Thermal energy storage apparatus, thermal energy storage module, method of operating a closed-loop power generation system with a thermal (HEAT) energy transfer fluid (HTF) as the working fluid, and method of operating a thermal energy storage apparatus

Abstract

The present invention provides a thermal energy storage device comprising: a housing defining a hollow internal chamber configured in use to contain a graphite solid material in an inert gas atmosphere; and at least one conduit configured to extend through the hollow internal chamber via an inlet opening and an outlet opening in the housing, the conduit being hermetically fitted to the housing at the inlet and outlet openings, and the outer surface of the conduit being configured to be in close facing relation to the graphite solid material located within the hollow internal chamber, wherein, in use, the conduit is configured to deliver a flow of fluid through the conduit such that, in a first configuration, the flow transfers thermal energy to the graphite solid material, and in a second configuration, the graphite solid material transfers thermal energy to the flow.

Description

[Technical Field] This invention generally relates to the field of energy storage, and more specifically, to devices for storing and using energy generated from renewable resources such as photovoltaic, wind, and wave energy. However, the disclosed concepts can be used with any energy source that generates more power than immediate needs during certain periods of the day and requires temporary energy storage solutions for time-shifting purposes. This invention relates to a heat storage device and method, but it should be understood that it is applicable to many other areas. For example, users may be able to capture waste heat generated by conventional fossil fuel combustion or power generation, as well as waste heat from various sources such as factory waste heat recovery and geothermal power generation. [Previous Technology] Any discussion of prior art throughout this specification should not be construed as an admission that such prior art is well known or common knowledge in the field. Globally, there is a growing recognition of the need to reduce reliance on fossil fuels and increase the use of renewable energy. Solar energy (and other types of photovoltaic (PV) energy capture) is virtually an unlimited primary renewable energy source for the foreseeable future. However, solar energy has drawbacks, such as being unusable at night, in inclement weather, or even on cloudy days. Therefore, if renewable energy conversion systems are to improve dispatchability and become a viable alternative to fossil fuels as an energy source, they need to include some form of energy storage. Other renewable energy sources, such as wind, wave, and tidal energy, also have variable outputs, and in some cases, unpredictable variations. To ensure capacity availability to meet demand, some form of storage is needed to match supply with demand if demand arises outside of peak renewable energy capture periods. Current battery systems are expensive and limited to short-term grid frequency stabilization, rather than load shifting to meet secondary peak demand when sunlight is absent. It is now known that a wide variety of technologies can be used to realize the general field of so-called "thermal energy storage" (TES). Depending on the specific technology, excess thermal energy can be stored and used after hours, days, or months, and its scale can range from individual programs, buildings, multi-user buildings, districts, towns, or regions. One method for energy storage has been proposed, which involves heating the host when energy production exceeds demand and recovering the heat and converting it into electrical energy when demand exceeds supply. Various materials have been proposed for the thermal storage host, and graphite has been found to be particularly useful in this role. However, graphite is known to be flammable at very high temperatures under certain conditions, which presents particular challenges if used as a thermal storage medium. Carbon in graphite form has a variety of uses, including storing heat or buffering heat generated in high-temperature devices. A persistent risk in these applications is that graphite exposed to oxygen (or air) at high temperatures could potentially ignite. The object of this invention is to overcome or improve at least one of the disadvantages of prior art, or to provide a useful and / or safer alternative. There is a general need in the art for an energy storage system that can overcome at least some of the identified limitations by providing a cost-effective, safe, and efficient way to store and distribute excess energy. Unless the context clearly requires otherwise, throughout the specification and the scope of the patent application, the terms "comprise" and similar terms should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to". Although the invention will be described with reference to specific examples, those skilled in the art will understand that the invention may be embodied in many other forms. [Summary of the Invention] In the first embodiment, a specific example of a thermal energy storage device is disclosed, comprising: a housing defining a hollow internal chamber configured in use to contain a graphite solid material in an inert gas atmosphere; and at least one conduit configured to extend through the hollow internal chamber via inlet and outlet openings in the housing, the conduit being hermetically fitted to the housing at the inlet and outlet openings, and the outer surface of the conduit being configured to be in close facing relation to the graphite solid material located within the hollow internal chamber, wherein, in use, the conduit is configured to transport a flow of fluid through the conduit such that, in a first configuration, the flow transfers thermal energy to the graphite solid material, and in a second configuration, the graphite solid material transfers thermal energy to the flow. In some specific instances, the fluid is a heat transfer fluid, which operates such that: in the first configuration, the fluid flow heats the conduit or each conduit in a conductive manner, and the conduit conducts and radiates heat toward the graphite solid material; and in the second configuration, the graphite solid material conducts and radiates heat toward the conduit or each conduit, and the conduit heats the fluid flow therein in a conductive manner. In some specific examples, graphite solid materials are repeatedly heated and cooled by transferring heat energy into the flow of the heat transfer fluid and from the flow of the heat transfer fluid. In some specific instances, when the device is configured to have a single conduit, the conduit is adapted to sequentially deliver different fluids through it in order to subsequently operate in the first and second configurations. In some specific examples, when in the first configuration, the conduit contains a material suitable for conveying the flow of a high-temperature fluid (HTF) or a supercritical fluid, and when in the second configuration, the conduit contains a material suitable for conveying the flow of a supercritical fluid. In alternative specific examples, when in the first configuration, the conduit contains a material suitable for conveying the flow of a high-temperature fluid (HTF) or a supercritical fluid, and when in the second configuration, the conduit contains a material suitable for conveying the flow of a high-temperature fluid (HTF). In some specific instances, when the device is configured to have at least two conduits, it is then adapted to deliver fluid in the first conduit in order to operate in the first configuration, and adapted to deliver fluid in the second separate conduit in order to operate in the second configuration. In some specific examples, the first conduit contains a material suitable for conveying the flow of a high-temperature fluid (HTF) or a supercritical fluid, and the second conduit contains a material suitable for conveying the flow of a supercritical fluid. In alternative specific examples, the first conduit contains a material suitable for conveying the flow of a high-temperature fluid (HTF) or a supercritical fluid, and the second conduit contains a material suitable for conveying the flow of a high-temperature fluid. In some specific instances, the high-temperature fluid (HTF) comprises at least one of the following groups: liquid sodium (Na); liquid potassium (K); liquid NaK (77.8% K); liquid tin (Sn); liquid lead (Pb); liquid lead bismuth (PbBi) (45% / 55%). In some specific examples, the supercritical flow system comprises at least one of the following: carbon dioxide (CO2), methane (CH4), ethane (C2H6), propane (C3H8), ethylene (C2H4), propylene (C3H6), methanol (CH3OH), ethanol (C2H5OH), acetone (C3H6O), and nitrous oxide (N2O). In some specific examples, the first and second conduits comprise a material with an operating temperature range of about 550°C to about 1000°C. In one particular form, the first and second conduits comprise a material with an operating temperature range of about 550°C to about 900°C, 700°C to about 900°C, or 550°C to about 800°C. In other specific instances, the operating temperature range may be approximately 600 to 1000°C, approximately 700 to 1000°C, approximately 800 to 1000°C, approximately 900 to 1000°C, approximately 550 to 900°C, approximately 550 to 800°C, approximately 550 to 700°C, approximately 550 to 600°C, approximately 600 to 900°C, approximately 600 to 800°C, or approximately 600 to 700°C. In some specific examples, the inert gas atmosphere within the hollow internal cavity is maintained by means of a substantially airtight shell covering the graphite solid material and an initial amount of inert gas introduced. In some alternative specific examples, the inert gas atmosphere within the cavity is maintained by a forward flow of inert gas fed into the shell covering the graphite solid material. For example, an inert gas such as argon can be periodically pumped to the uppermost end of the hollow cavity via a gas inlet located above the graphite block and powder contents to displace any oxygen that may enter. In some specific examples, the graphite solid material can generate inert gas during operation without relying on an external system. For example, heating the graphite solid material in air to an operating temperature such as about 550°C to 1000°C can generate carbon monoxide and carbon dioxide as inert gases. In some specific instances, the graphite solid material in the hollow internal cavity comprises a plurality of solid graphite blocks adapted to be embedded in the or each conduit, and powdered graphite placed around the conduit to substantially fill the remaining void space in the cavity. In some specific examples, the hollow chamber is shaped into a rectangular prism and presented as a panel with top, side edge lifts, and installation adaptability. Each thermal energy storage panel may contain no more than 5000 kg of graphite and may contain between 2000 kg and 3800 kg of graphite or between 2000 kg and 3000 kg of graphite. In some specific instances, the conduit used to transport either a high-temperature fluid (HTF) or a supercritical fluid in the first configuration provides fluid communication to an upstream source for heating the fluid. In some specific instances, the conduit used to transport one of the supercritical fluids in this second configuration provides fluid communication to a downstream supercritical fluid turbine. In the second embodiment, a specific example of a thermal energy storage module is disclosed, the thermal energy storage module comprising: a plurality of thermal energy storage devices disclosed in the first embodiment; a housing of each of the devices, which is adapted to be mounted and suspended from a frame that can be positioned inside a transshipment container; and inlet and outlet openings of the or each conduit, which are provided at the housing externally connected to an input and output manifold for conveying the flow of the fluid through the conduit(e). In some specific instances, the thermal energy storage module may be contained in between 2 and 40 thermal energy storage panels, and more preferably between 4 and 16 thermal energy storage panels. The thermal energy storage module inlet manifold can be connected to the conduit inlets of the plurality of thermal energy storage panels. An inlet manifold temperature sensor can measure the inlet manifold temperature. The thermal energy storage module may also include an outlet manifold connecting to the conduit outlets of the plurality of thermal energy storage panels. An outlet manifold temperature sensor can measure the outlet manifold temperature. In some specific instances of this module, each of the plurality of thermal energy storage devices has one or more associated sensors to measure the conditions of the graphite solid material within each of the plurality of thermal energy storage devices. In some specific instances of this module, the measurement conditions include one or more of the following: the temperature of the graphite solid material, the amount of inert gas pressure, and the amount of oxygen present. Each thermal energy storage device (shown in the figure as a panel) may have a level for monitoring an inert gas (such as argon) and / or an oxygen or inert gas sensor for detecting oxygen within the thermal energy storage panel, the inert gas being used to fill the voids in the thermal energy storage panel. Methods for testing the conditions of inert gas may include: i) performing a pressure holding test when the temperature is stable; ii) using an oxygen sensor to detect the presence of oxygen in the panel; iii) measuring the flow of inert gas into the panel to detect abnormal inflow rates. Sensors used to measure the conditions of inert gases such as argon in thermal energy storage panels can also be connected to a PLC. The PLC can be programmed to monitor the sensors and control valves, pumps, or other auxiliary devices, and may isolate the flow of supercritical fluids or cut off the power supply to a specific thermal energy storage panel in cases where the conditions of the inert gas therein, such as when the pressure drops to or below a predetermined level or decreases rapidly to below a predetermined level. Alternatively, a flow meter can be used on the inert gas inlet line to monitor gas consumption and operate the electronic power controller in the event of a sudden increase in gas supply that could indicate a possible rupture of the outer wall or cladding of the thermal energy storage panel's chamber. Detection of the presence of oxygen within the thermal energy storage panel can also be used to operate the electronic power controller. In some specific instances of this module, a programmable logic controller (PLC) is provided, such that signals from relevant sensors used to monitor graphite solid materials are connected to the PLC, and relevant responsive electronic controls are controlled by the PLC, wherein the PLC is programmed to monitor the relevant sensors and control the fluid flow to the module. The PLC can be programmed to provide signal outputs and inputs for transmission to system-level controllers and displays, such as Distributed Control Systems (DCS), and from which signals are transmitted. These displays provide control functions and indicate measured and calculated parameters including one or more of the following: average graphite temperature of the module; maximum graphite temperature of the module (indicating which temperature sensor is on which panel); minimum graphite temperature of the module (indicating which temperature sensor is on which panel); percentage of module state of charge; state of thermal charge of the module in kWht; pressure and / or flow rate of inert gas (e.g., argon); inlet and outlet manifold temperatures; and system generation commands to start or stop heating. A local display can be provided to show the output from the PLC. The PLC can measure the inlet manifold temperature and transmit it to the central controller. The PLC can also measure the outlet manifold temperature and transmit it to the central controller. In the third example, a specific example of a method for operating a closed-loop power generation system using a supercritical fluid as the working fluid is disclosed. The power generation system includes a thermal energy storage device and a supercritical fluid turbine, and the method includes the following steps: storing energy using a high-temperature thermal energy storage device containing a graphite solid material; and then, when energy is needed: heating the stored thermal energy by placing a component of a supercritical fluid flow into contact with the thermal energy storage device via a conduit; and placing the resulting supercritical fluid flow into fluid communication with a downstream supercritical fluid turbine. In some specific instances of this method, after the flow of supercritical fluid passes through a downstream supercritical fluid turbine, it returns to a duct for further heating. In some specific instances of this method, the supercritical fluid is used to operate the turbine to generate electricity. In some specific instances of this method, the thermal energy is stored in a graphite solid material contained in a chamber within an inert gas atmosphere. In the fourth embodiment, a specific example of a method for operating a thermal energy storage device is disclosed, the method comprising the steps of: fluidly connecting a housing comprising a hollow internal chamber substantially filled with a graphite solid material in an inert gas atmosphere; the housing having at least one conduit configured to extend through the hollow internal chamber via inlet and outlet openings in the housing; the conduit being hermetically fitted to the housing at the inlet and outlet openings; and the outer surface of the conduit being configured to be in close facing relation to the graphite solid material positioned within the hollow internal chamber; via The fluid connection delivers a flow of high-temperature fluid (HTF) or supercritical fluid from an upstream source to the duct or each conduit, thereby transferring heat to the graphite solid material until the desired graphite temperature is reached; then, at a future time, when the heat is needed downstream, the method includes the following additional steps: fluidly connecting the housing; heating the components of the supercritical fluid flow by placing a component of the supercritical fluid flow in contact with the heat storage device in the duct or each conduit; and placing the resulting supercritical fluid flow in fluid communication with a downstream supercritical fluid turbine. The features, characteristics, and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which form part of the invention and illustrate any of the principles of the disclosed invention.

Implementation Method

Claims

1. A thermal energy storage device comprising: a thermal energy storage panel housing defining a hollow internal chamber configured in use to contain a graphite solid material in an inert gas atmosphere; and at least one conduit configured to extend through the hollow internal chamber via an inlet opening and an outlet opening in the thermal energy storage panel housing, the conduit being hermetically fitted to the thermal energy storage panel housing at the inlet and outlet openings, and the outer surface of the conduit being configured to be in close facing relation to the graphite solid material positioned within the hollow internal chamber, wherein the thermal energy storage panel housing includes a gas inlet to maintain the inert gas atmosphere within the chamber by means of a forward flow of inert gas fed into the thermal energy storage panel housing covering the graphite solid material, wherein... In use, the conduit or each conduit is configured to convey a flow of fluid through it, such that in a first configuration, the flow transfers heat to the graphite solid material, and in a second configuration, the graphite solid material transfers heat to the flow, wherein the fluid is a heat transfer fluid (HTF), and its operation is such that: in the first configuration, the fluid flow conductively heats the conduit or each conduit, and the conduit conducts and radiates heat toward the graphite solid material; and in the second configuration, the graphite solid material conducts and radiates heat toward the conduit or each conduit, and the conduit conductively heats the fluid flow therein; wherein the graphite solid material is repeatedly heated and cooled by the individual transfer of heat energy to and from the flow of the heat transfer fluid; and wherein the operating temperature is 700°C to 900°C.

2. The thermal energy storage device of claim 1, wherein when the device is configured to have a single conduit, the conduit is then adapted to sequentially deliver different fluids through the conduit itself in order to operate in the first configuration and the second configuration.

3. The thermal energy storage device of claim 2, wherein in the first configuration, the conduit contains a material suitable for conveying the flow of HTF or supercritical fluid, and in the second configuration, the conduit contains a material suitable for conveying the flow of supercritical fluid.

4. The thermal energy storage device of claim 2, wherein in the first configuration, the conduit contains a material suitable for conveying the flow of HTF or supercritical fluid, and in the second configuration, the conduit contains a material suitable for conveying the flow of HTF.

5. The thermal energy storage device of claim 1, wherein when the device is configured to have at least two conduits, the device is then adapted to deliver fluid in the first conduit for operation in the first configuration, and adapted to deliver fluid in the second, separate conduit for operation in the second configuration.

6. The thermal energy storage device of claim 5, wherein the first conduit contains a material suitable for conveying the flow of HTF or supercritical fluid, and the second, separate conduit contains a material suitable for conveying the flow of supercritical fluid.

7. The thermal energy storage device of claim 5, wherein the first conduit contains a material suitable for conveying the flow of HTF or supercritical fluid, and the second, separate conduit contains a material suitable for conveying the flow of HTF.

8. A thermal energy storage device as claimed in any of claims 3, 4, 6 or 7, wherein the HTF comprises at least one of the following: liquid sodium (Na); liquid potassium (K); liquid NaK (77.8% K); liquid tin (Sn); liquid lead (Pb); liquid lead bismuth (PbBi) (45% / 55%).

9. A thermal energy storage device as claimed in any of claims 3, 4, 6 or 7, wherein the supercritical flow system comprises at least one of the following: carbon dioxide (CO2), methane (CH4), ethane (C2H6), propane (C3H8), ethylene (C2H4), propylene (C3H6), methanol (CH3OH), ethanol (C2H5OH), acetone (C3H6O) and nitrous oxide (N2O).

10. A thermal energy storage device as claimed in any of claims 1 to 7, wherein the gas inlet is configured to periodically pump inert gas into the thermal energy storage panel housing.

11. The thermal energy storage device of claim 1, wherein the graphite solid material in the hollow internal cavity comprises a plurality of solid graphite blocks adapted to be embedded in the or each conduit, and powdered graphite placed around the or each conduit to substantially fill the remaining void space in the cavity.

12. The thermal energy storage device of claim 11, wherein the solid graphite block is a graphite plate.

13. A thermal energy storage device as claimed in any of claims 3, 4, 6 or 7, wherein the conduit for conveying the flow of HTF or supercritical fluid in the first configuration provides fluid communication to an upstream source for heating the fluid.

14. A thermal energy storage device as claimed in any of claims 3, 4, 6 or 7, wherein the conduit for conveying the flow of supercritical fluid in the second configuration is provided with fluid communication to a downstream HTF turbine generator.

15. A thermal energy storage module comprising: a plurality of the thermal energy storage devices as claimed in any one of claims 1 to 14; a thermal energy storage panel housing of each of the devices, adapted to be mounted and suspended from a frame that can be positioned inside an intermodal transport container; and the inlet and outlet openings of the or each conduit, disposed at the thermal energy storage panel housing externally connected to an input manifold and an output manifold for conveying the flow of the fluid through the conduit(e).

16. The thermal energy storage module of claim 15, wherein each of the plurality of thermal energy storage devices has one or more associated sensors for measuring the condition of the graphite solid material within each of the plurality of thermal energy storage devices.

17. The thermal energy storage module of claim 16, wherein the measured conditions include one or more of the following: the temperature of the graphite solid material, the pressure of the inert gas, and the amount of oxygen present.

18. The thermal energy storage module of claim 16 or 17, wherein a programmable logic controller (PLC) is provided such that signals from relevant sensors for monitoring the graphite solid material are connected to the PLC, and relevant responsive electronic control devices are controlled by the PLC, wherein the PLC is programmed to monitor the relevant sensors and control the fluid flow to the module.

19. The thermal energy storage module of claim 15, wherein each of the plurality of thermal energy storage devices is positioned in use to be thermally connected to at least one other energy storage device.

20. A method for a closed-loop power generation system using a heat transfer fluid (HTF) as the working fluid, the power generation system comprising a thermal energy storage device as claimed in any one of claims 1 to 14 and an HTF turbine generator, the method comprising the steps of: storing energy using the thermal energy storage device comprising a graphite solid material; and then, when the energy is needed: heating the components by placing a component of the HTF flow into contact with the thermal energy storage device via a heat exchanger using the stored thermal energy; and placing the resulting HTF flow into fluid communication with a downstream HTF turbine generator.

21. The method of claim 20, wherein the HTF is a supercritical fluid.

22. The method of claim 21, wherein the supercritical fluid is carbon dioxide (sCO2) working fluid.

23. The method of claim 20, wherein the flow in the HTF, after passing through the downstream HTF turbine generator, returns to the heat exchanger for further heating.

24. The method of claim 20, wherein the HTF is used to operate the HTF turbine generator to generate electricity.

25. The method of claim 20, wherein the thermal energy is stored in a graphite solid material contained in a chamber in an inert gas atmosphere.

26. A method of operating a thermal energy storage device as claimed in any one of claims 1 to 14, the method comprising the steps of: fluidly connecting a thermal energy storage panel housing including a hollow internal cavity substantially filled with a graphite solid material in an inert gas atmosphere; the thermal energy storage panel housing having at least one conduit configured to extend through the hollow internal cavity via inlet and outlet openings in the thermal energy storage panel housing; the conduit being hermetically fitted to the thermal energy storage panel housing at the inlet and outlet openings; and the outer surface of the conduit being configured to be positioned within the hollow internal cavity. The graphite solid material within the chamber is in close facing relationship; the flow of heat transfer fluid (HTF) is delivered from an upstream source to the or each conduit via the fluid connection, thereby transferring heat to the graphite solid material until the desired graphite temperature is reached; then, at a future time, when the heat energy is needed downstream, the method includes the following additional steps: fluidly connecting the heat energy storage panel housing, using the stored heat energy to heat such components by placing a component of the HTF flow in contact with the heat energy storage device in the or each conduit, and placing the resulting HTF flow in fluid communication with the downstream HTF turbine generator.

27. The method of claim 26, wherein the HTF is a supercritical fluid.

28. The method of claim 27, wherein the supercritical fluid is carbon dioxide (sCO2) working fluid.

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