Electrolysis system and method for operating electrolysis system

Abstract

The invention relates to an electrolysis system (100) comprising a wind power plant (1) and an electrolysis plant (5) which is connected to the wind power plant (1) in order to provide electrolysis power, in which an islanding network which is not connected to a power supply network is achieved, and comprising a heat supply device (7) which is coupled to the electrolysis plant (5) and which can be operated using a working medium (23), said heat supply device having an evaporator (13) and a condenser (11), and the design of the heat supply device enables the condensation heat of the working medium (23) to be transferred to the electrolysis equipment (5) through the condenser (11) when the operation is stopped, so that the temperature is maintained above the lowest temperature. In this case, when the operation is stopped, the working medium (23) is evaporated by means of a heat supply device (7), and the evaporated working medium (23) is condensed, in which heat of condensation is generated and transferred to the electrolysis device (5), thereby maintaining the temperature above the minimum temperature and preventing the water delivery means of the electrolysis device (5) from freezing.

Description

Technical Field

[0001] This invention relates to an electrolysis system and a method for operating the electrolysis system. Background Technology

[0002] An electrolysis system is a device that uses electric current to perform the conversion (electrolysis) of substances. Corresponding to various electrochemical electrolysis processes, there are also various electrolysis devices, such as those used for water electrolysis. To provide direct current for the electrolysis process, the electrolysis device is connected to a power generation device, thus forming an electrolysis system. Typically, electrolysis devices have multiple electrolytic cells, allowing for large electrolysis power outputs when expanded accordingly, enabling electrochemical conversion of substances.

[0003] Currently, hydrogen is produced from water, for example, through proton exchange membrane (PEM) electrolysis or alkaline electrolysis. Electrolysis equipment uses electrical energy to produce hydrogen and oxygen from a supplied water source. This process takes place in an electrolytic reactor consisting of multiple electrolytic cells. In the electrolytic reactor, which operates under direct current voltage, water is introduced as a reactant, resulting in two fluid streams: one of water and the other of gas bubbles (oxygen or hydrogen), flowing through the electrolytic cells.

[0004] The current consideration is to utilize surplus energy from renewable energy sources to produce valuable substances during periods of abundant sunshine and strong winds (i.e., when solar or wind power generation is above average). Valuable substances could, in particular, be hydrogen produced through water electrolysis. Hydrogen can then be used to produce, for example, so-called renewable energy gas (RE-gas). Renewable energy gas is a combustible gas obtained from renewable energy sources using electricity.

[0005] Hydrogen is a particularly environmentally friendly and sustainable energy carrier. It has unique potential to enable many sectors of energy systems, transportation, and the chemical industry without emitting carbon dioxide. However, to achieve this, hydrogen cannot be derived from fossil fuels and must be produced using renewable energy sources.

[0006] Wind energy is a source of renewable energy. In particular, offshore wind power, especially near-shore wind turbines, can generate significant amounts of electricity. However, the challenge lies in traversing long distances from the load. Therefore, energy should be delivered to the load with as little loss as possible. Hydrogen is well-suited as a transport medium. It can be transported, for example, in gaseous form via pipelines. A positive side effect of this is that the hydrogen transport pipeline can also function as an energy storage device, as its internal pressure can vary within certain limits. For this reason, it is particularly important to produce hydrogen directly at the energy generation site, i.e., by installing electrolysis equipment directly at or near the offshore wind turbines. Thus, electrolysis systems at offshore locations are being discussed, for example, where electrolysis equipment is installed directly on the offshore wind turbine platform. Here, the wind turbines and electrolysis equipment can be interconnected to form a essentially self-sufficient, almost grid-independent electrolysis system, specifically designed for operation on isolated offshore islands. However, in remote onshore areas, isolated grids can also be established without connecting the electrolysis equipment to the grid.

[0007] In the best-case scenario, these electrolysis systems, combining wind power and electrolysis equipment, can thus be established entirely without auxiliary connection to the power grid and are designed for island operation, whether onshore or offshore. Offshore electrolysis systems face unique challenges, including avoiding long-distance connections to the coastal public power grid, or disregarding them from an economic standpoint. Ideally, electrolysis equipment with multiple electrolyzers is located directly near renewable energy sources (i.e., wind power equipment) to minimize or eliminate conversion and line losses. Therefore, offshore electrolysis systems, particularly those with integrated electrolysis equipment mounted directly on platforms with offshore wind power, are currently being heavily developed. In this configuration, the equipment can operate even without grid connection, whether "onshore" or "offshore." However, without grid connection, power cannot be supplied by either generators or the grid during periods of calm, low wind speeds, or planned maintenance of the wind turbines.

[0008] Offshore electrolysis systems require special attention to prevent corrosion of the equipment, as the presence of seawater significantly accelerates the corrosion rate, jeopardizing long-term uninterrupted operation. In principle, offshore electrolysis equipment can be equipped with electrolytic cells housed in enclosed hulls or containers. This provides a degree of protection against external environmental influences. However, during normal operation, the electrolytic cells must be cooled to continuously dissipate the heat generated by the electrolysis process. Thermal management of offshore electrolysis equipment is generally more challenging than that of onshore systems, specifically in terms of both the required cooling during normal operation and maintaining minimum temperatures during prolonged periods of inactivity. In the latter case, especially during periods of low wind and light, such as winter and when wind power equipment is shut down, it is crucial to ensure adequate freeze protection for the submerged electrolytic cells. Therefore, to meet the cooling requirements of offshore electrolysis equipment during normal operation, at least a closed container structure is required, i.e., the electrolyzer is protected by a shell. This requirement must simultaneously prevent overheating and failure of the electrolyzer, and also prevent harmful corrosion caused by exposure to seawater salinity. Thus, in offshore electrolysis equipment, the interface and exchange between the electrolyzer and the environment are ultimately unavoidable, in order to properly dissipate the heat flow from the process during normal operation and achieve safe operation.

[0009] To protect the electrolyzers from environmental impacts, they therefore require enclosures, such as containers, as mentioned above. Furthermore, PEM water electrolyzers must operate using deionized water, especially high-purity water. However, the internal temperature of the container must also not fall below approximately 5°C. Otherwise, the water-containing transport components may freeze, causing the entire system to malfunction. This would contradict the goal of offshore electrolysis systems with wind power that are not connected to the power grid and operate with minimal maintenance and as much self-sufficiency as possible.

[0010] When the external temperature outside the container is below 5°C, heat is transferred from the inside of the container to the outside through conduction, convection, and radiation. Thus, at the minimum design temperature of -20°C in the external area, approximately 1 to 2 kilowatts of heat energy are lost per hour from the corresponding container of the electrolysis equipment. However, this heat loss depends primarily on the insulation of the container itself. This heat must be supplied back to the container to maintain a relatively constant temperature of 5°C and reliably prevent freezing damage. During normal operation of the electrolysis equipment (i.e., when the electrolysis current is supplied by wind power), even at extremely low ambient temperatures, the temperature inside the container can be maintained because sufficient waste heat from the electrolysis process is available.

[0011] However, if renewable electricity is unavailable in extremely cold weather, for example due to lack of wind or the need to shut down wind power equipment for unforeseen maintenance purposes, then thermal energy must be reliably provided in other ways to maintain the required temperature for the electrolysis equipment. Otherwise, the electrolytic cells will suffer irreversible damage from freezing, and the electrolytic cells installed in the equipment may even become completely inoperable. Water pipes between containers or cladding must also be kept at minimum temperatures to prevent dangerous operation and freezing. This also requires energy, which must be obtained from other sources in the absence of wind.

[0012] Some proposed solutions involve using and utilizing appropriately designed battery energy storage devices within the electrolysis system. These storage devices provide power to maintain electric heating and keep the temperature. However, this solution has significant drawbacks. Firstly, the battery pack capacity is very limited; secondly, installation space on offshore platforms is also quite limited. For example, current applications on offshore wind power platforms require a relatively high battery capacity of at least approximately 100 to 150 kWh to ensure temperature maintenance even during extended periods of inactivity. This seems uneconomical given currently available battery technology. Especially at low ambient temperatures, the low temperature degrades battery performance. Due to the low temperature, the electrolyte viscosity increases, making it more difficult to penetrate. Consequently, the number of ions reaching the positive electrode decreases, leading to a sharp decline in battery performance. Low temperatures significantly slow down the internal reaction processes of the battery, resulting in faster battery degradation than usual. Furthermore, so-called battery energy storage systems (BESS) also suffer from drawbacks such as high cost, large size, and bulkiness. Therefore, there is an urgent need for other, better solutions to maintain temperature when the offshore electrolysis system is not in operation.

[0013] Another potentially simpler technical solution is to integrate a diesel generator onto the offshore platform for emergency power supply and operation of the heating system. However, a drawback of this solution is that the diesel fuel needs to be replenished periodically, thus the fundamental concept and goal of developing a reliable, carbon dioxide-free offshore electrolysis system cannot be achieved through this approach. Summary of the Invention

[0014] Therefore, an object of the present invention is to provide an electrolysis system that can operate safely and environmentally, while being designed for operation that is as self-sufficient as possible and with low maintenance. Another object is to provide a method for operating the electrolysis system.

[0015] According to the present invention, the objective relating to the electrolysis system is achieved by an electrolysis system comprising a wind power device and an electrolysis device connected to the electrolysis device to provide electrolysis current, wherein an islanded grid is achieved without connection to the power grid. The electrolysis system further comprises a heating device coupled to the electrolysis device and capable of operating with a working medium, the heating device having an evaporator and a condenser, the heating device being designed such that, when not in operation, the condensation heat of the working medium can be transferred to the electrolysis device through the condenser, thereby maintaining the temperature above a minimum temperature.

[0016] According to the present invention, the objective of the method for operating an electrolysis system is achieved by a method for operating an electrolysis system, wherein, when the system is not in operation, the working medium is evaporated by a heating device and the evaporated working medium is condensed, wherein condensation heat is generated and transferred to the electrolysis equipment, thereby maintaining the temperature above a minimum temperature and preventing the water supply components of the electrolysis equipment from freezing.

[0017] The advantages and preferred designs of the electrolysis system described below can be beneficially applied to the methods used to operate the electrolysis system.

[0018] This invention is based on the understanding that the increasing number of installed, more powerful, grid-independent wind power plants (especially offshore wind power plants) and their growing power generation capacity necessitate correspondingly more powerful electrolysis equipment. Therefore, the power levels and number of electrolysis systems are expected to increase significantly in the future. This is particularly relevant to offshore electrolysis systems.

[0019] The increasing demands for safe and environmentally friendly operation in marine environments must be considered. With the growing scale of large-scale offshore electrolysis systems far from the coast, achieving self-sufficiency (i.e., independence from the power grid) in isolated island operations, utilizing 100% renewable wind energy for hydrogen production, and ensuring the environmental compatibility of such systems have become key issues. From an environmental perspective, ensuring operation with minimal intervention is crucial. Therefore, for situations involving shutdowns, particularly wind power equipment failures and electrolysis current losses, a self-sufficient solution for reliably maintaining the temperature of water-transporting components (especially the highly sensitive submerged electrolysis cells in PEM electrolysis equipment) is essential. The design concept of this invention ensures heat supply and temperature maintenance, eliminating concerns about failure or loss of water-transporting components even during the low-temperature, windless, and dark winter months when freezing is a risk. This invention therefore employs an insulation design in electrolysis systems (especially offshore electrolysis systems) that exhibits high reliability and inherent fail-safety under extreme weather conditions and operational scenarios. This provides a virtually maintenance-free electrolysis system that reliably prevents the risk of freezing damage caused by the freezing of the water supply components of the electrolysis equipment, particularly the electrolytic cells and electrolytic pits. This results in a longer service life and immediate availability and readiness to resume normal operation after a shutdown.

[0020] The electrolysis system of the present invention recognizes and, for the first time, advantageously overcomes the disadvantages of conventional heating schemes in grid-independent electrolysis systems, as mentioned above, which rely on large battery packs or even diesel generators, for example, mounted on platforms of offshore facilities, to heat the electrolysis equipment. These schemes have also proven to be environmentally disadvantageous, and are expensive and cumbersome to maintain.

[0021] However, by employing an evaporation-based heating system, even during periods of extreme darkness and windlessness, stable temperatures can be maintained for several consecutive days, with heat transfer adjustable to target the minimum temperature to be maintained. Here, the enthalpy of vaporization of the working medium is advantageously utilized to provide the required heating heat. Using the vapor pressure curve of the working medium, the desired operating point of the heating system can be selectively set based on the pressure and temperature of the working medium. In the condenser, the working medium, previously evaporated in the evaporator, condenses, releasing condensation heat at a constant evaporation temperature. For this purpose, the condenser is thermally coupled to the radiator so that heat can be dissipated and transferred to the electrolysis equipment. The evaporator is thermally coupled to the heat source, causing the working medium to evaporate. This condensation-based heating system allows for targeted adjustments to minimum heat output and minimum heat consumption to maintain the temperature according to the needs of the electrolysis equipment. A thermodynamic cycle is advantageously achieved here, thus virtually eliminating the consumption of the working medium. Furthermore, only a small temperature difference is required to perform the evaporation and condensation processes at the operating temperature and pressure of the working medium. Here, the heating device is designed to utilize an isochoric circulation process using an evaporator and a condenser.

[0022] In a particularly preferred design of the electrolysis system, the heating device has a gravity-driven heat pipe, wherein a condenser is formed on the heat pipe above the evaporator.

[0023] Advantageously, a heating device based on a self-circulating working medium is provided. Due to the vertical arrangement and orientation of the heat pipes, the evaporator is vertically arranged at the bottom, and the condenser is vertically arranged at the top. Therefore, evaporative heat can be transferred vertically upward from a heat source located deep within the evaporator through the evaporating working medium to the condenser, wherein an autonomous gravity-driven circulation process is realized within the heat pipes.

[0024] A heat pipe or heat pipe is used here, which is advantageously integrated into the heating system. A heat pipe or heat pipe is a component that transfers heat through an evaporation and condensation cycle. When heat is supplied to one end of the heat pipe, the working medium evaporates and, driven by a temperature or pressure gradient, flows along an adiabatic zone towards the condenser. The vapor condenses here, releasing its latent heat to an external radiator. To maintain the cycle, the condensate must be resupplyed to the evaporator. This is typically achieved using an integrated wicking structure (e.g., a grooved structure, a mesh structure, or a sintered structure) that uses capillary force to return the condensate to the evaporator. If the condenser is located above the evaporator, gravity can also be used for return, which is currently preferred. This type of heat pipe is also called a two-phase thermosiphon. Other forces, such as centrifugal force, can also be considered for the return of the working medium. The working fluid used depends on the temperature range in which the heat pipe is used, where a wide operating range is typically available based on the vapor pressure profile. Advantageous applications exist in the range of approximately -100 to 300°C. For example, working media such as carbon dioxide, ethanol, acetone, water, or other working media whose vapor pressure profiles fall within the required minimum temperature range can be used.

[0025] Advantageously, two different construction methods can be used for heat pipes: heat pipes and two-phase thermosiphons. The basic operating principle of both methods is the same; the difference lies in the way the gaseous working medium is returned to the evaporator (and thus the location of the heat supply). In both methods, the return flow is passive, thus eliminating the need for auxiliary equipment such as circulation pumps. The thermal resistance of a heat pipe at operating temperature is much lower than that of a metal. Therefore, the characteristics of a heat pipe closely resemble isothermal state changes. The temperature remains almost constant along the length of the heat pipe.

[0026] In a particularly preferred design of the electrolysis system, the heating device includes a deep probe designed to extract heat from a deep heat reservoir in which the evaporator is immersed.

[0027] Heat pipes are thus advantageously designed as deep probes, allowing the extraction or extraction of evaporative heat from a deep heat reservoir that serves as a heat source. The term "immersion in a heat reservoir" is not currently limiting but should be understood functionally. This includes cases of thermal coupling, where the evaporator of the heat pipe is directly or indirectly thermally coupled to the heat reservoir. The evaporator of a deep probe can also be partially or completely immersed. Depending on the installation and mounting method of the electrolysis system (especially wind power equipment), the heat reservoir can be formed, for example, from deep soil or rock layers, aquifers, groundwater or geothermal reservoirs, seawater, or the seabed.

[0028] In a particularly preferred design of the electrolysis system, the heating device has a heat storage section formed inside the tower of the wind power equipment.

[0029] This advantageously provides an integrated solution for temperature maintenance within the electrolysis system. The heating unit itself is equipped with or has a heat storage compartment. By integrating the heat storage compartment into the tower of the wind turbine, heat pipes designed as deep probes are particularly efficient. These heat pipes are vertically arranged and oriented inside the tower and extend into the heat storage compartment, where they are also well protected against harmful environmental influences. However, it is also possible, in principle, to place the heating unit outside the tower of the wind turbine, where the heat pipes, designed as deep probes, are immersed in seawater at a suitable depth in offshore facilities, for example, as a heat source for the condenser. However, due to integration into the tower, the heat source deep within the tower of the wind turbine can be used very advantageously, while simultaneously providing a radiator for the operation of the heat pipes in the upper region of the tower. Therefore, the evaporator and condenser of the vertically mounted heat pipes are correspondingly placed at the heat source or radiator, thereby achieving thermal coupling.

[0030] In the preferred design of the electrolysis system, the heating device has heat pipes, wherein the evaporator and condenser are connected by an adiabatic zone, thereby enabling the working medium to circulate automatically within the heat pipes.

[0031] The heat pipe is designed with a sufficiently long adiabatic zone along its vertical extension, with the evaporator and condenser located at the ends of this zone. When heat is supplied to the evaporator, the working fluid evaporates and flows vertically upwards along the adiabatic zone to the condenser, driven by a temperature or pressure gradient. At the condenser, the vapor condenses and releases its latent heat to an external radiator, i.e., to the water supply system connected to the electrolysis unit to maintain temperature during shutdown operations. Due to its self-circulating nature, no additional circulation pump is required to maintain the circulation, thus providing a self-sufficient heat supply system via gravity-driven heat pipe. A small circulation pump can be additionally provided for the electrolysis unit to circulate the process water in the water supply system as needed and connect it to the condenser. However, a small auxiliary battery is still required for its operation, which is far more economical than using electricity to provide the heat energy needed to maintain the temperature. Furthermore, it can reliably withstand extended periods of shutdown operation.

[0032] In a particularly preferred design of the electrolysis system, the working medium is introduced into the heat pipe at a predetermined working pressure, thereby setting the evaporation temperature in the range of 2°C to 10°C, especially between 4°C and 8°C, at that working pressure.

[0033] To maintain temperature and to ensure the transfer of condensation heat from the working medium to the electrolysis equipment, an operating range is preferably employed, wherein the evaporation or condensation of the working medium is set near or above a minimum temperature based on the vapor pressure profile; for example, a few degrees higher than the evaporation temperature of 5°C at vapor pressure. To maintain the temperature of the electrolysis equipment, and especially its water supply lines and systems, during shutdown operation, a pressure range is determined by selecting a specific working medium within which the working medium evaporates at a preferred temperature range to maintain temperature. For operation at the evaporation or condensation point of the vapor pressure profile, a small temperature difference between the evaporator and condenser is sufficient for the heat pipe to operate. The heat pipe is pressure-sealed and gas-tightly filled with the working medium at a predetermined filling pressure, which serves as the operating pressure. This operating pressure is selected such that, under the application conditions within the electrolysis system, the working medium evaporates at a temperature slightly above the freezing point of water. Due to the pressure-sealed nature of the heat pipe, an isochoric cycle of evaporation and condensation is defined during heat pipe operation.

[0034] In a particularly optimized design of the electrolysis system, the heat pipe is designed as a deep carbon dioxide probe, using carbon dioxide (CO2) as the working medium.

[0035] Here, at pressures close to the evaporation pressure of carbon dioxide, and at the desired operating temperature and corresponding working pressure, carbon dioxide is introduced into a heat pipe designed as a carbon dioxide deep probe for cyclic applications. In the carbon dioxide deep probe, carbon dioxide (CO2) serves as the working medium and heat carrier for the cyclic process. The carbon dioxide deep probe is particularly advantageously designed for operation using the heat pipe (heat pipe) principle. Both liquid and vaporous carbon dioxide (CO2) exist within the probe tube. Liquid carbon dioxide (CO2) is located in the lower region of the probe, while vaporous CO2 is located in the upper region. Once the process begins, similar to a heat pump, vaporous CO2 is cooled in the condenser within the heat exchanger, i.e., it absorbs heat, thereby condensing the vaporous CO2. At this time, the liquid CO2 flows downward within the probe tube. The liquid CO2 absorbs heat from the heat reserve (e.g., geothermal) through the evaporator, thus becoming vapor and rising again. This achieves continuous circulation. Due to the fact that the carbon dioxide deep probe is self-circulating, probe regeneration begins immediately when the heat pump function is turned off or interrupted. In this state, the temperatures of the lower (warmer) and upper (cooler) layers reach equilibrium. Within just about 30 minutes, the initial temperature, similar to that before the device was last started, is regenerated. This means that as long as a temperature difference exists within the probe, and the lower layer is warmer than the upper layer, the carbon dioxide will automatically circulate, causing the probe to regenerate in the upper region. Due to the higher temperature at the bottom, the carbon dioxide evaporates, rises, and releases heat in the cooler region, causing it to condense and flow downwards again.

[0036] In a particularly preferred design of the electrolysis system, carbon dioxide is introduced into the heat pipe at an operating pressure of 35 to 45 bar, especially between 37 and 42 bar.

[0037] In this way, based on the vapor pressure curve of carbon dioxide (CO2), the heat pipe is made suitable for use in an electrolysis system, and the corresponding filling pressure is set. This design allows the evaporation temperature to be slightly above the freezing point of water, approximately 0.5°C to 10°C, particularly approximately 2.5°C to 7.5°C. Therefore, the heating unit is designed to operate according to a specified shutdown procedure, and the required evaporation temperature can be specifically set for the application at a reference temperature using the filling pressure.

[0038] In another preferred design of the electrolysis system, an internal thermal controller is provided for heat transfer, which uses valves or throttling elements as control elements to control the inflow and outflow of the working medium.

[0039] In this way, the temperature of the electrolysis equipment can be controlled within certain limits, maintaining and minimizing the achievable temperature, by means of the transferred heat flow. Heat transfer within the heat pipe itself can be controlled, specifically by valves or throttling devices inside the heat pipe acting as control elements. A rotatably supported throttling device, controlled externally by a small motor, can alter the flow of the heat transfer medium from the heat source to the radiator and vice versa. Alternatively, a small solenoid valve located inside the heat pipe (implemented by a magnetic ball with a return spring) allows for a significant halt or re-release of the heat flow through the heat pipe. A significant advantage of throttling devices over valves is the ability to continuously control thermal conductivity, specifically, based on the adjustment angle. Valves, on the other hand, only allow the heat pipe to be opened or closed, as it can only be opened or closed by electromagnet control. However, a disadvantage of throttling valves is their outwardly extending control shaft, which makes achieving a tight seal difficult. This can lead to undesirably short maintenance intervals.

[0040] In alternative designs, external thermal control can also be employed. In this thermal control configuration, two parallel heat pipes are positioned, correspondingly connecting the heat source and the radiator, respectively. These heat pipes extend parallel to each other at their ends with a small gap, without contacting each other. They are encased in this area by a solid structure, a so-called coupler, made of a thermally conductive material (such as copper or aluminum), with two precisely fitted guide holes for the heat pipes. The thermal conductivity of the entire system can be easily adjusted by pushing in or pulling out the coupler, as the contact area between the heat pipe and the coupler is linearly related to the depth of insertion. Coupled with the external control system by a small battery-powered servo motor, the system can be moved to an easily accessible location as needed, provided the very low additional thermal resistance of the longer heat pipes allows for this detour.

[0041] By selectively controlling the internal or external environment, the temperature can be maintained reliably and precisely even during prolonged periods of shutdown, and efficient thermal management can be achieved.

[0042] In a particularly advantageous design of the electrolysis system, the evaporator is located within the base of the wind power equipment, thereby utilizing deep heat to evaporate the liquid working medium within the evaporator.

[0043] Due to this arrangement and thermal coupling with the evaporator, a virtually unlimited heat storage section is provided or realized through the base, which, for example, can optionally be formed or opened from a cavity inside the tower of the wind power equipment itself. The heat storage section is thus preferably located deep below the water surface inside the tower to utilize the as constant as possible ambient temperature in the deep underground or underwater environment. With this construction, by incorporating it into the tower, a certain degree of thermal insulation and thermal inertia similar to that of a large heat storage unit is advantageously achieved, thereby achieving a substantially constant operating temperature and providing a heat source. Simultaneously, designing the heat storage unit within a cavity deep inside the tower has almost no impact on the tower structure and the mechanical stability of the nacelle housing the wind turbine. Furthermore, it provides installation space for the heat storage unit, or utilizes previously unused installation space. The heat storage unit does not require space or installation area on the platform itself. The platform can be used for electrolysis equipment and its components, without being limited by the heating system.

[0044] A particular advantage is that this simultaneously achieves efficient thermal bridging and coupling with ambient temperature through the base, thereby providing a heat source directly within or at the base. This ensures a continuous supply of heat to the heat storage section at operating temperatures, especially once the heat pipe is operational, and the liquid working medium evaporates through deep heat in the evaporator located deep within the wind turbine base.

[0045] In another particularly preferred design of the electrolysis system, the electrolysis equipment has an electrolytic cell arranged inside a container and a heat exchanger designed to remove the process heat from the electrolysis from the container during normal operation.

[0046] This advantageously allows the waste heat generated by the electrolysis process to be used for temperature maintenance during normal operation and when needed during shutdown, rather than simply being released into the environment. Typically, in electrolysis operation, process heat from the containers surrounding the electrolyzer and protecting it from weather and salt corrosion is released into the environment. However, current heat exchangers are advantageously designed so that the process heat from electrolysis is selectively transferred to an additional heat storage unit, i.e., the heating system, when needed, to specifically store heat and, when needed, can be used for subsequent temperature maintenance, in addition to utilizing heat pipes based on the heat of condensation. Therefore, process heat is not released, or only partially released, into the environment. This provides redundancy in the heating system.

[0047] Simultaneously, during normal operation, heat exchangers are used to assist in cooling the container, thereby cooling the electrolyzer with multiple electrolytic cells. For this purpose, the heat exchanger can be connected, for example, to a coolant circuit driven by a coolant pump on the primary side of the electrolyzer, and accordingly thermally coupled thereto, enabling targeted heat absorption and release, and further utilization of this heat in a heating system on the secondary side of the heat exchanger. This advantageously allows the offshore electrolysis system to operate safely and environmentally in a closed container construction, housing the electrolyzer (e.g., a PEM electrolyzer for hydrogen production) and the coolant pump located inside the container or flanged tightly connected to the container. In the latter case, a shell unit is formed between the container and the flanged coolant pump; therefore, in a sense, the coolant pump is also located inside the container. The closed cooling circuit allows for the absorption of process heat generated by electrolysis at the equipment location via heat exchangers within the container. It is also feasible to install multiple heat exchangers, one of which is specifically configured as part of the heating system.

[0048] Preferably, a heat exchanger thermally coupled to the condenser is provided in the electrolysis system, so that the condensation heat of the working medium can be transferred to the water supply component of the electrolysis equipment during shutdown.

[0049] The heat exchanger can be a dedicated heat exchanger thermally coupled to the condenser. However, the thermal path can also be implemented in a manner similar to, for example, in a containerized construction, using the same heat exchanger that is also used for cooling during normal operation to dissipate process heat from the electrolytic cell housed within the container. Therefore, heat exchangers are used to couple or transfer the condensing heat released from the condenser via heat pipes to or to the easily icing water supply components of the electrolysis unit. These heat exchangers can also be used during normal operation, i.e., for bidirectional cooling of the electrolysis unit by selectively dissipating process heat into the environment or optionally into the heat storage tank. This dual-purpose design, operating under different conditions and eliminating the need for additional heat exchangers, has a positive impact on the production and operating costs of the electrolysis system.

[0050] In a particularly preferred design of the electrolysis system, the wind power equipment has a tower and a platform fixed on the tower, on which the electrolysis equipment is installed.

[0051] This makes the electrolysis system particularly suitable for offshore applications, providing a self-sufficient offshore electrolysis system for operation at sea. The electrolysis equipment consists of multiple containers arranged on a platform, which contain electrolyzers, the control system of the electrolysis equipment, and auxiliary systems for its operation, electrical connections, and power supply by wind power equipment.

[0052] In the case of marine applications of electrolysis systems, the evaporator is preferably located in the underwater region in deep water or on the seabed.

[0053] Therefore, the evaporator of the heat pipe can be regulated directly or indirectly via seawater or the seabed (as a virtually unlimited heat reservoir and heat source). There, essentially constant temperature conditions are generated at depth, allowing the heat pipe to be designed and adjusted for evaporation temperature according to a predetermined operating point. This is particularly advantageous for designing the heat pipe as a deep carbon dioxide probe. The deep carbon dioxide probe can be installed within the tower of an offshore wind power system, with the evaporator positioned deep within the tower, for example, at the base, while the condenser is positioned at platform height, designed to achieve optimal thermal coupling with the electrolysis equipment.

[0054] Another aspect of the invention relates to a method for operating a corresponding electrolysis system. During shutdown operation, the working medium is evaporated or condensed by means of a heating device, wherein the heat of condensation is released and transferred to the electrolysis equipment, thereby maintaining the temperature above a minimum temperature and preventing the water supply components of the electrolysis equipment from freezing.

[0055] The method advantageously utilizes the enthalpy of vaporization of the working medium, allowing it to operate autonomously and with high reliability, without requiring the electrolysis system to be connected to the power grid. Therefore, it is advantageous for islanded operation in both offshore and onshore electrolysis systems. The electrolysis system is particularly advantageously designed for islanded operation because it ensures temperature maintenance, especially during the dark, windless, and low-light periods of winter or when there is a risk of freezing, and prevents freezing by providing and utilizing condensation heat.

[0056] Preferably, in this method, temperature maintenance is initiated when the external temperature is below 5°C, wherein the working medium circulates in a gravity-driven heat pipe, and the heat of condensation is extracted from the working medium and transferred to the water supply component of the electrolysis equipment, thereby achieving freeze protection.

[0057] Preferably, in this method, the heat flow is controlled by a control device, wherein the back-and-forth flow of the circulating working medium is regulated, and the condensation heat transferred to the electrolysis equipment is regulated.

[0058] More preferably, in this method, during normal operation, the electrolysis equipment is supplied with electrolysis current by wind power equipment, wherein the process heat from the electrolytic cell is dissipated through a heat exchanger. Attached Figure Description

[0059] The design, features, and / or advantages currently relating to electrolysis systems are similarly applicable to operating methods, and vice versa. Embodiments of the invention will now be described in more detail with the aid of the accompanying drawings. Wherein, schematically and in a highly simplified manner: Figure 1An electrolysis system with electrolysis equipment and wind power equipment is shown; Figure 2 A schematic side view of an electrolysis system with a heating device having heat pipes is shown; Figure 3 A schematic diagram of a heat pipe and its operation is shown. Detailed Implementation

[0060] The same reference numerals in the figure have the same meaning.

[0061] Figure 1 The diagram shows an electrolysis system 100 specifically designed for offshore (i.e., offshore) operation. The electrolysis system 100 includes an electrolysis unit 5 and a wind power unit 1, the wind power unit 1 having a tower 19, as shown... Figure 1 As shown in the upper right section. In the lower region of tower 19, at sea level 25 (see...) Figure 2 The platform 3 is secured to the tower 19 above, and this platform 3 is specifically designed and configured to accommodate the various equipment components of the electrolysis system 100 required for operation in offshore applications. These equipment components are located on... Figure 1 The lower part is shown exemplarily in a magnified view:

[0062] An electrolysis unit 5 is installed on platform 3, which is systematically connected to the wind power unit 1 to form an electrolysis system 100. For this purpose, containers 9 are specifically installed on platform 3, housing electrolysis elements (not shown in detail), such as individual electrolytic cells, thereby protecting the particularly sensitive functional components of the electrolysis unit 5 from weather conditions, especially in offshore applications. Each container 9 installed on platform 3 contains control devices 27, or so-called "auxiliary equipment" elements, and protectively houses them. These containers 9 are selected containers, typically prepared themselves to house and operate these control devices 27 and, if necessary, other auxiliary systems of the electrolysis unit 5. On the other hand, electrolytic cells for electrochemical material conversion are arranged in containers 9 specifically designed for this purpose. Other components or equipment installed within the containers 9 may also include storage containers for reactant water used in the electrolytic cells, etc.

[0063] The wind power unit 1 is preferably not currently connected to or connected to the power grid. Instead, the absorbed wind energy is directly supplied to the electrolysis unit 5 within a self-sufficient electrolysis system 100, which is designed to produce, preferably, green hydrogen, from water electrolysis. Therefore, the electrolysis system 100 is configured to operate independently of the power grid and is equipped for autonomous application in remote coastal areas. The wind power unit 1 is thus an offshore wind turbine. However, compared to… Figure 1 and Figure 2The facilities proposed in this invention for improving the heat supply of the offshore electrolysis system 100, which differ from the views in the original, can also be directly applied to onshore equipment.

[0064] The strategy of supplying the electrolysis unit 5 via multiple containers 9 (preferably ISO containers) advantageously ensures a simplified maintenance and repair process, while protecting equipment components from the effects of climate and weather, as well as from corrosion and harmful mechanical impacts during operation. The electrolysis system 100 is particularly vulnerable under freezing conditions where the wind power unit 1 cannot generate the electricity required for electrolysis, posing a serious risk of freezing to the water supply system of the electrolysis unit 5, especially during prolonged periods of "dark, windless, and low-light conditions" when the unit is shut down.

[0065] The present invention solves this problem by means of a heating device 7, which is advantageously integrated, for example, into the electrolysis system 100 (see...). Figure 2 The heating device 7 is connected to the electrolysis equipment 5. Its design allows the condensation heat to be transferred to the electrolysis equipment 5 during shutdown, thereby keeping the temperature of the water supply system above the minimum temperature. Figure 2The diagram shows, for example, a schematic side view of an electrolysis system 100 equipped with a corresponding heating device 7. The heating device 7 is integrated into a tower 19 of the wind power unit 1, which is mounted approximately at the height of a platform 3 and extends deep into an underwater region 31 below sea level 25. The platform 3, mounted on the tower 19 in the above-water region 31, forms the support structure for the electrolysis unit 5. The tower 19 is securely anchored to the seabed 35 via a base 33. The heating device 7 has a heat pipe 17 that extends vertically deep into the tower 19 approximately from the height of the platform 3, and includes a condenser 11 and an evaporator 13. The condenser 11 is formed at or located at the vertical upper end of the heat pipe 17, and the evaporator 13 is formed at or located at the vertical lower end of the heat pipe 17. The heat pipe 17 is currently designed as a carbon dioxide deep probe 37, using carbon dioxide (CO2) as the circulating working medium 23. The heat pipe 17 is pressure-sealed and filled with carbon dioxide (CO2) at a predetermined operating pressure of approximately 35 to 45 bar, particularly approximately 37 to 42 bar. In this way, a lower evaporation temperature of 2°C to 10°C, particularly 4°C to 8°C, is set based on the vapor pressure profile of the working medium 23. Depending on the selection of the working medium 23, different filling pressures can also be set within the heat pipe 17 to set the desired evaporation temperature slightly above the freezing point of water for the operation of the heat pipe 17. During operation, seawater or the seabed 35 serves as an external heat source for the CO2 deep probe 37. The base 33, surrounded by the seabed, also serves as a heat storage section 15 within the tower 19 of the wind power equipment 1 in the deep seabed. Therefore, during shutdown operation, the working medium 23 can evaporate in the evaporator 13. The heat of vaporization or enthalpy of vaporization required for the evaporation of the working medium 23 is obtained from the heat storage section 15, which serves as an external heat source, by the carbon dioxide deep probe 37 from the deep sea region 31. The evaporated working medium 23 is automatically conveyed upwards, with heat pipe principle specifically employed in heat pipe 17. The vaporized working medium 23 condenses in condenser 11. Through condenser 11, the condensation heat released from the working medium 23 (e.g., carbon dioxide CO2) can be transferred, for example, via heat exchanger 43 to the electrolysis device 5, which serves as an external radiator. The evaporator 13 of the carbon dioxide deep probe 37 is advantageously positioned at a depth at least approximately 5°C higher than the seawater temperature level compared to the external heat source temperature. For efficiency reasons, the hot end operating temperature of heat pipe 17 is only slightly higher than the boiling point temperature of the working medium 23, and the cold end operating temperature is only slightly lower than the boiling point temperature of the working medium 23. Therefore, the small temperature difference is sufficient to maintain the temperature of the electrolysis device 5 above the minimum temperature, thereby achieving freeze protection.

[0066] This provides a particularly advantageous solution for reliably protecting the off-grid electrolysis system 100 in offshore facilities from freezing damage when the ambient temperature above the water surface is below 5°C. The heat from the evaporation of the working medium 23 can be efficiently supplied to the electrolysis equipment 5, particularly the easily frozen electrolysis cells within the container 9, via a heating device 7 integrating a deep carbon dioxide probe 37. This heating device utilizes deep seawater as a heat storage section 15. The electrolysis equipment 5 has electrolysis cells arranged within the container 9, and the waste heat from these cells can be dissipated as process heat from the container 9 during normal operation, or, if necessary, through a heat exchanger 43 or a specially designed cooling circuit. Therefore, the heat exchanger 11 can also be used to cool the electrolysis equipment 5 during normal operation, if needed. The heat pipes 17 of the heating device 7 can be structurally integrated into the container 9 at the top via the evaporator 11 and the heat exchanger 43.

[0067] To illustrate the operation of the evaporation-based heating device 7, the following will use... Figure 3A schematic cross-sectional view of the heat pipe 17 is shown. The heat pipe 17 is designed as a gravity-driven carbon dioxide deep probe 37, using carbon dioxide (CO2) as the working medium 23. The heat pipe 17 has a cylindrical or tubular shape, extending primarily longitudinally along a vertical axis. The heat pipe 17 has a condenser 11 at its upper vertical end and an evaporator 13 at its lower vertical end. An adiabatic zone 39 is formed between the evaporator 13 and the condenser 11 of the heat pipe 17. Depending on the selected operating point, the heat pipe 17 is hermetically filled with carbon dioxide (CO2) for evaporation at an operating pressure of 35 bar to 45 bar, particularly 37 bar to 42 bar. This allows the corresponding evaporation temperature to be set from approximately 2°C to 6°C, particularly 4°C to 8°C, and adjusted according to usage. During operation, heat pipe 17 is thermally coupled to evaporator 13 and heat storage unit 15 to provide an external heat source for the evaporation of working medium 23, wherein the heating heat H is transferred to working medium 23 according to unit enthalpy of vaporization. Correspondingly, heat pipe 17 is thermally coupled to external radiator (currently heat exchanger 43) via condenser 11. At condenser 11, heating heat H is released again as condensation heat according to unit enthalpy. Condensation heat can be extracted and transferred to electrolysis equipment 5 through heat exchanger 43 to maintain the temperature of electrolysis equipment 5. Here, the main protection is to reliably prevent freezing of the water supply system of electrolysis equipment 5 when it stops operating. For heat transfer, a control device 41 is provided, which is designed as an internal heat controller 41 to control the heating heat H transferred through working medium 23. The internal heat controller 41 may have a controllable valve or a controllable throttling mechanism as a control element to control the back-and-forth flow of working medium 23, thereby controlling the heat transfer to condenser 11. In this way, the temperature of the electrolysis equipment can be controlled within certain limits, including maintaining and achieving the lowest achievable temperature, by means of the transferred heat flow. The internal heat transfer of the heat pipe 17 itself can thus be controlled, specifically by using valves or throttling devices inside the heat pipe as control components.

[0068] The heat transfer capacity of heat pipe 17 depends primarily on the enthalpy of vaporization of the working medium (in kJ / mol or kJ / kg), and not on the thermal conductivity of the wall of heat pipe 17 or the working medium 23. For efficiency reasons, the hot-end operating temperature of heat pipe 17 is only slightly higher than the boiling point temperature of the working medium 23 at a specified operating pressure, and the cold-end operating temperature is only slightly lower than that boiling point temperature.

[0069] The heat pipe 13 is typically an elongated metal container, or a tube, currently designed as a carbon dioxide depth probe 37, containing a sealed cavity. In this embodiment, the heat pipe 13 is filled with carbon dioxide (CO2) as the working medium 23. However, the heat pipe 13 can also be filled with other working media 23, such as water or ammonia, which fill the encapsulated cavity in a small liquid state and a large gaseous state. The part of the container that absorbs energy is the evaporator 13, and the part that releases energy is called the condenser 11. The operation is as follows: the input heating energy H raises the temperature of the container and the working medium 23 until it reaches the boiling point of the working medium 23. From this point, the working medium 23 begins to evaporate, and the temperature no longer rises. All the input heating energy H is instead converted into enthalpy of vaporization. This locally increases the pressure within the heat pipe 13 above the liquid surface, resulting in a slight pressure gradient within the heat pipe 13. The resulting vaporous working medium 23 begins to diffuse throughout the usable cavity, i.e., it flows towards areas of lower pressure. When the steam temperature is below the boiling point of the working medium 23, condensation occurs. For this to happen, the steam must transfer its heat energy H to the container, which in turn must transfer it to the surrounding environment. This transfer is most intense at the location of the condenser 11, where active cooling occurs if necessary, and it acts as a radiator. The temperature then stops decreasing until all the enthalpy of condensation has been transferred to the surrounding environment, currently to the heat exchanger 43 and its thermally coupled electrolytic tray 5. The liquid portion of the working medium 23 returns to the evaporator 13 by gravity (thermosiphon). For the evaporator to operate, the proportion of the liquid phase of the working medium 23 must be relatively low.

[0070] Because the vapor and liquid of the working medium 23 are confined within the same encapsulated space, the system is in a wet vapor zone. This results in a precisely defined temperature at a specific pressure within the heat pipe 17. Since the pressure difference within the heat pipe 17 is very small, typically only a few Pascals, the resulting temperature difference between the evaporator 13 and the condenser 11 is also small, at most a few Kelvin. Therefore, the thermal resistance of the heat pipe 17 is very low. The region between the evaporator 13 and the condenser 11 is practically isothermal.

[0071] The gravity-driven heat pipe 17 is a two-phase thermosiphon, or gravity heat pipe. Here, the working medium 23 circulates spontaneously due to gravity. This causes the working medium 23 to automatically flow back into the evaporator 13. The heating heat H is supplied only through the collection tank, i.e., to the liquid level. This depends on the liquid film formed by the refluxed liquid working medium 23.

Claims

1. An electrolysis system (100) comprising a wind power unit (1) and an electrolysis unit (5), wherein the wind power unit (1) is connected to the electrolysis unit to provide power for electrolysis, wherein, An islanded grid, not connected to the power grid, is achieved. The electrolysis system also includes a heating device (7) coupled to the electrolysis equipment (5) and operated using the working medium (23). The heating device has an evaporator (13) and a condenser (11), and is designed such that, during shutdown operation, the condensation heat of the working medium (23) can be transferred to the electrolysis equipment (5) through the condenser (11), thereby maintaining the temperature above the minimum temperature.

2. The electrolysis system (100) according to claim 1, wherein, The heating device (7) has a gravity-driven heat pipe (17), wherein the condenser (11) is formed on the heat pipe (17) above the evaporator (13).

3. The electrolysis system (100) according to claim 1 or 2, wherein, The heating device (7) has a deep probe (37) designed to extract heat from a deep heat storage section (15) in which the evaporator (13) is immersed.

4. The electrolysis system (100) according to any one of the preceding claims, wherein, The heating device (7) has a heat storage section (15) formed within the tower (19) of the wind power equipment (5).

5. The electrolysis system (100) according to any one of the preceding claims, wherein, The heating device (7) has a heat pipe (17), wherein the evaporator (13) is connected to the condenser (11) through an adiabatic zone (39), thereby enabling the working medium (23) to circulate autonomously in the heat pipe (17).

6. The electrolysis system (100) according to any one of claims 2 to 5, wherein the electrolysis system has a working medium (23) introduced into the heat pipe (17) at a predetermined working pressure, such that the evaporation temperature is set in the range of 2°C to 10°C at the working pressure, particularly between 4°C and 8°C.

7. The electrolysis system (100) according to any one of claims 2 to 6, wherein, The heat pipe (17) is designed as a carbon dioxide deep probe (37) with carbon dioxide (CO2) as the working medium (23).

8. The electrolysis system (100) according to claim 7, wherein, The carbon dioxide (CO2) is introduced into the heat pipe (17) at an operating pressure of 35 bar to 45 bar, especially between 37 bar and 42 bar.

9. The electrolysis system (100) according to any one of the preceding claims, wherein, For heat transfer, an internal heat controller (41) is provided, which uses a valve or throttling element as a control element to control the back-and-forth flow of the working medium (23).

10. The electrolysis system (100) according to any one of claims 3 to 9, wherein, The evaporator (13) is disposed within the base (33) of the wind power equipment (1), such that the liquid working medium (23) is evaporated in the evaporator (13) by deep heat.

11. The electrolysis system (100) according to any one of the preceding claims, wherein, The electrolysis equipment (5) has an electrolysis cell and a heat exchanger (11) disposed in a container (9), the heat exchanger being designed to dissipate the process heat from electrolysis from the container (9) during normal operation.

12. The electrolysis system (100) according to any one of the preceding claims, wherein, A heat exchanger (11) is provided that is thermally coupled to the condenser (11) so that the condensation heat of the working medium (23) can be transferred to the water supply component of the electrolysis device (5) during shutdown operation.

13. The electrolysis system (100) according to any one of the preceding claims, the electrolysis system comprising a wind power device (1), the wind power device having a tower (19) and a platform (3) fixed on the tower (19), the electrolysis device (5) being disposed on the platform.

14. The electrolysis system (100) according to claim 13, wherein, The evaporator (13) is located in the deep water layer or seabed (35) in the underwater region (31).

15. A method for operating an electrolysis system (100) according to any one of the preceding claims, wherein, During shutdown operation, the working medium (23) is evaporated by the heating device (7) and the evaporated working medium (23) is condensed, whereby condensation heat is generated and transferred to the electrolysis equipment (5), thereby maintaining the temperature above the minimum temperature and preventing the water supply components of the electrolysis equipment (5) from freezing.

16. The method according to claim 15, wherein, The temperature is maintained when the external temperature is below 5°C. The working medium (23) circulates in the gravity-driven heat pipe (17), extracts condensation heat from the working medium (23), and transfers it to the water supply component of the electrolysis device (5) to achieve antifreeze protection.

17. The method according to claim 15 or 16, wherein, The heat flow is controlled by a control device (41), which regulates the back-and-forth flow of the circulating working medium (23) and regulates the condensation heat transferred to the electrolysis equipment (5).

18. The method according to any one of claims 15, 16 or 17, wherein, During normal operation, the electrolysis equipment (5) is supplied with electrolysis current by the wind power equipment (1), wherein the process heat from the electrolytic cell is dissipated through the heat exchanger (11).

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