SOEC-SOFC-HBR hybrid system for green ammonia production

Abstract

Provided is a SOFC-SOEC-HBR hybrid system for green ammonia production. 【Solution means】Basically, an electric solid oxide electrolysis cell (SOEC) is driven by electricity produced from renewable energy such as wind power and solar power, but the intermittency of renewable energy is complemented by a solid oxide fuel cell (SOFC). Hydrogen produced by the water electrolysis cell (SOEC) and nitrogen discharged by the fuel cell (SOFC) are input into a Haber-Bosch reactor (Habor-Bosch Reactor), and heat from the SOFC and the Haber-Bosch reactor is recovered to provide a SOFC-SOEC-HBR hybrid system that efficiently and continuously produces green ammonia.

Description

Technical Field

[0001] The present invention relates to a SOFC-SOEC-HBR hybrid system for green ammonia production, which basically drives a solid oxide electrolysis cell (SOEC) by electricity produced from renewable energy such as wind power and sunlight. However, the intermittency of renewable energy is complemented by a solid oxide fuel cell (SOFC), and hydrogen produced by the electrolysis cell (SOEC) and nitrogen discharged from the fuel cell (SOFC) are input into a Haber-Bosch reactor (Habor-Bosch Reactor). By recovering the heat of the SOFC and the Haber-Bosch reactor, the present invention relates to a SOFC-SOEC-HBR hybrid system for efficiently and continuously producing green ammonia.

Background Art

[0002] Green ammonia is produced by reacting green hydrogen generated by electrolyzing renewable energy electricity with nitrogen collected during standby. Since it does not contain carbon, its net emissions are close to zero from the perspective of life cycle assessment.

[0003] Green ammonia sometimes means a synthetic fuel that can be converted into electricity and thermal energy. Recently, however, its role as an energy carrier for storing and transporting green hydrogen produced by electrolyzing renewable energy in liquid form has been more focused. In particular, a new industry has emerged to produce ammonia, which is advantageous for storage and transportation, without carbon generation in regions rich in renewable energy, synthesize green ammonia by the Haber-Bosch reaction, and then export it to regions such as Northeast Asia, North America, and Europe with high energy demand.

[0004] For green ammonia production, a hybrid technology that links renewable energy such as wind power and sunlight, an electrolysis cell (SOEC), and a Haber-Bosch reactor (HBR) has been proposed.

[0005] However, conventionally proposed hybrid systems have the following problems:

[0006] Firstly, renewable energy sources have an intermittent power generation characteristic, resulting in inconsistent power output, which makes it difficult to reliably start up water electrolysis batteries (SOECs). Therefore, energy storage systems (ESSs) are sometimes added to compensate for the unstable power output of renewable energy sources, but this requires enormous costs.

[0007] Secondly, while it varies depending on the type, water electrolysis (SOEC) batteries require operating temperatures of 20-200°C for low-temperature operation and 500-1000°C for high-temperature operation. Therefore, a separate heat source and heat exchanger are required to operate a water electrolysis battery (SOEC), but if fossil fuels are used to produce the heat, the goal of carbon neutrality will inevitably be lost.

[0008] Thirdly, producing ammonia in a Haber-Bosch reactor (HBR) requires nitrogen in addition to the hydrogen supplied by the water electrolysis cell (SOEC). Therefore, additional equipment such as an air separation unit (ASU) must be added to supply nitrogen, but the operation of the air separation unit generates a large amount of nitrous oxide (N2O), which contradicts the goal of producing green ammonia.

[0009] Fourthly, the operation of a water electrolysis cell (SOEC) also emits oxygen in addition to hydrogen. Utilizing this by-product oxygen requires a sophisticated collection facility, which further increases the cost of system construction.

[0010] For reference, Korean Registered Patent No. 10-2186440 (prior art) relates to an electrochemical ammonia synthesis method, disclosing a technology for synthesizing green ammonia by an electrochemical method without using fossil fuels.

[0011] Prior art, which produces ammonia using an electrochemical cell in which the oxidizing electrode and reducing electrode are separated by a cationic conductive membrane, may appear to be an environmentally friendly technology at first glance. However, it does not clarify the source of the nitrogen supplied to the electrochemical cell for ammonia synthesis or the electricity used to drive the electrochemical cell. As a result, the sources of nitrogen and power supply may induce carbon emissions, and the aforementioned conventional problems still persist. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Korean Registered Patent Publication No. 10-2186440 (November 27, 2020) [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] One of the problems that this invention aims to solve is to provide a solution for supplying a stable power source to a water electrolytic cell (SOEC) in a hybrid system of a water electrolytic cell (SOEC) and a Haber-Bosch reactor (HBR) for green ammonia production.

[0014] Another problem that the present invention aims to solve is to provide a method for generating and supplying the heat necessary to drive the water electrolytic cell (SOEC) in an environmentally friendly manner in a water electrolytic cell (SOEC)-Haber-Bosch reactor (HBR) hybrid system.

[0015] Another problem that the present invention aims to solve is to provide a method for generating and supplying nitrogen, which is necessary for a Haber-Bosch reactor (HBR) in an environmentally friendly manner, in a hybrid system of a water electrolysis cell (SOEC) and a Haber-Bosch reactor (HBR).

[0016] Another problem that this invention aims to solve is to provide a method for reusing oxygen generated during the operation of a water electrolytic cell (SOEC) within the system. [Means for solving the problem]

[0017] As a means of solving the problem, the present invention proposes a SOEC-SOFC-HBR hybrid system for green ammonia production, which includes a solid oxide fuel cell (SOFC), a power compensator that uses a renewable energy source and the solid oxide fuel cell to adjust the supplied power to a constant level, a solid oxide water electrolytic cell (SOEC) that produces hydrogen using the supplied power adjusted by the power compensator, and a Haber-Bosch reactor that produces ammonia using the hydrogen produced by the solid oxide water electrolytic cell and the nitrogen provided by the solid oxide fuel cell.

[0018] In one embodiment, the solid oxide water electrolytic cell can also vaporize the feedwater using heat provided from at least one of the Haber-Bosch reactor and the solid oxide fuel cell.

[0019] In one embodiment, at least a portion of the oxygen input to the air electrode of the solid oxide fuel cell may be supplied from the solid oxide water electrolysis battery.

[0020] In one embodiment, the solid oxide fuel cell uses ammonia as a raw material, and at least a portion of the ammonia produced by the Haber-Bosch reactor may be reused as fuel for the solid oxide fuel cell.

[0021] In one embodiment, a controller may be further included to adjust the ammonia production amount of the Haber-Bosch reactor by controlling the output of the solid oxide fuel cell.

Advantages of the Invention

[0022] According to an embodiment of the present invention, even when renewable energy is used to drive a green ammonia production system based on a solid oxide electrolysis cell (SOEC)-Haber-Bosch reactor (HBR), a constant and stable power supply can be provided to the solid oxide electrolysis cell (SOEC).

[0023] According to an embodiment of the present invention, in a green ammonia production system based on a solid oxide electrolysis cell (SOEC)-Haber-Bosch reactor (HBR), the heat required to drive the solid oxide electrolysis cell (SOEC) can be generated and supplied in an environmentally friendly manner.

[0024] According to an embodiment of the present invention, in a green ammonia production system based on a solid oxide electrolysis cell (SOEC)-Haber-Bosch reactor (HBR), the nitrogen required for the Haber-Bosch reactor (HBR) can be generated and supplied in an environmentally friendly manner.

[0025] According to an embodiment of the present invention, oxygen generated during the operation of a green ammonia production system based on a solid oxide electrolysis cell (SOEC)-Haber-Bosch reactor (HBR) can be reused within the system.

Brief Description of the Drawings

[0026] [Figure 1] It is a configuration diagram of a SOEC-SOFC-HBR hybrid system according to Embodiment 1 of the present invention. [Figure 2] It is a configuration diagram of a SOEC-SOFC-HBR hybrid system according to Embodiment 2 of the present invention. [Figure 3] It is a configuration diagram of a SOEC-SOFC-HBR hybrid system according to Embodiment 3 of the present invention. [Figure 4]This is a diagram showing the configuration of the SOEC-SOFC-HBR hybrid system according to Embodiment 4 of the present invention. [Modes for carrying out the invention]

[0027] Several embodiments of the present invention will be described in detail below with reference to the drawings. However, this is not intended to limit the present invention to any particular embodiment, and all transformations, equivalents, and substitutions, including the technical concept of the present invention, should be understood to be within the scope of the present invention.

[0028] In this specification, singular expressions include plural expressions unless otherwise specified in the context.

[0029] In this specification, when a configuration is described as "have" or "comprise" a subconfiguration, unless otherwise specified, it means that other configurations may be included, rather than being excluded.

[0030] In this specification, the terms "...Unit," "...Module," and "Component" mean a unit that processes at least one function or operation, which may be embodied by hardware, software, or a combination of hardware and software.

[0031] In this specification, the term "connected" may mean, but is not limited to, two components being directly connected, or they may be connected with one or more other components placed between them.

[0032] <Example 1> Figure 1 is a diagram showing the configuration of the SOEC-SOFC-HBR hybrid system according to Embodiment 1 of the present invention.

[0033] The SOEC-SOFC-HBR hybrid system of Example 1 includes a solid oxide water electrolytic cell 110, a Haber-Bosch reactor 120, a solid oxide fuel cell 130, and a power compensator 140.

[0034] In Figure 1, renewable power sources 10 are a general term for power generation methods that obtain power from natural forces such as wind, sunlight, river water, ocean currents, and solar heat. These are environmentally friendly because they produce very little carbon during the power generation process, but they have the disadvantage that it is difficult to maintain homeostasis in power production because the supply of natural forces is not constant.

[0035] In this embodiment, to compensate for these shortcomings, a solid oxide fuel cell 130 is used as an auxiliary means for a stable power supply. Specifically, when the power supplied by the renewable energy source 10 does not reach a predetermined standard amount required by the hybrid system of this embodiment, the deficit is supplemented by the power supplied by the solid oxide fuel cell 130, thereby ensuring a constant power supply to the solid oxide water electrolytic battery 110 or the hybrid system of this embodiment including it.

[0036] The following describes in detail each element that constitutes the SOEC-SOFC-HBR hybrid system of Example 1.

[0037] The Solid Oxide Electrolysis Cell (SOEC) 110 is a ceramic battery that uses a solid oxide permeable to oxygen ions as an electrolyte, and produces hydrogen and oxygen by electrolyzing water. The Solid Oxide Electrolysis Cell 110 is supplied with energy for electrolysis from at least one of the renewable energy source 10 and the solid oxide fuel cell 130.

[0038] The solid oxide water electrolytic battery 110 may be implemented as a high-temperature water electrolytic battery that requires temperatures of 500°C to 1000°C, among water electrolytic batteries.

[0039] The high-temperature steam electrolysis method used in high-temperature water electrolysis batteries utilizes the phenomenon that the electrical energy required for water decomposition decreases as the temperature rises. High-temperature steam electrolysis enables highly efficient water decomposition with minimal electrical energy, and because its structure and principle are identical to that of solid oxide fuel cells, bidirectional operation is possible with a single solid oxide fuel cell or solid oxide water electrolysis battery. Furthermore, the use of a solid electrolyte provides excellent corrosion resistance and eliminates the need for electrolyte replenishment, making maintenance easy. However, heating the steam to over 700°C requires a significant amount of heat.

[0040] Therefore, the solid oxide water electrolytic cell 110 of Example 1 basically receives the heat necessary for water vaporization from the Haber-Bosch reactor 120, but any insufficient heat is further supplied from the exhaust gas of the solid oxide fuel cell 130. Alternatively, the solid oxide water electrolytic cell 110 of Example 1 basically receives the heat necessary for water vaporization from the exhaust gas of the solid oxide fuel cell 130, but any insufficient heat may be further supplied from the Haber-Bosch reactor 120.

[0041] The Habor-Bosch reactor (HBR) 120 produces ammonia using hydrogen produced by the solid oxide water electrolysis cell 110 and nitrogen provided by the solid oxide fuel cell 130.

[0042] The Haber-Bosch reactor 120 is a device that produces ammonia using the Haber-Bosch process, which is a chemical reaction that synthesizes ammonia (NH3) by reacting nitrogen gas (N2) from the air with hydrogen gas (H2) extracted from natural gas or other sources.

[0043] The chemical reaction requires a catalyst such as iron or iron oxide, in addition to small amounts of other accelerators, and takes place under high temperature (>400°C) and high pressure (>200 Bar). Since the Haber-Bosch reaction is an exothermic reaction, at least a portion of the high-temperature heat generated in the Haber-Bosch reactor 120 can be recovered in a heat exchanger (not shown) and supplied to the solid oxide water electrolytic battery 110 or used for other purposes.

[0044] The equation for the Haber-Bosch process is as follows: (chemical 1) N2(g)+3H2(g)2NH3(g) (Formula 1)

[0045] This process releases heat through an exothermic reaction, and the reaction proceeds toward ammonia synthesis while the temperature decreases.

[0046] As shown in Equation 1, nitrogen is required for the chemical reaction in the Haber-Bosch process. Conventionally, a separate air separation unit (ASU) was required to supply nitrogen to the Haber-Bosch reactor. However, in Example 1, nitrogen contained in the exhaust gas of the solid oxide fuel cell 130 can be supplied to the Haber-Bosch reactor 120. Therefore, ammonia synthesis is possible even if no separate air separation unit is required for nitrogen supply, or if only an air separation unit of minimum capacity is provided. Eliminating the air separation unit reduces the construction costs of the equipment, as well as the electricity used to drive the air separation unit.

[0047] The ammonia synthesized in the Haber-Bosch reactor 120 is stored in storage 150, but at least some of it is fed back to the solid oxide fuel cell 130 and used as fuel, while the rest is sold through distribution channels.

[0048] For reference, while it is possible to transport hydrogen by liquefying it directly rather than synthesizing it as ammonia, the liquefaction conditions for hydrogen are -253°C under atmospheric pressure, while those for ammonia are -33°C. Therefore, less energy is required to liquefy ammonia compared to hydrogen. Consequently, liquefying ammonia is more advantageous than liquefying hydrogen, and is beneficial in terms of efficiently storing and transporting large quantities of green energy.

[0049] The Solid Oxide Fuel Cell (SOFC) 130 is a fuel cell that uses an ion-conducting ceramic as an electrolyte, and comprises an oxygen ion-conducting electrolyte and air electrodes (cathode) and fuel electrodes (anode) located on both sides thereof.

[0050] When air and hydrogen are supplied to the air electrode and fuel electrode, respectively, a reduction reaction of oxygen occurs at the air electrode, generating oxygen ions. These oxygen ions then move to the fuel electrode via the electrolyte and react with the hydrogen supplied to the fuel electrode to produce water. At this time, electrons are generated at the fuel electrode and consumed at the air electrode, so electricity is produced by the principle that an electric current flows when both electrodes are connected to each other.

[0051] The solid oxide fuel cell 130 can use pure hydrogen as fuel, hydrogen obtained by reforming hydrocarbon fuels such as liquefied natural gas (LNG), liquefied propane gas (LPG), and methane gas, and ammonia as fuel.

[0052] In one embodiment using ammonia as fuel, the solid oxide fuel cell 130 thermally decomposes the supplied ammonia to produce nitrogen and hydrogen. The generated hydrogen is used to produce electricity, and the nitrogen contained in the exhaust gas is supplied to the Haber-Bosch reactor 120. The solid oxide fuel cell 130 may also be supplied with a portion of the ammonia produced in the Haber-Bosch reactor 120 as fuel, or ammonia may be supplied through a route other than the Haber-Bosch reactor 120.

[0053] In one embodiment where pure hydrogen or hydrogen produced by reforming is used as fuel, the exhaust gas of the solid oxide fuel cell 130 contains nitrogen that was present in the outside air and does not participate in the chemical reaction of the stack. Therefore, the nitrogen contained in the exhaust gas of the solid oxide fuel cell 130 is supplied to the Haber-Bosch reactor 120.

[0054] The solid oxide fuel cell 130 supplies at least a portion of the high-temperature heat contained in the stack's exhaust gas to the solid oxide water electrolytic cell 110 through a heat exchanger (not shown).

[0055] The air electrode of the stack contained in the solid oxide fuel cell 130 may be supplied with oxygen from external air (AIR), or at least a portion of the oxygen obtained by the electrolysis of water in the solid oxide water electrolytic battery 110 may be supplied.

[0056] In one embodiment, the air electrode of the solid oxide fuel cell 130 preferentially receives oxygen from the solid oxide water electrolytic cell 110, but any insufficient oxygen may be replenished from external air. Alternatively, in another embodiment, the air electrode of the solid oxide fuel cell 130 preferentially receives oxygen from external air, but any insufficient oxygen may be replenished from the solid oxide water electrolytic cell 110.

[0057] The electricity produced by the solid oxide fuel cell 130 may be supplied or sold externally, or used as internal power for the green ammonia hybrid plant.

[0058] The power compensator 140 adjusts the power supply to the renewable energy source 10 or the solid oxide fuel cell 130 so that the solid oxide water electrolytic battery 110 can perform electrolysis smoothly. In one embodiment, the power compensator 140 preferentially uses the renewable energy source 10 as the power source, but controls the output of the solid oxide fuel cell 130 so that the power supplied to the solid oxide water electrolytic battery 110 remains constant.

[0059] As a concrete example of its operation, the power compensator 140 senses the amount of electricity supplied by the renewable energy source 10 to the solid oxide water electrolytic battery 110, and if the amount supplied by the renewable energy source 10 falls short of the amount of electricity required by the solid oxide water electrolytic battery 110, it controls the solid oxide fuel cell 130 to replenish the missing amount of electricity with electricity produced by the solid oxide fuel cell 130. In this sense, the power compensator 140 may be considered a controller (not shown) of the solid oxide fuel cell 130.

[0060] Therefore, the hybrid system according to Example 1 can operate stably through the complementary power supply of a renewable energy source and a solid oxide fuel cell. As a result, a separate energy storage system (Electric Power Storage System, ESS) to compensate for the intermittency of renewable energy is not required, or a minimum capacity energy storage system is sufficient, which can dramatically reduce the construction costs of the system.

[0061] <Example 2> Example 2 relates to a case where the heat required for water evaporation in a solid oxide water electrolytic battery is supplied solely from a Haber-Bosch reactor, in contrast to Example 1.

[0062] Figure 2 is a diagram showing the configuration of the SOEC-SOFC-HBR hybrid system according to Embodiment 2 of the present invention.

[0063] The SOEC-SOFC-HBR hybrid system of Example 2 includes a solid oxide water electrolytic cell 210, a Haber-Bosch reactor 220, a solid oxide fuel cell 230, and a power compensator 240.

[0064] In Example 2, the solid oxide water electrolytic cell 210, the Haber-Bosch reactor 220, and the power compensator 240 have the same technical configuration as the solid oxide water electrolytic cell 110, the Haber-Bosch reactor 120, and the power compensator 140 of Example 1, so a redundant explanation will be omitted.

[0065] The solid oxide fuel cell 230 differs from the solid oxide fuel cell 130 of Example 1 only in that it does not send the heat generated in the stack to the solid oxide water electrolysis battery 210; all other technical configurations are identical.

[0066] If the heat supplied from the Haber-Bosch reactor 220 is sufficient for generating steam in the solid oxide water electrolytic cell 210, the heat discharged from the solid oxide fuel cell 230 may be used for other purposes required by the system.

[0067] <Example 3> Example 3 relates to a case where the oxygen required by the air electrode of a solid oxide fuel cell is supplied solely from external air, in contrast to Example 1.

[0068] Figure 3 is a diagram showing the configuration of the SOEC-SOFC-HBR hybrid system according to Embodiment 3 of the present invention.

[0069] The SOEC-SOFC-HBR hybrid system of Example 3 includes a solid oxide water electrolytic cell 310, a Haber-Bosch reactor 320, a solid oxide fuel cell 330, and a power compensator 340.

[0070] In Example 3, the Haber-Bosch reactor 320 and the power compensator 340 have the same technical configuration as the Haber-Bosch reactor 120 and power compensator 140 in Example 1, so a redundant explanation will be omitted.

[0071] The solid oxide water electrolytic battery 310 differs from the solid oxide water electrolytic battery 110 of Example 1 in that it does not send the oxygen produced by electrolysis to the solid oxide fuel cell 330; all other technical configurations are identical.

[0072] Furthermore, the solid oxide fuel cell 330 differs from the solid oxide fuel cell 130 of Example 1 in that the oxygen required by the air electrode is supplied only from external air (Air), but all other technical configurations are the same.

[0073] The solid oxide water electrolytic battery 310 can supply the produced oxygen to a system burner (not shown), store it in an external storage tank, or use it for other necessary applications.

[0074] <Example 4> Example 4, compared to Example 1, uses hydrogen as fuel for a solid oxide fuel cell, but the ammonia synthesized in the Haber-Bosch reactor is used for other purposes, such as being sold entirely.

[0075] Figure 4 is a diagram showing the configuration of the SOEC-SOFC-HBR hybrid system according to Embodiment 4 of the present invention.

[0076] The SOEC-SOFC-HBR hybrid system of Example 4 includes a solid oxide water electrolytic cell 410, a Haber-Bosch reactor 420, a solid oxide fuel cell 430, and a power compensator 440.

[0077] In Example 4, the solid oxide water electrolytic cell 410, the Haber-Bosch reactor 420, and the power compensator 440 have the same technical configuration as the solid oxide water electrolytic cell 110, the Haber-Bosch reactor 120, and the power compensator 140 of Example 1, so a redundant explanation will be omitted.

[0078] The solid oxide fuel cell 430 uses hydrogen as fuel, but pure hydrogen may be used, or hydrogen reformed with carbonized gas may be used. Therefore, all other technical configurations are the same as those of the solid oxide fuel cell 130 of Example 1.

[0079] In Examples 1 to 4 described above, modified embodiments for adjusting the ammonia production rate of the hybrid system may be presented.

[0080] In other words, in order to adjust the amount of ammonia synthesized in the Haber-Bosch reactors 120, 220, 320, and 420, it is necessary to adjust either the hydrogen supply from the solid oxide water electrolytic cells 110, 210, 310, and 410, or the nitrogen supply from the solid oxide fuel cells 130, 230, 330, and 430.

[0081] As one embodiment of this, the power compensators 140, 240, 340, and 440 can be equipped with a function to adjust the amount of power supplied to the solid oxide water electrolytic batteries 110, 210, 310, and 410, in addition to the function of maintaining a constant amount of power supplied to them. By adjusting the power supplied to the solid oxide water electrolytic batteries 110, 210, 310, and 410, the amount of hydrogen generated by the water electrolytic batteries can be reduced or increased.

[0082] In another embodiment, the controllers for the solid oxide fuel cells 130, 230, 330, and 430 can decrease or increase the amount of nitrogen supplied to the solid oxide water electrolytic batteries 110, 210, 310, and 410 by adjusting the amount of power generated by the fuel cells.

[0083] As described above with reference to several embodiments relating to the present invention, a person with ordinary skill in the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as described in the following claims. [Explanation of Symbols]

[0084] 10: Renewable energy sources 110,210,310,410:Solid oxide water electrolysis battery 120, 220, 320, 420: Haber-Bosch reactor 130,230,330,430: Solid oxide fuel cell 140,240,340,440: Power compensator

Claims

1. Solid oxide fuel cells (SOFCs) and A power compensator that adjusts the supplied power to a constant level using a renewable energy source and the solid oxide fuel cell, A solid oxide water electrolytic cell (SOEC) that produces hydrogen using the power supply adjusted by the aforementioned power compensator, A Haber-Bosch reactor that produces ammonia using hydrogen produced by the solid oxide water electrolysis cell and nitrogen provided by the solid oxide fuel cell, SOEC-SOFC-HBR hybrid system for green ammonia production, including [specific component].

2. The aforementioned solid oxide water electrolytic battery is The SOEC-SOFC-HBR hybrid system for green ammonia production according to claim 1, characterized in that it vaporizes feedwater using heat provided from at least one of the Haber-Bosch reactor and the solid oxide fuel cell.

3. The SOEC-SOFC-HBR hybrid system for green ammonia production according to claim 1, characterized in that at least a portion of the oxygen input to the air electrode of the solid oxide fuel cell is supplied from the solid oxide water electrolysis battery.

4. The aforementioned solid oxide fuel cell uses ammonia as a raw material, The SOEC-SOFC-HBR hybrid system for green ammonia production according to claim 1, characterized in that at least a portion of the ammonia produced by the Haber-Bosch reactor is reused as fuel for the solid oxide fuel cell.

5. The SOEC-SOFC-HBR hybrid system for green ammonia production according to any one of claims 1 to 4, further comprising a controller that adjusts the ammonia production amount of the Haber-Bosch reactor by controlling the output of the solid oxide fuel cell.

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