Hydrogen storage method combinations

Abstract

The invention relates to a system (1) for generating electrical energy, comprising: a first oxygen reservoir (2) for oxygen or for oxygen-containing gas; and a first hydrogen reservoir (3) for hydrogen in flowable state; a first fuel cell (4) connected to the first oxygen reservoir (2) by a first oxygen line (5) and to the first hydrogen reservoir (3) by a first hydrogen line (6) and having a first water outlet (7); the system (1) further comprising a second hydrogen reservoir (8) for hydrogen bound to a hydrogen carrier and releasable again by adding water; a second fuel cell (9) which can be supplied with oxygen by a second oxygen line (10), which is further connected to the second hydrogen reservoir (8) by a second hydrogen line (11) and has a second water outlet (12), wherein the first water outlet (7) and the second water outlet (12) are connected to a water inlet (15) of the second hydrogen reservoir (8) by a first water line (13) and a second water line (14). The invention further relates to a method for generating electrical energy.

Description

Technical Field

[0001] The present invention relates to a system for generating electrical energy using a fuel cell and a corresponding method. Background Technology

[0002] As is known from the prior art, when hydrogen (e.g., from a gaseous hydrogen storage tank or a liquid hydrogen storage tank) is supplied to a fuel cell along with a corresponding amount of oxygen, water is produced in addition to electrical energy and heat.

[0003] Existing technology also reveals hydrogen carriers (e.g., NaBH4) that require liquid water to release hydrogen. Once the process is started and hydrogen is fed into the fuel cell along with a corresponding amount of oxygen, water is one of the byproducts, in addition to electrical energy and heat. It should be noted, in particular, that when hydrogen and oxygen combine in the fuel cell, at least theoretically, a corresponding stoichiometric amount of water is also produced.

[0004] Documents EP 1 880 439 A1 and US 6,864,002 B1 disclose a fuel cell system in which hydrogen-containing fuel, contained in a fuel container, absorbs and reacts with water as a byproduct to produce hydrogen, which is then supplied to the fuel cell to sustain its operation without requiring an external water supply for the device's operation. This results in a reduction in the device's weight and size, and enables internal chemical control of hydrogen production to sustain power generation and internal water management. Summary of the Invention

[0005] However, two problems exist here. First, liquid water is required as the initial substance to initiate the reaction; second, since the reaction usually does not have a 100% yield, additional water is required within the system boundary, that is, additional water (e.g., in an additional tank) must be introduced into the closed system from the beginning.

[0006] Therefore, the object of the present invention is to provide a system for generating electrical energy that solves the problems of initial water supply and incomplete stoichiometric yield of water. Furthermore, the object of the present invention is to provide a corresponding method.

[0007] The purpose of this system is achieved by a system for generating electrical energy, comprising: a first oxygen storage unit for oxygen or an oxygen-containing gas; a first hydrogen storage unit for flowing hydrogen; a first fuel cell connected to the first oxygen storage unit via a first oxygen line and connected to the first hydrogen storage unit via a first hydrogen line to obtain a hydrogen supply, and having a first water outlet; the system further comprising a second hydrogen storage unit for hydrogen bound to a hydrogen carrier and which can be released again by adding water, characterized in that the first water outlet is connected to the water inlet of the second hydrogen storage unit via a first water line, and the second hydrogen line branches out from the second hydrogen storage unit to supply hydrogen to the system. Here, a fuel cell should generally be understood as a fuel cell unit or fuel cell stack.

[0008] By combining different hydrogen storage devices, where one hydrogen storage device produces water in total equilibrium and another hydrogen storage device tends to consume water, the capacity of the system in terms of energy density (watt-hours per unit volume or watt-hours per unit mass) can be increased.

[0009] In an advantageous embodiment of the invention, the first hydrogen storage device is a pressurized gas storage device. Higher energy density is achieved by compressing hydrogen to high pressure (typically 350 to 700 bar). This means that more energy can be stored in a smaller volume, which is particularly useful in situations where space is limited or the storage device must be transported. Furthermore, pressurized gas storage devices enable relatively efficient storage and extraction of hydrogen because the pressure within the storage device can be rapidly adjusted as needed. This makes it possible to quickly use hydrogen for various applications, such as fuel cells, for example, in this case. In addition, pressurized gas storage devices are generally more cost-effective than other storage technologies, such as those storing liquid hydrogen or metal hydride storage devices. Finally, pressurized gas storage devices have a smaller environmental impact compared to other storage technologies because they do not require chemical reactions or complex cooling processes.

[0010] In an alternative embodiment of the invention, the first hydrogen storage device is a liquid gas storage device. At ambient temperature, liquid hydrogen has a higher energy density than gaseous hydrogen. By converting hydrogen into a liquid gas at extremely low temperatures, more hydrogen can be stored in a given volume. This can be particularly useful in situations where space is limited or the storage device must be transported. Furthermore, the risk of leakage is lower for liquid hydrogen than for gaseous hydrogen because liquid hydrogen can be stored at lower pressures. This reduces the risk of accidents and explosions compared to pressurized gas storage devices.

[0011] Advantageously, in addition to the first fuel cell, the system includes a second fuel cell. The second fuel cell receives oxygen or oxygen-containing gas via a second oxygen line. It is also connected to a first hydrogen storage tank via a first hydrogen line, or to a second hydrogen storage tank via a second hydrogen line, or to both hydrogen storage tanks. It has a second water outlet connected to the inlet of the second hydrogen storage tank via a second water line. Due to the presence of the second fuel cell, the system can still generate energy even if one of the fuel cells fails, improving system reliability and availability. The two fuel cells also contribute to improved system efficiency, as they can operate in parallel to increase power or maintain the individual fuel cell at its optimal power. With two fuel cells, the system can also respond more flexibly to changing energy demands by individually controlling and adjusting the power of each fuel cell. Furthermore, the second fuel cell, connected via the second hydrogen line, the second oxygen line, and the second water outlet, can help optimize the system's thermal and water management. For example, waste heat from one fuel cell can be used to heat water in the second hydrogen storage tank, thus improving system efficiency.

[0012] Equally important, the fuel cell is not fixed to a specific hydrogen storage unit, but can obtain hydrogen from two hydrogen storage units. In particular, this also allows the fuel cell to operate using hydrogen primarily from, for example, a second hydrogen storage unit, which can then be designed to be larger.

[0013] This has several advantages. Hydrogen as a fluid is flammable and can pose safety risks when stored under pressure or at low temperatures. In a combined hydrogen storage device, the hydrogen is bound to a carrier material, which reduces the risk of fire or explosion.

[0014] The storage density of hydrogen in its bound form can be higher than that of hydrogen in its gaseous or liquid state. This makes it possible to store hydrogen more compactly and efficiently, which can benefit energy storage and transportation.

[0015] Gaseous hydrogen must be stored under high pressure, liquid hydrogen must be stored at very low temperatures, while bound hydrogen can be stored at ambient temperature and pressure in many cases. This reduces the requirements for storage facilities and their associated costs.

[0016] Furthermore, bound hydrogen can be stored for a long time without significant loss, while gaseous or liquid hydrogen may be more easily lost due to diffusion or evaporation.

[0017] In one embodiment of the invention, the second fuel cell is connected to the first oxygen reservoir via a second oxygen line. This has the advantage that by sharing a single oxygen reservoir for both fuel cells, the system utilizes resources more efficiently. This can help reduce system size and weight, which can be advantageous, especially in mobile applications or where space is limited. Furthermore, the shared oxygen reservoir for both fuel cells can help reduce system costs because fewer components are required. This can impact not only acquisition costs but also maintenance costs. Additionally, using a shared oxygen reservoir for both fuel cells simplifies system design due to fewer required components and connections. This can help reduce sources of error and improve system maintainability.

[0018] In an alternative embodiment of the invention, the second fuel cell is connected to the second oxygen reservoir via a second oxygen line. When multiple fuel cells must operate under different operating conditions, using a separate oxygen reservoir allows for better control over the individual requirements of each cell. This can help optimize the efficiency and power of each fuel cell while enabling precise control of oxygen flow under different operating conditions. A separate oxygen reservoir can improve fail-safety and redundancy in critical applications. In the event of a failure or damage to one oxygen reservoir, this only hinders that individual fuel cell, rather than affecting the entire system. In such cases, the failure of one fuel cell can be compensated for by having other fuel cells increase their power to cover the total energy demand. In some applications, it may be necessary to install fuel cells spatially separate from each other, for example, due to space constraints or thermal limitations. In such cases, using a separate oxygen reservoir simplifies the installation and operation of the fuel cells because it simplifies the connection between the cell and its corresponding oxygen reservoir.

[0019] Advantageously, the system includes a control unit that controls the mass flow rates of oxygen or oxygen-containing gases, hydrogen, and water in the system based on the electrical energy to be generated. This is crucial for the efficient operation of the system. The control unit enables precise adjustment of the mass flow rates of oxygen and hydrogen in the fuel cell to generate the desired electrical energy. This helps maximize system efficiency and optimize power output. The control unit can dynamically adjust the mass flow rates of oxygen, hydrogen, and water based on current power demands and operating conditions. This allows for rapid response to fluctuations in power demand and ensures the system operates efficiently at all times. The control unit can monitor and control the consumption of hydrogen and oxygen to ensure optimal resource utilization. This helps minimize hydrogen and oxygen consumption and reduce system operating costs. By precisely controlling the mass flow rates, the control unit can help extend the lifespan of the fuel cell. Uniform and optimal supply of oxygen and hydrogen to the cell reduces fuel cell degradation and extends its lifespan. The control unit also helps improve system safety by continuously monitoring and adjusting the mass flow rates of oxygen, hydrogen, and water to avoid potential hazards such as leaks, overpressure, or uncontrolled reactions. The control unit enables the easy integration of fuel cell systems into other electrical systems, such as the power grid or hybrid drive systems in vehicles. The control unit can adjust power production based on the needs of these systems, thus ensuring seamless collaboration.

[0020] Ideally, the control unit is connected to a controllable valve for controlling the mass flow rate of oxygen or oxygen-containing gases and hydrogen. This allows the oxygen and hydrogen supplies to be flexibly adapted to different operating conditions and power demands. This enables optimization of system performance under varying loads or environmental conditions.

[0021] Furthermore, it is suitable that the control unit is connected to a controllable pump for controlling the mass flow rate of water. In the case where hydrogen is supplied by a second hydrogen storage unit (the second hydrogen storage unit is a hydrogen storage system based on hydrolysis), that is, if the stored hydrogen is chemically bound to the carrier material and can only be released by adding water (or water vapor), then the desorption of hydrogen is also automatically regulated by the amount of water supplied.

[0022] Logically, a controllable pump used to control the mass flow rate of water for hydrogen desorption is supplied with a pre-installed water reservoir. Specifically, this means that the first outlet of the first fuel cell is connected to the first water reservoir, and the second outlet of the second fuel cell is connected to either the first or second water reservoir. These measures allow for more efficient utilization of the carrier material in the second hydrogen reservoir, as water can be supplied to the carrier material uniformly by controlled addition of water from the buffer reservoir. This allows for more efficient utilization of the carrier material and a higher hydrogen yield. Furthermore, the water reservoir enables adjustment of hydrogen production according to demand over a much larger range than that achieved solely through valves in the water pipeline. This is because it not only reduces water delivery and thus slows hydrogen release when hydrogen demand is low, but also allows for further increases in water delivery when demand is high, resulting in faster hydrogen production.

[0023] The objective of the method is achieved by a method for generating electrical energy, in which oxygen or an oxygen-containing gas is electrochemically combined with hydrogen from a first hydrogen storage tank for flowing hydrogen, wherein electrical energy and water are generated, characterized in that the water is supplied to a second hydrogen storage tank for hydrogen bound to a hydrogen carrier and which can be released again by adding water, wherein hydrogen is generated, and the hydrogen is then electrochemically combined with oxygen or an oxygen-containing gas, and the water generated at this time is also supplied to the second hydrogen storage tank.

[0024] Instead of discharging excessive amounts of water, it can be stored and supplied to a second hydrogen storage tank when needed.

[0025] Particularly advantageous is that the method is initiated by electrochemically combining oxygen or an oxygen-containing gas with hydrogen from a first hydrogen storage unit for flowing hydrogen, wherein heat is generated in addition to electrical energy and water, which is used to heat a second hydrogen storage unit, and wherein the method is continued by stopping the hydrogen supply from the first hydrogen storage unit and using hydrogen from the second hydrogen storage unit instead.

[0026] However, it is also advantageous not to completely stop the hydrogen supply from the first storage tank, but to make up for the water lost in order to release hydrogen from the second hydrogen storage tank by extracting a corresponding amount of hydrogen from the first hydrogen storage tank and electrochemically combining it with oxygen or an oxygen-containing gas.

[0027] According to the present invention, by combining different hydrogen storage methods, the energy density of the entire system can be improved, for example, by eliminating or minimizing the need for an additional water tank.

[0028] Furthermore, utilizing the heat generated by hydrogen passing through the direct hydrogen storage unit in the fuel cell can help accelerate the release of hydrogen from the indirect hydrogen storage unit.

[0029] Furthermore, fuel cell systems with integrated liquid or gaseous hydrogen storage devices have shorter start-up times compared to other hydrogen storage methods. Attached Figure Description

[0030] Figure 1 A system for generating electrical energy according to the present invention is shown;

[0031] Figure 2 Alternative systems for generating electrical energy according to the invention are shown; and

[0032] Figure 3 Another system for generating electrical energy according to the present invention is shown. Detailed Implementation

[0033] Figure 1 An embodiment of a system 1 for generating electrical energy 22 according to the present invention is shown. Furthermore, Figure 1 It is shown that not only is electrical energy 22 generated, but also water (first water storage 20, second water storage 21), and a certain amount of heat 23 is also generated.

[0034] System 1 includes a first oxygen reservoir 2 for oxygen or for an oxygen-containing gas and a first hydrogen reservoir 3 for liquid hydrogen. The hydrogen reservoir 3 can be implemented as a pressurized gas reservoir or a liquid gas reservoir. System 1 also includes a first fuel cell 4, which is connected to the first oxygen reservoir 2 via a first oxygen line 5 and to the first hydrogen reservoir 3 via a first hydrogen line 6, and has a first outlet 7.

[0035] System 1 also includes: a second hydrogen storage tank 8, which is used to hold hydrogen on a hydrogen carrier and can be released again by adding water; a second fuel cell 9, which can obtain oxygen supply through a second oxygen line 10, and is also connected to the second hydrogen storage tank 8 through a second hydrogen line 11, and has a second water outlet 12.

[0036] According to the present invention, the first water outlet 7 and the second water outlet 12 are connected to the water inlet 15 of the second hydrogen storage tank 8 via the first water pipeline 13 and the second water pipeline 14.

[0037] exist Figure 1 In this embodiment, the second fuel cell 9 is connected to the second oxygen storage device 16.

[0038] The efficient operation of System 1 is ensured by Control Unit 17, which controls the mass flow rates of oxygen, hydrogen, and water based on the electrical energy to be generated. For example, the amount of oxygen to be supplied to the first fuel cell 4 and the second fuel cell 9 is controlled by Controllable Valve 18 arranged in the first oxygen line 5 and the second oxygen line 10.

[0039] Similarly, controllable valves 18 are arranged in the first hydrogen line 6 and the second hydrogen line 11 to regulate the hydrogen supply to fuel cells 4 and 9. Additionally, adjustable pumps 19 are arranged in the first water line 13 and the second water line 14 to regulate the hydrogen supply to the second fuel cell 9, and these pumps are connected to the control unit 17.

[0040] To provide greater flexibility during system 1 operation, the first outlet 7 is connected to the first water storage tank 20. The second outlet 12 can be connected to the first water storage tank 20, or as... Figure 1 The water is introduced into the second water storage tank 21 as shown.

[0041] Figure 2 It shows the relationship with Figure 1 This embodiment is a significantly simplified variation of the system 1 for generating electrical energy according to the invention. Here, the system 1 for generating electrical energy still includes only: a first oxygen storage tank 2 for oxygen or an oxygen-containing gas; a first hydrogen storage tank 3 for flowing hydrogen; a first fuel cell 4, which is connected to the first oxygen storage tank 2 via a first oxygen line 5 and to the first hydrogen storage tank 3 via a first hydrogen line 6 to obtain a hydrogen supply, and has a first water outlet 7. According to the invention, the system 1 also includes a second hydrogen storage tank 8 for hydrogen bound to a hydrogen carrier and which can be released again by adding water; the first water outlet 7 is connected to the water inlet 15 of the second hydrogen storage tank 8 via a first water line 13; and a second hydrogen line 11 branches off from the second hydrogen storage tank 8 and leads into the first fuel cell 4.

[0042] For System 1 to operate efficiently, Figure 2 In one embodiment, a control device 17 is also provided, which has an associated controllable valve 18 and a controllable pump 19.

[0043] Figure 3 An embodiment illustrates a system 1 according to the invention for generating electrical energy, comprising a first fuel cell 4 and a second fuel cell 9. As... Figure 1 In an additional embodiment, the first fuel cell 4 is not only connected to the first hydrogen storage tank 3, but can also obtain hydrogen supply from the second hydrogen storage tank 8, such as... Figure 2 As already shown. For clarity, Figure 3Not shown, this method of supplying hydrogen from the two hydrogen storage tanks 3 and 8 is also reasonable and feasible for the second fuel cell 9. List of reference numerals in the attached diagram: 1. Systems for generating electrical energy 2. First oxygen storage unit 3. First hydrogen storage unit (for flowing hydrogen) 4 First Fuel Cell 5. First Oxygen Pipeline 6. First Hydrogen Pipeline 7 First outlet 8. Second hydrogen storage unit (with hydrogen carrier) 9. Second Fuel Cell 10 Second Oxygen Pipeline 11 Second Hydrogen Pipeline 12 Second outlet 13 First Water Pipeline 14 Second water pipeline 15. Water Inlet 16 Second Oxygen Storage Unit 17 Control Unit 18 Controllable valve 19 Controllable Pumps 20 First Water Storage Unit 21 Second Water Storage Unit 22 Electrical energy 23 calories

Claims

1. A system (1) for generating electrical energy, the system comprising: The system (1) further includes a first oxygen storage unit (2) for oxygen or for oxygen-containing gases; and a first hydrogen storage unit (3) for flowing hydrogen; a first fuel cell (4) connected to the first oxygen storage unit (2) via a first oxygen line (5) and connected to the first hydrogen storage unit (3) via a first hydrogen line (6) to obtain a hydrogen supply, and the first fuel cell having a first water outlet (7); the system (1) further includes a second hydrogen storage unit (8) for hydrogen combined on a hydrogen carrier and capable of being released again by adding water, characterized in that the first water outlet (7) is connected to the water inlet (15) of the second hydrogen storage unit (8) via a first water line (13), and a second hydrogen line (11) branches out from the second hydrogen storage unit (8) in order to supply hydrogen in the system (1).

2. The system (1) according to claim 1, wherein, The first hydrogen storage device (3) is a pressurized gas storage device.

3. The system (1) according to claim 1, wherein, The first hydrogen storage device (3) is a liquid gas storage device.

4. The system (1) according to any one of the preceding claims, wherein, The system also includes a second fuel cell (9), which is capable of obtaining oxygen or oxygen-containing gas through a second oxygen line (10). The second fuel cell is also connected to the first hydrogen storage unit (3) through the first hydrogen line (6), or to the second hydrogen storage unit (8) through the second hydrogen line (11), or to both hydrogen storage units (3, 8). The second fuel cell has a second water outlet (12), which is connected to the water inlet (15) of the second hydrogen storage unit (8) through a second water line (14).

5. The system (1) according to claim 4, wherein, The second fuel cell (9) is connected to the first oxygen storage device (2) via the second oxygen line (10).

6. The system (1) according to claim 4, wherein, The second fuel cell (9) is connected to the second oxygen storage unit (16) via the second oxygen line (10).

7. The system (1) according to any one of the preceding claims, the system further comprising a control unit (17) for controlling the mass flow rate of oxygen or oxygen-containing gas, hydrogen and water in the system (1) according to the electrical energy to be generated.

8. The system (1) according to claim 7, wherein, The control unit (17) is connected to a controllable valve (18) for controlling the mass flow rate of oxygen or oxygen-containing gas and hydrogen.

9. The system (1) according to any one of claims 7 or 8, wherein, The control unit (17) is connected to a controllable pump (19) for controlling the mass flow rate of water.

10. The system (1) according to any one of the preceding claims, wherein, The first outlet (7) leads into the first water storage tank (20).

11. The system (1) according to claims 4 and 10, wherein, The second outlet (12) leads into the first water storage tank (20) or the second water storage tank (21).

12. A method for generating electrical energy, wherein oxygen or an oxygen-containing gas is electrochemically combined with hydrogen from a first hydrogen storage tank (3) for flowing hydrogen, wherein electrical energy and water are generated, characterized in that, The water is supplied to a second hydrogen storage tank (8) for binding hydrogen to a hydrogen carrier and being able to release hydrogen again by adding water, wherein hydrogen is generated, which then electrochemically combines with oxygen or an oxygen-containing gas, and the water generated at this time is also supplied to the second hydrogen storage tank (8).

13. The method according to claim 12, wherein, Storing excessive amounts of water.

14. The method according to any one of claims 12 or 13, wherein, The method is initiated by electrochemically combining oxygen or an oxygen-containing gas with hydrogen from the first hydrogen storage unit (3) for flowing hydrogen, wherein heat is generated in addition to electrical energy and water, which is used to heat the second hydrogen storage unit (8), and wherein the method is continued by stopping the supply of hydrogen from the first hydrogen storage unit (3) and instead using hydrogen from the second hydrogen storage unit (8).

15. The method according to any one of claims 12 or 13, wherein, The amount of water lost in order to release hydrogen from the second hydrogen storage unit (8) is compensated by extracting the corresponding amount of hydrogen from the first hydrogen storage unit (3) and electrochemically combining it with oxygen or an oxygen-containing gas.

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