tank may be buoyant due to the floating submersible storage having a lower density or a lower average density than the surrounding seawater.

[0185] Illustrative exemplary embodiments: A low density liquid-water reservoir having a physical barrier or separation between the low density liquid and the water. Illustrative Embodiments 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be located at the higher elevation and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located at a lower elevation and configured to store water and a fluid having a density lower than water; a third storage reservoir configured to store water; A pump and a generator; the pump, the generator, and the first, second, and third reservoirs are operatively connected to store electricity by pumping a low-density fluid in the first storage reservoir into the second storage reservoir, thereby displacing water within the second storage reservoir into the third reservoir;

[0186] A system in which water in a third reservoir generates or discharges electricity by allowing a less dense fluid in a second storage reservoir to displace into the first storage reservoir.

[0187] Illustrative Embodiments 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir;

[0188] The second storage reservoir is configured to store water and a low density liquid.

[0189] Illustrative Embodiments 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; The system, wherein the second storage reservoir is a rigid tank configured to store water and low density liquids.

[0190] Illustrative Example Embodiments 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a low density liquid; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density liquid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density liquid in the second storage reservoir to return to the first storage reservoir;

[0191] The system, wherein the second storage reservoir is configured to store water and a low-density liquid, the low-density liquid having a density less than the density of liquid water. Illustrative Example Sub-Embodiments 2. The system of Exemplary Embodiment 1, wherein the second storage reservoir comprises a rigid tank. 3. The system of exemplary embodiment 1, wherein the lower density liquid is located above the water inside the second reservoir. 4. The system of exemplary embodiment 1, wherein the less dense liquid floats above the water inside the second reservoir. 5. The system of exemplary embodiment 1, wherein the system further comprises a hydraulic fluid in the pump, the hydraulic fluid being the same as the low density liquid. 6. The system of exemplary embodiment 1, wherein the pump, the generator, and the first and second reservoirs are operably connected by a pipe. 7. The system of exemplary embodiment 6, wherein a low-density liquid is transferred between the first reservoir and the second reservoir using the pipe. 8. The system of exemplary embodiment 1, further comprising a physical barrier in the second reservoir to separate the low density liquid from the water in the second reservoir. 9. The system of exemplary embodiment 8, wherein the second reservoir is configured to prevent leakage of the low-density liquid in the event of damage to the physical barrier. 10. The system of exemplary embodiment 8, wherein the physical barrier comprises a material having an average density less than that of liquid water and greater than that of a low-density liquid at a temperature greater than 3°C and less than 50°C at the same hydrostatic pressure. 11. The system of exemplary embodiment 8, wherein at least a portion of the physical barrier is located above the water and at least a portion of the physical barrier is located below the less dense liquid. 12. The system of exemplary embodiment 8, wherein the physical barrier comprises a liquid. 13. The system of exemplary embodiment 8, wherein the physical barrier comprises a solid. 14. The system of exemplary embodiment 8, wherein the physical barrier is configured to prevent (1) substantial dissolution of the low density liquid in water, (2) substantial dissolution of water in the low density liquid, (3) substantial formation of low density liquid-water hydrates, or a combination thereof. 15. The system of exemplary embodiment 1, further comprising a barrier positioned above at least a portion of the second reservoir. 16. The system of exemplary embodiment 15, wherein the barrier is configured to contain a low-density liquid, a low-density liquid-water composition, or a combination thereof, in the event of a defect in the second reservoir. 17. The system of exemplary embodiment 15, wherein the barrier comprises an apparatus for detecting low-density liquids. 18. The system of exemplary embodiment 15, wherein the barrier is configured to funnel low-density liquids to facilitate collection. 19. The system of exemplary embodiment 15, wherein the barrier is suspended above at least a portion of the second reservoir. 20. The system of exemplary embodiment 19, wherein the barrier is suspended by a tether connected to a mooring, an anchor, the seabed, or a combination thereof. 21. The system of exemplary embodiment 15, wherein the barrier is buoyant, connected to a buoyant floating object, or a combination thereof. 22. The system of exemplary embodiment 1, wherein the second reservoir is buoyant, connected to a buoyant floating object, or a combination thereof. 23. The system of exemplary embodiment 22, wherein the second reservoir is floating or suspended above the seabed. 24. The system of exemplary embodiment 23, wherein the second reservoir is suspended by a tether connected to a mooring, an anchor, the seabed, or a combination thereof. 25. The system of exemplary embodiment 1, further comprising a third reservoir operably connected to transfer water displaced by the lower density liquid during charging from the second reservoir to the third reservoir. 26. The system of exemplary embodiment 25, wherein the water has a density that is within ±5% of the density of seawater at temperatures above 3°C and below 40°C under the same hydrostatic pressure. 27. The system of exemplary embodiment 25, wherein at least a portion of the third reservoir contains seawater. 28. The system of exemplary embodiment 25, wherein at least a portion of the third reservoir contains treated seawater. 29. The system of exemplary embodiment 26, wherein at least a portion of the third reservoir has a pressure within ±10 atmospheres of the hydrostatic pressure of seawater at the depth of the second reservoir. Exemplary Sub-embodiments 2. The system of embodiment 1, wherein a fluid having a lower density than water is located above the water inside the second reservoir. 3. The system of embodiment 1, wherein a fluid having a lower density than water floats above the water inside the second reservoir. 4. The system of embodiment 1, wherein the hydraulic or working fluid in the pump and generator comprises a fluid having a density lower than water. 5. The system of embodiment 4, wherein the pump, the generator, and the first and second reservoirs are operably connected by a pipe. 6. The system of embodiment 5, wherein a fluid having a density lower than that of water is transferred between the first reservoir and the second reservoir using the pipe. 7. The system of embodiment 1, wherein the fluid having a lower density than water and the water in the second reservoir are separated by a physical barrier. 8. The system of embodiment 7, wherein the physical barrier is floating. 9. The system of embodiment 7, wherein the physical barrier has an average density less than that of water and greater than that of a fluid having a density less than that of water. 10. The system of embodiment 7, wherein at least a portion of the physical barrier is located above water and below a fluid having a lower density than water. 11. The system of embodiment 7, wherein the physical barrier comprises a liquid. 12. The system of embodiment 7, wherein the physical barrier comprises a solid. 13. The system of embodiment 7, wherein the physical barrier prevents dissolution of water into a fluid having a density lower than that of water in water, dissolution of water into a fluid having a density lower than that of water, formation of a fluid-water hydrate having a density lower than that of water, or a combination thereof. 14. The system of embodiment 1, wherein a containment cover or barrier is located over one or more portions of the second reservoir. 15. The system of embodiment 14, wherein the containment cover or barrier captures or collects a fluid or derivative of this fluid having a density lower than water in the event of a leak, break, or accidental release. 16. The system of embodiment 14, wherein the containment cover or barrier includes a system for detecting the capture of a fluid having a density lower than that of water. 17. The system of embodiment 14, wherein the containment cover or barrier is configured to admit a fluid having a density lower than water or a derivative of this fluid to facilitate capture or recovery. 18. The system of embodiment 14, wherein the containment cover or barrier is suspended above at least a portion of the second reservoir, the third reservoir, or both. 19. The system of embodiment 18, wherein the suspension is by a tether connected to a mooring, or an anchor, or the seabed, or a combination thereof. 20. The system of embodiment 14, wherein the containment cover or barrier is buoyant, connected to a buoyant floating object, or a combination thereof. 21. The system of embodiment 1, wherein the second reservoir is buoyant, connected to a buoyant floating object, or a combination thereof. 22. The system of embodiment 21, wherein the second reservoir floats above the seabed. 23. The system of embodiment 22, wherein the second reservoir is suspended above the seabed. 24. The system of embodiment 23, wherein the suspension is by a tether connected to a mooring, or an anchor, or the seabed, or a combination thereof. 25. The system of embodiment 1, wherein the third reservoir contains a liquid having the same density as seawater. 26. The system of embodiment 1, wherein the third reservoir contains a liquid having a density that is within ±0.5%, or within ±1%, or within ±2%, or within ±3%, or within ±4%, or within ±5%, or within ±6%, or within ±7%, or within ±8%, or within ±9%, or within ±10% of the density of seawater. 26. The system of embodiment 1, wherein the third reservoir contains a liquid having a density that is within ±0.5%, or within ±1%, or within ±2%, or within ±3%, or within ±4%, or within ±5%, or within ±6%, or within ±7%, or within ±8%, or within ±9%, or within ±10% of the density of seawater, and the liquid may be a liquid at a temperature above 3°C and below 40°C at the same hydrostatic pressure. 27. The system of embodiment 1, wherein the third reservoir comprises at least a portion of seawater. 28. The system of embodiment 26, wherein the liquid is less corrosive than seawater, or less prone to biofouling or scaling than seawater, or a combination thereof. 29. The system of embodiment 26, wherein the liquid comprises treated seawater. 30. The system of embodiment 26, wherein at least a portion of the liquid is at a pressure having a hydrostatic pressure of 10 atmospheres of seawater near the second reservoir.

[0192] 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be located at the higher elevation and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located at a lower elevation; a third storage reservoir configured to store water; A pump and a generator; The pump, the generator, and the first, second, and third reservoirs store electricity by pumping a low-density fluid in the first storage reservoir into the second storage reservoir, thereby transferring water in the second storage reservoir into the third storage reservoir; the water in the third reservoir is operably connected to generate or discharge electricity by allowing the lower density fluid in the second storage reservoir to transfer to the first storage reservoir; The second storage reservoir is configured to store water and a low density liquid.

[0193] 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be located at the higher elevation and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located at a lower elevation and configured to store low density liquid and water; a third storage reservoir configured to store water; A pump and a generator; The pump, the generator, and the first, second, and third reservoirs store electricity by pumping a low-density fluid in the first storage reservoir into the second storage reservoir, thereby transferring water in the second storage reservoir into the third storage reservoir; A system operatively connected to generate or discharge electricity by allowing water in the third reservoir to displace a lower density fluid in the second storage reservoir into the first storage reservoir.

[0194] 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir;

[0195] The second storage reservoir is configured to store water and a low density liquid.

[0196] 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; the second storage reservoir is configured to store water and a low density liquid; Low density liquids include hydraulic fluids in pumps and generators; The low density liquid is located above the water inside the second storage reservoir, 2. The system of embodiment 1, wherein the low-density liquid is located above the water inside the second reservoir. 3. The system of embodiment 1, wherein the less dense liquid floats above the water inside the second reservoir. 4. The system of embodiment 1, wherein the hydraulic or working fluid in the pump and generator comprises a low-density liquid. 5. The system of embodiment 4, wherein the pump, the generator, and the first and second reservoirs are operably connected by a pipe. 6. The system of embodiment 5, wherein the low-density liquid is transferred between the first reservoir and the second reservoir using the pipe. 7. The system of embodiment 1, wherein the water and the low-density liquid in the second reservoir are separated by a physical barrier. 8. The system of embodiment 7, wherein the physical barrier is floating. 9. The system of embodiment 7, wherein the physical barrier has an average density less than that of water and more than that of a low-density liquid. 10. The system of embodiment 7, wherein the physical barrier is located above the water and below the less dense liquid. 11. The system of embodiment 7, wherein the physical barrier comprises a liquid. 12. The system of embodiment 7, wherein the physical barrier comprises a solid. 13. The system of embodiment 1, wherein the physical barrier prevents dissolution of the low-density liquid in water, dissolution of water in the low-density liquid, formation of low-density liquid-water hydrates, or a combination thereof. 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; the second storage reservoir is configured to store water and a low density liquid; A system in which the water and the low-density liquid are separated by a physical barrier 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; the second storage reservoir is configured to store water and a low density liquid; A system in which water and a low-density liquid are separated by a floating physical barrier 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; the water and the low density liquid in the second storage reservoir are in direct contact at a water-low density liquid liquid-liquid interface. 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping the low density fluid in the first storage reservoir into the second storage reservoir to displace water within the second storage reservoir, and to generate or discharge electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; The second storage reservoir comprises a low density liquid-water liquid-liquid interface. Containment Cover or Containment Barrier ("CB" or "CCB"): Floating / buoyancy tanks: 1. A system for storing and generating electricity, comprising: a first storage reservoir configured to be near the surface of the body of water and configured to store a fluid having a density lower than water; a second storage reservoir configured to be located below the surface of the body of water and configured to store a fluid having a density lower than water; A pump and a generator; the pump, the generator, and the first and second reservoirs are operatively connected to store electricity by pumping a low density liquid in the first storage reservoir into the second storage reservoir to displace water adjacent to the second storage reservoir, and to generate electricity by allowing the low density fluid in the second storage reservoir to return to the first storage reservoir; Water and fluids having a density lower than that of water are both in liquid form, The second storage reservoir is a floating system.

[0197] 2. The system of embodiment 1, wherein the floating object is moored to the bottom of the ocean. 3. The system of embodiment 1, wherein the floating body is suspended above the bottom of the ocean. Condensable gases in surface water tanks: Exemplary interconnected rigid tanks with pressure equalization 1. An energy storage system comprising: It includes surface tanks, subsea tanks, pipes, pumps, and generators. storing electricity by displacing water in said subsea tank using a low density liquid; an energy storage system that generates electricity by allowing water to displace a low-density liquid in said subsea tank; 1. An energy storage system comprising: Surface tanks, subsea tanks, pipes, pumps, and generators Store energy by pumping a low density liquid into a subsea tank to replace the water in the tank. 2. The pressure inside the subsea tank is balanced with the hydrostatic pressure of the surrounding water. 3. Subsea tanks contain a water-low density liquid interface 4. The water inside the subsea tank is in direct contact with the lower density liquid. 5. The water inside the subsea tank is separated from the less dense liquid by a floating barrier. 1. A rigid tank having a low density liquid and water and configured to store the LDL and water; a swim bladder tank configured to store water 2. The swim bladder tank is located at the same elevation as the rigid tank. 3. The swim bladder tank is located at a different elevation than the rigid tank. Note: The location of the bladder tank relative to the rigid tank and the elevation of the bladder tank can be virtually any elevation below the body of water, since the water inside the tank has the same density as the water in the surrounding body of water.

[0198] Note Note: The float tank may be submerged as a fully collapsed tank and connected to the rigid tank, for example, via a pipe. The rigid tank is submerged by flooding the rigid tank. As the water in the rigid tank is displaced by the LDL, the displaced water fills the float tank. The float tank may be floating or rest on the seabed. ●Note: Energy storage systems can be charged when in a partially charged state. ●Note: Energy storage systems can be charged when in a fully discharged state. ●Note: An energy storage system can be discharged when it is in a partially charged or partially discharged state. ●Note: The energy storage system can be discharged when in a fully charged state. Note: It may be desirable for the pressure of water being transferred to or from the surface water tank ("internal water") to be equal to the gravitational hydrostatic pressure of the water surrounding the pipe ("external water"). Alternatively or additionally, the pressure of the internal water may be less than or greater than the external water, depending on the pressure tolerances of the subsea tank, or one or more components or parts in contact with the internal water, or a combination thereof. An exemplary method for ensuring that the pressures of the internal and external water are similar is to place a valve or pressure regulator between the surface water tank(s) and the subsea tank(s). For example, the valve or pressure regulator may be attached to or inside a pipeline connecting the surface water tank(s) and the subsea tank(s). Note: It may be desirable for the pressure within the second reservoir to be the same as the hydrostatic pressure surrounding or adjacent to the second reservoir. The pressure within the second reservoir may differ from the hydrostatic pressure surrounding or adjacent to the second reservoir by less than 10 PSI, or less than 15 PSI, or less than 20 PSI, or less than 1 atmosphere, or less than 2 atmospheres, or less than 3 atmospheres, or less than 4 atmospheres, or less than 5 atmospheres, or less than 6 atmospheres, or less than 7 atmospheres, or less than 8 atmospheres, or less than 9 atmospheres, or less than 10 atmospheres, or less than 11 atmospheres, or less than 12 atmospheres, or less than 15 atmospheres, or less than 20 atmospheres, or less than 30 atmospheres, or less than 40 atmospheres, or less than 50 atmospheres, or less than 60 atmospheres, or less than 70 atmospheres, or less than 80 atmospheres, or less than 90 atmospheres, or less than 100 atmospheres. Note: Within the underwater storage reservoir, a low-density liquid or a high-density liquid may be enclosed in a bladder tank within the rigid submersible tank. For example, water may be enclosed within a bladder tank within the rigid submersible tank, while a low-density liquid may float above the bladder tank. For example, a low-density liquid may be enclosed within a bladder tank within the rigid submersible tank, while water may sink or reside below the bladder tank. The water within the rigid submersible tank may contain, be fluidly connected to, or be in hydrostatic equilibrium with adjacent or surrounding seawater. Note: In some embodiments, the separator or physical barrier may include a layer of solid hydrate of a low-density liquid. The solid hydrate may have a density greater than that of the low-density liquid and less than that of water. The solid hydrate layer may inhibit further mixing or formation of hydrates. Note: The pump / generator in the present invention may include a hydraulic power recovery turbine (HPRT). HPRTs may currently be employed as pump / generators in industries including, but not limited to, hydrocarbon transportation, processing, and refining. HPRTs are known to be more energy efficient using lower viscosity working fluids. The present invention may employ ultra-low viscosity liquids, such as liquid propane, liquid butane, or LPG, which may have viscosities substantially lower than water, allowing the HPRT to have a round-trip efficiency that exceeds that associated with water. Note: A surface water tank or a third reservoir configured to store water on the surface or at a higher elevation than the second reservoir may include a rigid tank or a swim bladder tank or a combination thereof. For example, a third reservoir configured to store water and / or located near, on, or above the ocean surface may include a swim bladder tank, which may be at a pressure equilibrated with the pressure outside or adjacent to the third reservoir. Note: Fluid properties affect HPRT efficiency in the same manner as centrifugal pumps, with more viscous fluids reducing efficiency. The fact that propane and some other exemplary LDLs have lower viscosities than water means that some LDLs may have greater energy / round trip efficiency in HPRT than water. Note: HPRTs can operate most efficiently within a certain range of capacity utilization (flow rate) and pressure head. HPRTs are generally most efficient closer to their maximum capacity utilization and pressure head. For example, when employing HPRTs, there are several ways to ensure near-maximum pump / generator efficiency, which may include, but are not limited to, one or more or a combination of the following: ○ Multiple smaller HPRTs may be employed, with those operating at maximum or near maximum efficiency and / or maximum or near maximum capacity (highest efficiency is near the highest or highest capacity). As demand for storage changes, the number and / or capacity of HPRTs paralleled or "turned on" for storage may be adjusted. As demand for generation changes, the number and / or capacity of HPRTs paralleled or "turned on" for generation may be adjusted. If the energy you need to store is less than the capacity of the HPRT, you have several options: Designing a system with additional lower capacity HPRTs (e.g., two or three or four or five or more HPRTs, each a fraction of the total capacity of each of the larger HPRTs), each of which can operate at near maximum efficiency and / or capacity during operation. For a small number of lower capacity HPRTs or charging variants that are a fraction of the capacity of the lowest capacity HPRTs, a flywheel or capacitor or lithium ion battery or other standard energy storage device may be employed to meet this relatively smaller storage need. The "other standard energy storage device" may be discharged to charge a liquid displacement energy storage technology by powering a pump (such as an HPRT) when desired, or may directly supply electricity to the grid or an application or a combination thereof. Note: Floating subsea tanks may be rigid or collapsible / inflatable or a combination thereof. Floating subsea tanks may be suspended above the seabed by tethers or anchors or attachment lines or other mechanisms. Note: In the event of a subsea landslide or other catastrophic event, the floating subsea tank may be designed to disconnect from the floating subsea tank's tether(s) and / or pipeline(s) as part of an emergency disconnection system that may allow the subsea tank to float to the surface, thereby enabling the subsea tank to avoid rupture or other catastrophic failure that may otherwise occur due to debris from the underwater landslide or other catastrophic event. • Note: Floating subsea tanks may make it easier to implement tanks, for example, where the seabed is uneven, steep, or otherwise difficult to place on the seabed surface. Note: The installation of floating submersible tanks may involve, for example: 1) Sinking the completely crushed float tank to the seabed 2) Attaching the float tank tether and / or anchor to the seabed and / or mooring or sinker. Attaching the LDL pipeline to the float tank. o 3) Using an LDL pipeline to add LDL to the float tank, resulting in the float tank becoming buoyant. The float tank may be floating above the seabed and / or may be suspended above the seabed due to one or more or a combination of the following, including but not limited to: tethers or anchors. Note: An LDL pipeline may be placed or sunk on the seabed while containing or filled with LDL. The LDL pipeline may be weighted or attached to anchors or weights or a combination thereof, for example, to prevent the LDL pipeline from floating to the surface. Note: The LDL pipeline may be placed or sunk on the seabed. The LDL pipeline may be flooded with seawater during the sunk process. Once on the seabed or in place, the water in the LDL pipeline may be replaced with LDL by pumping the LDL into the pipeline and / or allowing the replaced seawater to exit the pipeline. The replaced seawater may exit the pipeline and, for example, into the surrounding ocean or into a separate containment tank. Such a separate containment tank, if employed, may be temporary or permanent. When the pipeline is sufficiently filled with LDL, one or more valves may be closed, for example, to prevent the LDL from leaking into the surrounding ocean and / or to prevent seawater from entering the LDL pipeline. Alternatively or additionally, for example, when the pipeline is sufficiently filled with LDL, the pipeline may be attached to a submersible tank or a floating submersible tank. The LDL pipeline may be weighted or attached to an anchor or weight, or a combination thereof, for example, to prevent the LDL pipeline from floating to the sea surface. • Note: The minimum volume or minimum amount of LDL in a floating submersible tank may include the minimum amount of LDL required to ensure that the floating submersible tank is buoyant. Note: One or more or a combination of the components of the present invention may be located underground or partially underground. For example, a first storage reservoir, which may comprise a land or underwater rigid tank, may be located underground. For example, one or more or portions or combinations of pipes, or valves, or pumps, or generators may be located underground or partially underground. For example, a second reservoir, which may comprise a submerged rigid tank, may be located underground. Note: Locating one or more tanks or other components underground may hide the tank from public view, thereby increasing safety and / or reducing the tank's potential eyesore. Locating one or more tanks or other components underground may increase the tank's useful life. Locating one or more tanks or other components underground may increase the system's resilience to severe weather, natural disasters, or man-made risks. Note: An "8" may be buoyant or neutrally buoyant, or may be denser than the surrounding waters, or a combination thereof. For example, the density of a subsea tank may vary depending on the volume or amount of liquid stored in the tank. Note: LPG, propane, butane, or other liquefied gases that may be employed as low-density liquids may be semi-refrigerated, partially refrigerated, or refrigerated in surface storage tanks. By employing semi-refrigerated storage, the surface storage tank, floating storage tank, or primary reservoir may be able to have a greater carrying capacity, or may have a lower capital cost, or a combination thereof. • Note: The low density liquid may be stored at ambient temperature and / or at a temperature that matches or is close to the temperature of the surrounding water in the second storage reservoir, and / or may be stored under pressure. Note: Due to butane's higher boiling point and lower vapor pressure than propane, and the possibility of constructing larger, less expensive pressure vessels, it may be desirable to employ butane or butane-propane mixtures or combinations thereof. Note: Refrigerated or semi-refrigerated or partially refrigerated or cooled containers may contain temperatures up to one or more or combinations of the following: 50°C, or 40°C, or 30°C, or 20°C, or 10°C, or 5°C, or 0°C, or -10°C, or -20°C, or -30°C, or -40°C, or -50°C. Note: A configuration including a subsea rigid tank configured to store water and LDL and a separate or interconnected float bladder tank configured to store water may be advantageous due to, for example, but not limited to, one or more or a combination of the following: No need for surface water pipelines or surface tanks The underwater swim bladder tanks store primarily water instead of LDL. · The swim bladder tank may have a longer service life or lifespan in water compared to the LDL Bladder tanks configured for water may be less expensive or may include less expensive materials than bladder tanks configured for LDLs In the event of a rupture or catastrophic failure of the bladder tank, a valve on the pipe connecting the bladder tank to the rigid tank may be closed, which may include an emergency shut-off procedure. If the valve fails to close, the LDLs within the rigid tank will naturally remain within the rigid tank; for example, the LDLs may remain within the rigid tank due to the location or configuration of the pipe connecting the rigid tank to the bladder tank. Advantageously, in the event of a catastrophic failure or rupture of the bladder tank, the pressure within the rigid tank is likely to remain constant, and the composition of the water within the rigid tank may remain constant. A swim bladder tank allows a rigid submersible tank to be subjected to a pressure inside the tank that is the same as the pressure outside the tank, or the surrounding hydrostatic pressure. • Note: Some embodiments may include a floating separator that separates the water from the LDL in the submersible tank. ●Note: The round trip electrical efficiency can be 30% or more, or 40% or more, or 50% or more, or 60% or more, or 70% or more, or 80% or more, or 90% or more. • Note: The present invention may include multiple pipelines, surface tanks, subsea tanks, HPRT units or pump-generator units, valves, other components, or combinations thereof. Note: A rigid tank or rigid containment structure may enclose at least a portion or an upper portion of an internal sub-reservoir or sub-tank, which may include a flexible structure or an inflatable or collapsible structure, such as a floatation bladder. The rigid structure may include a steel tank or a composite tank or a combination thereof. If the internal sub-tank is damaged or leaks, the leaked low-density liquid may remain inside the rigid tank or rigid containment structure, preventing exposure of the low-density liquid to the surrounding environment. Alternatively or additionally, the internal sub-tank may store water, while the low-density liquid may be stored within the rigid tank. Alternatively or additionally, the low-density liquid and water are stored in an internal sub-tank inside the rigid tank or rigid containment structure. A "rigid containment structure" may also or alternatively be a flexible structure. Note: Dashed lines in the diagram may indicate labeling lines. Dashed lines or dashed boxes may indicate labels only. Dashed lines or dashed boxes may not themselves be process elements. * Note: The boxes with dashed lines in the figures and the dashed lines in the figures are labels only and are not themselves components of the figures. ●Note: Numbers may not be to scale. For example, the depth of the second reservoir may be greater than or equal to one or more or combinations of the following: 200 meters, or 300 meters, or 400 meters, or 500 meters, or 600 meters, or 700 meters, or 800 meters, or 900 meters, or 1,000 meters, or 1,100 meters, or 1,200 meters, or 1,300 meters, or 1,400 meters, or 1,500 meters, or 1,600 meters, or 1,700 meters, or 1,800 meters, or 1,900 meters, or 2,000 meters, or 2,100 meters, or 2,200 meters, or 2,300 meters, or 2,400 meters, or 2,500 meters, or 2,600 meters, or 2,700 meters, or 2,800 meters, or 2,900, or 3,000 meters. Notes: The water reservoir may contain a liquid that is the same density as, and in pressure equilibrium with, the surrounding or adjacent seawater. It may be desirable to prevent mixing between the water in the water reservoir and the surrounding seawater. To prevent this mixing, it may be desirable to employ a flexible barrier between the water reservoir and the surrounding seawater, which may be classified as a reservoir boundary layer. If the reservoir were to break or suffer a catastrophic failure, or were at risk of breaking or catastrophic failure, a valve on the pipe interconnecting the water reservoir with the rigid tank could close, if desired. The valve could prevent the low-density liquid, or other contents of the rigid tank or end-to-end system, from spilling into or contaminating the surrounding ocean. If the valve were to fail to close, the rigid tank and pipe could be configured to allow the low-density liquid to naturally remain within the tank and / or to minimally spill or leak from the rigid tank. For example, the low-density liquid could float above the water in the second reservoir, and the pipe interconnecting the water reservoir with the rigid tank could be located below the liquid-liquid interface of the low-density liquid and the water. Note: A reservoir may include multiple interconnected reservoirs or tanks or storage vessels, or multiple interconnected process elements, or a combination thereof. For example, a submersible storage reservoir may include multiple interconnected submersible tanks. Note: The third reservoir may be less corrosive than seawater or may have biofouling-resistant properties while allowing the same hydrostatic pressure as seawater. For example, the third reservoir may include seawater treated with an oxygen scavenger to remove dissolved oxygen and / or prevent corrosion. For example, the third reservoir may include seawater treated with a biocide or a non-corrosive or non-oxidizing biocide. For example, the third reservoir may include an aqueous solution having the same or similar density as seawater, except that it includes a different mixture or salt composition and / or a reagent other than seawater, which may be less corrosive than seawater or have other advantageous properties. For example, the third reservoir may include an aqueous solution having the same or similar density as seawater, except that it includes a reagent that inhibits the formation of low-density liquid-water hydrates. For example, the third reservoir may include deep-sea seawater, which may have a low dissolved oxygen concentration and may be less corrosive than surface seawater. Note: The separator or flexible tank or bladder inside the rigid tank may be removable or replaceable. This allows the separator or flexible tank or bladder inside the rigid tank to undergo maintenance or be replaced near its end of life or end-of-life. Note: Low density liquids may include, but are not limited to, one or more or combinations of the following: propane, butane, ethane, pentane, hexane, LPG, gas liquids, oils, or other low density liquids described herein or in the art. ●Note: The temperature of ocean water generally ranges from -2℃ to 40℃. Deep ocean water is generally around 4℃. ●Note: The density of a low density liquid is less than that of water in the temperature range at least above 3°C and / or below 40°C. Note: If the third reservoir is located underwater, the condensable gas in the head space may ensure that the pressure inside the third reservoir is close to the hydrostatic pressure of the ocean at the same underwater depth, which may be beneficial, for example, if the third reservoir is a rigid tank. The vapor pressure of the condensable head space gas may be adjusted or engineered to ensure that it matches or is close to the hydrostatic pressure of the ocean at the same underwater depth at the expected operating temperature. The expected operating temperature may range from -2°C to 50°C, depending, for example, on the body of water, depth, time of year, surface temperature, microclimate, water temperature surrounding or in contact with one or more components of the system, other conditions, or a combination thereof. Note: The pipe connection between the submersible tank and the pipe may be designed to allow for safe disconnection or reconnection, or both. The submersible tank may be disconnected from the pipe for maintenance, replacement, expansion, or monitoring of the submersible tank, the submersible pipe, other submersible components, or a combination thereof. In some cases, the submersible tank or the pipe, or both, may contain a low-density liquid during disconnection. The submersible tank may be disconnected from the pipe for maintenance or replacement. In some cases, the submersible tank or the pipe, or both, may contain a low-density liquid during disconnection. In some cases, the low-density liquid may be removed from the submersible tank before disconnecting the submersible tank. A safe disconnection may include minimal or no leakage of the low-density liquid. Some embodiments of the present invention may be designed to allow for replacement or maintenance of the submersible tank. Some embodiments of the present invention may be designed to allow for transport of the submersible tank to the surface and / or return of the submersible tank to its original location. Some embodiments of the present invention may allow for the removal, replacement, or maintenance of one or more components or subcomponents of a submersible tank or other underwater component, if desired. Some embodiments of the present invention may allow for the addition of one or more tanks underwater while integrating with existing underwater and / or surface infrastructure. For example, a separator inside a rigid tank or a flexible tank or bladder may be removable or replaceable. • Removability or replaceability may encompass the ability to remove or replace a component while maintaining operation or with minimal interruption to operation.

[0199] Additional notes: Exemplary Cost Drivers ●The larger the scale, the lower the cost per kWh of energy storage capacity and the cost per kW of power capacity. The deeper the water depth, the greater the energy density and the smaller the tank volume and pipe diameter required per kWh and kW of storage capacity. To ensure that the project can be structured with pipelaying technology and subsea services, the project may initially employ water depths of 3,000 meters or less. As pipelaying technology and subsea services advance, water depths greater than 3,000 meters may be employed. The longer the energy storage time (i.e., the greater the energy storage capacity relative to the power capacity), the lower the cost per kWh. ○Pipe diameter is determined by the energy density and required "power capacity" Tank capacity is determined by the energy density and the required "energy storage capacity" Distance to the power grid and power grid transmission equipment, and / or modifications to the power grid infrastructure Proximity to onshore and offshore EPC assets, and logistics for delivery and installation of equipment and materials Exemplary Revenue Drivers (Maximizing Revenue and ROI) The price per kWh of electricity in the local electricity market and the expected price / terms of power purchase agreements Demand for grid services due to intermittency of renewable energy in the power grid Solar or wind potential of the location • the structure of the electricity market and its relationship with the power grid and / or local electric utilities; Economic Model: Solar Power Plus Storage (PPA) vs. Grid Services

[0200] Additional notes: Propane gas, or LP gas, or refrigerant, or a boiling point liquid at about room temperature, or a liquid condensable at room temperature, or a combination thereof, in the headspace of a rigid water tank above the surface.

[0201] Exemplary purposes for condensable gases in a water tank 1) To allow the tank to remain rigid without creating a vacuum as the water exits 2) To allow the water to not release any propane into the air. Due to the high pressure in the water which allows some propane solubility, dilute concentrations of propane may be present in the water. This embodiment is closed / not open to the air, so the propane cannot be released into the air.

[0202] Note: The head space can be occupied by a hydrocarbon refrigerant that boils near room temperature. For example, a combination of butane and pentane. As the water fills the tank, the refrigerant is compressed and condensed to a liquid (greatly reducing the amount of compression required). The condensed refrigerant forms a floating layer on top of the water. As the water exits, the refrigerant boils on top of the water.

[0203] Note: Once the water has filled the tank, propane or butane gas can be removed from the tank headspace to allow the water to occupy space without compressing the propane. Propane gas can be removed by compression into a separate tank.

[0204] Note: Gas within the water tank or in the headspace of the water tank that is compressed as the water enters the tank. If desired, the gas may be at least partially condensed.

[0205] Flywheel you compensate for pauses at start

[0206] It may be desirable for the near room temperature boiling liquid to be non-flammable. The near room temperature boiling liquid may include a refrigerant or combination of refrigerants. For example, the near room temperature boiling liquid may include a fluorinated hydrocarbon.

[0207] Overview: This invention can store electricity by replacing water with a low density liquid (LDL). Electricity can be stored in the form of gravitational potential energy from the gravitational hydrostatic pressure difference between the LDL and the water. Step-by-step overview: 1. Charge: The valve at the surface is opened (5). The LDL in the rigid LDL surface tank (1) is pumped (4) through a pipe (3) into the submerged rigid tank (2). As the LDL fills the submerged rigid tank, it displaces the water inside the tank. The displaced water travels through a water pipe (7) to the surface water tank (6). When charging is complete, the valve at the surface (5) is closed. 2. Power Generation: The surface valve (5) is opened. Water inside the surface water tank (6) travels through the water pipe (7) and naturally displaces the LDL inside the submerged rigid tank (2). The displaced LDL travels through the LDL pipe (3) and enters the generator (4) at the surface, generating electricity and allowing the LDL to flow into the rigid LDL surface tank. When charging is complete, the surface valve (5) is closed. Illustrative Definitions Auxiliary Thermal Storage: Auxiliary thermal storage may include a process or system for storing and / or recovering thermal energy from low-density liquids, high-density liquids, or a combination thereof. Recovered thermal energy may include, for example, thermal energy held at the "cold" temperature of a refrigerated or cooled low-density liquid. Auxiliary thermal storage may be required to enable efficient operation in systems having various system components operating at different temperatures. Auxiliary thermal storage may be required to enable efficient operation in systems having cooled or refrigerated high-side elevation low-density liquid reservoirs that may operate at temperatures below the temperature of surface seawater or ground or air or a combination thereof. • Parasitic energy: Energy consumption that reduces the performance or efficiency or both of a system. • Non-parasitic energy: Energy consumption that has a non-negligible impact on the performance or efficiency or both of the system, or no impact, or a positive impact, or a combination thereof. Reservoir or Tank: A reservoir or tank may include an apparatus or device for storing materials such as low-density liquids or high-density liquids or both. Reservoir or tank may be used interchangeably. It is important to note that in some cases, reservoir may be used broadly to describe the general storage of fluids within an area, or zone, or depth, or range, or combinations thereof. It is important to note that in some cases, tank may be used broadly to describe the general storage of fluids within an area, or zone, or depth, or range, or combinations thereof. It is important to note that in some cases, tank may be used narrowly to describe an individual storage unit for the storage of one or more fluids within an area, or zone, or depth, or range, or combinations thereof. It is important to note that in some cases, reservoir may be used narrowly to describe an individual storage unit for the storage of one or more fluids within an area, or zone, or depth, or range, or combinations thereof. • High-side elevation reservoir: A liquid reservoir located at a higher elevation than the elevation of a low-side elevation reservoir within the same storage system. • Low-elevation reservoir: A liquid reservoir located at an elevation lower than that of a higher-elevation reservoir within the same storage system. Low density liquid or lower density liquid or LDL: A working fluid that has a lower density than a high density liquid. A working fluid that has a lower density than the different working fluid with which it exchanges pressure. High density liquid or higher density liquid or HDL or higher density liquid: A working fluid that has a higher density than a low density liquid. A working fluid that has a density in g / mL greater than a low density liquid. A working fluid that has a higher density than the different working fluid with which it is exchanging pressure. Cooling or "refrigerating": The removal of heat from a fluid or system or both, for example, using heat transfer, heat exchange, a refrigeration cycle, radiative cooling, or other heat removal, or a combination thereof. Partially refrigerated: A reservoir and / or working fluid that is cooled to a temperature below at least some ambient temperature. A reservoir and / or working fluid that is cooled to a temperature below at least some ambient temperature, provided that the working fluid may require a pressure above atmospheric pressure to be stored in the liquid phase. • Working fluid: A liquid or gas or both employed in a system to store potential energy or heat or both. • One or more heat storage media or liquids: materials that store or transfer heat, or a combination thereof. ● One or more "cold" thermal storage media: materials that are cooler than one or more "warm" thermal storage media. The one or more "cold" thermal storage media may be at or near the temperature of a refrigerated or cooled low-density liquid, or at or near the temperature of a low-density liquid in a refrigerated or refrigerated or semi-refrigerated upper elevation low-density liquid reservoir. For example, the one or more "cold" thermal storage media may be the temperature of the refrigerated or cooled low-density liquid plus or minus heat exchanger losses and other potential losses. ● One or more "warm" thermal storage media: materials that are warmer than one or more "cold" thermal storage media. The one or more "warm" thermal storage media may be at a temperature above the temperature of a refrigerated or cooled low-density liquid, or may be at a temperature above the temperature of a low-density liquid in a cooled or refrigerated or semi-refrigerated high-side elevation low-density liquid reservoir. ● "Cold": A temperature of a medium that is below the temperature of the same medium at a "warm" temperature. In some embodiments, a "cold" temperature can be a temperature below ambient air temperature, or below ambient water temperature, or below ambient soil temperature, or a combination thereof. In some embodiments, a "cold" temperature can be close to or at or below the temperature or temperature range of a cooled or refrigerated or semi-refrigerated reservoir of low-density liquid. ● "Warm": The temperature of a medium that is above the temperature of the same medium at a "warm" temperature. In some embodiments, a "warm" temperature can be a temperature above ambient air temperature, or ambient water temperature, or ambient soil temperature, or a combination thereof. In some embodiments, a "warm" temperature can be near or at or above the temperature or temperature range of a cooled, refrigerated, or semi-refrigerated reservoir of low-density liquid. ● "Cold" low density liquid: A low density liquid that is at a temperature below the temperature of a "warm" low density liquid. In some embodiments, a "cold" low density liquid can be a low density liquid temperature where the low density liquid has a vapor pressure close to or below the pressure limit or pressure rating of a cooled or refrigerated or semi-refrigerated high side low density liquid reservoir. ● "Warm" low density liquid: A low density liquid at a temperature above that of a "cold" low density liquid. In some embodiments, a "warm" low density liquid can be a temperature of a low density liquid where the low density liquid has a vapor pressure that is close to or above the pressure limit or pressure rating of a cooled or refrigerated or semi-refrigerated high side low density liquid reservoir. Thermal Management: A process for removing, adding, or otherwise transferring heat. A process that may monitor and / or regulate the temperature of one or more or a combination of fluids or components and may automatically, monitor, or both regulate, or add or remove heat, or a combination thereof. Low boiling point, low density liquid, or high vapor pressure, low density liquid: a liquid that has a vapor pressure of about 1 atmosphere or greater at potential ambient temperature conditions. In some embodiments, a low boiling point liquid can include a liquid that has a vapor pressure of about 1 atmosphere or greater at temperatures below 60°C, or below 50°C, or below 40°C, or a combination thereof. In some embodiments, a low boiling point liquid can include a liquid that has a vapor pressure of about 1 atmosphere or greater at temperatures below 100°C, or below 90°C, or below 80°C, or below 70°C, or below 60°C, or below 50°C, or below 40°C, or below 30°C, or a combination thereof. Higher density liquid: in some embodiments, a liquid having a density greater than that of water, seawater, or the water of a body of water, or a combination thereof. In some embodiments, a solution comprising a solvent and a reagent having a density greater than that of the solvent. ● Insoluble or limited solubility: A reagent or liquid or combination thereof that has a solubility in another reagent or liquid of less than 99%, or less than 90%, or less than 80%, or less than 70%, or less than 60%, or less than 50%, or less than 40%, or less than 30%, or less than 20%, or less than 10%, or less than 5%, or less than 1%. Parasitic Load: A demand for energy or materials, or a combination thereof, from a process that reduces the performance or efficiency of a system, but which may be required or useful or desired for the operation of that system. • Ocean: may include an ocean, or a body of water, or a lake, or a body of water containing dense liquid, or a combination thereof. • Higher density liquid or denser liquid: A liquid that has a density greater than that of a lower density liquid. A liquid that has a density greater than that of a lower density liquid in the same energy storage system or process. A liquid that has a density less than that of the higher density liquid it replaces in an energy storage system or process. ● Less dense or denser liquid: A liquid that has a density less than that of a denser liquid. A liquid that has a density less than that of a denser liquid in the same energy storage system or process. A liquid that has a density less than that of the denser liquid it replaces in an energy storage system or process.

[0208] Illustrative Figure Description Figure 88: A process for energy storage that stores electricity by displacing a higher elevation liquid with a lower density liquid. This embodiment may include, but is not limited to, one or more or combinations of the following: a higher elevation low density liquid reservoir, a refrigeration system for cooling the higher elevation low density liquid reservoir, a cold auxiliary thermal storage reservoir, a warm auxiliary thermal storage reservoir, a heat exchanger, a pump and / or generator, a lower elevation reservoir, and interconnecting piping. This figure may show this embodiment stores energy, such as electricity, which may also be referred to as going through a state of charge.

[0209] Figure 89: A process for energy storage by displacing a higher elevation low density liquid with a lower density liquid. This embodiment may include, but is not limited to, one or more or combinations of the following: a higher elevation low density liquid reservoir, a refrigeration system for cooling the higher elevation low density liquid reservoir, a cold auxiliary thermal storage reservoir, a warm auxiliary thermal storage reservoir, a heat exchanger, a generator and / or pump, a lower elevation reservoir, and interconnecting piping. This figure may show this embodiment producing energy, such as electricity, which may also be referred to as undergoing a state of discharge.

[0210] Figure 90: A process for energy storage that stores electricity by displacing a higher elevation liquid with a lower density liquid. This embodiment may include, but is not limited to, one or more or combinations of the following: a higher elevation low density liquid reservoir, a refrigeration system for cooling the higher elevation low density liquid reservoir, a higher elevation high density liquid reservoir, a cold auxiliary thermal storage reservoir, a warm auxiliary thermal storage reservoir, a heat exchanger, a generator and / or pump, a lower elevation reservoir, and interconnecting piping. This figure may show this embodiment stores energy, such as electricity, which may also be referred to as going through a state of charge.

[0211] Figure 91: A process for energy storage by displacing a higher elevation liquid with a lower density liquid. This embodiment may include, but is not limited to, one or more or combinations of the following: a higher elevation low density liquid reservoir, a refrigeration system for cooling the higher elevation low density liquid reservoir, a higher elevation high density liquid reservoir, a cold auxiliary heat storage reservoir, a warm auxiliary heat storage reservoir, a heat exchanger, a pump and / or generator, a lower elevation reservoir, and interconnecting pipes. This figure may show this embodiment producing energy, such as electricity, which may also be referred to as undergoing a state of discharge.

[0212] Figure 92: A process for energy storage that stores electricity by displacing a higher-density liquid with a lower-density liquid. This embodiment may include, but is not limited to, one or more or combinations of the following: a higher elevation low-density liquid reservoir, a refrigeration system for cooling the higher elevation low-density liquid reservoir, an auxiliary thermal storage reservoir that may have a temperature layer or temperature gradient, a heat exchanger, a pump and / or generator, a lower elevation reservoir, and interconnecting pipes. This figure may show this embodiment storing energy, such as electricity, which may also be referred to as going through a state of charge.

[0213] Figure 93: A process for energy storage by displacing a higher elevation liquid with a lower density liquid. This embodiment may include, but is not limited to, one or more or combinations of the following: a higher elevation low density liquid reservoir, a refrigeration system for cooling the higher elevation low density liquid reservoir, an auxiliary thermal storage reservoir that may have a temperature layer or temperature gradient, a heat exchanger, a generator and / or pump, a lower elevation reservoir, and interconnecting pipes. This figure may show this embodiment producing energy, such as electricity, which may also be referred to as going through a state of discharge.

[0214] Figure 94: A process for energy storage that stores electricity by displacing a higher-density liquid with a lower-density liquid. This embodiment may include, but is not limited to, one or more or combinations of the following: a higher elevation low-density liquid reservoir, a refrigeration system for cooling the higher elevation low-density liquid reservoir, a higher elevation high-density liquid reservoir, an auxiliary thermal storage reservoir that may have a temperature layer or temperature gradient, a heat exchanger, a pump and / or generator, a lower elevation reservoir, and interconnecting pipes. This figure may show this embodiment stores energy, such as electricity, which may also be referred to as going through a state of charge.

[0215] Figure 95: A process for energy storage by displacing a higher elevation liquid with a lower density liquid. This embodiment may include, but is not limited to, one or more or combinations of the following: a higher elevation low density li...

Claims

1. 1. A system for storing and generating electricity, comprising: a first storage reservoir near the surface of the body of water and configured to store a first fluid; a second storage reservoir located below the surface of the body of water and configured to store a second fluid having a density greater than that of the first fluid; A pump and a generator; the pump, the generator, and the first and second storage reservoirs are operatively connected to store electricity by pumping the first fluid in the first storage reservoir into the second storage reservoir to displace the second fluid having a higher density than the first fluid in the second storage reservoir, and to generate or discharge electricity by allowing the first fluid in the second storage reservoir to return to the first storage reservoir; the first fluid is a liquid; The system further comprises a pressure exchanger; the pressure exchanger adjusts pressure extraction to ensure that the pressure of the fluid within the second storage reservoir differs from the hydrostatic pressure of the body of water at the same elevation as the second storage reservoir by less than an allowable tolerance pressure of the second storage reservoir; system.

2. The system of claim 1 , wherein the elevation of the first storage reservoir is greater than the elevation of the second storage reservoir.

3. The system of claim 1 , further comprising a third storage reservoir configured to store the second fluid.

4. The system of claim 3 , wherein the third storage reservoir is at substantially the same elevation as the first storage reservoir.

5. The system of claim 3 , wherein the elevation of the third storage reservoir is greater than the elevation of the first storage reservoir.

6. The system of claim 3 , wherein the second fluid displaced from the second storage reservoir during charging is transferred to and stored in the third storage reservoir.

7. 10. The system of claim 1, wherein the second fluid comprises brine, or reverse osmosis effluent brine, or sodium chloride, or sea salt, or calcium chloride, or magnesium chloride, or potassium formate, or magnesium sulfate, or calcium bromide, or sodium bromide, or potassium acetate, or sodium formate, or calcium nitrate, or sodium nitrate, or sodium sulfite, or potassium sulfite, or sodium bisulfite, or potassium bisulfite, or magnesium bisulfite, or calcium bisulfite, or corn syrup, or glycerin, or propylene glycol, or ethylene glycol, or propylene carbonate, or a halogenated hydrocarbon, or a halogen, or a fluorocarbon, or an organic acid, or an inorganic acid, or carbon dioxide, or sulfur dioxide, or nitric oxide, or any combination thereof.

8. The system of claim 1 , wherein the first fluid is selected from a hydrocarbon, water, or ammonia.

9. The system of claim 1 , wherein the pressure exchanger is located near the second storage reservoir.

10. The system of claim 1 , wherein during storage, the pressure exchanger extracts pressure from the first fluid and transfers the extracted pressure to the second fluid.

11. The system of claim 1 , wherein the pressure exchanger extracts pressure from the second fluid and transfers the extracted pressure to the first fluid during power generation.

12. the second storage reservoir includes an internal pressure sensor and an external pressure sensor; the internal pressure sensor measures the pressure of fluid within the second storage reservoir; the external pressure sensor measures the pressure in the body of water adjacent the second storage reservoir; The system of claim 1 , wherein the internal pressure sensor and the external pressure sensor are configured to communicate with the pressure exchanger.

13. 1. A method for storing and generating electricity, comprising: operatively connecting a pump, a generator, a first storage reservoir near a surface of a body of water, and a second storage reservoir located below the surface of the body of water, the first storage reservoir configured to store a first fluid and the second storage reservoir configured to store a second fluid having a higher density than the first fluid; storing electricity by pumping the first fluid in the first storage reservoir into the second storage reservoir to replace the second fluid in the second storage reservoir; generating or discharging electricity by allowing the first fluid in the second storage reservoir to return to the first storage reservoir; the first fluid is a liquid, and the method further includes regulating pressure extraction using a pressure exchanger to ensure that the pressure of the fluid within the second storage reservoir differs from the hydrostatic pressure of the body of water at the same elevation as the second storage reservoir by less than an allowable tolerance pressure of the second storage reservoir. method.

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