Energy storage system

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 a novel energy storage system for long-term energy storage. Further, the present disclosure relates to such an energy storage system and its integration with a renewable energy source (such as solar energy and wind energy), a flywheel energy storage system (optionally), and a steam pressure regulation system for supplying an electric generating steam turbine.

Background Art

[0002] The Earth receives energy from the sun that is more than 10,000 times the energy consumed by all humans on Earth. Wind energy is a derivative of the energy from the sun. However, the high-energy consumption society depends mostly on the combustion of fossil fuels for energy. International pressure is being exerted to reduce the consumption of fossil fuels and switch to renewable energy sources such as sunlight or wind.

[0003] Currently, the cost of renewable energy is approximately equal to or lower than the cost of energy generated by fossil fuels. However, a serious problem with renewable energy is that the electricity generated by solar panels and wind turbines cannot be stored economically for a long period. This ultimately boils down to the fact that there is a need for a way to store large amounts of energy from the sun economically over a long period.

[0004] Currently, various different energy storage systems ("ESS (energy storage system)") are available. The main 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 gravitational energy storage systems. Each of these ESS has characteristic advantages and disadvantages. However, as shown by the present disclosure, new integration of such storage systems and new technologies for insulating HESS solve problems that cannot be solved by such stand-alone systems.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Means for Solving the Problems

[0006] The present disclosure describes a novel HESS for storing large amounts of thermal energy in high-temperature materials over a long period of time. In some examples, such a HESS receives electrical energy from a renewable energy source such as, for example, a solar panel or a wind turbine. By utilizing the novel technologies described below, this HESS converts electrical energy into thermal energy, which is stored in a high-temperature material such as, for example, molten silicon or molten salt. The HESS described herein employs a thermal energy storage tank that houses a high-temperature material and is very excellent in heat insulation. Therefore, the efficiency of this thermal energy storage is high. Furthermore, this HESS is configured to release its thermal energy to an electric generating steam turbine in an efficient manner by utilizing the novel heat exchanger system and heat exchanger technology described below. 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), this HESS can achieve very efficient energy reception, storage, and delivery. This type of HESS can significantly enhance the practical feasibility of renewable energy sources such as, for example, wind power and sunlight.

[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 wall portions defining (i) a sealed interior space and (ii) a plurality of open spaces extending within the sealed interior space. Further, the ESS comprises a thermal energy storage medium disposed within the sealed interior space, a first heating device disposed within a first open space of the plurality of open spaces, and a radiation barrier disposed on an outer surface of one or more wall portions of the thermal energy storage tank. A first portion of the radiation barrier is disposed between (a) one or more wall portions defining the first open space and (b) the first heating device. Further, the ESS comprises a first actuator system coupled to the first portion of the radiation barrier. The first actuator system is operable to increase radiative heat transfer from the first heating device to the thermal energy storage medium by at least partially moving the first portion of the radiation barrier from between one or more wall portions defining the first open space and the first heating device.

[0008] Such an ESS can optionally have one or more of the following features. The radiation barrier may comprise a plurality of material sheets spaced apart from one or more wall portions and from each other. The ESS may further comprise spacer members disposed between at least some of the plurality of material sheets such that the plurality of material sheets are spaced apart from each other. In some embodiments, these spacer members consist of a plurality of separate parts stacked on top of each other. The ESS may further comprise 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 further comprise a second actuator system coupled to a second portion of the radiation barrier disposed between (i) one or more wall portions defining the second open space and (ii) the heating reservoir. This second actuator system may be operable to increase radiative 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 radiation barrier between one or more wall portions defining the second open space and the heating reservoir. The plurality of open spaces extending within the sealed interior space may consist of at least two open spaces. The ESS may further comprise 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 consist of salt or silicon. The first heating device may comprise a resistive heating element. A portion of the radiation barrier not disposed on one or more wall portions defining the plurality of open spaces may be configured to be fixed relative to the thermal energy storage tank. The radiation barrier may comprise at least two material sheets spaced apart from one or more wall portions and from each other.

[0009] In another aspect, the present disclosure relates to a method of storing energy. The method includes delivering electrical energy to one or more resistive heating devices disposed within respective open spaces 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 a sealed interior space that houses a thermal energy storage medium. The plurality of open spaces extend into the sealed interior space. A radiation barrier is disposed on an outer surface of the thermal energy storage tank. Further, the method includes increasing radiative heat transfer from the one or more resistive heating devices to the thermal energy storage medium by at least partially moving one or more portions of the radiation barrier away from the respective open spaces.

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

[0011] Some embodiments of the subject matter described in this document can be implemented to realize one or more of the following advantages. The HESS described herein maximizes the thermal energy density per unit weight and per unit volume by making the most of the physical principle of vacuum insulation that substantially eliminates heat loss caused by conventional insulation systems. This HESS employs a novel heat exchange system and heat exchange technology between a resistive heating device and a thermal energy storage medium and between the thermal energy storage medium and a heating reservoir of the working fluid of a heat engine. Such systems and technologies enhance the process efficiency during the radiative heat transfer process and minimize heat loss and inefficiencies at the completion of this process.

[0012] Furthermore, advantageously, the HESS described herein is designed to include a structural support member optimized to reduce heat loss due to conduction. Additionally, the HESS described herein includes a highly efficient radiation barrier that virtually eliminates heat loss due to radiation. Therefore, the efficiency and storage time of the HESS described herein are significantly improved compared to systems known heretofore.

[0013] The performance of the HESS described herein does not degrade regardless of the frequency of energy charge and discharge over many years (e.g., 20 years or more). In contrast, the performance of widely used battery ESSs gradually degrades annually, and their service life is only about 5 to 8 years on average. The HESS described herein is an alternative energy storage system that can replace the current specific 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 the long - term and 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 a time period of 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 by the latest commercially available flywheel energy storage systems (FESS) widely used in the renewable energy industry and other conventional ESSs such as, for example, lithium - battery ESSs. Further, the overall efficiency of the HESS described herein improves as the energy storage capacity increases.

[0015] Furthermore, the HESS described herein may enable large - scale energy storage of renewable energy without using environmentally and biologically harmful materials. Further, the land occupation area by this HESS is very narrow.

[0016] Furthermore, the HESS described herein can also be used to reduce the high dependence on energy generated by the combustion of fossil fuels in this high - power - consumption society.

[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 technical field related to this disclosure. Further, the materials, methods, and examples of the embodiments described herein are illustrative only and not limiting.

[0018] Details of one or more embodiments of the invention are set forth in the accompanying drawings and the description herein. The scope and application of the HESS described herein are not limited by any of the specific numbers mentioned in this disclosure. Other features, objects, and advantages of the invention will become apparent from these descriptions and drawings and the claims.

Brief Description of the Drawings

[0019]

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[0020] Like reference numerals represent corresponding parts throughout.

[0021] The present disclosure describes a novel HESS for long-term storage of large amounts of thermal energy in high-temperature materials in a temperature range such as, for example, from about 200 °C to 1,500 °C. In some examples, such a HESS receives electrical energy from a renewable energy source such as, for example, a solar panel or a wind turbine. By utilizing the novel techniques described below, this HESS converts electrical energy into thermal energy, which is stored in a high-temperature material such as, for example, molten silicon, molten salt, or any of a variety of materials that can store large amounts of heat within the thermal energy storage tank of the HESS. The HESS described herein employs a thermal energy storage tank that houses a high-temperature material and is very good in heat insulation. Measures are taken to minimize any form of potential heat loss. Thus, its thermal energy storage is very efficient.

[0022] Furthermore, this HESS is configured to release its thermal energy in an efficient manner to the working fluid of an electric generating steam turbine by using the novel heat exchanger system and heat exchanger technology 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 an optional flywheel energy storage system (“FESS”), this HESS can achieve very efficient energy reception, storage, and delivery. This type of HESS can significantly enhance the practical viability of renewable energy sources such as, for example, wind power and sunlight. For example, the HESS described herein can be advantageously integrated into a more extensive energy management system, such as the hybrid energy storage system described in U.S. Patent Application No. 17 / 530,219, filed on November 18, 2021. Specifically, the HESS described herein can be integrated into the hybrid energy storage system disclosed therein by substituting this HESS in place of the molten salt energy storage system (e.g., reference numeral 120), which is a subsystem of the entire hybrid energy storage system described in the aforementioned patent application. By integrating the HESS described herein into such a hybrid energy storage system, a novel system is realized that includes a hot body energy storage system, a steam temperature control system, a steam turbine system, and an optional FESS as a fourth subsystem. Such a hybrid energy storage system enables the storage of large amounts of energy received from a solar and / or wind energy source over a long period of time, and the continuous delivery of power to users over a long period of time in the event that the power generated from a solar and / or wind energy source becomes unavailable or is interrupted due to causes such as the day-night cycle, daily weather changes, long periods of adverse weather such as rain over several days in the summer and snowstorms in the winter, or sudden failures of the power grid in a town, building, and campus, etc.Accordingly, U.S. Patent Application No. 17 / 530,219 is hereby incorporated by reference in its entirety for all practical purposes.

[0023] FIG. 1 shows an example of a heat energy storage system 100 (or HESS 100). HESS 100 includes a vacuum chamber 110. Electrical connection portion 102 and working fluid connection portion 104 extend through the wall of vacuum chamber 110. These will be described in detail below. Further, a plurality of actuator motors 152 can be seen, and these will also be described in detail below.

[0024] In this view of HESS 100, only the outer wall surface of vacuum chamber 110 can be substantially seen. The internal components of HESS 100 are shown in subsequent drawings.

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

[0026] HESS 100 can be adjusted to substantially any desired size. For example, in some embodiments, the outer diameter of HESS 100 is 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, without limitation.

[0027] FIG. 2 shows a view of HESS 100 where the lower portion of vacuum chamber 110 is transparent. FIG. 3 shows an exploded view of HESS 100. Specifically, vacuum chamber 110 is illustrated in an exploded state such that the contents inside are visible.

[0028] Both of these figures show an assembly comprising a radiation barrier 120 surrounding a heat storage tank 130 (not visible, see Fig. 5 etc.) disposed within a vacuum chamber 110. The vacuum in the vacuum chamber 110 fills all the spaces within the vacuum chamber 110. Thus, all the internal spaces within the radiation barrier 120 and the heat storage tank 130 are vacuum spaces, and this vacuum space substantially eliminates the occurrence of heat transfer by convection and conduction.

[0029] Furthermore, Fig. 3 shows a portion of a plurality of actuator systems 150 (comprising the actuator motor 152 shown in Fig. 1). The structure and function of the actuator system 150 will be further described below.

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

[0031] The plurality of movable parts 124a - 124d and 126 are physically moved in and out of the fixed part 122 at appropriate timings by the plurality of actuator systems 150. Here, the plurality of movable parts 124a - 124d and 126 are shown in positions outside the fixed part 122. The importance of the mobility of the plurality of movable parts 124a - 124d and 126 will be further described hereinafter.

[0032] The radiation barrier 120 is made of a plurality of material sheets spaced apart from each other (for example, spaced apart by 2 mm or more). These sheets constituting the radiation barrier 120 are a heat-resistant metal sheet, a metal alloy sheet, or a non-metal sheet having a smooth and shiny surface and a low emissivity of thermal radiation (for example, having an emissivity of about 0.2 or less). However, in some embodiments, these sheets constituting the radiation barrier 120 may have an emissivity higher than 0.2. In any case, the sheets constituting the radiation barrier 120 function to block, mitigate, or prevent radiative heat transfer.

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

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

[0035] Referring further to FIGS. 5-8, the thermal energy storage tank 130 is disposed within the radiation barrier 120 (see particularly the exploded view of FIG. 8. In this figure, the upper part of the thermal energy storage tank 130 or the radiation barrier 120 is not shown for improved visibility). The innermost layer of the radiation 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 the radiation barrier 120) is cylindrical. However, FIGS. 9 and 10 show two other possible shapes. Specifically, FIG. 9 shows a thermal energy storage tank 130' having a rectangular cross-sectional shape, and FIG. 10 shows a thermal energy storage tank 130'' having a hexagonal cross-sectional shape. Further, various other possible shapes of thermal energy storage tanks are possible.

[0037] The thermal energy storage tank 130 can be made of materials such as, for example, molybdenum, stainless steel, metal alloys, ceramic coating materials, and other metal or ceramic compositions, but is not limited thereto.

[0038] Referring further to FIGS. 5-8, the thermal energy storage tank 130 includes one or more wall portions defining (i) a sealed inner space 132 and (ii) a plurality of open spaces 134a, 134b, 134c, 134d, and 136 extending within this sealed inner space 132. In the illustrated embodiment, these plurality of open spaces 134a-134d and 136 extend over the entire length from the upper portion to the lower portion of the thermal energy storage tank 130. Thus, it can be said that the wall portions of the thermal energy storage tank 130 defining the plurality of open spaces 134a-134d and 136 are tube-shaped or through-hole-shaped. In this example, these tubes have a rectangular cross-sectional shape. However, it is possible to use any other type of cross-sectional shape, such as circular, triangular, polygonal, etc. Further, in a single embodiment of the thermal energy storage tank 130 (and the radiation barrier 120), it is also possible to combine a plurality of different types of shapes.

[0039] The sealed inner space 132 houses a thermal energy storage medium 140 (not shown). The thermal energy storage medium 140 can be a material such as, for example, silicon, salt, or other materials. When heated, for example, silicon or salt melts within the sealed inner space 132 to store a high level 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. This is only an example, and it should be understood that any number of open spaces can be provided 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 therein the plurality of movable parts 124a - 124d and 126 of the radiation barrier 120. That is, the plurality of movable parts 124a - 124d and 126 of the radiation barrier 120 can extend into (and can be withdrawn from) the plurality of open spaces 134a - 134d and 136 defined by the thermal energy storage tank 130. The fixed part 122 of the radiation barrier 120 surrounds the other outer wall part of the thermal energy storage tank 130 (i.e., the outer wall part other than the wall part that defines the plurality of open spaces 134a - 134d and 136). Thus, all the outer wall part surfaces of the thermal energy storage tank 130 are covered by the radiation barrier 120. Advantageously, this configuration minimizes the radiant heat loss from the thermal energy storage tank 130. However, heat transfer to or from the energy storage tank 130 may be desirable (e.g., when transferring heat energy to the thermal energy storage medium 140 or extracting heat energy from the thermal energy storage medium 140). In such cases, and as further described below, some or all of the plurality of movable parts 124a - 124d and / or 126 of the radiation barrier 120 can be moved out of the plurality of open spaces 134a - 134d and 136 defined by the thermal energy storage tank 130.

[0042] Referring to FIGS. 11 and 12, as described above, the innermost layer of the radiation barrier 120 is spaced from the outer wall part surface of the thermal energy storage tank 130. Further, each layer of the radiation barrier 120 is spaced from an adjacent layer. Spacers 160 can be incorporated into the HESS 100 to provide structural support to the layers of the radiation barrier 120 and the thermal energy storage tank 130 while achieving this physical spacing (which contributes to the achievement of high - level insulation).

[0043] The exemplary spacer 160 is a rectangular member that forms a mechanically robust stack (such as that shown in FIG. 12) by nesting and interlocking with each other. FIGS. 13 and 14 show an L-shaped spacer 160' that is an alternative to the rectangular spacer 160.

[0044] As a result of using the spacer 160, some loss of thermal energy is caused by conduction from the thermal energy storage tank 130 to the radiation barrier 120 and from the radiation barrier 120 to the vacuum chamber 110, but the spacer 160 is specially designed to minimize such losses. For example, the spacer 160 consists of a plurality of pieces of small solid blocks that are stacked vertically and interlocked with each other. The resistance to heat conduction between the minimized boundary surfaces of these stacked spacers 160 is very high. These boundary surfaces are ideally dry boundaries where there is no wetting and fusion between adjacent spacers 160. The resistance to heat conduction at a boundary such as that between two solid blocks is much higher than the resistance to heat conduction through the solid block itself. Therefore, it is advantageous to use a plurality of spacers 160 stacked on top of each other. Furthermore, the solid material of the spacer 160 itself should be selected to have a low thermal conductivity and also sufficient hardness.

[0045] A vertical stack of a plurality of thin solid spacers 160 made of a material such as zirconia, for example, has a very high resistance to heat conduction from one end of the stack to the other end of the stack. Zirconia, which is an oxide of zirconium, has a maximum use temperature of 2249 °C. The compressive strength of zirconia is 5200 Mpa and its low thermal conductivity is 2.7 W / m-K. However, the material for the solid spacer 160 for this purpose is not limited to zirconia.

[0046] The main reason for the very high resistance to heat conduction in the stack of spacers 160 is due to the high resistance to heat conduction at the boundary contact surfaces of each adjacent spacer 160 in the stack. For this reason, it is desirable that a large number of solid spacers 160 be stacked vertically (for example, 5 or more). Furthermore, for this reason, the surface area of the interfacial contact surface should be minimized. The vertical stack of a large number of such solid spacers 160 should be used as one of a number of support columns that support and hold the weight of the plurality of sheets of the thermal energy storage tank 130 and the radiation barrier 120 (for example, the fixed portion 122 of the radiation barrier 120).

[0047] FIG. 15 schematically shows the HESS 100 having a thermal energy storage tank 130 that houses a thermal energy storage medium 140. This thermal energy storage tank 130 is surrounded by a radiation barrier 120 (specifically, the fixed portion 122 of the radiation barrier 120), and the radiation barrier 120 is disposed inside the vacuum chamber 110. Further, a plurality of stacks of spacers 160 are illustrated. As shown, the spacers 160 are used to provide vertical support and physical rigidity to the structure of the HESS 100.

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

[0049] FIG. 16 is another schematic view showing the use of a stack of spacers 160 in the HESS 100. Here, a top view of the HESS 100 shows a thermal energy storage tank 130 that houses a thermal energy storage medium 140, and this thermal energy storage tank 130 is surrounded by a radiation barrier 120 (specifically, the fixed portion 122 of the radiation barrier 120).

[0050] In the schematic example shown, the stack of spacers 160 is arranged in two radial groups (an inner radial group and an outer radial group). Such an arrangement of multiple stacks of spacers 160 can be utilized to provide vertical support and physical rigidity to the structure of HESS100. Further, as shown in FIG. 8, it should be noted that in some embodiments, the inner wall portion of the thermal energy storage tank 130 can be provided with vertical beams 138 to provide additional rigidity to the wall portion of the thermal energy storage tank 130.

[0051] Further, FIG. 16 shows a plurality of movable parts 124a - 124d and 126 of the radiation barrier 120 illustrated within a plurality of open spaces 134a - 134d and 136 defined by the thermal energy storage tank 130. The movement of the plurality of movable parts 124a - 124d and 126 of the radiation barrier 120 will be described below with reference to FIGS. 17 - 25.

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

[0053] As shown in FIG. 22, in the fully deployed configuration, all the sheets of the movable portion 124 of the radiation barrier 120 are positioned to block radiative heat transfer between the thermal energy storage tank 130 and the thermal member 170. In this illustration, there are nine separate sheets that make up the fixed portion 122 and the movable portion 124 of the radiation barrier 120. This is merely an example. In some embodiments, it is possible for ten or more or eight or fewer separate sheets to make up the fixed portion 122 and the movable portion 124 of the radiation barrier 120.

[0054] Further, FIG. 22 shows an example of a manner in which the sheets of the fixed portion 122 and the movable portion 124 of the radiation barrier 120 can be joined to each other. 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. Further, the upper edge portion of the sheet of the movable portion 124 extends horizontally in an almost aligned (almost contacting) state with the edge portion of the horizontally extending sheet of the fixed portion 122. These types of proximity or overlapping boundaries between the sheets of the fixed portion 122 and the movable portion 124 of the radiation barrier 120 are specially designed to block radiative heat transfer through these boundaries.

[0055] Referring to FIG. 18, here, the configuration of the movable portion 124 of the radiation barrier 120 is adjusted by pulling up some of the sheets of the movable portion 124 from a previous position where they blocked radiation between the thermal energy storage tank 130 and the thermal member 170 (in comparison with FIG. 17). This is also schematically shown in FIG. 23. In this example, one group of three out of the nine sheets of the movable portion 124 has been pulled up from a previous position where they blocked radiation between the thermal energy storage tank 130 and the thermal member 170. Therefore, it can be assumed that here, the resistance to heat transfer between the thermal energy storage tank 130 and the thermal member 170 realized by the movable portion 124 of the radiation barrier 120 is adjusted to a lower resistance.

[0056] The upward movement of the three sheets of the movable part 124 can be caused as a result of the operation of the actuator system 150. Next, an example of this actuator system 150 will be described in more detail.

[0057] Referring to FIG. 21, an example of the actuator system 150 is shown separated so that its components can be more easily observed. The actuator system 150 includes a plurality of actuator motors 152 (e.g., DC servo motors, stepping motors, etc.), and each motor drives one or more pinion gears 154 that respectively mesh with a rack 156 mounted to the vertical plate 158. Further, the vertical plate 158 is respectively mounted to one or more sheets of the movable part 124 of the radiation barrier 120. In this non-limiting example, each of the vertical plates 158 is attached to a group consisting of three sheets of the movable part 124 of the radiation barrier 120. It is possible to group any number of sheets, or these sheets can also be moved individually by the actuator system 150. In any case, when the actuator motor 152 is activated, each vertical plate 158 is driven upward or downward, and further the associated sheets of the movable part 124 are driven upward or downward.

[0058] In the illustrated embodiment, a corresponding pair of actuator motors 152 are activated simultaneously, whereby two vertical plates 158 (one located on each side of a group of sheets of the movable part 124) are moved synchronously. It should be understood that this type of actuator system 150 is only an example, and the use of other types of actuator systems (e.g., cable and capstan systems, linear actuator systems, etc.) is also possible.

[0059] Referring further to FIG. 18, it can be seen here that two vertical plates 158 are driven upward and extend far above the height of the actuator motor 152. These vertical plates 158 are accommodated in the upper attached chamber portion 110' of the vacuum chamber 110 within 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 actuated to pull up a second group consisting of three sheets of the movable portion 124 of the radiation barrier 120. This configuration is also schematically shown in FIG. 24. In this example, at this time, it can be seen that the six sheet layers of the movable portion 124 have been moved from a state of blocking radiative heat transfer between the thermal energy storage tank 130 and the thermal member 170, and only three sheets of the movable portion 124 remain. Therefore, here, the resistance to radiative heat transfer between the thermal energy storage tank 130 and the thermal member 170 is further reduced (compared to the conventional configuration shown in FIGS. 18 and 23). Advantageously, this configuration can be used to adjust the amount of heat transfer between the thermal energy storage tank 130 and the thermal member 170 in some scenarios.

[0061] Referring to FIG. 20, in the illustrated configuration, yet another pair of actuator motors 152 is actuated to pull up a third group consisting of three sheets of the movable portion 124 of the radiation barrier 120. This configuration is also schematically shown in FIG. 25. In this example, at this time, it can be seen that all nine sheet layers of the movable portion 124 have been moved from a state of blocking radiative heat transfer between the thermal energy storage tank 130 and the thermal member 170, and no sheets of the movable portion 124 remain. Therefore, here, the resistance to radiative heat transfer between the thermal energy storage tank 130 and the thermal member 170 is eliminated. Advantageously, this configuration can be used to maximize the amount of heat transfer between the thermal energy storage tank 130 and the thermal member 170 in some scenarios.

[0062] FIG. 26 is an exploded view showing a multi-sheet radiation barrier 120 (having movable parts 124a to 124d and 126 and a fixed part 122) that covers the entire outer wall surface of a thermal energy storage tank 130 (not shown). Further, as an example, four heating devices 180a to 180d and a heating reservoir 190 are also shown. Corresponding to FIG. 1, the heating devices 180a to 180d have electrical connection parts 102, and the heating reservoir 190 has a working fluid connection part 104.

[0063] Referring further to FIG. 27 (the radiation barrier 120 and the thermal energy storage tank 130 are transparent), each of the four heating devices 180a to 180d is disposed within a corresponding one of the closed spaces of the movable parts 124a to 124d of the radiation barrier 120, and the heating reservoir 190 is disposed within the closed space of the movable part 126 of the radiation barrier 120. It should be understood that this configuration is merely exemplary. That is, the HESS 100 can be provided with various other configurations and / or amounts of heating devices and / or heating reservoirs that are similarly envisioned within the scope of the present disclosure.

[0064] FIG. 28 shows 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, for example, a solar panel or a wind turbine. At step 220, the electricity from the renewable energy source is used to energize one or more heating devices of the HESS (e.g., one or more of the heating devices 180a to 180d as described above are energized by the electricity received from the renewable energy source).

[0065] In step 230, one or more first portions of the movable radiation barriers of the HESS are moved from the first configuration to the second configuration, increasing the radiative heat transfer from the energized heating device 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 radiation barrier 120 are moved (upward) away from a state that blocks the radiative 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] In step 240, the previously energized heating device is de-energized.

[0067] In step 250, after de-energizing the previously energized heating device, one or more first portions of the movable radiation barriers of the HESS are moved so as to return from the second configuration to the first configuration, reducing the radiative 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 radiation barrier 120 are moved downward, blocking the radiative heat transfer from the thermal energy storage medium 140 contained within the thermal energy storage tank 130.

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

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

[0070] In step 280, one or more second portions of the movable radiation barrier are moved from the second configuration to the first configuration, thereby reducing the radiative heat transfer from the thermal energy storage medium. For example, in the case of the HESS100 described herein, when the movable part 126 of the radiation barrier 120 is moved downward, the radiative heat transfer from the thermal energy storage medium 140 contained in the thermal energy storage tank 130 is blocked.

[0071] Additional features and explanations The HESS as described herein is a new energy storage system with extremely excellent heat insulation properties that stores thermal energy for a long time by a sophisticated heat insulation system in a vacuum chamber by converting electrical energy from renewable energy sources such as sunlight and wind power into thermal energy of high-temperature materials such as high-temperature silicon / molten silicon or high-temperature salt / molten salt.

[0072] As described herein, HESS can be considered to comprise the following four main components: (i) a thermal energy storage medium contained in a heat-resistant thermal energy storage tank made of tungsten, molybdenum, stainless steel, or other heat-resistant materials having suitable physical properties; (ii) a first heat exchange system that transfers the thermal energy of 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 the heat generated by an energized ohmic heating device (resistance 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 a plurality of radiation barrier shielding sheet layers surrounding the thermal energy storage tank, the two heat exchange systems, and other auxiliary components of HESS. The unique and novel feature of the support structure of HESS is that the inevitable heat energy loss of the thermal energy storage tank due to heat conduction through the direct contact between the materials of the support structure is significantly minimized. Further, the HESS described herein can also be synergistically integrated into a hybrid energy storage system that can optionally include a heat engine (having a steam turbine and a power generation system) and a FESS (flywheel energy storage system).

[0073] The salts present in conventional molten salt ESS are heated by an ohmic heating unit driven by electricity when the ohmic heating unit and the molten salt or molten salt container are in direct contact. Similarly, conventionally, a heat exchanger between a high-temperature salt or molten salt and the working fluid of a heat engine (e.g., a steam turbine, etc.) is heated by the molten salt when the molten salt and the heat exchange pipes carrying steam from and to the steam turbine are in direct contact. The materials used for the heat exchanger are excellent heat conductors, and thus the heat conduction of these materials of the heat exchanger results in significant heat energy loss.

[0074] Another new feature of HESS described herein is that the heat exchange between the thermal energy storage tank and the ohmic heating unit driven by the power from renewable energy, and the heat exchange between the thermal energy storage tank and the working fluid of the heat engine capable of generating electricity, are 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 the heating reservoir containing the working fluid of the heat engine.

[0075] As further important features of HESS described herein, there are the extremely excellent heat insulation of the thermal energy storage tank, non-contact heat transfer between the main components, the built-in type controllability of the heat exchange rate between the main components, and the unique and new support structure that supports and maintains the structural integrity of the thermal energy storage tank while minimizing heat loss due to conduction through physical contact of the support structure between the thermal energy storage tank and the radiation shielding sheet of the radiation barrier.

[0076] The shape of the HESS thermal energy storage tank described in this specification is not a very simple shape in terms of topology. The reason why the shape of the thermal energy storage tank is not very simple in terms of topology 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 where heat radiation transfer occurs between the thermal energy storage tank and 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. Furthermore, this is also the reason why the heating reservoir for the working fluid of the heat engine is arranged inside the through-hole of the thermal energy storage tank. These are the reasons why the 3D shape of the thermal energy storage tank is significantly different topologically from the 3D shape of a conventional molten salt container for energy storage.

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

[0078] The novel feature of the HESS described herein is that the number of sheets of the radiation 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 the operation of the HESS. By doing so, advantageously, the heat transfer rate due to radiative 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 be adjusted or controlled (automatically or manually) during the operation of the HESS described herein. These features can be used, for example, to avoid overheating of the working fluid when passing through the heating reservoir when the temperature of the thermal energy storage tank is excessively high. For example, in the case of molten salt, 700 °C may be too high. In the case of molten silicon, 1,800 °C may be too high. When the temperature of the thermal energy storage tank is excessively high, most of the sheets of the tube of the movable sheet of the radiation barrier stay in its through holes, so it is necessary to avoid overheating of the working fluid by attenuating the heat transfer from the thermal energy storage tank to the heating reservoir. When the temperature of the thermal energy storage tank is excessively low, most or all of the sheets of the tube of the movable sheet of the radiation barrier are pulled up, so it is necessary to avoid underheating of the working fluid by increasing the heat transfer from the thermal energy storage tank to the working fluid in the heating reservoir. When the HESS itself is in an idle state, in other words, when heating of the working fluid is not required, all the sheets of the movable sheet of the radiation barrier are kept deployed in the through holes of the thermal energy storage tank, so it is necessary to minimize the heat energy loss via thermal radiation from the thermal energy storage tank. This feature can also be used to avoid 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 the sheets of the movable sheet of the radiation barrier surrounding the ohmic heating unit stay in the through holes, thereby minimizing the heat energy loss of the thermal energy storage tank.

[0079] This specification includes many specific implementation details, but 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. Specific features described in the context of separate embodiments herein may also be implemented in combination in a single embodiment. In contrast, the various features described in the context of one embodiment may also be implemented separately or in any suitable sub-combination in multiple embodiments. Further, even if a feature is described herein as acting in a particular combination and is initially claimed as such, one or more features in the claimed combination may, in some cases, be deleted from that combination, and the claimed combination may be directed to a sub-combination or a modified sub-combination.

[0080] Similarly, while operations are shown in the drawings in a particular order, this should not be understood as requiring that those operations be performed in the particular order or sequence shown, or that all of the illustrated operations be performed, in order to achieve the desired result. In some situations, concurrent and parallel processing may be advantageous. Further, the separation of the 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 appended claims. For example, the acts recited in the claims can be performed in a different order and still achieve the desired result. As one example, the processes illustrated in the accompanying drawings do not necessarily require the particular order or sequential order shown to achieve the desired result. In some implementations, simultaneous and parallel processing may be advantageous.

Explanation of Reference Numerals

[0082] 100 Thermal energy storage system 102 Electrical connection part 104 Working fluid connection part 110 Vacuum chamber 110' Upper attached chamber part 120 Radiation barrier 122 Fixed part 124 Movable part 124a Movable part 124b Movable part 124c Movable part 124d Movable part 126 Movable part 130 Thermal energy storage tank, energy storage tank, heat storage tank 130' Thermal energy storage tank 130'' Thermal energy storage tank 132 Internal space 134a Open space 134b Open space 134c Open space 134d Open space 136 Open space 138 Vertical beam 140 Thermal energy storage medium 150 Actuator system 152 Actuator motor 154 Pinion gear 156 Rack 158 Vertical plate 160 Spacer, rectangular spacer 160' L-shaped spacer 170 Heat member 180a Heating device 180b Heating device 180c Heating device 180d Heating device 190 Heating reservoir

Claims

1. A vacuum chamber, A thermal energy storage tank disposed within the vacuum chamber, the thermal energy storage tank comprising one or more wall portions defining (i) a sealed internal space and (ii) a plurality of open spaces extending within the sealed internal space, A thermal energy storage medium disposed within the sealed internal space, A first heating device disposed within a first open space of the plurality of open spaces, A radiation barrier disposed on an outer surface of the one or more wall portions of the thermal energy storage tank, a first portion of the radiation barrier being disposed between (a) the one or more wall portions defining the first open space and (b) the first heating device, A first actuator system coupled to the first portion of the radiation barrier Comprising, The first actuator system is operable to increase radiative heat transfer from the first heating device to the thermal energy storage medium by at least partially moving the first portion of the radiation barrier from between the one or more wall portions defining the first open space and the first heating device, an energy storage system.

2. The energy storage system according to claim 1, wherein the radiation barrier comprises a plurality of material sheets spaced apart from the one or more wall portions and from each other.

3. The energy storage system according to claim 2, further comprising spacer members disposed between at least some of the plurality of material sheets such that the plurality of material sheets are spaced apart from each other.

4. The energy storage system according to claim 3, wherein the spacer members comprise a plurality of discrete portions stacked on top of each other.

5. Further comprising a heating reservoir configured to contain a fluid, the heating reservoir being disposed within a second open space of the plurality of open spaces, the energy storage system according to any one of claims 1 to 4.

6. Further comprising a second actuator system coupled to a second portion of the radiation barrier disposed between (i) the one or more wall portions defining the second open space and (ii) the heating reservoir The energy storage system according to claim 5, wherein the second actuator system is operable to increase radiative heat transfer from the thermal energy storage medium to the fluid contained in the heating reservoir by at least partially moving the second portion of the radiation barrier from between the one or more wall portions defining the second open space and the heating reservoir.

7. The energy storage system according to any one of claims 1 to 6, wherein the plurality of open spaces extending into the sealed interior space comprises at least two open spaces.

8. The energy storage system according to any one of claims 1 to 7, further comprising at least one additional heating device in addition to the first heating device, each additional heating device being disposed within a respective one of the plurality of open spaces.

9. The energy storage system according to any one of claims 1 to 8, wherein a horizontal cross-section of the thermal energy storage tank has a circular or polygonal outer contour.

10. The energy storage system according to any one of claims 1 to 9, wherein the thermal energy storage medium comprises salt or silicon.

11. The energy storage system according to any one of claims 1 to 10, wherein the first heating device comprises a resistive heating element.

12. The energy storage system according to any one of claims 1 to 11, wherein a portion of the radiation barrier that is not disposed on the one or more wall portions defining the plurality of open spaces is configured to be fixed relative to the thermal energy storage tank.

13. The energy storage system according to any one of claims 1 to 12, wherein the radiation barrier comprises at least two material sheets spaced apart from the one or more wall portions and from each other.

14. A method of storing energy, comprising Delivering electrical energy to one or more resistance heating devices respectively disposed within each of a plurality of open spaces defined by a thermal energy storage tank disposed within a vacuum chamber, wherein the thermal energy storage tank further defines a sealed internal space containing a thermal energy storage medium, the plurality of open spaces extending into the sealed internal space, and a radiation barrier being disposed on an outer surface of the thermal energy storage tank, the step; Increasing radiative 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 radiation barrier out of each of the respective open spaces; A method comprising.

15. The method according to claim 14, further comprising reducing radiative heat transfer from the thermal energy storage medium by moving the one or more portions of the radiation barrier back into the respective open spaces after the step of delivering electrical energy to the one or more resistance heating devices.

16. The method according to claim 14 or 15, further comprising delivering a fluid to a heating reservoir disposed within an additional open space of the plurality of open spaces defined by the thermal energy storage tank.

17. The method according to claim 16, further comprising increasing radiative heat transfer from the thermal energy storage medium to the fluid by at least partially moving an additional portion of the radiation barrier out of the additional open space.

18. The method according to claim 17, further comprising reducing radiative heat transfer from the thermal energy storage medium by moving the additional portion of the radiation barrier back into the additional open space after the step of heating the fluid by the radiative heat transfer from the thermal energy storage medium.

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