Energy storage

Abstract

An energy storage device for storing thermal energy is disclosed.SOLUTION: The energy storage device comprises at least one heating device, a heat reservoir 101 comprising at least one heat storage block 102 formed from a miscible gap alloy, insulation 108 surrounding the heat reservoir 101, and at least one substantially impermeable shell 106 surrounding the heat reservoir 101 and / or the insulation 108. The device is arranged such that heat can be charged or discharged from the heat store 101 by heat transfer between the at least one heat transfer channel 103 and the at least one heat storage block 102. The present invention also relates to a method and system for storing thermal energy in at least one heat storage block 102 formed from a miscible gap alloy.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of the earlier filing date of Australian Provisional Patent Application No. 2021 / 904176, filed on December 21, 2021, the entirety of each such application being incorporated herein by reference as if fully set forth herein.

[0002] The present invention relates to devices for the capture, storage and release of thermal energy and methods of energy capture, storage and release. [Background technology]

[0003] Renewable energy sources, such as wind and solar power, are becoming increasingly important both environmentally and economically. According to the World Meteorological Organization (WMO), atmospheric greenhouse gas concentrations reached 400 ppm in 2015 and exceeded 413 ppm in 2020. A rapid transition is required to stabilize greenhouse gas concentrations at the generally accepted critical threshold of 450 ppm. Delays in implementing renewable and carbon-neutral energy sources narrow the room for action and increase the cost of transforming the energy sector by an estimated $500 billion per year.

[0004] Unfortunately, most forms of renewable energy (except geothermal and hydroelectric) suffer from intermittent supply. For example, diurnal cycles and weather conditions directly affect solar power generation. Wind and wave sources are also intermittent, and energy is dependent on prevailing environmental conditions.

[0005] To make renewable energy sources more attractive and to increase the availability of electrical energy generated from such sources, energy needs to be stored when in surplus and released at times when demand would otherwise exceed supply.

[0006] Conventional energy storage technologies exist based on well-established chemical, electrochemical, or mechanical means. For example, batteries are well known, and pumping water to reservoirs for subsequent hydroelectric power generation is also a well-established technology. Unfortunately, many of these technologies have relatively low energy storage densities (low stored energy per unit volume), and energy storage by chemical, electrochemical, or mechanical means all incur energy losses in the storage-retrieval cycle in addition to those associated with the final energy utilization.

[0007] For thermal energy sources, direct thermal energy storage (TES) can be done very efficiently, with only environmental losses incurred through an insulating envelope. For example, sensible-heat-based concentrated solar thermal (CST) plants use thousands of tons of molten KNO3 / NaNO3 salts for sensible heat storage and have relatively high reduction thermal efficiencies.

[0008] Recently, energy storage devices have been proposed that use solid storage materials in the form of stone or concrete to store thermal energy, which can then be used when demand increases to generate steam for heating or to drive a steam power plant to convert the stored thermal energy back into electrical energy.

[0009] One such form of solid state energy storage material is that disclosed in WO2014 / 063191(A1) which utilises miscible gap alloys as the heat storage material.

[0010] These materials comprise a containment matrix within which are dispersed particles of a fusible material. At temperatures below the melting point of the fusible material, the entire material is solid. At temperatures above the melting point of the alloy from which the particles are made, the particles are liquid. This material is highly efficient in terms of energy storage and release, which occurs via heat transfer with the surface of the matrix.

[0011] The term "microparticle" can be used in an absolute or relative sense. For example, in an absolute sense, microparticle can refer to particles that are less than 100 μm in size, such as 10 μm or even 1 μm or less.

[0012] Alternatively, in a relative sense, particulate can refer to particles that are at least two orders of magnitude (>100x) smaller than the overall storage block dimensions from which the thermal storage material is formed.

[0013] This form of heat storage can be direct, either as sensible heat due to a temperature increase or as latent heat due to a phase change. Such phase change systems are potentially very useful because they exhibit very high energy storage densities, far greater than competing technologies. Furthermore, the phase change systems can be easily adapted to target applications by modifying their components to have melting points within the desired temperature range, thus modifying their heat storage and release properties.

[0014] In addition to a high energy density per unit volume, such materials have relatively short time requirements for recharging and discharging, and are relatively cost effective.

[0015] The application of efficient thermal energy storage systems to capture heat from renewable energy sources such as sunlight or waste heat from existing industries can significantly save and reduce greenhouse gas emissions.

[0016] Approximately 50% of the energy used for heating is consumed by residential space heating applications, with the remainder being utilized by industry for low temperature steam generation and dry drying.

[0017] Furthermore, if an effective thermal storage solution is developed, the range of applications is not limited to renewable energy sources. This technology can also be used for load shifting applications in conventional technology, for example, by converting fossil fuel power plants into storage and dispatch systems. Alternatively, thermal storage solutions can be implemented to recover wasted energy from large industrial processes and re-dispatch it during plant start-up.

[0018] Any discussion of prior art throughout this specification should not be construed as an admission that such prior art is widely known or forms part of the general knowledge in the art.

[0019] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative material, preferably a new material, that is suitable for use as a high energy density, high thermal conductivity heat storage material. Summary of the Invention

[0020] In a first aspect of the present invention, there is provided an energy storage device comprising: at least one heating device; a heat store comprising at least one heat storage block formed from a miscible gap alloy, said at least one heat storage block being arranged such that at least one heat transfer channel adapted to receive a flow of a heat transfer fluid and / or said at least one heating device is formed therein; an insulating unit surrounding the thermal storage unit such that the thermal storage unit is substantially insulated; and at least one substantially impermeable shell surrounding the heat store and / or the insulation so as to substantially contain the heat transfer fluid; An energy storage device is provided, wherein heat can be charged or released from said heat store by heat transfer between said at least one heat transfer channel and at least one heat storage block.

[0021] Device Structure In some embodiments, the energy storage device is a thermal energy storage device. The devices are configured to store thermal energy to overcome or ameliorate the drawbacks of known thermal energy storage solutions, including, but not limited to, those utilizing materials with high dead-space volumes, such as molten salts, conductive solid materials such as graphite, and granular materials. These include disruptive expansion, collapse or erosion of the solid storage material itself or the vessel carrying the fluid, spontaneous release of stored thermal energy, difficulty in maintaining thermal contact with heat exchange infrastructure, and long-term degradation of storage and release capacity due to their high setup costs. In comparison, thermal energy storage utilizing miscible gap alloys has a higher energy density than appreciable heat-only solutions due to the fact that it also stores latent thermal energy, while also exhibiting little hysteresis or long-term degradation in structural stiffness / performance associated with repeated charging, storage, and release of thermal energy.

[0022] In some embodiments of the invention, the thermal store comprises one or more thermal storage blocks arranged to form at least one heat transfer channel within the thermal store, the heat transfer channel providing an exposed surface that acts as an interface for transferring thermal energy between a heat transfer fluid or heating device and the store by conduction, convection, and / or radiation.

[0023] Those skilled in the art will understand that heat transfer between the solid heat store and the heat transfer fluid can occur by direct contact therebetween or through a heat exchanger device. Thus, at least one heat store block formed from the miscible gap alloy (herein "MGA store block") can be directly exposed to the flow of heat transfer fluid or can be in contact with the electrically conductive wall of the heat exchanger device. The heat store comprises a heat transfer channel having at least two openings so that forced flow of the heat transfer fluid therein can be facilitated by devices such as a pump and / or a blower located outside the energy storage device.

[0024] MGA storage blocks can be of any shape, but are described herein with reference to hexahedral storage blocks, examples of which are cubes or elongated square or rectangular prisms.

[0025] Preferably, the heat storage block is directly exposed to the heat transfer fluid by passing said fluid directly through the heat transfer channels. In this embodiment, thermal energy is passed directly by conduction and convection between the fluid and the MGA heat storage block, without a conductive barrier such as a heat exchanger device wall between them. The inventors have found this configuration to be advantageous in view of the density and conductivity of the MGA material forming the heat storage block, which negates the benefits of heat exchanger tubing, resulting in improved heat retention during transfer during charging / discharging.

[0026] Those skilled in the art will understand that the thermal storage body can be constructed from a single thermal storage block, but this is not necessarily required. Preferably, the thermal storage body is assembled from multiple thermal storage blocks that have sufficient strength to support the weight of itself and the storage body. While a single structure of the thermal storage body allows for improved conduction and heat retention within the miscible gap alloy forming the single thermal storage block, such a structure can present difficulties in forming heat transfer channels, resulting in insufficient heating and / or heat extraction during operation of the energy storage device. Advantages of constructing a thermal storage body from multiple thermal storage blocks include improved uniformity of charge / discharge across the internal cross-section of the storage body, achievable through the increased number and ease of incorporating heating devices and heat transfer channels for the fluid.

[0027] The thermal storage blocks may be shaped to meet various criteria or sized to retain a predetermined amount of heat, as needed, for example, to maximize contact area with the heat transfer flow, for modular storage and assembly, or to facilitate transportation.

[0028] Preferably, at least one thermal storage block is fabricated so that, when fully assembled, the thermal storage body it comprises includes appropriate channels or recesses for accommodating fluid flow and heating devices. If the thermal storage body is constructed from multiple thermal storage blocks formed from miscible gap alloys, the blocks may simply be stackable hexahedral blocks, or in some embodiments, may be fabricated to provide structural support for the assembled thermal storage blocks. In one embodiment, the thermal storage blocks fit together via prefabricated slots. In this regard, heat transfer channels may be fabricated within the thermal storage block to accommodate the flow of heating devices and / or heat transfer fluids, or may be formed by the specific arrangement of the thermal storage blocks, resulting in channels formed between them.

[0029] When the thermal store is constructed from multiple thermal storage blocks, the thermal storage blocks are arranged such that their structural support and rigidity take into account their dimensional expansion under thermal load. In this regard, permanent deformation of the thermal store caused by thermal expansion-related stresses and strains during heating and heat storage can be prevented by incorporating at least one spacer between said multiple thermal storage blocks. Furthermore, by preventing excessive strain of the thermal storage blocks under thermal expansion, thermally related creep and related problems can also be mitigated, including loss of structural strength, block fracture, and internal pressure buildup due to the expansion of the blocks relative to one another (also known as thermal ratcheting).

[0030] In this regard, the spacer is a solid, heat-resistant material adapted to abut the outer surface of each of the plurality of heat storage blocks so that a gap space is created and maintained between the array. In one example, a spacer is provided adjacent each corner of the hexahedral MGA block comprising the heat storage body so that a gap space is provided adjacent at least two sides thereof. The gap space provided between the MGA blocks can constitute a heat transfer channel for facilitating heat transfer between the MGA block and the heating element and / or heat transfer fluid. Preferably, the spacer is formed from a metallic material so as to maintain the gap space and to maintain structural rigidity under expansion loads of the MGA block to prevent deformation of the block.

[0031] The shape of the spacers in this respect is adapted based on several factors, including the shape of the heat storage block, the desired volume of the interstitial space and therefore the heat transfer channels, as well as the thermal expansion coefficient of the material used for the heat storage block. In one embodiment, the spacers are formed from metal bars with a "T" shaped cross section, adapted to accommodate and abut both corners and sides of the hexahedral heat storage block. In another embodiment, the spacers are elongated cylindrical bars of different lengths. In a further embodiment, both types of spacers are used alternately to secure the MGA blocks in their array and form the heat storage body.

[0032] To avoid energy loss to the external environment, the thermal store is surrounded by insulating material comprising an insulating unit. The insulating material in the form of panels, blocks, mineral wool, foams and / or insulating blanks is suitably located on the external surface of the thermal store to substantially insulate therein, thus minimizing the thermal energy lost to the external environment. A person skilled in the art will understand the need for insulation for a thermal store and will be able to suitably design an insulating solution according to the required specifications.

[0033] In addition to the above, a substantially fluid-dense containment or shell structure is provided to prevent the expanding heated gas and / or heat transfer fluid from escaping the energy storage device. In this regard, at least one impermeable material layer is provided on the exterior of the heat store to surround it and contain the heat transfer fluid therein. Preferably, this containment / shell structure is formed from a metal, more preferably a steel alloy such as mild steel or stainless steel. Further preferred embodiments may also include an inner shell and an outer shell with insulating material disposed therebetween. In such a structure, the inner shell provides a substantial seal for the heat store and the heat transfer fluid, while the outer shell provides improved thermal containment and structural rigidity by enclosing the insulating material.

[0034] Using MGA As discussed above, at least one of the thermal storage blocks comprising the thermal storage body is formed from a miscible gap alloy (MGA). The term "miscible gap" in the context of this alloy means that there is a degree of immiscibility between the components of the alloy, and that at certain ratios and temperatures, the alloy separates from the miscible alloy to form different phases that coexist in the microstructure of the thermal storage block. An alloy in this context refers to a material that includes a thermodynamically stable mixture of at least two constituent materials selected from metals, semi-metals, or non-metallic materials.

[0035] As discussed in PCT / AU2013 / 001227, high temperature heat storage is known to be efficiently achieved in a compact footprint using thermodynamically stable two-phase mixtures, where the active phase, which undergoes melting and solidification during the charge / discharge cycle, exists as separate particles completely enclosed within a dense, continuous, thermally conductive matrix. The inventors have discovered that by charging thermal energy and maintaining a specific temperature within a block formed from MGA, the miscibility gap in the alloy's phase diagram is utilized to store said energy in the form of latent heat of transformation and fusion in addition to the sensible heat initially charged.

[0036] In addition to the above, in a preferred embodiment, the MGA in the heat storage block is (i) a dense, continuous, thermally conductive matrix of a first component; (ii) particles of a second component dispersed throughout a matrix of the first component; the first and second components are wholly or partially immiscible in solid form, the first component melts at a higher temperature than the second component, and the first component contains and encapsulates the second component at all times, including when the second component is in a molten or flowable state; The first and second components can independently be metallic or non-metallic, with the particles of the second component being particulate.

[0037] In this preferred embodiment, the MGA has an "inverse microstructure" in which a low-melting-point, high-energy-density phase is trapped as small particles within a high-thermal-conductivity solid matrix that can rapidly deliver heat over long distances. This contrasts with the naturally formed microstructure of miscible gap alloys, in which a high-melting-point phase is trapped within a matrix of a low-melting-point material. As discussed in PCT / AU2013 / 001227, this preferred alloy system overcomes the electrical conductivity, energy density, corrosion, and instability problems of conventional phase-change thermal storage systems.

[0038] The first component can be formed from a single compound or element, or it can be a mixture of compounds or elements. Similarly, the fusible second component can be a single compound or element, or it can be a mixture of compounds or elements. In the simplest case, where the first and second components are elements or a single compound, the overall system is a binary system with two distinct phases. If one component is an alloy of two elements or compounds and the other component is an element or a single compound, the system becomes a ternary system with two distinct phases. Depending on the components of the system, ternary, quaternary, and higher systems are possible; i.e., if the first component has n compounds or elements and the second component has m compounds or elements, the phase diagram is an n+m system. Important factors in selecting a combination of first and second components are the presence of a miscibility gap in the associated phase diagram and the temperature or temperature range over which the phase of the "active" fusible second component changes with the production / consumption of potential energy.

[0039] In one embodiment, the first component is a metal and the second component is a metal. Alternatively, the first component is a metal and the second component is a non-metal, or the first component is a non-metal and the second component is a metal. Alternatively, both the first component and the second component are non-metals. Each metal component can be an element, or an alloy, metal, or semi-metal compound. If a component is a non-metal component, it can be an inorganic material, such as a salt or a mixture of salts. A binder material can also be present in the alloy, but is specifically selected so as not to contribute to or affect the miscibility of the components or their phase change properties.

[0040] Table 1 below shows a range of alloy systems that are contemplated for incorporation as a particulate second component containing the inverse microstructure miscible gap alloys of the present invention.

[0041] The transition temperature is the melting point of the low melting (dispersion) component and determines the storage temperature characteristics of the material. The table also shows the relative composition ranges of the elements that comprise the particulate second component of the present invention. [Table 1-1] [Table 1-2]

[0042] Preferably, the second component is present in an amount of at least 30% by volume of the thermal storage material, more preferably, the second component is present in an amount of at least 35% by volume of the thermal storage material, even more preferably, the second component is present in an amount of at least 40% by volume of the thermal storage material, and most preferably, the second component is present in an amount of at least 50% by volume of the thermal storage material. Preferably, the second component is present in an amount of less than about 70% by volume of the thermal storage material.

[0043] The particles are preferably sized to avoid problems due to thermal expansion, hi one embodiment, the particles of the second component are less than 100 μm in size, or even less than 80 μm.

[0044] Any suitable alloy material can include the first matrix component of the miscible gap alloy, provided that it contains and encapsulates a particulate second component, preferably selected from the group consisting of Al, Fe, C, and SiC. Preferably, the second component is selected from the group consisting of Al, Bi, Mg, Cu, Zn, and Si, or a combination thereof. In another preferred embodiment, the first component is C and the second component is an alloy containing any combination of Zn, Cu, Mg, Bi, and Si. In another preferred embodiment, the first component is C and the second component is an alloy of Al and Si. In another preferred embodiment, the first component is C and the second component is an alloy of Al, Mg, and Si. In another preferred embodiment, the first component is C and the second component is an alloy of Cu, Mg, and Si. In another preferred embodiment, the first component is C and the second component is an alloy of Cu, Mg, and Si. In another preferred embodiment, the first component is C and the second component is an alloy of Cu and P. In another preferred embodiment, the first component is C and the second component is an alloy of Cu and Si. In another preferred embodiment, the first component is C and the second component is an alloy of Cu and Zn. In another preferred embodiment, the first component is C and the second component is an alloy of Cu and Al. In another preferred embodiment, the first component is Al and the second component is Bi. In another preferred embodiment, the first component is Fe and the second component is Mg. In another preferred embodiment, the first component is Fe and the second component is Cu. In another preferred embodiment, the first component is C in graphite form and the second component is Cu. In another preferred embodiment, the first component is SiC and the second component is Si.

[0045] Preferably, when the first component is Al, the second component is not Pb in an amount of 3-26%.

[0046] An inverse microstructure is one in which a matrix of a first component contains and encapsulates a second component, including when the second component is in a molten or flowable state.

[0047] It should be understood that the materials described for both the first and second components are not an exhaustive list, but are merely illustrative of the types of materials that may be used depending on the operating parameters selected.

[0048] Advantages of MGA in TES systems By utilizing MGA thermal storage blocks, the present invention is believed to overcome the well-known shortcomings of many current TES systems. Advantages of using such materials as thermal storage blocks include: High energy density per unit volume by exploiting the high latent heat of fusion per unit volume of metal. In many cases, 0.2-2.3 MJ / L or even more can be achieved at 50% loading of the active (molten) phase. The volume of such storage devices is therefore relatively small compared to the energy they store.

[0049] A range of melting temperatures for the active phase is available, so the material can be individually adapted to useful operating temperatures: low temperature (<300°C) for applications such as space heating and industrial heat for food processing, mid-range temperature (300°C-400°C) for process heat in chemical processing, and high temperature (400°C-700°C) for steam turbine power generation, even higher temperatures (700°C-1400°C) for high-temperature industrial processes.

[0050] Latent heat is delivered (or accepted) over a narrow temperature range which allows for more precise control of process parameters, which may facilitate easier adaptation of turbine generators or other process equipment from a steam generation perspective.

[0051] Heat is transferred to and recovered from the PCM by conduction solely through the matrix component of the alloy, eliminating the need to transport the molten phase around the system and allowing for very high heat transfer rates.

[0052] · The matrix phase always remains solid and encapsulates the active phase, so no special containment is required.

[0053] · Because the two materials are thermodynamically stable and immiscible at operating temperatures, chemical reactions between the components are avoided, which means the system is likely to remain stable over long periods of time.

[0054] The use of thermodynamically stable or metastable immiscible materials presents a new direction for developing efficient TESs using the latent heat of fusion. Material systems can be selected to match the desired operating temperature. No external containment is required, as the matrix phase always remains solid and self-supporting. This simplifies the design, no hydraulic pressure is developed, and improves the safety of large PCM storage tanks, as volume changes during freezing / melting are limited to the volume of the small active phase particles.

[0055] The class of miscible gap alloys disclosed herein has the potential to significantly reduce the demand for traditional forms of energy, for example, through the use of concentrated solar radiation or industrial waste heat recovery and utilization, which, by definition, reduces the demand for fossil fuel-generated energy, leading to substantial environmental benefits.

[0056] Thermal energy storage is well known, and it is estimated that of the approximately 2000 MW of global advanced energy storage capacity, over half is stored in the form of heat or molten salts. Inverse microstructure alloys have the potential to anchor a large portion of that sector by directly replacing the heat storage material and associated pumps, heat exchangers, piping, etc.

[0057] By optimizing the thermal storage materials of the present invention, renewable power generation becomes increasingly feasible as intermittency issues due to wind conditions, weather, and diurnal cycles are overcome in a way that allows the use of traditional steam turbine technology as well as advanced power cycles still under development, such as supercritical CO2 Brayton cycle turbines.

[0058] heat transfer fluid As discussed above, heat transfer channels are provided in the heat store to charge and discharge thermal energy thereto, respectively. A heat transfer fluid flows through these channels and transfers heat between at least one MGA heat store block by a combination of conduction and convection. The transfer of heat between the fluid and the MGA can be done directly by passing the heat transfer fluid directly over / through the heat transfer block, or indirectly through the pipe walls of the heat exchanger device in contact with the at least one block, or through a highly conductive intermediate material surrounding the pipe to reduce thermal interface losses.

[0059] In the context of the present invention, a heat transfer fluid is a medium (such as a gas, liquid, or supercritical gas) that facilitates the transfer of thermal energy to and from the thermal store and, therefore, the energy storage device. In certain embodiments where the energy storage device is connected to a power generator, the heat transfer fluid can be used to conductively transfer heat from the thermal store, conventionally by forced fluid flow in a heat exchanger, to a generator for electromechanical conversion to electrical energy.

[0060] In this regard, a heat transfer fluid includes any medium capable of flowing as a fluid and capable of transferring thermal energy by both conduction and convection, as discussed above. Heat transfer fluids may therefore include, but are not limited to, thermal oil, water, steam, nitrogen, argon, hydrocarbons, and carbon dioxide (CO2). In one embodiment, the forced flow of the heat transfer fluid through at least one heat transfer channel and through the heat store is facilitated by at least one opening located at each end of the channel, fluidly and / or thermally connecting at least one heat store block adjacent the channel to the outside atmosphere or any external device, such as a generator, heat exchanger, and / or cooler.

[0061] In some embodiments, the extracted heat is injected directly into an industrial or commercial process requiring thermal energy using a heat transfer fluid to extract the energy, or a secondary heat transfer fluid such as steam using a secondary heat exchanger.

[0062] In embodiments in which the energy storage device is connected to a generator, those skilled in the art will understand that the heat transfer fluid is selected according to the generation mechanism used, the target temperature, and the heat exchanger used. Generation methods that can be driven by thermal energy released from the energy storage device can include, but are not limited to, Rankine cycle turbine generators, Brayton cycle turbine generators, Barton cycle engines, Stirling engines, and gas turbines. For example, a Brayton cycle turbine generator can use a supercritical fluid, such as supercritical CO2, as the heat transfer fluid. Alternatively, the heated heat transfer fluid can be fed to an intermediate heat exchange process to heat another fluid, such as a working fluid, to power any of the above turbines / generators.

[0063] Preferably, heat is transferred from the heat store and rejected to the steam-driven turbine by flowing steam generated from the auxiliary heat recovery process from the heat transfer fluid through at least one heat transfer channel. This steam is generated from a heat recovery steam generator (HRSG) located external to the energy storage device, where the steam is generated from a heat transfer fluid heated by passing through the heat transfer channels in the heat store. In another embodiment, the heat exchanger (including, but not limited to, an HRSG), energy storage device, and turbine-generator form a closed or recirculation loop that includes pumps and other cooling equipment to charge / discharge, generate electricity, and drive the fluid circulation. Alternatively, waste heat from an industrial process can be transferred to and stored in the energy storage device by passing through the heat transfer fluid for later dispatch.

[0064] heating device At least one heating device is provided within the energy storage device to charge the heat store with energy in the form of thermal energy. This at least one heating device is positioned adjacent to or within at least one heat store block so that thermal energy in the form of conductive, convective, or radiant heat can be transferred from the heating device to the heat store. Thus, the heating device can be positioned along or within a heat transfer channel formed in the heat transfer body to be received thereby, or adjacent to the inner and / or outer surface of the heat store. In this regard, those skilled in the art will understand that the number of heating devices used, their position relative to the heat store, and the heat transfer mechanism will be selected according to factors including, but not limited to, the material used in the heat store, the type of energy converted into thermal energy, and the desired energy transfer rate.

[0065] Providing two or more heating devices adjacent to or positioned within the heat transfer channels of the heat store can provide more uniform and rapid heat transfer to the heat store. For example, each subunit of the heat store can be equipped with anywhere from two to several hundred such heating devices to ensure efficient and uniform heating of the heat store blocks contained therein.

[0066] In certain embodiments, the at least one heating device comprises one or more electrical resistance elements. Such a heating device would be capable of converting electrical energy supplied to the energy storage device to directly heat the thermal store. In further embodiments, the at least one heating device is an electrically powered radiant heater adapted to heat the thermal store block by electromagnetic radiation generated by one or more resistance elements contained therein. This EM radiation preferably consists primarily of infrared radiation.

[0067] In a preferred embodiment, the radiant portion of the heating device, which includes at least one resistive element as a radiation source, is held at a predetermined distance from the heat storage block, thereby transferring heat by radiation when energized. Depending on the radiation mechanism used, improved heat transfer is achieved by holding the radiant portion at this distance rather than in contact with the at least one heat storage block. In contrast to conductive or convective heat transfer, the radiant heating device provides improved heat transfer during thermal charging of the miscible gap alloy forming the heat storage block due to the dense and conductive continuous matrix of the first material comprising the MGA material. During use, the radiated heat is transferred to the heat storage body and then conducted to the interior portion of the MGA heat storage block, effectively heating both the conductive first material and the fusible second material contained therein. Advantageously, the use of a non-contact radiant heating device also facilitates effective and efficient electrical insulation of the MGA material, including the at least one heat storage block. Furthermore, the use of an efficient, typically electrically powered, heating device separated from the discharge path provided by the heat transfer fluid flow allows the energy storage device to simultaneously charge and discharge thermal energy through each path, a mode of operation not possible with chemical energy storage devices.

[0068] Those skilled in the art will readily understand that the at least one heating device can take any particular form, such as a rod- or panel-shaped heating device located near or adjacent to the at least one thermal storage block. In this regard, one or more radiant heaters can be disposed on the exterior surface of the thermal storage block or within its interior cavity to facilitate radiant heat transfer. A panel structure effectively maximizes the radiant surface for heat transfer between it and the at least one thermal storage block. In this regard, each radiant heating device can also include any suitable number of resistive elements, depending on factors including, but not limited to, the charging temperature, the heat transfer rate, the size of the heating element, and the power efficiency of the heating device.

[0069] In another embodiment, the electrical resistance heater can be located within the heat transfer fluid circulation system, for example, in the inlet duct of the thermal energy store. This alternative location of the heater allows the heat transfer fluid system to heat the storage block.

[0070] operation Now consider the operation of the energy storage device.

[0071] In a second aspect of the present invention, there is provided a method for storing energy, comprising the steps of: a) charging at least one heat storage block comprising a heat storage unit by heating at least one heating unit adjacent to at least one heat transfer channel formed therein; b) storing the thermal energy in the heat storage blocks by substantially insulating the heat storage unit formed by the heat storage blocks from the external atmosphere; c) releasing heat from the heat storage unit by flowing a lower temperature heat transfer fluid through at least one heat transfer channel such that heat is removed from the at least one heat transfer block.

[0072] Thus, thermal energy is charged, stored, and released from the energy storage device by heating, maintaining the temperature, and transferring heat from at least one thermal storage block contained therein. As such, there are three distinct phases of operation of the device - a charging phase, a storage phase, and a release phase, described in steps a), b), and c), respectively.

[0073] During the charging phase, thermal energy is input into the thermal store by at least one heating device. In one embodiment, the heating device is an electric heater used to convert electrical energy into thermal energy. In an even more preferred embodiment, the thermal energy is transferred radially to the thermal store block using a radiant electric heater.

[0074] As a result of the thermal energy input into the heat store, at least one heat store block contained therein heats up significantly until the second phase of the miscible gap alloy material forming said block melts inside the solid conductive first phase. Upon melting (or fusion), additional energy is absorbed within said block in the form of fusion or transformation potential energy. Given the emitted form of the MGA material, which now has both the first and second phases as solids, this additional fusion potential energy is effectively stored within the storage block until the second phase is released and returns to a solid state.

[0075] In certain embodiments, the energy storage device is configured to enable at least one heating device to charge the thermal store with between 2 kWh and 10 GWh of energy over a certain period of time ranging from a few minutes to multiple days. In one non-limiting development of the invention, both the heating device and the thermal store are adapted to transfer 300 kW of thermal energy to the thermal store over a period of 5 to 14 hours per day of operation. In another embodiment, the electrical energy for the at least one heating device is supplied by renewable power generation, including, but not limited to, solar, wind, and / or any surplus renewable generated power from the electric grid.

[0076] During the storage phase, thermal energy is stored in at least one charged thermal energy block by insulating the thermal store it comprises from the external atmosphere. In this regard, an insulating material is configured to surround the thermal store to substantially insulate it. In one specific non-limiting embodiment, the insulating material, in combination with the thermal store block, is adapted to substantially maintain between 2 kWh and 100 TWh of thermal energy within the thermal store for up to 50-500 hours after charging. In one development, the energy storage device is configured to store a total of 500 kWh (1.8 GJ) of thermal energy for up to 96 hours.

[0077] In another non-limiting embodiment, the device is adapted to charge and store up to 5 MWh of thermal energy and release or dispatch that energy at a rate of up to 500 kW over a four hour period.

[0078] Under energy release, heat can be conducted / convected from the heating thermal store to the flowing cooling heat transfer fluid by direct contact, or through the heat exchanger walls. Preferably, the movement of the heat transfer fluid directly through the heat transfer channels facilitates controlled extraction of thermal energy from the thermal store without contact resistance or thermal interface losses between the storage material and the internal heat exchanger.

[0079] When an "inverse" microstructure miscible gap alloy (MGA) is used to form at least one heat storage block, the block releases an intense burst of latent heat locally during release (solidification of the active second phase), which is then conducted to the heat transfer fluid by the surrounding matrix phase. This energy release is in addition to the aforementioned release / transfer of sensible heat energy stored in the heat storage body.

[0080] In certain embodiments, the energy storage device is configured to release 300 kWh to 400 MWh of thermal energy therefrom over an extended period of 2 to 24 hours. In one development of the invention, the heat transfer fluid flow and conductivity of the fluid, block material, and insulation are adapted to controllably release 500 kWh of thermal energy over a 4-hour period. A heat release rate of 100 kW to 500 MW is maintained throughout the release period, and the heat transfer fluid discharge temperature does not exceed 300 to 800°C. In the exemplary development discussed above, the energy storage device can maintain a heat release rate of 100 to 125 kW over a 4-hour period during which the heat transfer fluid temperature at its outlet is maintained above 500°C.

[0081] Accordingly, in a third aspect of the present invention there is provided a system for storing energy, comprising: at least one energy source; at least one energy storage device, the energy storage device comprising: at least one heating device; and at least one heat storage block formed from a miscible gap alloy, the at least one heat storage block being arranged such that at least one heat transfer channel adapted to receive a flow of a heat transfer fluid and / or the at least one heating device is formed therein; an insulating material surrounding the heat storage such that the heat storage is substantially insulated; and at least one substantially impermeable shell surrounding the heat storage and / or the insulating material such that the heat transfer fluid is substantially contained, wherein heat can be thermally charged or released from the heat storage by heat transfer between the at least one heat transfer channel and the at least one heat storage block; at least one pumping means; and at least one heat transfer and / or energy conversion means; The unit operations are in fluid communication with one another such that the system forms at least one fluid path for transferring thermal energy therebetween.

[0082] Those skilled in the art will appreciate that the rate of heat release at this point can be controlled through the heat transfer fluid flow rate and pressure through the heat transfer channels.

[0083] definition In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the present invention only, and is not intended to be limiting. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0084] Unless the context clearly requires otherwise, throughout this specification and claims, the terms "comprises," "comprises," and the like are to be interpreted in an inclusive sense, i.e., in the sense of "including but not limited to," as opposed to an exclusive or exhaustive sense.

[0085] As used herein, the phrase "consisting of" excludes any element, step, or ingredient not specified in the claim. When the phrase "consisting of" (or variations thereof) appears in a phrase in the body of a claim rather than immediately following the preamble, it limits only the elements recited in that phrase; other elements are not excluded from the claim as a whole. As used herein, the phrase "consisting essentially of" limits the claim to certain elements or method steps, plus those that do not materially affect the basic and novel characteristics of the claimed subject matter.

[0086] With respect to the terms "comprising," "consisting of," and "consisting essentially of," when one of these three terms is used herein, the subject matter disclosed and claimed herein may include the use of either of the other two terms. Thus, in some embodiments not expressly stated otherwise, any instance of "comprising" may be replaced by "consisting of," or alternatively, by "consisting essentially of."

[0087] Other than in the working examples, or unless otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein should be understood as being modified in all instances by the term "about." Additionally, the examples are not intended to limit the scope of the invention. Hereinafter, or where otherwise indicated, "%" means "volume %," "ratio" means "volume ratio," and "parts" means "volume parts."

[0088] As used herein, the term "substantially" means, unless otherwise indicated, including more than 50% by volume, mass, or weight, depending on the context. Preferably, it means more than 75%. Even more preferably, it means more than 90%. Most preferably, it means 100% or close to 100%.

[0089] The recitation of numerical ranges using endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0090] The terms "preferred" and "preferably" refer to embodiments of the invention that may offer certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

[0091] It should also be noted that as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0092] The prior art cited herein is hereby incorporated by reference in its entirety.

[0093] Although illustrative embodiments of the disclosed technology are described herein in detail, it should be understood that other embodiments are contemplated. Accordingly, it is not intended that the disclosed technology be limited in scope to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosed technology is capable of other embodiments and of being practiced or carried out in various ways. [Brief explanation of the drawings]

[0094] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1]FIG. 1 is a cross-sectional view of an energy storage device showing heat transfer channels formed by the assembly of multiple thermal storage blocks surrounded by insulating panels. [Figure 2] FIG. 10 is an orthogonal view of an energy storage device as part of a closed-loop heat dispatch configuration with a pump and an external heat exchanger. [Figure 3] FIG. 10 is a piping and instrumentation diagram showing the energy storage device as part of a closed loop configuration including a gas cooler heat exchanger. [Figure 4] FIG. 1 illustrates a cross-sectional view of an embodiment of an energy storage device including flowing a heat transfer fluid through a heat exchanger pipe. [Figure 5] 1 shows a graphical representation of the thermodynamic conditions during the release phase of the present invention. [Figure 6] FIG. 1 is a side view of a large-scale steam turbine-based power generation configuration using the energy storage devices disclosed herein. [Figure 7a] FIG. 1 is a cross-sectional plan view of an embodiment of an energy storage device showing multiple thermal masses enclosed in an insulating containment structure. [Figure 7b] FIG. 2 is a horizontal cross-sectional view of the embodiment taken along line AA, showing the interstitial spaces between the thermal storage blocks that form the heat transfer channels. [Figure 7c] FIG. 7b is an enlarged cross-sectional view of the heat storage body shown in FIG. [Figure 7d] FIG. 10 is a cutaway side cross-sectional view of an energy storage device showing multiple access ports in the form of doors. [Figure 7e] FIG. 10 is an enlarged view of one of the heat stores showing the arrangement of heat storage blocks fixed together using spacers. [Figure 7f] FIG. 7e is an enlarged side view of the thermal mass of FIG. 7e, showing the use of two different spacer types to secure the blocks. DETAILED DESCRIPTION OF THE INVENTION

[0095] Those skilled in the art will understand that the present invention includes the embodiments and features disclosed herein, and all combinations and / or permutations of the disclosed embodiments and features.

[0096] Example 1 - Direct Extraction 1, there is shown the internal structure of an energy storage device 100 comprising a thermal storage body 101 formed from a plurality of miscible gap alloy thermal storage blocks 102. The thermal storage body 101 is assembled from a plurality of thermal storage blocks 102 that have been milled, machined, stacked, or the like in a configuration that, when assembled, provides a plurality of heating element channels 103 adapted to receive the flow of a heat transfer fluid.

[0097] Located adjacent to the thermal mass in one of the heat transfer channels is a panel-shaped heating device 104. The heating device is an electrical resistance heater having at least one resistive element electrically powered via electrical leads or bus bars 105. The panel heating device 104 is received in the heat transfer channel 103 and secured to the gas-sealed outer shell 106 of the energy storage device 100 by mounting a bracket 107. The mounting bracket 107 can be adjusted to bring the panel heating device 104 into contact with the thermal mass 101 or at a distance therefrom, depending on the heat transfer rate and type (i.e., radiation, convection, and / or conduction) desired by one skilled in the art. The embodiment shown in FIG. 1 includes a panel-style heating device 104 that is close to, but not in contact with, the thermal mass 102. The bracket-based mounting of the heating device 104 to the outer shell 106 allows for its independent adjustment, extraction, and / or replacement. The heating device 104, mounting bracket 107, and outer shell 106 comprise suitable gas-sealing materials, such as rubber, ceramic, or soldered gaskets, so that the energy storage device 100 is substantially airtight and thermally insulated during use.

[0098] 1 as thicker insulation panels 108 are provided on the interior surface of the exterior shell 106. The insulation panels 108 are constructed and positioned such that, in use, the thermal mass 101 and the heat transfer fluid received in the heat transfer channels 103 are substantially insulated from the external atmosphere. The insulation panels 108 are positioned internally and attached to the exterior shell 106 by pins 109 such that the insulation panels 108 are held in abutting engagement.

[0099] Finally, the exterior shell 106 comprises a weight-bearing frame and legs 110a and 110b that provide substantial structural rigidity and support to the energy storage device 100 so that it can support its own weight when placed on a surface and so that it can support the weight of at least another energy storage device placed thereon. In the embodiment shown, the upper and lower legs 110a and 110b are formed with complementary shapes so that when the energy storage devices 100 are placed on top of each other, they can be secured together using hook-and-loop engagement.

[0100] 2 comprises multiple energy storage devices 100 as a series of subunits in fluid communication with one another, collectively forming a larger energy storage device 100a. In this embodiment, this larger storage device 100a is also in fluid communication with a fluid pump 112, a heat transfer fluid reservoir 113, and a heat exchanger 114, forming a recirculating closed loop configuration.

[0101] In the particular embodiment shown, the fluid pump 112 is a powered fan or blower adapted to pump a substantially gaseous heat transfer fluid, such as steam, hydrocarbon, subcritical CO2, and / or nitrogen, throughout the loop and its constituent unit operations. In this regard, the blower is sized to provide sufficient head and flow through both the heat exchanger 114 and the energy storage device 100a to maintain the flow rate and fluid velocity required for heat transfer and to prevent fouling in both respective unit operations.

[0102] Consistent with the gas heat transfer fluid, a gas cooler heat exchanger is selected as the heat exchanger 114 in this embodiment. The heat transfer fluid, heated by the release of thermal energy from the thermal store 101 to the fluid flowing therethrough, is routed to the gas cooler heat exchanger 114, where it is placed in thermal communication with another heat transfer or working fluid by passing both fluids through a shell-and-tube heat exchanger configuration. The device including the heat exchanger 114 can be selected and modified depending on the use and purpose of the thermal energy released from the energy storage device 100a. For example, a shell-and-tube heat exchanger can be used to transfer energy to a working fluid for spinning a turbine to generate electricity, or alternatively, the heat can be transferred via a spray-contact heat exchanger to another heat transfer fluid, such as water for heating an industrial process.

[0103] A simplified process flow for the embodiment of Figure 2 is further explained in the piping and instrumentation diagram (P&ID) shown in Figure 3. As discussed above, the energy storage device 100a, the blower 112, and the heat exchanger 114 are fluidly connected in a closed loop that recirculates a heat transfer fluid. A heat transfer fluid reservoir 113 in the form of a tank is also provided and fluidly connected to a channel 115 that bypasses the blower 112 of the loop. Valves attached to these bypass and reservoir feed channels are used to control the pump pressure as well as the heat transfer fluid level within the closed loop.

[0104] 3 also includes a coolant-side pump 116 for pumping at least another heat transfer fluid or working fluid that cools the heated heat transfer fluid from the energy storage device 100a. As noted in the P&ID and discussed above, the energy storage device 100a is not limited to being connected to a heat exchanger, and its use is not limited to heating a secondary heat transfer or working fluid. In this regard, those skilled in the art will understand that the energy storage device 100a can directly power selected industrial and power generation devices, including, but not limited to, at least one steam turbine and a Rankine cycle generator, in a single pass configuration without a secondary fluid.

[0105] In addition to the above, various sensors, including flow (FI), temperature (TI), and pressure (PI) sensors, controllers, motors, heaters, and valves, are attached to the embodiment to monitor and control the thermal charging, discharging, and heat transfer processes. Specifically, it should be noted that the energy storage device 100a is monitored by multiple probes, including temperature sensors, and the multiple heaters inserted therein, forming the heater array 104a, are also controlled by a temperature controller (TC). Those skilled in the art will appreciate that the above components, including the heater array 104a, can be controlled manually or using a computer control system in communication therewith. As an example, a feedback control regime for the thermal charging process can be implemented using a proportional-integral-derivative (PID) controller in communication with the TC of the heating array 104a and the TI sensor of the energy storage device 100a. Additionally, temperature, pressure, and flow sensors, TI, PI, and FI sensors monitoring the heat transfer fluid can also be incorporated into a control regime along with valves into and out of the energy storage device 100a to control the flow of the heat transfer fluid and the heat transfer rate to control and determine the device status during start-up, steady state operation, and shutdown.

[0106] Example 2 - Indirect Extraction 4, an energy storage device 200 may comprise an array of heat exchanger pipes 217 and an intermediate material 218 surrounding said array, both received in a heat transfer channel 203 formed by a plurality of heat storage blocks 202 containing a heat store 201. In use during the release phase, a heat transfer fluid flows through the heat exchanger pipes 217 and conductively receives thermal energy from the heat storage blocks 202 through the intermediate material 218 surrounding said pipes 217.

[0107] The intermediate material 218 is formed of a dense, highly thermally conductive material such as silicon carbide or graphite adapted to rapidly and efficiently conduct heat between the heat exchanger pipe wall and the miscible gap alloy thermal storage block 202. By assembling the thermal storage body 201 to include an alternating layered structure of thermal storage blocks 202 and heat transfer channels 203, the embodiment of Figure 3 eliminates the lossy pipe-to-MGA interface and replaces it with a buffer intermediate material 218 that exhibits an improved thermal interface with both the MGA and typical heat exchanger pipe materials such as copper, aluminum, boiler steel, stainless steel, and Inconel.

[0108] Similarly, an array of panel-shaped heating devices 204 is provided adjacent to the thermal store 201 along the heat transfer channel 203a between the thermal store 201 and the inner shell 209 of the energy storage device 200. As with the direct fluid transfer embodiment, the heating devices 204 are powered by electrical power supplied via leads 205. The inner shell 209, insulating panels 210, and outer shell are all constructed to provide a substantially airtight, insulated seal around the thermal store 201 to retain the stored thermal energy during the storage phase.

[0109] Example 3 - Thermodynamic Analysis The expected thermal performance during the release phase of the embodiment shown in Example 1 is disclosed in Figure 5. From a steady-state internal temperature of 600°C maintained during the storage phase, circulation of the heat transfer fluid is initiated and maintained at a flow rate such that a relatively constant heat release rate of 100-130 kW is maintained.

[0110] Expected results indicate that the embodiment described in Example 1 can maintain a relatively constant heat release output while maintaining a discharge fluid temperature above 500°C for over 240 minutes (4 hours) of continuous heat release. In this regard, maintaining 500°C for up to 4 hours when the discharge temperature is in the range of 400-700°C is advantageous because it can increase the energy levels and power many industrial and power generation processes. Compared to heat storage processes known in the art, the energy storage configuration disclosed in Example 1 can maintain an operational and useful temperature for a longer period of time.

[0111] Example 4 - Scale Referring to FIG. 6 , the disclosed energy storage device can be scaled up to provide thermal energy to a grid-scale turbine generation system. In this embodiment, an array of energy storage devices is fluidly connected to form a larger device 300. This larger energy storage device 300 is further fluidly connected to a heat recovery steam generator (HRSG) 319 and a circulating fan 320 to power a steam turbine 321 in a two-pass configuration. During use, the thermal energy stored in the storage device 300 is released with a flow of gaseous heat transfer fluid, such as steam, air, subcritical CO2, or nitrogen, to heat the hot fluid and supply it to the HRSG for recovery, and heat transfer to the working fluid (steam in this case) to power the turbine. While those skilled in the art will appreciate that energy storage devices are scalable to provide various amounts of thermal energy for power generation, the embodiment shown in FIG. 6 is scaled to generate 75 MW of dispatchable electricity from thermally storing intermittently generated renewable energy.

[0112] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described, and it is understood that the invention includes all such variations and modifications that come within the spirit and scope of the invention.

[0113] Example 5 - Scale-up Example 2 Another scaled-up version of the energy storage device 400 is disclosed in Figures 7a-7g. Referring to Figures 7a-7c, multiple arrays of multiple thermal storage blocks 401, each with a separate thermal storage body 402, are all contained within an insulated, substantially airtight containment structure 403. In this embodiment, four thermal storage bodies 402 are provided along the length of an elongated containment structure 403, allowing a flow of gaseous heat transfer fluid introduced through horizontally facing openings 404 to flow through the thermal storage bodies via heat transfer channels 405 located therethrough to an exit opening 406 of the containment structure 403. The containment structure 403 is substantially insulated by insulating material 407, which is preferably 300 mm thick. A plurality of heating element ports 408 each connected to a heating element (each single port 408 may be connected to a single heating element, or multiple ports 408 may be connected to a single heating element, or multiple heating elements may be connected to a single port 408) are provided in the interstitial spaces between each of the plurality of thermal storage blocks 401 such that insulating material 407 is provided and a heating element inserted therethrough can provide radiant heating during thermal charging of the thermal storage body 402.

[0114] 7b, the containment structure 403 includes an airtight casing 409 adapted to substantially prevent leakage of heat transfer fluid from the thermal storage device 400. Additionally, multiple electric heating element ports 408 are inserted substantially perpendicular to both the direction of elongation of the heating device casing 403 and the general direction of heat transfer fluid flow. This perpendicular arrangement allows the heating element ports 408 to be conveniently withdrawn from the device for servicing or depending on the level of desired heat input. Furthermore, the use of multiple heating element ports 408 allows the thermal storage to be thermally charged in an even and efficient manner.

[0115] Referring to FIG. 7c, horizontal rows of MGA blocks 401 forming one of the heat stores 402 are positioned in a staggered pattern, with heat transfer channels defined between offset faces of the hexahedral MGA blocks 401 forming at least three rows. The offset positions of the MGA blocks in each row are fixed by a combination of "T"-shaped spacers 410 and horizontal bar spacers 411, which are horizontally alternately positioned between the blocks. Preferably, filler blocks 412 are positioned at the end of every second row to support the weight of the MGA blocks 401 on the edges of the other rows and stabilize the heat store 402. The filler blocks 412 may be smaller blocks formed from MGA material, or may be made of any material to provide rigidity to the entire array of blocks.

[0116] Depending on the size of the energy storage device, access to the internal volume is provided by access ports. In the embodiment illustrated in Fig. 7d, a number of doors 413 are provided for human access to the internal volume of the device, and thus the thermal store and the MGA blocks that form it. Furthermore, the hexahedral MGA blocks 401 are configured such that a heat transfer channel for radiant heating elements via ports 408 is provided between said MGA blocks. Preferably, the MGA blocks are offset in pairs to create this heat transfer channel for placement of heating elements.

[0117] A closer side elevation view of one heat store in Figure 7e and the plan view provided in Figure 7f show that horizontal bar spacers of two different lengths are provided to secure the MGA block 401 within the heat store 402. In this regard, both figures illustrate that a longer "B1" type bar spacer is arranged across the length of a pair of hexahedral MGA blocks, while a second, shorter "B2" type bar spacer is adapted and used to secure a single MGA block to the edge of the body 402, allowing for the creation of the staggered arrangement and heat transfer channels 405.

[0118] The three types of spacers, "T"-shaped, "B1" and "B2" bar spacers, together create heat transfer channels in the form of vertical interstitial spaces and vertical heating element spaces, while also fixing the MGA blocks for structural rigidity. Furthermore, the combination of bars prevents unnecessary distortion of the MGA blocks that make up the thermal store, so as to substantially mitigate thermal ratcheting.

Claims

1. 1. An energy storage device comprising: at least one heating device; a heat storage body comprising at least one heat storage block formed from a miscible gap alloy, the at least one heat storage block being arranged such that at least one heat transfer channel is formed in the at least one heat storage block, the at least one heat transfer channel being adapted to receive a flow of a heat transfer fluid and / or the at least one heating device; an insulating material surrounding the thermal store such that the thermal store is substantially insulated; at least one substantially impermeable shell surrounding the thermal mass and / or the thermal insulation so as to substantially contain the heat transfer fluid; heat can be stored or released from the heat store by heat transfer between the at least one heat transfer channel and the at least one heat storage block; the heat transfer fluid is in direct thermal contact with the at least one heat storage block when flowing through the at least one heat transfer channel; The miscible gap alloy is (i) a dense, continuous, thermally conductive matrix of a first component; (ii) particles of a second component dispersed throughout the matrix of the first component; the first and second components may independently be metallic or non-metallic, and the particles of the second component are particulates; the particulates of the second component comprising the miscible gap alloy forming the at least one heat storage block melt during the accumulation of heat in the heat storage body and remain molten until both sensible and latent heat are removed therefrom; Energy storage devices.

2. The heat transfer fluid is supercritical CO ２ , subcritical CO ２ 10. The energy storage device of claim 1, wherein the gas is selected from the group consisting of water vapor, nitrogen gas, air, organic gases, or mixtures thereof.

3. The energy storage device of claim 1 , wherein a plurality of the heat storage blocks are arranged to define a plurality of the heat transfer channels therein.

4. The energy storage device of claim 1 , wherein the at least one heating device is a heat exchanger coil and / or an electric heater, preferably one or more electrically powered radiant heaters.

5. 5. The energy storage device of claim 4, wherein the at least one heating device is one or more radiant heaters located near but not in contact with the heat store for radiative transfer of heat to the at least one heat store block.

6. 10. The energy storage device of claim 1, wherein the thermal energy transferred to the heat transfer fluid is used to operate and / or heat additional process equipment.

7. 7. The energy storage device of claim 6, wherein the energy storage device and the additional process equipment are fluidly connected in a closed loop that recirculates the heat transfer fluid.

8. 8. The energy storage device of claim 7, wherein the closed loop that recirculates the heat transfer fluid further comprises at least one of a fluid pump, a heat transfer fluid reservoir, or a heat exchanger.

9. 9. The energy storage device of claim 6, wherein the additional process equipment is selected from the group consisting of a turbine, a Rankine cycle turbogenerator, a Barton cycle engine, a Stirling cycle engine, a Brayton cycle turbogenerator, a heat exchanger, a steam generator, or a combination thereof.

10. 10. The energy storage device of claim 1, wherein the at least one heating device is adapted to store additional heat in the heat store while the heat store simultaneously releases stored heat.

11. 1. A method for storing energy, comprising: a) storing heat in a heat store comprising at least one heat storage block formed from a miscible gap alloy by heating at least one heating device adjacent to at least one heat transfer channel, said at least one heat storage block being arranged such that said at least one heat transfer channel is formed in said at least one heat storage block; b) storing thermal energy in the at least one thermal storage block by substantially insulating and sealing the thermal storage body formed by the at least one thermal storage block from the external atmosphere; c) releasing heat from the heat store by flowing a lower temperature heat transfer fluid through the at least one heat transfer channel so that heat is removed from the at least one heat store block; the heat transfer fluid is in direct thermal contact with the at least one heat storage block when flowing through the at least one heat transfer channel; The at least one heat storage block is formed from a miscible gap alloy, the miscible gap alloy comprising: (i) a dense, continuous, thermally conductive matrix of a first component; (ii) particles of a second component dispersed throughout the matrix of the first component; the first and second components may independently be metallic or non-metallic, and the particles of the second component are particulates; the stored heat melts the particles of the second component of the miscible gap alloy forming the at least one heat storage block during step a), so that both sensible and latent heat are stored in the heat storage body during step b); method.

12. The method of claim 11 , wherein the heat storage in step a) is performed by heating at least one heat exchanger coil and / or at least one electrically driven radiant heater.

13. 13. The method of claim 12, wherein the heat store is heated by flowing the heat transfer fluid at a higher temperature than the at least one heat storage block such that heat is transferred to the at least one heat storage block.

14. 13. The method of claim 12, wherein said heat storage is performed by energizing said at least one radiant heater located near, but not in contact with, said heat store.

15. 12. The method of claim 11, wherein the at least one heating device is heated by renewable energy and / or industrial waste heat recovery.

16. 12. The method of claim 11, wherein the heat storage and release of steps a) and c) occurs simultaneously.

17. 1. A system for storing energy, comprising: at least one energy source; at least one energy storage device, the energy storage device comprising: at least one heating device; a heat storage body including at least one heat storage block formed from a miscible gap alloy, the at least one heat storage block being arranged such that at least one heat transfer channel is formed in the at least one heat storage block, the at least one heat transfer channel being adapted to receive a flow of heat transfer fluid and / or the at least one heating device, the heat transfer fluid being in direct thermal contact with the at least one heat storage block when flowing through the at least one heat transfer channel; an insulating material surrounding the heat storage body such that the heat storage body is substantially insulated; and at least one substantially impermeable shell surrounding the heat storage body and / or the insulating material such that the heat transfer fluid is substantially contained, wherein heat can be stored or released from the heat storage body by heat transfer between the at least one heat transfer channel and the at least one heat storage block; at least one pumping means; at least one heat transfer and / or energy conversion means; contains the unit element of the unit elements are in fluid communication with one another such that the system forms at least one fluid path for transferring thermal energy between the unit elements; The at least one heat storage block is formed from a miscible gap alloy, the miscible gap alloy comprising: (i) a dense, continuous, thermally conductive matrix of a first component; (ii) particles of a second component dispersed throughout the matrix of the first component; The first and second components may independently be metallic or non-metallic, and the particles of the second component are particulates. system.

18. 18. The system of claim 17, wherein the energy source is an electrical and / or thermal energy source, preferably the energy source is a renewable energy source.

19. 20. The system of claim 18, wherein the heating device is electrically powered by a renewable energy source that generates electrical energy.

20. 20. The system of claim 18, wherein the thermal energy source is heat recovered from a fluid industrial waste stream.

21. The heat transfer fluid is supercritical CO ２ , subcritical CO ２ 18. The system of claim 17, wherein the gas is selected from the group consisting of water vapor, nitrogen gas, air, organic gases, or mixtures thereof.

22. 20. The system of claim 17, wherein the energy conversion means is selected from the group consisting of a turbine, a Rankine cycle turbogenerator, a Barton cycle engine, a Stirling cycle engine, a Brayton cycle turbogenerator, a steam generator, or combinations thereof.

23. 20. The system of claim 17, wherein the at least one heat transfer and / or energy conversion means is a heat exchanger for transferring thermal energy from the hot heat transfer fluid discharged from the at least one energy storage device to at least another heat transfer fluid or working fluid in a multi-pass system.

24. The system of claim 17 , wherein the at least one path comprises a closed-loop circulating path.

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