Energy Storage Systems

Abstract

The thermal energy storage system described in the present disclosure can be used to store large amounts of thermal energy over a long period of time. In some examples, such a system receives electrical energy from a renewable energy source such as, for example, a solar panel or a wind turbine. By utilizing new technologies, this thermal energy storage system converts electrical energy into thermal energy, which is stored in a high-temperature material such as, for example, molten silicon, molten salt, or any other material capable of storing large amounts of heat. This thermal energy storage system employs a thermal energy storage tank that houses a high-temperature material and is very excellent in heat insulation. Furthermore, these systems are configured to release thermal energy in an efficient manner to an electric generating steam turbine by using the novel heat exchanger systems and heat exchanger technologies described. The energy storage system described herein has a higher overall efficiency that is more realistic than currently available energy storage systems.

Description

[Technical Field]

[0001] The present disclosure relates to novel energy storage systems for long-term energy storage. Further, the disclosure relates to the integration of such energy storage systems with renewable energy sources (e.g., solar and wind energy), optionally with flywheel energy storage systems, and with steam pressure regulation systems that supply electricity-generating steam turbines. [Background technology]

[0002] The Earth receives more than 10,000 times the energy from the sun as consumed by all humans on Earth. Wind energy is a derivative of solar energy. However, our energy-hungry society relies on the burning of fossil fuels for most of its energy. There is international pressure to reduce fossil fuel consumption and switch to renewable energy sources such as solar or wind power.

[0003] Currently, the cost of renewable energy is roughly equal to or less than the cost of energy produced by fossil fuels. However, a serious challenge with renewable energy is that the electricity generated by solar panels and wind turbines cannot be stored economically for long periods of time. This results in the need for a way to economically store large amounts of energy from the sun for long periods of time.

[0004] A variety of different energy storage systems ("ESS") are currently available. The major types of ESS are battery energy storage systems, flywheel energy storage systems, thermal energy storage systems ("HESS") such as molten salt energy storage systems, compressed air energy storage systems, and gravity energy storage systems. Each of these ESS has distinctive advantages and disadvantages. However, as shown by this disclosure, novel integration of such storage systems and novel techniques for insulating HESS solve problems that such standalone systems cannot solve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Application No. 17 / 530,219 Summary of the Invention [Means for solving the problem]

[0006] This disclosure describes a novel HESS for long-term storage of large amounts of thermal energy in high-temperature materials. In some examples, such a HESS receives electrical energy from a renewable energy source, such as a solar panel or a wind turbine. Using novel technology described below, the HESS converts the electrical energy into thermal energy, which is stored in a high-temperature material, such as molten silicon or molten salt. The HESS described herein employs a thermal energy storage tank containing a high-temperature material with excellent thermal insulation. Therefore, the thermal energy storage efficiency is high. Furthermore, by utilizing novel heat exchanger systems and heat exchanger technology described below, the HESS is configured to release the thermal energy in an efficient manner to an electricity-generating steam turbine. Therefore, when the HESS described below is integrated with an energy source (e.g., a renewable energy source), a steam turbine power generation system, and one or more flywheel energy storage systems (optionally), the HESS can achieve highly efficient energy reception, storage, and delivery. This type of HESS can significantly increase the practical feasibility of renewable energy sources, such as wind and solar power.

[0007] In one aspect, the present disclosure relates to an energy storage system (ESS) comprising a vacuum chamber and a thermal energy storage tank disposed within the vacuum chamber. The thermal energy storage tank comprises one or more walls defining (i) an enclosed interior space and (ii) a plurality of open spaces extending within the enclosed interior space. The ESS further comprises a thermal energy storage medium disposed within the enclosed interior space, a first heating device disposed within a first open space of the plurality of open spaces, and a radiant barrier disposed on an outer surface of the one or more walls of the thermal energy storage tank. The first portion of the radiant barrier is disposed between (a) the one or more walls defining the first open space and (b) the first heating device. The ESS further comprises a first actuator system coupled to the first portion of the radiant barrier. The first actuator system is operable to at least partially move the first portion of the radiant barrier from between the one or more walls defining the first open space and the first heating device, thereby increasing radiant heat transfer from the first heating device to the thermal energy storage medium.

[0008] Such an ESS may optionally include one or more of the following features: The radiant barrier may comprise a plurality of sheets of material spaced apart from one or more walls and from one another. The ESS may also include spacer members disposed between at least some of the plurality of sheets of material such that the sheets of material are spaced apart from one another. In some embodiments, the spacer members are comprised of a plurality of separate sections stacked on top of one another. The ESS may also include a heating reservoir configured to contain a fluid. The heating reservoir may be disposed within a second open space of the plurality of open spaces. The ESS may also include a second actuator system coupled to a second portion of the radiant barrier disposed between (i) one or more walls defining the second open space and (ii) the heating reservoir. The second actuator system may be operable to at least partially move the second portion of the radiant barrier from between the one or more walls defining the second open space and the heating reservoir, thereby increasing radiant heat transfer from the thermal energy storage medium to the fluid contained within the heating reservoir. The plurality of open spaces extending within the enclosed interior space may consist of at least two open spaces. The ESS may further include at least one additional heating device in addition to the first heating device. Each additional heating device may be disposed within a respective one of the plurality of open spaces. The horizontal cross section of the thermal energy storage tank may have a circular or polygonal outer contour. The thermal energy storage medium may be made of salt or silicon. The first heating device may include a resistive heating element. Portions of the radiant barrier not disposed on the one or more walls defining the plurality of open spaces may be configured to be fixed relative to the thermal energy storage tank. The radiant barrier may include at least two sheets of material spaced apart from each other and from the one or more walls.

[0009] In another aspect, the present disclosure relates to a method for storing energy, the method including delivering electrical energy to one or more resistance heating devices disposed within each of a plurality of open spaces defined by a thermal energy storage tank disposed within a vacuum chamber. The thermal energy storage tank further defines an enclosed interior space containing a thermal energy storage medium. The plurality of open spaces extend within the enclosed interior space. A radiant barrier is disposed on an exterior surface of the thermal energy storage tank. The method further includes increasing radiant heat transfer from the one or more resistance heating devices to the thermal energy storage medium by at least partially moving one or more portions of the radiant barrier from the respective open spaces.

[0010] Such a method may optionally include one or more of the following features. The method may further include, after delivering electrical energy to the one or more resistive heating devices, moving one or more portions of the radiant barrier back into the respective open spaces to reduce radiant heat transfer from the thermal energy storage medium. The method may also include delivering fluid to a heating reservoir disposed in an additional open space of the plurality of open spaces defined by the thermal energy storage tank. The method may also include increasing radiant heat transfer from the thermal energy storage medium to the fluid by at least partially moving an additional portion of the radiant barrier out of the additional open space. The method may also include, after heating the fluid via radiant heat transfer from the thermal energy storage medium, moving an additional portion of the radiant barrier back into the additional open space to reduce radiant heat transfer from the thermal energy storage medium.

[0011] Some embodiments of the subject matter described in this document can be implemented to achieve one or more of the following advantages: The HESS described herein maximizes thermal energy density per unit weight and volume by taking full advantage of the physical principles of vacuum insulation, which substantially eliminates heat losses associated with conventional insulation systems; The HESS employs novel heat exchange systems and techniques between the resistive heating device and the thermal energy storage medium, and between the thermal energy storage medium and the heated reservoir of the heat engine's working fluid; Such systems and techniques increase the efficiency of the radiative heat transfer process during the process and minimize heat losses and inefficiencies upon completion of the process;

[0012] Additionally, advantageously, the HESS described herein is designed with structural support members optimized to reduce heat loss due to conduction. Additionally, the HESS described herein includes a highly efficient radiant barrier that virtually eliminates heat loss due to radiation. Thus, the efficiency and storage time of the HESS described herein are significantly improved over such systems known to date.

[0013] The performance of the HESS described herein does not degrade over many years (e.g., 20 years or more), regardless of the frequency of energy charging and discharging. In contrast, the performance of widely used battery ESSs gradually degrades every year, with an average useful life of only about 5 to 8 years. The HESS described herein is an alternative energy storage system that can replace certain current applications of battery-based energy storage systems (e.g., lithium battery energy storage systems) as a more economical and environmentally friendly, large-scale, long-term system for storing energy from renewable energy sources.

[0014] The HESS described herein enables long-term, low-cost storage of renewable energy obtained from solar panels, wind turbines, and / or other forms of renewable energy devices. In this context, "long-term" means days or weeks. "Low-cost" means that the initial capital storage cost per kilowatt-hour (kWh) is significantly lower than the storage cost per kWh of state-of-the-art commercially available flywheel energy storage systems (FESSs) widely used in the renewable energy industry and other conventional ESSs, such as lithium battery ESSs. Furthermore, the overall efficiency of the HESS described herein improves as the energy storage capacity becomes higher.

[0015] Furthermore, the HESS described herein may enable large-scale energy storage of renewable energy without the use of environmentally and biologically harmful materials, and the HESS has a very small land footprint.

[0016] Furthermore, the HESS described herein can also be used to reduce our power-hungry society's high reliance on energy generated by burning fossil fuels.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, the materials, methods, and examples of the embodiments described herein are illustrative only and not limiting.

[0018] The details of one or more embodiments of the present invention are set forth in the accompanying drawings and description herein. The scope and application of the HESS described herein is not limited by any of the specific numbers referenced in this disclosure. Other features, objects, and advantages of the present invention will be apparent from the description and drawings, and from the claims. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view of an example HESS according to certain embodiments described herein. [Figure 2] FIG. 2 shows the HESS of FIG. 1 with a portion of the vacuum chamber transparent. [Figure 3] FIG. 2 shows the HESS of FIG. 1 with a portion of the vacuum chamber removed. [Figure 4] FIG. 2 illustrates a radiant barrier for the example HESS of FIG. 1. [Figure 5] FIG. 2 shows a thermal energy storage tank of the HESS of FIG. 1. [Figure 6] FIG. 6 is an exploded view of the thermal energy storage tank of FIG. [Figure 7] FIG. 6 is an oblique cross-sectional view of the thermal energy storage tank of FIG. [Figure 8] FIG. 6 is an exploded perspective view of portions of the thermal energy storage tank of FIG. 5 and the radiant barrier of FIG. 4. [Figure 9] FIG. 10 illustrates another example thermal energy storage tank. [Figure 10] FIG. 10 illustrates another example thermal energy storage tank. [Figure 11] 2A-2C show two example spacer members that can be used with the HESS of FIG. 1. [Figure 12] FIG. 12 shows five of the spacer members of FIG. 11 interlocked together in a stacked configuration. [Figure 13] 2A-2C show two further example spacer members that can be used with the HESS of FIG. 1. [Figure 14] FIG. 14 shows five of the spacer members of FIG. 13 interlocked together in a stacked configuration. [Figure 15] FIG. 2 is a schematic diagram illustrating the use of spacer members in the HESS of FIG. 1. [Figure 16] 16 is another schematic diagram illustrating the use of spacer members in the HESS of FIG. 1 taken along section plane 16-16 as shown in FIG. 15. [Figure 17] FIG. 2 shows the movable radiation barrier and actuator system of the HESS of FIG. 1 in a first configuration. [Figure 18] FIG. 18 shows the moveable radiation barrier and actuator system of FIG. 17 in a second configuration. [Figure 19] FIG. 18 shows the moveable radiation barrier and actuator system of FIG. 17 in a third configuration. [Figure 20] FIG. 18 shows the moveable radiation barrier and actuator system of FIG. 17 in a fourth configuration. [Figure 21] FIG. 18 shows the actuator system of FIG. 17. [Figure 22] FIG. 18 is a schematic diagram of the configuration of FIG. 17. [Figure 23] FIG. 19 is a schematic diagram of the configuration of FIG. 18. [Figure 24] FIG. 20 is a schematic diagram of the configuration of FIG. 19. [Figure 25] FIG. 21 is a schematic diagram of the configuration of FIG. 20. [Figure 26] 2 is an exploded view of a portion of the HESS of FIG. 1 including a radiant barrier, a heating device, and a heating reservoir. [Figure 27] FIG. 27 shows the components of FIG. 26 arranged in an operational configuration, with the radiant barrier being transparent. [Figure 28] 2 is a flow chart illustrating a method of using the HESS of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] Like numbers refer to corresponding parts throughout.

[0021] This disclosure describes a novel HESS for long-term storage of large amounts of thermal energy in a high-temperature material, such as in a temperature range of about 200°C to 1,500°C. In some examples, such a HESS receives electrical energy from a renewable energy source, such as a solar panel or a wind turbine. Utilizing novel techniques described below, the HESS converts the electrical energy into thermal energy, which is stored in a high-temperature material, such as molten silicon, molten salt, or any of a variety of materials capable of storing large amounts of heat within the HESS's thermal energy storage tank. The HESS described herein employs a thermal energy storage tank containing the high-temperature material that is highly insulated. Measures are taken to minimize any form of potential heat loss. Therefore, the thermal energy storage is highly efficient.

[0022] Furthermore, the HESS is configured to efficiently release its thermal energy to the working fluid of an electricity-generating steam turbine by using novel heat exchanger systems and heat exchanger technologies described below. Thus, when the HESS described below is integrated with an energy source (e.g., a renewable energy source), a steam turbine power generation system, and, optionally, a flywheel energy storage system ("FESS"), the HESS can achieve highly efficient energy reception, storage, and delivery. This type of HESS can significantly increase the practical feasibility of renewable energy sources, such as wind and solar. For example, the HESS described herein can be advantageously integrated into a broader energy management system, such as the hybrid energy storage system described in U.S. Patent Application No. 17 / 530,219, filed November 18, 2021. Specifically, the HESS described herein can be integrated into the hybrid energy storage system disclosed therein by substituting the HESS for the molten salt energy storage system (e.g., reference numeral 120), which is a subsystem of the overall hybrid energy storage system described therein. Integrating the HESS described herein into such a hybrid energy storage system results in a novel system comprising a hot-body energy storage system, a steam temperature conditioning system, a steam turbine system, and an FESS as an optional fourth subsystem. Such a hybrid energy storage system allows for long-term storage of large amounts of energy received from solar and / or wind energy sources and for continuous delivery of power to users over long periods of time when power generated from solar and / or wind energy sources is unavailable or interrupted due to factors such as day-night cycles, daily weather changes, prolonged periods of severe weather such as multi-day summer rains and winter snowstorms, or sudden power grid failures for towns, buildings, campuses, etc.Accordingly, U.S. Patent Application No. 17 / 530,219 is incorporated herein by reference in its entirety for all purposes.

[0023] 1 illustrates an example thermal energy storage system 100 (or HESS 100). The HESS 100 comprises a vacuum chamber 110. Electrical connections 102 and working fluid couplings 104 extend through the walls of the vacuum chamber 110, which are described in more detail below. Additionally, a number of actuator motors 152 are visible, which are also described in more detail below.

[0024] In this view of the HESS 100, substantially only the outer wall surfaces of the vacuum chamber 110 are visible. The internal components of the HESS 100 are shown in subsequent figures.

[0025] The HESS 100 includes a vacuum chamber 110 to enhance the thermal insulation of the HESS 100. That is, the vacuum within the vacuum chamber 110 serves to reduce energy (heat) loss that might otherwise occur due to convective and conductive heat transfer.

[0026] The HESS 100 can be scaled to virtually any desired size, for example, but not limited to, in some embodiments, the outer diameter of the HESS 100 can be in the range of 5 feet to 20 feet, 10 feet to 30 feet, 20 feet to 40 feet, 30 feet to 50 feet, 40 feet to 60 feet, or more.

[0027] Figure 2 shows a view of the HESS 100 in which the lower portion of the vacuum chamber 110 is transparent. Figure 3 shows an exploded view of the HESS 100. Specifically, the vacuum chamber 110 is shown exploded so that its internal contents are visible.

[0028] Both of these figures show an assembly comprising a radiant barrier 120 surrounding a thermal storage tank 130 (not visible, see e.g., FIG. 5) located within a vacuum chamber 110. The vacuum of the vacuum chamber 110 permeates all spaces within the vacuum chamber 110. Thus, all interior spaces within the radiant barrier 120 and the thermal storage tank 130 are vacuum spaces, which virtually eliminate the occurrence of heat transfer by convection and conduction.

[0029] 3 also shows a portion of a multiple actuator system 150 (including actuator motors 152 shown in FIG. 1). The structure and function of actuator system 150 is further described below.

[0030] 4 shows the radiant barrier 120 in more detail. Here, it can be seen that the radiant barrier 120 is made up of multiple parts. Specifically, the radiant barrier 120 comprises a fixed part 122 and multiple movable parts 124a, 124b, 124c, 124d, and 126.

[0031] The plurality of movable portions 124a-124d and 126 are physically moved in and out of the fixed portion 122 at appropriate times by a plurality of actuator systems 150. Here, the plurality of movable portions 124a-124d and 126 are shown in a position outside the fixed portion 122. The significance of the mobility of the plurality of movable portions 124a-124d and 126 will be explained further below.

[0032] The radiant barrier 120 is made from multiple sheets of material spaced apart from one another (e.g., spaced apart by at least 2 mm). The sheets that make up the radiant barrier 120 are heat-resistant metal sheets, metal alloy sheets, or non-metallic sheets with smooth, shiny surfaces and low thermal emissivity (e.g., emissivity of about 0.2 or less). However, in some embodiments, the sheets that make up the radiant barrier 120 may have an emissivity higher than 0.2. In either case, the sheets that make up the radiant barrier 120 function to block, mitigate, or prevent radiant heat transfer.

[0033] The plurality of sheets comprising the radiant barrier 120 can include, but is not limited to, 4-10, 8-14, 12-18, 16-22, 20-26, 24-30, 28-34, 32-38, 36-44, 10-20, 20-30, 30-40, or 40-50 spaced apart sheets (or layers). In some embodiments, the fixed portion 122 and the plurality of movable portions 124a-124d and 126 have the same number of spaced apart sheets. In some embodiments, the fixed portion 122 and the plurality of movable portions 124a-124d and 126 have different numbers of spaced apart sheets.

[0034] In some embodiments, the sheets constituting the radiant barrier 120 can all be made of the same material. Alternatively, the sheets constituting the radiant barrier 120 can all be made of different materials (e.g., in different layers). The innermost layer of these sheets directly or indirectly receives the strongest thermal radiation from the thermal storage tank 130. In one example, if the thermal energy storage medium in the thermal storage tank 130 is molten silicon, the maximum temperature of the thermal storage tank 130 is approximately 1,500°C. Therefore, molybdenum may be a preferred material choice for the innermost sheet constituting the radiant barrier 120. However, the temperature of the outermost sheet constituting a radiant barrier 120 with 20 or more layers of sheets can reach several hundred degrees Celsius. Therefore, stainless steel may be a preferred material choice for the outermost sheet constituting the radiant barrier 120. In one example, if the thermal energy storage medium in the thermal storage tank 130 is molten salt, the maximum temperature of the thermal storage tank 130 is approximately 580°C. Therefore, stainless steel is an excellent alternative material for all sheets that make up the radiant barrier 120 of the thermal storage tank 130 containing molten salt. However, the material for the sheets that make up the radiant barrier 120 is not limited to molybdenum or stainless steel.

[0035] 5-8, the thermal energy storage tank 130 is disposed within the radiant barrier 120 (see particularly the exploded view of FIG. 8, which does not show the top of the thermal energy storage tank 130 or the radiant barrier 120 for clarity). The innermost layer of the radiant barrier 120 is spaced from the outer wall surface of the thermal energy storage tank 130.

[0036] In this example, the thermal energy storage tank 130 (and radiant barrier 120) is cylindrical. However, Figures 9 and 10 show two other possible shapes. Specifically, Figure 9 shows a thermal energy storage tank 130' having a rectangular cross-sectional shape, and Figure 10 shows a thermal energy storage tank 130'' having a hexagonal cross-sectional shape. Additionally, a variety of other possible shapes for the thermal energy storage tank are possible.

[0037] The thermal energy storage tank 130 can be made from materials such as, but not limited to, molybdenum, stainless steel, metal alloys, ceramic coated materials, and other metallic or ceramic compositions.

[0038] 5-8 , the thermal energy storage tank 130 includes one or more walls that define (i) an enclosed interior space 132 and (ii) a plurality of open spaces 134a, 134b, 134c, 134d, and 136 extending within the enclosed interior space 132. In the illustrated embodiment, the plurality of open spaces 134a-134d and 136 extend the entire length of the thermal energy storage tank 130, from the upper portion to the lower portion. Therefore, the walls of the thermal energy storage tank 130 that define the plurality of open spaces 134a-134d and 136 can be described as tubular or perforated. In this example, the tubes have a rectangular cross-sectional shape. However, any other type of cross-sectional shape, such as a circle, a triangle, a polygon, or the like, can be used. Furthermore, a single embodiment of the thermal energy storage tank 130 (and the radiant barrier 120) can combine multiple different types of shapes.

[0039] The enclosed interior space 132 contains a thermal energy storage medium 140 (not shown). The thermal energy storage medium 140 can be a material such as silicon, a salt, or other material. When heated, the silicon or salt, for example, becomes molten within the enclosed interior space 132 and stores high levels of thermal energy.

[0040] In the illustrated embodiment, the thermal energy storage tank 130 defines a total of five open spaces 134a-134d and 136. It should be understood that this is by way of example only, and that any number of open spaces may be included in various configurations of the thermal energy storage tank 130.

[0041] The plurality of open spaces 134a-134d and 136 defined by the thermal energy storage tank 130 are shaped and dimensioned to receive the plurality of movable portions 124a-124d and 126 of the radiant barrier 120 therein. That is, the plurality of movable portions 124a-124d and 126 of the radiant barrier 120 can extend into (and be withdrawn from) the plurality of open spaces 134a-134d and 136 defined by the thermal energy storage tank 130. The fixed portion 122 of the radiant barrier 120 surrounds the other exterior wall portions of the thermal energy storage tank 130 (i.e., the exterior wall portions other than the walls defining the plurality of open spaces 134a-134d and 136). Thus, all exterior wall surfaces of the thermal energy storage tank 130 are covered by the radiant barrier 120. Advantageously, this configuration minimizes radiant heat loss from the thermal energy storage tank 130. However, there are situations where heat transfer to or from the energy storage tank 130 is desirable (e.g., when transferring thermal energy to or extracting thermal energy from the thermal energy storage medium 140). In such cases, and as described further below, some or all of the movable portions 124a-124d and / or 126 of the radiant barrier 120 may be moved out of the open spaces 134a-134d and 136 defined by the thermal energy storage tank 130.

[0042] 11 and 12 , as described above, the innermost layer of the radiant barrier 120 is spaced from the outer wall surface of the thermal energy storage tank 130. Additionally, each layer of the radiant barrier 120 is spaced from adjacent layers. To achieve this physical spacing (which helps achieve a high level of insulation) while providing structural support for the layers of the radiant barrier 120 and the thermal energy storage tank 130, spacers 160 can be incorporated into the HESS 100.

[0043] The exemplary spacers 160 are rectangular members that nest and interlock together to form a mechanically sturdy stack (e.g., as shown in Figure 12). Figures 13 and 14 show an L-shaped spacer 160', which is an alternative to the rectangular spacers 160.

[0044] Although the use of the spacers 160 results in some loss of thermal energy due to conduction from the thermal energy storage tank 130 to the radiant barrier 120 and from the radiant barrier 120 to the vacuum chamber 110, the spacers 160 are specially designed to minimize such loss. For example, the spacers 160 consist of multiple pieces of small, interlocking solid blocks stacked vertically. The resistance to heat conduction between the minimized boundary surfaces of these stacked spacers 160 is very high. These boundary surfaces are ideally dry interfaces with no wetting or fusion between adjacent spacers 160. The resistance to heat conduction at such an interface between two solid blocks is much higher than the resistance to heat conduction through the solid blocks themselves. Therefore, using multiple spacers 160 stacked on top of each other is advantageous. Furthermore, the solid material of the spacers 160 itself should be selected to have low thermal conductivity and should also have sufficient hardness.

[0045] A vertical stack of multiple thin solid spacers 160 made from a material such as zirconia provides a very high resistance to thermal conduction from one end of the stack to the other. Zirconia, an oxide of zirconium, has a maximum use temperature of 2249°C. Zirconia has a compressive strength of 5200 MPa and a low thermal conductivity of 2.7 W / mK. However, the material of the solid spacers 160 for this purpose is not limited to zirconia.

[0046] The high thermal resistance of the stack of spacers 160 is primarily due to the high thermal resistance at the interface contact surfaces of each adjacent spacer 160 in the stack. For this reason, it is desirable to vertically stack a large number of solid spacers 160 (e.g., five or more). Furthermore, for this reason, the surface area of ​​the interface contact surfaces should be minimized. A vertical stack of multiple such solid spacers 160 should be used as one of multiple support columns to support and hold the weight of the thermal energy storage tank 130 and multiple sheets of the radiant barrier 120 (e.g., the fixed portion 122 of the radiant barrier 120).

[0047] 15 shows a schematic representation of a HESS 100 having a thermal energy storage tank 130 containing a thermal energy storage medium 140. The thermal energy storage tank 130 is surrounded by a radiant barrier 120 (specifically, a fixed portion 122 of the radiant barrier 120), which is disposed within the vacuum chamber 110. Also shown are multiple stacks of spacers 160. As shown, the spacers 160 are used to provide vertical support and physical rigidity to the structure of the HESS 100.

[0048] In the illustrated schematic example, a stack of spacers 160 is positioned between the inner wall surface of the vacuum chamber 110 and the outermost layer of the radiant barrier 120. Additional stacks of spacers 160 are positioned between adjacent layers of the radiant barrier 120. In addition, a stack of spacers 160 is also positioned between the innermost layer of the radiant barrier 120 and the outer wall surface of the thermal energy storage tank 130.

[0049] 16 is another schematic diagram illustrating the use of a stack of spacers 160 in a HESS 100. Here, a top view of the HESS 100 shows a thermal energy storage tank 130 containing a thermal energy storage medium 140, surrounded by a radiant barrier 120 (specifically, a fixed portion 122 of the radiant barrier 120).

[0050] In the illustrated schematic example, the stacks of spacers 160 are arranged in two radial groups: a radially inner group and a radially outer group. Such an arrangement of multiple stacks of spacers 160 can be utilized to provide vertical support and physical rigidity to the structure of the HESS 100. Additionally, as shown in FIG. 8 , it should be noted that in some embodiments, the interior walls of the thermal energy storage tank 130 can include vertical beams 138 to provide additional rigidity to the walls of the thermal energy storage tank 130.

[0051] 16 also shows the multiple movable portions 124a-124d and 126 of the radiant barrier 120 depicted within the multiple open spaces 134a-134d and 136 defined by the thermal energy storage tank 130. The movement of the multiple movable portions 124a-124d and 126 of the radiant barrier 120 is described below with reference to FIGS. 17-25.

[0052] FIG. 17 illustrates an example actuator system 150 coupled to an example movable portion 124 of a radiant barrier 120. In the illustrated configuration, the movable portion 124 of the radiant barrier 120 is configured in a fully deployed configuration. That is, in the illustrated configuration, the movable portion 124 is configured to be fully disposed within the respective open space of the thermal energy storage tank 130 (the thermal energy storage tank 130 is not illustrated here to enhance the visibility of the movable portion 124). This fully deployed configuration is also schematically illustrated in FIG. 22, which shows a cross-sectional view of an assembly including the thermal energy storage tank 130 containing the thermal energy storage medium 140, the fixed portion 122 of the radiant barrier 120, the movable portion 124 of the radiant barrier 120, and a representative thermal member 170. The thermal member 170 corresponds to a heating device or heating reservoir, as further described below with reference to FIGS. 26 and 27.

[0053] 22 , in the fully deployed configuration, all sheets of the movable portion 124 of the radiant barrier 120 are positioned to block radiant heat transfer between the thermal energy storage tank 130 and the thermal element 170. In this illustration, there are nine separate sheets that make up the fixed portion 122 and movable portion 124 of the radiant barrier 120. This is by way of example only. In some embodiments, more than ten or less than eight separate sheets can make up the fixed portion 122 and movable portion 124 of the radiant barrier 120.

[0054] 22 shows one example of how the sheets of the fixed portion 122 and the movable portion 124 of the radiant barrier 120 may be joined to one another. Specifically, in the illustrated embodiment, the lower edge portion of the sheet of the movable portion 124 overlaps the vertically extending edge portion of the sheet of the fixed portion 122. Furthermore, the upper edge portion of the sheet of the movable portion 124 extends horizontally in substantial alignment with (substantially in contact with) the edge portion of the horizontally extending sheet of the fixed portion 122. These types of close or overlapping interfaces between the sheets of the fixed portion 122 and the movable portion 124 of the radiant barrier 120 are specifically designed to block radiant heat transfer across these interfaces.

[0055] Referring to Figure 18, here the configuration of the movable part 124 of the radiant barrier 120 has been adjusted (compare to Figure 17) by lifting some sheets of the movable part 124 from their previous position blocking radiation between the thermal energy storage tank 130 and the thermal element 170. This is also shown diagrammatically in Figure 23. In this example, a group of three of the nine sheets of the movable part 124 have been lifted from their previous position blocking radiation between the thermal energy storage tank 130 and the thermal element 170. It can therefore be assumed that the resistance to heat transfer between the thermal energy storage tank 130 and the thermal element 170 provided by the movable part 124 of the radiant barrier 120 has now been adjusted to a lower resistance.

[0056] The upward movement of the three seats of the movable portion 124 can be caused as a result of operation of the actuator system 150. An example of this actuator system 150 will now be described in more detail.

[0057] 21 , an example of an actuator system 150 is shown separated so that its components can be more easily observed. The actuator system 150 includes multiple actuator motors 152 (e.g., DC servo motors, stepper motors, etc.), each driving one or more pinion gears 154 that mesh with a rack 156 mounted to a vertical plate 158. Furthermore, the vertical plates 158 are each mounted to one or more seats of the movable portion 124 of the radiant barrier 120. In this non-limiting example, each vertical plate 158 is attached to a group of three seats of the movable portion 124 of the radiant barrier 120. Any number of seats can be grouped, or the seats can be moved individually by the actuator system 150. In either case, when the actuator motor 152 is actuated, the respective vertical plate 158 is driven upward or downward, which in turn drives the associated seat of the movable portion 124 upward or downward.

[0058] In the illustrated embodiment, a matched pair of actuator motors 152 are simultaneously actuated, thereby synchronously moving two vertical plates 158 (one on each side of a group of seats in the movable portion 124). It should be understood that this type of actuator system 150 is exemplary only, and that other types of actuator systems (e.g., cable and capstan systems, linear actuator systems, etc.) can also be used.

[0059] 18, it can now be seen that two vertical plates 158 are driven upwardly and extend well above the height of the actuator motor 152. These vertical plates 158 are housed within the upper appendage chamber portion 110' of the vacuum chamber 110 (best seen in FIG. 1).

[0060] Referring to FIG. 19 , in the illustrated configuration, another pair of actuator motors 152 is activated to raise a second group of three sheets of the movable portion 124 of the radiant barrier 120. This configuration is also shown schematically in FIG. 24 . In this example, it can be seen that six sheet layers of the movable portion 124 have now been moved from blocking radiant heat transfer between the thermal energy storage tank 130 and the thermal element 170, leaving only three sheets of the movable portion 124. Thus, there is now even less resistance to radiant heat transfer between the thermal energy storage tank 130 and the thermal element 170 (compared to the conventional configurations shown in FIGS. 18 and 23 ). Advantageously, this configuration can be utilized to adjust the amount of heat transfer between the thermal energy storage tank 130 and the thermal element 170 in some scenarios.

[0061] Referring to FIG. 20 , in the illustrated configuration, yet another pair of actuator motors 152 has been activated to raise a third group of three sheets of the movable portion 124 of the radiant barrier 120. This configuration is also shown schematically in FIG. 25 . In this example, it can be seen that all nine sheet layers of the movable portion 124 have now been moved from blocking radiant heat transfer between the thermal energy storage tank 130 and the thermal element 170, and no sheets of the movable portion 124 have remained. Thus, resistance to radiant heat transfer between the thermal energy storage tank 130 and the thermal element 170 is now eliminated. Advantageously, this configuration can be utilized to maximize the amount of heat transfer between the thermal energy storage tank 130 and the thermal element 170 in some scenarios.

[0062] 26 is an exploded view showing a multi-sheet radiant barrier 120 (with movable portions 124a-124d and 126 and fixed portion 122) covering all of the exterior wall surfaces of a thermal energy storage tank 130 (not shown). Also shown are four heating devices 180a-180d and a heating reservoir 190, by way of example. Corresponding to FIG. 1, the heating devices 180a-180d have electrical connections 102, and the heating reservoir 190 has a working fluid connection 104.

[0063] 27 (in which the radiant barrier 120 and thermal energy storage tank 130 are transparent), each of the four heating devices 180a-180d is disposed within the enclosed space of a corresponding one of the movable portions 124a-124d of the radiant barrier 120, and the heating reservoir 190 is disposed within the enclosed space of the movable portion 126 of the radiant barrier 120. It should be understood that this configuration is exemplary only; that is, the HESS 100 can include various other configurations and / or quantities of heating devices and / or heating reservoirs that are also contemplated within the scope of the present disclosure.

[0064] 28 illustrates a method of using a HESS, such as the HESS 100 described herein. At step 210, the HESS receives electricity generated by a renewable energy source, such as a solar panel or a wind turbine. At step 220, the electricity from the renewable energy source is used to power one or more heating devices of the HESS (e.g., one or more of heating devices 180a-180d, as described above, are powered by electricity received from the renewable energy source).

[0065] At step 230, one or more first portions of the movable radiant barrier of the HESS are moved from a first configuration to a second configuration to increase radiant heat transfer from the energized heating devices to the thermal energy storage medium contained within the thermal energy storage tank of the HESS. For example, in the case of the HESS 100 described herein, one or more of the movable portions 124a-124d of the radiant barrier 120 are moved (upward) away from blocking radiant heat transfer from the energized heating devices 180a-180d to the thermal energy storage medium 140 contained within the thermal energy storage tank 130.

[0066] At step 240, any previously energized heating devices are de-energized.

[0067] At step 250, after de-energizing the previously energized heating device, one or more first portions of the movable radiant barriers of the HESS are moved from the second configuration back to the first configuration to reduce radiant heat transfer from the thermal energy storage medium contained within the thermal energy storage tank of the HESS. For example, in the case of the HESS 100 described herein, one or more of the movable portions 124a-124d of the radiant barrier 120 are moved downward to block radiant heat transfer from the thermal energy storage medium 140 contained within the thermal energy storage tank 130.

[0068] At step 260, one or more second portions of the movable radiant barriers are moved from the first configuration to the second configuration to increase radiant heat transfer from the thermal energy storage medium to the working fluid in the heating reservoir. For example, in the case of the HESS 100 described herein, the movable portion 126 of the radiant barrier 120 is moved (upward) away from blocking radiant heat transfer from the thermal energy storage medium 140 contained in the thermal energy storage tank 130 and the working fluid in the heating reservoir 190.

[0069] In step 270, the working fluid is conveyed through a heating reservoir 190 (where it is heated) and then conveyed to a steam turbine coupled to drive a generator. This process allows for the generation of electricity that can be transmitted to users when the electrical output from the renewable energy source is insufficient to meet user demand.

[0070] At step 280, one or more second portions of the movable radiant barrier are moved from the second configuration to the first configuration to reduce radiant heat transfer from the thermal energy storage medium. For example, in the case of the HESS 100 described herein, the movable portion 126 of the radiant barrier 120 is moved downward to prevent radiant heat transfer from the thermal energy storage medium 140 contained within the thermal energy storage tank 130.

[0071] Additional Features and Descriptions The HESS as described herein is a novel energy storage system with excellent thermal insulation that converts electrical energy from renewable energy sources, such as solar and wind power, into thermal energy in high temperature materials, such as high temperature silicon / molten silicon or high temperature salt / molten salt, and then stores the thermal energy for long periods of time through an elaborate insulation system within a vacuum chamber.

[0072] A HESS as described herein can be considered to comprise four main components: (i) a thermal energy storage medium contained in a heat-resistant thermal energy storage tank made from tungsten, molybdenum, stainless steel, or other heat-resistant material with suitable physical properties; (ii) a first heat exchange system that transfers thermal energy from the thermal energy storage medium to the working fluid of the heat engine by non-contact radiative heat transfer from the thermal energy storage tank to the working fluid in the heating reservoir; (iii) a second heat exchange system that transfers heat generated by an energized ohmic heating device (resistive heating device) from a renewable energy source (e.g., solar panel or wind turbine) to the thermal energy storage tank by non-contact radiative heat transfer from the ohmic heating unit to the thermal energy storage tank; and (iv) a support structure system that supports the weight of the thermal energy storage tank and multiple layers of radiant barrier shielding sheeting that surround the thermal energy storage tank, two heat exchange systems, and other ancillary components of the HESS. A unique and novel feature of the support structure of the HESS is that the unavoidable thermal energy losses of the thermal energy storage tank due to heat conduction through direct contact between the materials of the support structure are significantly minimized. Furthermore, the HESS described herein can also be synergistically integrated into a hybrid energy storage system that may comprise a heat engine (with a steam turbine and power generation system) and optionally an FESS (flywheel energy storage system).

[0073] The salt present in a conventional molten salt ESS is heated by an electrically powered ohmic heating unit through direct contact between the molten salt or molten salt container and the unit. Similarly, the heat exchanger between the hot salt or molten salt and the working fluid of a heat engine (e.g., a steam turbine) is conventionally heated by the molten salt through direct contact between the molten salt and the heat exchange pipes that carry steam to and from the steam turbine. The materials used for heat exchangers are good heat conductors, and therefore heat conduction through these materials in the heat exchanger results in significant heat energy losses.

[0074] Another novel feature of the HESS described herein is that the heat exchange between the thermal energy storage tank and the ohmic heating unit powered by electricity from renewable energy, and between the thermal energy storage tank and the working fluid of the heat engine capable of generating electricity, is achieved by non-contact radiative heat transfer in a vacuum between the ohmic heating unit and the thermal energy storage tank, and between the thermal energy storage tank and a heating reservoir containing the working fluid of the heat engine.

[0075] Additional key features of the HESS described herein include exceptional thermal insulation of the thermal energy storage tank, non-contact heat transfer between major components, built-in control of the heat exchange rate between major components, and a unique and novel support structure that supports and maintains the structural integrity of the thermal energy storage tank while minimizing heat loss by conduction through physical contact of the support structure with the thermal energy storage tank and the radiation shielding sheeting of the radiant barrier.

[0076] The shape of the thermal energy storage tank of the HESS described herein is not topologically simple. The reason for this topologically non-simple shape is to minimize heat loss due to thermal radiation during the heat exchange process between the thermal energy storage tank and the ohmic heating unit and between the thermal energy storage tank and the heating reservoir. The space in which thermal radiation transfer occurs between the thermal energy storage tank and the ohmic heating is the narrow, closed space of the through-hole defined by the thermal energy storage tank. Therefore, during the energy exchange process between the thermal energy storage tank and the ohmic heating unit, there is virtually no energy loss to the open space outside the thermal energy storage tank. In other words, there is no "leakage" of thermal radiation to the open space outside. This is a beneficial reason for the thermal energy storage tank to have a through-hole. This is also why the heating reservoir for the heat engine's working fluid is located within the through-hole of the thermal energy storage tank. These are the reasons why the 3D shape of the thermal energy storage tank is topologically significantly different from the 3D shape of a conventional molten salt vessel for energy storage.

[0077] The radiant barrier sheets "shield" radiant heat transfer from the ohmic heating unit to the thermal energy storage tank in a vacuum. The rate of heat transfer from the ohmic heating unit to the thermal energy storage tank can be adjusted or controlled by controlling the number of radiant barrier sheets located between the ohmic heating unit and the thermal energy storage tank. Similarly, the rate of heat transfer from the thermal energy storage tank to the working fluid heating reservoir can be adjusted or controlled by controlling the number of radiant barrier sheets located between the thermal energy storage tank and the heating reservoir.

[0078] A novel feature of the HESS described herein is that the number of sheets of radiant barrier disposed between the thermal energy storage tank and the heating device (ohmic heating unit) and / or the working fluid heating reservoir can be easily changed / controlled during operation of the HESS. In this manner, the rate of radiant heat transfer between the thermal energy storage tank and the ohmic heating unit or between the thermal energy storage tank and the working fluid heating reservoir can advantageously be adjusted or controlled (automatically or manually) during operation of the HESS described herein. These features can be used, for example, to avoid overheating of the working fluid as it passes through the heating reservoir when the temperature of the thermal energy storage tank is excessively high. For example, 700°C may be too high for molten salt. For example, 1,800°C may be too high for molten silicon. When the temperature of the thermal energy storage tank is excessively high, most of the sheets of the tubes of the movable sheets of radiant barrier must remain within their through-holes to attenuate heat transfer from the thermal energy storage tank to the heating reservoir and avoid overheating of the working fluid. When the temperature of the thermal energy storage tank is excessively low, most or all of the sheets of the movable radiant barrier sheet tubes should be raised to increase heat transfer from the thermal energy storage tank to the working fluid in the heating reservoir and prevent underheating of the working fluid. When the HESS itself is idle, i.e., when heating of the working fluid is not required, all of the movable radiant barrier sheets should remain deployed within the through-holes of the thermal energy storage tank to minimize heat energy loss via thermal radiation from the thermal energy storage tank. This feature can also be used to prevent overheating of the thermal energy storage tank by the ohmic heating unit. Similarly, when heating of the thermal energy storage tank by the ohmic heating unit is not required, all of the movable radiant barrier sheets surrounding the ohmic heating unit remain within the through-holes, thereby minimizing heat energy loss from the thermal energy storage tank.

[0079] While the specification contains many specific implementation details, these details should not be construed as limiting the scope of the invention or what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of a particular invention. Certain features that are described herein in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of an embodiment may also be implemented in multiple embodiments individually or in any suitable subcombination. Furthermore, even if features are described herein as acting in a particular combination, and even initially claimed as such, one or more features in a claimed combination may, in some cases, be deleted from the combination, and the claimed combination may be directed to a subcombination or a modified subcombination.

[0080] Similarly, while the figures may show operations in a particular order, this should not be understood as requiring the operations to be performed in the particular order or sequential order shown, or that all of the operations shown be performed, to achieve desired results. In some situations, concurrent execution and parallel processing may be advantageous. Furthermore, the separation of various modules and components in the embodiments described herein should not be understood as requiring such separation in all embodiments, and it should be understood that the components and systems described may generally be integrated together in a single product or packaged into multiple products.

[0081] Specific embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As an example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some implementations, concurrency and parallel processing may be advantageous. [Explanation of symbols]

[0082] 100 Thermal Energy Storage System 102 Electrical Connections 104 Working fluid connection 110 Vacuum Chamber 110' Upper auxiliary chamber 120 Radiant Barrier 122 Fixed part 124 Moving parts 124a Moving parts 124b Moving parts 124c moving parts 124d moving parts 126 Moving parts 130 Thermal energy storage tanks, energy storage tanks, heat storage tanks 130' Thermal Energy Storage Tank 130'' Thermal Energy Storage Tank 132 Interior Space 134a open space 134b open space 134c open space 134d open space 136 open space 138 Vertical Beam 140 Thermal Energy Storage Media 150 Actuator System 152 Actuator Motor 154 Pinion gear 156 racks 158 Vertical Plate 160 spacer, rectangular spacer 160' L-shaped spacer 170 Heating element 180a heating device 180b Heating device 180c heating device 180d heating device 190 Heated Reservoir

Claims

1. a thermal energy storage tank defining (i) an enclosed interior space and (ii) an open space extending within the enclosed interior space; a thermal energy storage medium disposed within the enclosed interior space; and a first heating device disposed within the first open space; a radiation barrier disposed within the open space; and a first actuator system coupled to the radiant barrier; and Equipped with The first actuator system is operable to increase radiant heat transfer from the first heating device to the thermal energy storage medium by at least partially moving the radiant barrier from its position between the open spaces, an energy storage system.

2. 10. The energy storage system of claim 1, further comprising a vacuum chamber containing the thermal energy storage tank; Energy storage systems.

3. the thermal energy storage tank defining a plurality of open spaces extending within the enclosed interior space; The energy storage system of claim 1 .

4. 10. The energy storage system of claim 1, wherein the radiant barrier comprises a plurality of sheets of material spaced apart from the thermal energy storage tank and spaced apart from each other.

5. 5. The energy storage system of claim 4, further comprising spacer members disposed between at least some of the plurality of sheets of material such that the plurality of sheets of material are spaced apart from one another.

6. 6. The energy storage system of claim 5, wherein the spacer member comprises a plurality of separate sections stacked on top of one another.

7. 10. The energy storage system of claim 1, further comprising a heating reservoir configured to contain a fluid, the heating reservoir disposed within a second open space defined by the thermal energy storage tank.

8. a second actuator system coupled to a second portion of the radiant barrier disposed between (i) the thermal energy storage tank and (ii) the heating reservoir; 8. The energy storage system of claim 7.

9. 10. The energy storage system of claim 8, wherein the second actuator system is operable to increase radiant heat transfer from the thermal energy storage medium to the fluid contained within the heating reservoir by at least partially moving the second portion of the radiant barrier from between the thermal energy storage tank and the heating reservoir.

10. 10. The energy storage system of claim 1, wherein the horizontal cross section of the thermal energy storage tank has a circular or polygonal outer contour.

11. 10. The energy storage system of claim 1, wherein the thermal energy storage medium comprises a salt or silicon.

12. 10. The energy storage system of claim 1, wherein the first heating device comprises a resistive heating element.

13. 10. The energy storage system of claim 1, wherein a portion of the radiant barrier not disposed within the open space is configured to be fixed relative to the thermal energy storage tank.

14. 10. The energy storage system of claim 1, wherein the radiant barrier comprises at least two sheets of material spaced apart from the thermal energy storage tank and spaced apart from each other.

15. 1. A method for storing energy, comprising: delivering electrical energy to energize one or more resistance heating devices respectively disposed within each of one or more open spaces defined by an outer surface of a thermal energy storage tank, the outer surface of the thermal energy storage tank further defining an enclosed interior space containing a thermal energy storage medium, and prior to delivering the electrical energy to energize the one or more resistance heating devices, a movable radiant barrier is disposed over the outer surface of at least a portion of the thermal energy storage tank defining the one or more open spaces; delivering a fluid to a heating reservoir disposed within an additional open space of the one or more open spaces defined by the thermal energy storage tank; increasing radiant heat transfer from the thermal energy storage medium to the fluid by at least partially moving an additional portion of the movable radiant barrier out of the additional open space; A method comprising:

16. 16. The method of claim 15, further comprising increasing radiant heat transfer from the energized one or more resistive heating devices to the thermal energy storage medium by moving one or more portions of the movable radiant barrier.

17. 16. The method of claim 15, further comprising, after the step of delivering electrical energy to energize the one or more resistive heating devices, reducing radiant heat transfer from the thermal energy storage medium by moving the one or more portions of the movable radiant barrier back onto the exterior surface of at least a portion of the thermal energy storage tank.

18. 16. The method of claim 15, further comprising, after the step of heating the fluid by radiant heat transfer from the thermal energy storage medium, reducing radiant heat transfer from the thermal energy storage medium by moving the additional portion of the movable radiant barrier back into the additional open space.

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