Energy Storage Device

Abstract

The energy storage device includes a plurality of plates, each plate having a first surface and a second surface, with a plurality of grooves formed in at least one of the surfaces. The device further includes an inlet plenum and an outlet plenum for providing a heat transfer medium to or receiving a heat transfer medium from the plurality of grooves. At least one of the first surface and the second surface of a first plate having the plurality of grooves formed therein is positioned in direct contact with the other of the at least the first surface and the second surface of an adjacent second plate. As the heat transfer medium passes along the plurality of grooves, heat is transferred from the transfer medium to the plate in a charging mode of operation or from the plate to the transfer medium in a discharging mode of operation.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 522,737, entitled "Energy Storage Device", filed June 21, 2017, which is a continuation-in-part of U.S. Provisional Patent Application No. 15 / 979,628, entitled "Energy Storage Device", filed May 15, 2018, which claims priority to U.S. Provisional Patent Application No. 62 / 522,737, entitled "Energy Storage Device", filed June 21, 2017, the contents of which are incorporated herein by reference.

[0002] The present invention relates generally to energy storage, and more particularly to a modular, low-cost thermal energy storage device. [Background technology]

[0003] Creating an energy storage means that will level the power grid without requiring a large amount of spinning reserve has been a huge challenge. Non-dispatchable renewable energy devices such as solar cells and wind turbines are becoming more and more prevalent, which is detrimental to the stability of the power grid. Traditional energy storage solutions such as pumped hydro storage and batteries are extremely difficult to address due to their limited capacity and environmental concerns. Relatively low-cost storage could be achieved and utilized in nuclear power plant reactors by storing energy not as electricity but as heat generated just prior to power generation, either from a heat pump arrangement or from the heat source used to generate electricity. While heat storage is not new per se, designs that allow for efficient storage of energy in relatively low-cost modules using common materials, rather than due to expensive salt or terrain that is not always present everywhere, have been difficult to achieve. It is therefore an object of the present invention to provide a low-cost modular energy storage device constructed from common and readily available materials. Summary of the Invention [Means for solving the problem]

[0004] These and other objects are achieved in one embodiment by an energy storage device comprising a plurality of plates made of a concrete-like material and supported in parallel with flow spaces therebetween large enough to allow a heat transfer medium to pass substantially over their faces. An inlet plenum in fluid communication with a first end of the flow spaces is configured to receive the heat transfer medium from a heat source and distribute the heat transfer medium through the flow spaces across the faces of the plates. An outlet plenum in fluid communication with a second end of the flow spaces is configured to receive the heat transfer medium from the flow spaces and discharge the heat transfer medium to a return destination. A portion of the heat in the heat transfer medium is transferred to the plates in a charging mode of operation, or a portion of the heat in the plates is transferred to the heat transfer medium in a discharging mode of operation.

[0005] In one embodiment, the plates are housed in a metallic casing, preferably the plates are supported on opposite edges and extend horizontally such that the heat transfer medium flows horizontally in parallel flows through the flow spaces between the plates, preferably the heat transfer medium is oil or salt.

[0006] In other embodiments, the plates are grooved in a direction perpendicular to the flow direction of the heat transfer medium, the grooves being spaced along the length of the plates to provide a thermal break and slow the diffusion of heat along the length of the plates following partial filling, i.e., the transfer of heat between areas of the plate that contain heat and areas of the plate that do not contain as much heat. Preferably, the grooves are spaced at intervals of 6 inches to 4 feet along the length of the plates. The energy storage device is desirably configured to operate between about 140°F and 600°F. In such embodiments, the energy storage device has charging and discharging operations each performed in opposite fluid flow directions, similar to the operation of a counterflow heat exchanger. In such embodiments, the concrete-like plates may include micro-rebar or other similar three-dimensional reinforcement. In further embodiments, at least a portion of the flow space between the plates includes insulation and / or at least some portions of the plates are insulated from downstream portions of the plates to form a thermal break. Other embodiments employ smaller plates, with the breaks between the plates providing such a thermal break.

[0007] The present invention also contemplates a method of storing thermal energy comprising forming a heat transfer module comprising a plurality of heat transfer plates made of a concrete-like material, spaced apart from one another and supported in parallel to define a flow space therebetween, the heat transfer plates being enclosed within a housing having an inlet plenum at one end of the flow space and an outlet plenum at the other end of the flow space, the method directing a heat transfer medium across and between faces of the plurality of heat transfer plates through the inlet plenum, transferring heat from the heat transfer medium to the plurality of heat transfer plates, and expelling the heat transfer medium from the housing through the outlet plenum.

[0008] Preferably, the directing step includes directing the heat transfer medium parallel and horizontally across and between a plurality of heat transfer medium plates. In one embodiment, the method includes reinforcing the heat transfer plates with micro-rebar or other similar three-dimensional reinforcement. Preferably, the method applies thermal breaks to the plates to retard heat diffusion along the length of the plates after partial filling. In one embodiment, the thermal breaks are flutes extending perpendicular to the flow direction of the heat transfer medium. Preferably, the flutes are spaced at intervals of 6 inches to 4 feet. In another embodiment, the thermal breaks are separators between adjacent smaller plates.

[0009] The method also operates the heat transfer module between about 140° F. and 600° F. The method also includes charge and discharge operations performed in opposite fluid flow directions, similar to the operation of a counterflow heat exchanger.

[0010] In yet another embodiment, an energy storage device includes a plurality of separation plates, each of the separation plates having a first surface and an opposing second surface, at least one of the first surface and the second surface having a plurality of grooves formed therein; an inlet plenum configured to receive a heat transfer medium from a heat source and distribute the heat transfer medium through the plurality of grooves; and an outlet plenum configured to receive the heat transfer medium from the plurality of grooves and discharge the heat transfer medium to a return destination. Each groove extends from a first edge disposed near the inlet plenum to an opposing second edge disposed near the outlet plenum of a respective plate of the plurality of separation plates. At least one of the first surface and the second surface of the first plate having the plurality of grooves formed therein is disposed in direct contact with the other of at least the first surface and the second surface of an adjacent second plate. A portion of the heat in the heat transfer medium is transferred to the plate in a charging mode of operation when the heat transfer medium passes along the grooves, or a portion of the heat in the plate is transferred to the heat transfer medium in a discharging mode of operation when the heat transfer medium passes along the plurality of grooves.

[0011] Each plate may be formed from a high specific heat material. Each plate may be formed from a concrete material. Each channel may be generally shaped like a circular segment when viewed along each channel. The plurality of separation plates may be arranged vertically stacked with the first and second faces arranged horizontally. The plurality of separation plates may be arranged vertically at the edges with the first and second faces arranged vertically. Each plate may have a thickness of about 0.5 inches to about 6 inches. Each plate may have a thickness of about 4 inches. Each channel may have a depth of about 0.25 inches to about 1 inch. Each channel may have a width of about 0.5 inches to about 2.5 inches and may be spaced from adjacent channels by a separation distance of about 0.25 inches to about 2 inches. The energy storage device may be configured to operate between about 140°F and 600°F. The plates may include micro-rebar or other three-dimensional reinforcement.

[0012] The present invention further contemplates another method of storing thermal energy, the method comprising forming a heat transfer module comprising a plurality of separator plates, each of the plates having a first side and an opposing second side, at least one of the first side and the second side having a plurality of grooves formed therein; an inlet plenum; and an outlet plenum, each groove extending from a first edge of each of the plurality of separator plates disposed near the inlet plenum to an opposing second edge disposed near the outlet plenum. the first plate extending from the inlet plenum to the outlet plenum, with at least one of the first and second faces of the first plate having the plurality of grooves formed therein being disposed in direct contact with the other of the at least the first and second faces of the adjacent second plate; directing a heat transfer medium from the inlet plenum to the outlet plenum through the plurality of grooves of the plurality of separation plates; transferring heat from the heat transfer medium to the plurality of separation plates in a charging mode of operation or transferring heat from the plurality of separation plates to the heat transfer medium in a discharging mode of operation; and discharging the heat transfer medium from the outlet plenum.

[0013] The method may include operating the heat transfer module at between about 140° F. and 600° F. A charge mode of operation, in which heat is transferred from the heat transfer medium to the plurality of separator plates, and a discharge mode of operation, in which heat is transferred from the plurality of separator plates to the heat transfer medium, may each be performed in opposite fluid flow directions, similar to the operation of a counterflow heat exchanger.

[0014] These and other objects, features, and properties of the present invention, as well as its method of operation and function of the associated elements of its structure, and combination of parts and economies of manufacture, will become more apparent from a consideration of the following description and appended claims, taken in conjunction with the accompanying drawings, all of which form a part hereof, and in which like reference numerals indicate corresponding parts in the various views, It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.

[0015] A further understanding of the invention can be obtained from the following description of the preferred embodiments, when read in conjunction with the accompanying drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a simplified perspective view of a portion of a housing of an energy storage device according to an exemplary embodiment of the present invention, showing several plates in a position having flow spaces therebetween. [Diagram 2] FIG. 1 is a cross-sectional view of an entire module of an energy storage device according to an exemplary embodiment of the present invention, including all plates showing the intake plenum and thermal break. [Diagram 3] FIG. 3 is a simplified perspective view of one of the plates of the arrangement of FIG. 1 or FIG. 2; [Figure 4] FIG. 2 is a simplified perspective view of a generally assembled energy storage device housing according to an exemplary embodiment of the present invention. [Diagram 5]FIG. 5 is a simplified perspective view of the elongated outer shell of FIGS. 1, 2 and 4, shown extending the longitudinal extent of the housing and in a position such that the plate holder supports the plate horizontally. [Figure 6] FIG. 6 is a simplified perspective view of one end cap closing one end of the shell shown in FIG. 5. [Figure 7] 7 is a simplified perspective view of a second end cap closing a second end of the shell shown in FIG. 5 and is a mirror image of the one end cap shown in FIG. 6. [Figure 8] FIG. 13 is a simplified partial schematic perspective view of another energy storage device utilizing an alternative arrangement of plates according to another exemplary embodiment of the present invention, shown disposed within a housing (shown with hidden lines); [Figure 9] FIG. 9 is a simplified perspective view of one of the plates of the arrangement of FIG. 8. [Figure 10] FIG. 9 is a simplified elevational view of one end of the plate arrangement of FIG. 8. [Figure 11] 11 is an enlarged view of a portion of the elevation view of FIG. 10 as shown in FIG. 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention provide an arrangement and method for storing thermal energy in a modular manner using low cost materials.

[0018] One exemplary approach according to the present invention is illustrated in Figures 1-7. In this first embodiment, thermal energy storage is achieved by arranging a plurality of plates 10 (shown in Figures 1, 2, and 3). Each plate 10 has a thin cross-section and is formed from a high specific heat material. As used herein, a "high specific heat material" is a material having a heat capacity of at least 0.75 kJ / kg·K. Some examples of suitable high specific heat materials employed in embodiments of the present invention include concrete, high performance concrete, ultra-high performance concrete, high strength concrete, and high temperature concrete. Phase change materials, thermochemical materials, and / or concrete containing large amounts of fly ash may also be employed. Such concrete materials can be easily formed from readily available low-cost materials to provide a sturdy plate with a high heat capacity. Some other examples of high specific heat materials from which the plate 10 may be constructed include firebrick, ceramics, solid salt, and metals.

[0019] The plates 10 are positioned close to each other, forming flow passages 12 between them. The plates 10 are then assembled into a low-cost metallic modular housing shell 14 that incorporates guide slots 16 formed between adjacent separators 18 to maintain the spacing between the plates 10 that form the flow passages 12. Alternatively, separators, which may be attached to or cast into the plates 10, may be utilized to space the concrete plates. The shell 14 is assembled, and then two end caps 22, 24 are placed on either end of the shell 14, respectively, and attached to the shell 14, such as by welding, to form plenums 26 between each end of the plate 10 and each of the respective end caps 22, 24. The two plenums 26 and flow passages 12 are placed horizontally to allow circulation of a heat transfer fluid (oil, salt, etc.) between the plates 10, transferring energy to the plates 10 with a thermal gradient down the assembly length as the "fill level" increases. When heat is to be removed, the flow is reversed, allowing the device to operate like a counter-flow heat exchanger. It should be understood that the illustrated plenum 26 is shown for illustrative purposes only, and one or more of the shape, size, inlet size, location, quantity, etc. may be modified without departing from the scope of the present invention.

[0020] Each of the plates 10 may be grooved, i.e., grooved vertically (i.e., perpendicular to the flow direction) substantially along the entire height of the concrete plate 10, at predetermined distances along the length of the plate 10, to reduce the effect of heat waves traveling down the plate 10 when no heat transfer fluid is flowing. The predetermined distance is preferably 6 inches to 4 feet, but may be longer depending on the length of the module 100 (FIG. 2). In FIG. 2, the grooves 28 can be clearly seen. Alternatively, smaller separation plates 10 may be used, with the gaps between adjacent plates 10 functioning similarly to the grooves 28. Also, such smaller plates generally provide easier assembly.

[0021] Thin strips of material, including but not limited to insulating material, figuratively represented in Figure 1 by reference numeral 34, may run from one plenum to the other along the center of the channels 12 to bind the structure and maintain plate spacing while not adversely affecting performance characteristics. Insulation may also be embedded in the flutes 28 or may replace the flutes entirely with insulating material to bind adjacent portions of the heat transfer plates. Although the plates 10 are shown extending horizontally, it should be understood that they may alternatively be configured to extend vertically and still be within the scope of the present invention, although in comparable embodiments horizontal channels are preferred due to the lower static pressure.

[0022] Thus, in one embodiment of the present invention, a concrete structure formed of multiple plates 10 encased in a housing 20 (i.e., shell 14 and end caps 22 and 24) is employed to provide a large surface area to volume ratio for storing thermal energy from a heat source such as a nuclear reactor or heat pump. Preferably, the plates 10 are formed from concrete material and contain micro-rebar or other similar admixtures for strength, durability, and heat transfer. Alternatives to micro-rebar include steel, steel fiber, glass fiber, carbon fiber, other metals, composites, and high temperature plastics. It is not necessary to utilize piping, but metal or composite tubes may be employed in place of the preferred flow path structure described above. All heat transfer media within the module is conducted by a metal casing and relatively thin concrete plates employed within the casing to store heat.

[0023] Flow paths for the heat transfer medium or fluid are formed between adjacent plates 10 to maximize surface area while minimizing conduction distances and pumping power required to move the heat transfer medium. The separators 18 may be thin strips, rods or bars of material and may be constructed of high temperature plastics, metals, composites or fiberglass. Preferably, the heat transfer medium is non-pressurized and constructed of oils or salts with suitable properties to prevent negative interactions with concrete or metal structures and may be treated with a protective film to inhibit such interactions. Heat transfer media may be hydrocarbon-based fluids such as Therminol, Duratherm HF, Calder 1, Mobiltherm, Paratherm, Dowtherm, Phillips 66, silicon-based fluids such as Duratherm S, Syltherm, solution salts such as nitrates.

[0024] In one embodiment, the plates 10 are grooved along their height, i.e., perpendicular to the flow of the heat transfer medium, to provide a thermal break to slow down heat diffusion between the plates 10 following partial filling, i.e., heat transfer from the heat transfer medium to the plates 10 that only partially fills the thermal capacity of the plates 10 to store heat. The thermal break prevents the plates 10 from equalizing the temperature between them, which would otherwise prevent high quality heat recovery during heat dissipation after partial filling. In other embodiments, smaller separating plates are used, with the separation between adjacent plates providing the thermal break.

[0025] The housing 20 may be made of plastic, coated carbon steel, stainless steel, composites or fiberglass and preferably has a layer of insulation either inside, around the inside perimeter or around the outside of the housing, which may be air gaps in a multi-layer shell, fiberglass, foam glass, aerogel, ceramic, mineral fiber / cotton, or silica.

[0026] 1-7 may be operated with plates 10 in either a horizontal or vertical orientation. Additionally, shell 14, end caps 22 and 24, and plates 10 may be constructed at the site of use, or a fully constructed housing 20 and plates 10 may be shipped separately and assembled at the site, or any combination thereof.

[0027] Thermal energy is input and output from the fluted structure using a thermal gradient that varies along the long axis of the plate 10. Operating temperatures can range from as low as 140°F to as high as 600°F. Heat charge and discharge operations are performed in opposite fluid flow directions, similar to the operation of a counterflow heat exchanger. To minimize labor and maximize production efficiency, micro-rebar or similar admixtures may be used in place of traditional concrete reinforcement.

[0028] Preferably, the pressure of the incoming heat transfer medium is atmospheric or slightly above, i.e., 14.5-21.8 psia. The flow rate of the heat transfer medium is desirably about 0-22.0 lbs / s per module, preferably about 4 lbs / s. The plates 10 are about 0.5-6 inches thick, more preferably about 4 inches thick. The flow spaces are about 0.04 inches to 0.5 inches wide, more preferably about 0.4 inches wide.

[0029] 1 shows a shell 14 having three plates 10 spaced apart by module guide slots 16 extending from the underside of the top wall of the shell 14 portion of a housing 20 to form flow spaces or flow channels 12 between the plates 10. Although the flutes 28 are shown as vertically extending grooves, it should be understood that the flow of heat transfer medium preferably extends parallel, horizontally through the flow spaces across substantially the entire face of the plates 10, although the flow may also be directed vertically by plenums at the top and bottom of the modules instead of at the ends.

[0030] FIG. 2 shows a cutaway of the entire module 100 including all plates 10 with plenums 26 at each end of the elongated dimension of the plates 10, with the left plenum being more evident and having an inlet or outlet nozzle 30 shown in the upper left corner of the module 100. It makes no difference whether the plenum 26 on the right or left side is an inlet or outlet plenum, since the heat transfer medium, indicated by the double arrow 32 in FIG. 2, will flow in both directions, i.e., in the direction to fill the plates 10 with heat and in the opposite direction to release heat from the concrete plate. FIG. 3 shows a perspective view of one of the plates 10. FIG. 4 shows a perspective view of the housing parts assembled, and FIG. 5, FIG. 6, and FIG. 7 show perspective views of the housing parts disassembled.

[0031] Referring now to Figures 8-11, another embodiment of an energy storage device 200 according to another exemplary embodiment of the present invention will be described. Similar to the arrangement previously described with respect to Figures 1-7, the device 200 employs a plurality of plates 210 having similar material construction as the plates 10 previously described and positioned within a low-cost metal modular housing shell 220 (shown diagrammatically in hidden lines in Figure 8) such that a plenum 226 is formed at each end of the device 200. Unlike the previously described arrangements that rely on spacing of the plates 10 to form flow paths 12, the arrangement shown in Figures 8-11 utilizes a plurality of grooves 212 formed in each of the plates 210 to create flow paths for circulating a heat transfer fluid (e.g., oil, salt, etc.) between the plates 210. Each groove 212 extends from a first edge (not numbered) of the respective plate 210 located near a first one of the plenums 226 to an opposite, opposing second edge (not numbered) located near an opposite second one of the plenums 226. 8-11, each groove 212 may extend linearly across each plate 210. Alternatively, one or more of the plurality of grooves 212 may extend non-linearly (e.g., curved, serpentine, zigzag, etc.) without departing from the scope of the present invention.

[0032] Because the grooves 212 function as flow paths for the heat transfer fluid, the plates 210 are preferably placed in direct contact with one another and thus may be easily placed edge-on (similar to books on a bookshelf) as shown in FIG. 8 or may be laid flat in a stack. In one exemplary embodiment, the grooves 212 are cast as a feature of each plate 210 during the formation of the plates 210 themselves, although it should be understood that such grooves 212 may be formed via any other suitable method and / or subsequently without departing from the scope of the present invention. It should also be understood that, although in the illustrated embodiment, such grooves 212 are formed on only one side of each plate 210, such grooves may be formed on multiple sides (e.g., opposing opposite sides) without departing from the scope of the present invention.

[0033] In the exemplary embodiment shown in detail in FIG. 11, each groove 212 is generally shaped like a circular segment when viewed along each groove, although other shapes or grooves of multiple shapes may be employed without departing from the scope of the present invention. Preferably, the edges of each groove are radiused or chamfered to minimize stress concentrations. With continued reference to FIG. 11, each groove 212 extends inwardly from a first face 210A of each plate 210 to an opposing second face 210B to a depth d, the first face 210A and the second face 210B generally defining a thickness T of each plate 210, with adjacent grooves spaced apart by a separation distance S. In the exemplary embodiment of the present invention, plates 210 having a thickness T generally between 0.5 and 6 inches are employed, although other thicknesses may be employed without departing from the scope of the present invention. In such embodiments, grooves having a depth d of about 0.25 inches to about 1 inch, a width W of about 0.5 inches to about 2.5 inches, and a separation distance S of about 0.25 inches to about 2 inches are employed, although it is understood that other dimensions may be employed without departing from the scope of the invention. It is also understood that grooves of other shapes may be employed without departing from the scope of the invention.

[0034] 8 and 9, each plate 210 extends a length L in a direction between opposing edges with grooves 212 extending therebetween, and a height H in a direction generally perpendicular to the direction in which the grooves 212 extend. In an exemplary embodiment of the invention, plates 210 having lengths L of about 2 feet to about 4 feet and heights of about 8 feet to about 9 feet are employed, although plates 210 of other dimensions may be employed without departing from the scope of the invention. The plurality of plates 210 utilized in the energy storage device 200 illustrated in FIG. 8 are arranged in ten rows with 23 plates in each row. It should be understood that the number of rows and / or the number of plates per row may be varied without departing from the scope of the invention.

[0035] It should be appreciated that embodiments of the present invention eliminate the need for metal piping within the module. Metal casings that are part of the functional units allow for easy installation of simple plenums at each end of the flow space. The module takes advantage of the beneficial thermal properties of concrete, i.e., specific heat, durability, low cost, and ready availability. The module requires relatively low pump power to move the heat transfer medium due to the size and low velocity of the flow space between the concrete plates (and / or grooves formed in the plates). The large wetted area provided by designs according to this concept helps eliminate the heat transfer challenges encountered with many materials with high specific heat, and provides short-term energy storage along the axis of flow, which supports the creation of a thermal gradient. The horizontal flow arrangement allows for longer thermal gradient distances without creating large static head pressures from the fluid. The horizontal flow arrangement also allows for easy installation of inlet and outlet piping and unit replacement. The horizontal flow arrangement also allows for easy addition of "thermal breaks" by simply fluting the concrete, i.e., adding vertical grooves to the concrete, or by using a separation section of concrete. This concept further eliminates the need for traditional, labor-intensive reinforcing steel bars.

[0036] Heat for heating the heat transfer fluid or medium may be derived from a heat exchanger in heat exchange relationship with a primary or secondary loop of a nuclear reactor, coal plant, solar thermal, or other similar heat source. Alternatively, heat may be derived from a gas turbine cycle or a heat pump.

[0037] Thus, embodiments of the present invention provide the most economical energy storage currently available outside of pumped hydro or compressed air in suitable terrains, and without site restrictions. The present invention can utilize existing heat source equipment, such as nuclear power plants, inexpensive materials, and simple design to solve grander pre-existing challenges without practical solutions on a large commercial scale. The present invention does not require a pressurized environment, reducing the risk of catastrophic safety events.

[0038] Although specific embodiments of the present invention have been described in detail above, those skilled in the art will appreciate that various modifications and substitutions to those details may be made in light of the overall teachings of the present disclosure. Accordingly, the specific embodiments disclosed are illustrative only and are not intended to limit the scope of the invention to which the full scope of the appended claims and any and all equivalents thereof is entitled.

Claims

1. a plurality of separation plates, each of the plates having a first side and an opposing second side, the first side having a plurality of grooves formed therein and the second side having a substantially flat surface; an inlet plenum configured to receive a heat transfer medium from a heat source and distribute the heat transfer medium through the plurality of channels; an outlet plenum configured to receive the heat transfer medium from the plurality of grooves and to discharge the heat transfer medium to a return destination; each groove extends from a first edge of a respective one of the plurality of separation plates disposed near the inlet plenum to an opposing second edge of the respective one of the plurality of separation plates disposed near the outlet plenum; the first face of a first plate having the plurality of grooves formed therein is disposed in direct contact with the second face of an adjacent second plate having the substantially flat surface; the plurality of grooves and the substantially flat surface form a plurality of separate flow paths between the first plate and the adjacent second plate; each of the plurality of individual flow paths extends horizontally from the inlet plenum to the outlet plenum; an energy storage device, wherein a portion of the heat in the heat transfer medium is transferred to the plate in a charging mode of operation as the heat transfer medium passes along the plurality of grooves, or a portion of the heat in the plate is transferred to the heat transfer medium in a discharging mode of operation as the heat transfer medium passes along the plurality of grooves.

2. 10. The energy storage device of claim 1, wherein each plate is formed from a high specific heat material.

3. The energy storage device of claim 2 , wherein each plate is formed from a concrete material.

4. 10. The energy storage device of claim 1, wherein each groove is shaped generally like a segment of a circle when viewed along each groove.

5. The energy storage device of claim 1 , wherein the plurality of separation plates are arranged in a vertical stack with the first surface and the second surface disposed horizontally.

6. 2. The energy storage device of claim 1, wherein the plurality of separator plates are vertically disposed at an edge with the first surface and the second surface vertically disposed.

7. 10. The energy storage device of claim 1 , wherein each plate has a thickness of about 0.5 inches to about 6 inches.

8. 8. The energy storage device of claim 7, wherein each plate has a thickness of about 4 inches.

9. 10. The energy storage device of claim 1 , wherein each groove has a depth of about 0.25 inches to about 1 inch.

10. 10. The energy storage device of claim 9, wherein each groove has a width of about 0.5 inches to about 2.5 inches and is spaced from adjacent grooves by a separation distance of about 0.25 inches to about 2 inches.

11. 10. The energy storage device of claim 1, wherein the energy storage device is configured to operate between about 60° C. and 315° C. (about 140° F. and 600° F.).

12. 10. The energy storage device of claim 1, wherein the plate comprises micro-rebar or other three-dimensional reinforcement.

13. A method for storing thermal energy, comprising: forming a heat transfer module comprising: a plurality of separator plates, each of the plates having a first side and an opposing second side, the first side having a plurality of grooves formed therein, the second side having a substantially flat surface; an inlet plenum; and an outlet plenum, each groove extending from a first edge of a respective one of the plurality of separator plates disposed near the inlet plenum to an opposing second edge disposed near the outlet plenum, the first side of a first plate having the plurality of grooves formed therein being disposed in direct contact with the second side of an adjacent second plate having the substantially flat surface, the plurality of grooves and the substantially flat surface forming a plurality of individual flow paths between the first plate and the adjacent second plate, each of the plurality of individual flow paths extending horizontally from the inlet plenum to the outlet plenum; directing a heat transfer medium from the inlet plenum to the outlet plenum through the grooves of the separator plates; transferring heat from the heat transfer medium to the plurality of separator plates in a charging mode of operation or from the plurality of separator plates to the heat transfer medium in a discharging mode of operation; discharging the heat transfer medium from the outlet plenum; A method for storing thermal energy comprising:

14. The method of claim 13, comprising operating the heat transfer module at between about 60° C. and 315° C. (about 140° F. and 600° F.).

15. 14. The method of claim 13, wherein the fill mode of operation, in which heat is transferred from the heat transfer medium to the plurality of separation plates, and the discharge mode of operation, in which heat is transferred from the plurality of separation plates to the heat transfer medium, are performed in opposite fluid flow directions, respectively.

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