Energy supply system for coupling to a wind turbine used in island mode, and method for supplying the wind turbine with solar energy

Abstract

The invention relates to an energy supply system (20) for coupling to a wind turbine (30) used in island mode, wherein the wind turbine (30) is configured to operate an electrolysis system (11) for producing green hydrogen using wind energy, wherein the energy supply system (20) has a solar energy source (21), comprising a photovoltaic module (22) and / or a solar thermal collector (23), which is configured to supply the electrolysis system (21), in particular an enclosure (12) and water-conducting lines of electrolysis units of the electrolysis system (11), with thermal energy in the event of the absence of wind energy. The invention also relates to a corresponding method for supplying solar energy to a wind turbine (30) used in island mode.

Description

[0001] Description

[0002] Energy supply system for coupling to a wind turbine used in island operation and method for supplying the wind turbine with solar energy

[0003] The present invention relates to an energy supply system for coupling to a wind turbine used in island mode, i.e., without grid connection, wherein the wind turbine supplies, in particular, an electrolysis plant for producing green hydrogen with wind energy. Furthermore, a corresponding method for supplying the wind turbine with solar energy is specified.

[0004] In the future, there is an urgent need to prioritize renewable energy sources such as wind and solar power to reduce (global) carbon dioxide emissions. In addition to direct use as electricity, renewable electricity should also be able to serve as a raw material for the production of basic chemicals or fuels such as hydrogen.

[0005] These combinations of wind turbine and electrolyzer can also be operated without being connected to the grid. The electrolysis units are ideally located close to the renewable energy sources in order to reduce or avoid transformation and / or transmission losses. For example, electrolysis plants are being developed which are installed directly on a platform at an offshore wind turbine. With this type of coupling, regardless of whether it is onshore or offshore, the plant can also be operated without being connected to the power grid. Without being connected to the grid, however, during calm or no wind there is no power available from the wind generator or the power grid. So-called PEM electrolysis (PEM for "polymer electrolyte membrane" or "proton exchange membrane") is becoming increasingly popular as an energy source due to its great potential for producing cost-effective green hydrogen, e.g.for industrial applications or as a storage medium. In the wake of climate change, the element hydrogen (H2) and / or the possibility of producing H2 from renewable energy via PEM or water electrolysis has long emerged as a key factor for the energy industry and related sectors.

[0006] Even though most of the hydrogen is still produced today by steam reforming of methane, aggressive investments and support measures are expected to lead to a trend towards renewable hydrogen production.

[0007] A particularly promising process for producing hydrogen (H2) is the electrolysis of water, particularly using renewable electrical energy. Hydrogen can serve, among other things, as an energy store, for example by being used as a fuel to stabilize the electrical energy supply, particularly from renewable sources such as wind power, photovoltaics, or the like. But hydrogen can also be used for other processes that require a fuel or a reducing agent. The hydrogen produced during electrolysis can therefore be used industrially, for example, or electrical energy can be generated again electrochemically using fuel cells.

[0008] The separation of water into its chemical components, hydrogen and oxygen (O2), can therefore be carried out using suitable electrolysis cells. A particularly important form is the described PEM electrolysis, which, particularly compared to alkaline electrolysis approaches, has proven to be very load-dynamic and better suited for coupling fluctuating current levels due to its less complex peripherals. In particular, high current densities and power outputs can be achieved with PEM electrolysis even at higher load gradients, whereby the high quality or purity of the hydrogen product is advantageously maintained, for example, even in partial or overload operation.

[0009] Hydrogen is already used in countless applications in industry and technology. The potential to produce large quantities of hydrogen in a climate-neutral manner and / or to store or transport it "carbon-free," for example using hydrogen carriers such as ammonia, continues to open up completely new ways for the transport, chemical, and steel industries, for example, to supply entire sectors with green energy or to operate them in a climate-friendly manner. Furthermore, hydrogen is already, and will continue to be, highly interesting as a fuel or additive for conventional fuels because of its potential to produce no or fewer emissions.

[0010] A PEM electrolysis cell features a membrane with a catalyst layer on opposite surfaces. The catalyst layers are typically bordered by gas diffusion layers, which in turn are bordered by electrically conductive contact plates, occasionally called bipolar plates, which serve, among other things, to establish electrical contact.

[0011] Hydrogen is produced electrolytically from water as the reactant. This is an electrochemical process in which water is separated into its chemical components, oxygen and hydrogen. The electrochemical cell reactions can be described and differentiated as follows:

[0012] In polymer electrolyte membrane electrolysis, the two partial reactions are spatially separated by an ion-conductive membrane, which is preferably equipped with electrodes, particularly a cathodic catalyst and an anodic catalyst. In addition to material improvements, improvements in manufacturing processes can also lead to significant cost reductions.

[0013] Since the production of PEM hydrogen electrolyzers (PEMWE) must increase significantly in terms of throughput and scale to achieve agreed climate targets, there is a compelling need for techniques that enable the throughput and manufacturing capacity of so-called corresponding catalyst-coated membranes or membrane electrode assemblies to be improved.

[0014] To protect the electrolysis units from environmental influences, they require an enclosure such as a container. PEM water electrolyzers must also be operated with demineralized, particularly ultrapure, water. The temperature inside the container must therefore not fall below approximately 5°C. Otherwise, the water-bearing components, which contain water, can freeze and paralyze the operation of the entire system. This would defeat the purpose of low-maintenance and self-sufficient operation of (offshore) wind turbines without grid connection.

[0015] At an outside temperature below 5°C, heat is transported to the outside. At the minimum design temperature outside of -20°C, approximately 1 to 2 kW of heat dissipates per hour. The heat loss depends, among other things, on the insulation of the container. This heat must be returned to the container to maintain a relatively constant 5°C.

[0016] However, if no renewable electricity is available during cold weather (e.g., because there is no wind), the energy must be provided from other sources to enable plant operation and the continuous use of renewable wind energy. The water pipes between the containers or enclosures must also be heated to prevent them from freezing. This also requires energy, which must be provided from other sources when there is no wind.

[0017] Some existing solutions already include the provision of battery storage. The battery storage provides electrical power to maintain heating. However, this solution has disadvantages. For example, its capacity is significantly limited. Realistically, capacities of around 100 to 150 kWh would be necessary for this application. So-called (BESS) battery energy storage systems have the particular disadvantage of being expensive, large, and heavy. Therefore, other, better solutions are urgently needed.

[0018] Another, technically more obvious, solution is a diesel generator. However, this solution has the disadvantage that the diesel fuel must be regularly refilled, and the basic idea of ​​developing a sensible, CO2-emission-free offshore technology cannot be realized.

[0019] It is therefore an object of the present invention to provide means which allow wind turbines without grid connection in direct operation with electrolysis plants, in particular plants for water electrolysis, whether "onshore" or "offshore", to be supplied with energy as simply and reliably as possible, and at the same time to make the operation of the plant(s) as self-sufficient and low-maintenance as possible.

[0020] This problem is solved by the subject matter of the independent patent claims. Advantageous embodiments are the subject matter of the dependent patent claims.

[0021] One aspect of the present invention relates to an energy supply system for coupling to a wind turbine used in island operation, i.e. without grid connection, for example as a decentralized energy system.

[0022] The wind turbine is designed to operate an electrolysis plant or electrolyzer for the production of green hydrogen using wind energy. The electrolysis plant is preferably a PEM water electrolysis plant. Alternatively or additionally, alkaline electrolysis can be used to produce hydrogen.

[0023] The energy supply system has a solar energy source, comprising (at least) one solar thermal collector and / or (at least) one photovoltaic module. The solar energy or solar energy source is further configured to supply the electrolysis plant, in particular a housing or enclosure thereof and its water-carrying pipes, with thermal energy (auxiliary energy) in the event of a lack of wind energy, i.e. preferably when no wind energy can be tapped when there is no wind, or in the event of a defect in the plant. This is particularly necessary to ensure the operation of the plant beyond the aforementioned (short-term) “obstacle”. A design of the solar energy plant as a solar thermal collector can, just like a photovoltaic module, indirectly provide thermal energy for grid-independent electrolysis operation via an electric heater, for example.The overriding advantage of the inventive solution presented is that solar energy is often available as an energy source when the wind is calm and can therefore be used advantageously. Both photovoltaics and solar thermal energy can be used for this solution. Photovoltaics offers the particular advantage of being able to operate an electrical system control system for both the wind turbine and the electrolysis system during calm wind periods. An existing battery used as an electrical buffer can therefore be made significantly smaller. This requires less space, reduces the weight on the platform and is much lower.

[0024] The present inventive idea, in particular to provide a further renewable energy source, does not appear intuitive with regard to the application of wind turbines, in which the wind turbine itself offers hardly any usable area, whereas the generation of solar energy offers a great deal.

[0025] In one embodiment, the photovoltaic module is (additionally or alternatively) configured to supply a control system and / or a water treatment system of the electrolysis plant with electrical energy.

[0026] In one embodiment, the energy supply system comprises (several) photovoltaic modules with a module area of ​​at least 50 m 2 per electrolysis unit. An electrolysis unit can preferably be provided with an enclosure of a maximum size of an ISO container. In this context, for example, at least 50 m 2The photovoltaic module area per container is to be installed, particularly on the container. This design is particularly advantageous and balanced with regard to the solar-active area available on the respective container or wind turbine platform, as well as the solar energy requirement for the grid-independent, temporary operation of the wind turbine or electrolyzer in calm conditions.

[0027] In one embodiment, the photovoltaic module is designed to be mounted on the roof of an electrolysis unit or a container forming the housing of the unit (space-optimized).

[0028] In one embodiment, the at least one solar thermal collector, and possibly also the photovoltaic module, is preferably configured to be installed on the wind turbine tower during operation. Given the above-described difficulty of operating wind turbines or electrolysis systems autonomously and thus making renewable energies viable in the first place, this embodiment actually offers the synergy of advantageously utilizing the otherwise unused area of ​​the wind turbine tower for energy supply.

[0029] In one embodiment, the wind turbine is an offshore wind turbine, and the solar thermal collector or photovoltaic module is designed to float (on the sea) during operation of the wind turbine. Furthermore, the corresponding solar energy sources are, of course, suitably coupled or can be coupled to the electrolysis plant and electrically connected.

[0030] In one embodiment, the solar thermal collector has a reservoir for a heat transfer medium and is designed, in particular, as a flat-plate collector or as a vacuum tube collector, wherein a heat-absorbing surface of the solar thermal collector transfers heat to the heat transfer medium during operation of the system (the wind turbine). According to this embodiment, the required heat can be gradually adjusted as needed (temporarily) or tailored to the heating system required for the self-sufficiency of the system, preferably by storing the heat transfer medium in the reservoir.

[0031] In one embodiment, the reservoir is installed beneath a platform supporting the electrolysis system during operation or within the tower of the wind turbine. This positional relationship allows—as described above—the advantageous and inventive use of unused space within the wind turbine.

[0032] A further aspect of the present invention relates to a method for supplying a wind turbine used in island mode with solar energy, in particular using the described energy supply system. The supply method can therefore advantageously represent an operating method of the energy supply system.

[0033] The wind turbine supplies wind energy for operating the electrolysis plant to provide green hydrogen, wherein the solar energy source, comprising a solar thermal collector and / or a photovoltaic module, is used to supply the electrolysis plant with thermal energy in the event of a lack of wind energy (as described above).

[0034] In one embodiment of the method, the at least one solar thermal collector and / or the at least one photovoltaic module—of course, several of these components can also be provided—are used to supply the housing and water-carrying lines of the electrolysis units with thermal energy, in particular to heat them or to maintain them at the described operating temperature and thus to protect them from freezing in an emergency. In one embodiment, the photovoltaic module is additionally used to supply a control system and / or water treatment system of the electrolysis system with electrical energy.

[0035] In one embodiment, the solar thermal collector supplies the electrolysis plant with thermal energy only when no wind energy can be tapped, i.e. wind energy is missing due to a lack of wind or a plant defect.

[0036] In one embodiment, the solar thermal collector transfers heat from its heat-absorbing surface to the described heat transfer medium during operation of the system, this heat being used to heat the electrolysis units only when required or gradually, for example in phases overnight or when there is no wind.

[0037] In one embodiment, the electrical energy provided by the photovoltaic module is used to operate an air conditioning system for the wind turbine and / or the electrolysis system. The term "air conditioning system" is to be understood broadly here and includes, among other things, heating, ventilation, and air conditioning technology in general.

[0038] In one embodiment, the electrical energy provided by the photovoltaic module is used to charge a battery storage system (BESS system) or so-called uninterruptible power supply systems of the wind turbine when required.

[0039] Configurations, features and / or advantages that relate to the energy supply system in the present case relate analogously to supply methods, and vice versa.

[0040] As used herein, the term "and / or" or "respectively," when used in a series of two or more elements, means that any one of the listed elements may be used alone, or any combination of two or more of the listed elements may be used.

[0041] Further details of the invention are described below with reference to the figures.

[0042] Figure 1 shows a schematic overview of an offshore wind turbine including an electrolysis plant, which is set up to operate the wind turbine for the production of green hydrogen with wind energy.

[0043] Figure 2 shows a schematic side view with details of the energy supply system according to the invention as well as other components of the wind turbine.

[0044] Figure 3 shows - in a representation analogous to Figure 1 - parts of the energy supply system according to the invention in a perspective view of the platform.

[0045] Figure 4 shows a schematic simplified view of a floating embodiment of the solar energy source according to the invention.

[0046] Figure 5 shows an embodiment of the solar energy source according to the invention as a solar thermal collector.

[0047] Finally, Figure 6 shows a diagram of how water electrolysis works.

[0048] In the exemplary embodiments and figures, identical or equivalent elements may be provided with the same reference numerals. The illustrated elements and their relative sizes are generally not to scale; rather, individual elements may be exaggeratedly thick or oversized for clarity and / or clarity.

[0049] Figure 1 shows a wind turbine 30 in the upper right-hand part. In the lower part of the tower (see reference numeral 33 below) above sea level, a platform 34 is provided, which is shown in more detail in the remaining illustration.

[0050] The platform carries, in particular, containers 12, which comprise electrolysis elements, i.e., for example, individual electrolyzers or electrolysis systems 11. Parts of these containers 12 may also comprise control elements or "balance-of-plant" elements 14, which, for example, include all components of the electrolysis units, except for the individual electrolysis cells 11 themselves. Other components or system parts accommodated in the containers may also be storage tanks for the reactant water of the electrolyzers 11, or the like.

[0051] The wind turbine 30 preferably has no grid connection or grid coupling, but instead uses the absorbed wind energy to directly operate the described electrolysis plant 11 for the production of preferably green hydrogen. Further details on the reactions involved and the functioning of water electrolysis are described below with reference to Figure 6.

[0052] The wind turbine 30 is preferably an offshore wind turbine. Deviating from the illustrations in Figures 1 and 3, the means presented according to the invention for improving the energy supply of the system can also be readily applied to onshore systems.

[0053] The strategy of providing the electrolysis plant 11 via individual containers 12 , preferably ISO containers, advantageously ensures a simple maintenance and repair process and at the same time protects the plant components from climatic and weather influences as well as from corrosion and damaging mechanical influences.

[0054] Figure 2 shows a simplified alternative (schematic) view of the described wind turbine 30, which is also equipped with an inventive energy supply system 20 (see right in the figure). Rotor blades (not explicitly marked) of the turbine 30 are indicated in the left-hand area of ​​the illustration, and directly adjacent to them is a nacelle 31, or the generator part of the turbine.

[0055] The above-described platform 34 on the tower 33 is arranged above a base indicated by the reference numeral 32. Although the sea level is intended to be indicated by the wave contour, the present invention is also applicable to wind turbines installed on land without grid connection.

[0056] The platform 34 carries in particular the electrolysis system 11, which usually comprises a plurality of “electrolysis stacks”. Each of the stacks in turn preferably has a plurality of electrolysis cells 11 (cf. Figure 6 below), which are connected together in a row to form the stacks and connected accordingly.

[0057] Enclosing the electrolysis plant components in the container 12 is important, among other things, for the required "air conditioning" of the electrolysis plant 11 .

[0058] The purpose of electrolysis systems directly connected to renewable energy plants, such as wind turbines, is to achieve long-term, low-maintenance and self-sufficient operation. The costs of maintaining and replacing components are very complex and expensive, particularly offshore. In the future, such energy plants, and therefore such electrolysis plants, will largely have to operate without a grid connection in order to avoid corresponding transformation or line losses. Nevertheless, hydrogen or comparable energy sources can be efficiently produced on-site at the energy plant and, for example, stored as an energy storage device or indirectly via an energy source, or alternatively, fed into pipelines.

[0059] This advantage is accompanied by the difficulty of not having grid energy available for auxiliary systems and for heating or maintaining the operating temperature of the wind turbine and electrolysis plant.

[0060] An area of ​​the container indicated by the reference numeral 14 represents, for example, balance-of-plant components and / or a control system for the electrolyzers, transformers, rectifiers or also a battery “back-up” or BESS battery system, which is advantageously dimensioned small by the present invention.

[0061] In contrast, the area 13 can designate a water treatment for the reactant water, in particular comprising a seawater desalination plant (corresponding water-carrying lines are not explicitly shown in the figures here, but expediently extend from a holding tank to each of the electrolysis units shown in order to supply the units accordingly with reactant water).

[0062] Above, preferably on the roof of the container 12, a portion of the energy supply system 20 according to the invention is installed. The system 20 comprises a solar energy source 21, comprising a photovoltaic module 22 and / or a solar thermal collector 23. The solar energy source 21 is further configured to supply the electrolysis system 11, in particular the housing 12 and water-carrying pipes, with thermal energy in the event of a lack of wind energy.

[0063] An embodiment of the solar energy source as a photovoltaic module 22 can additionally be used to supply a control system 14 and / or a water treatment system 13 of the electrolysis system with electrical energy.

[0064] In addition, water treatment / water purification or desalination 13 may require thermal energy, i.e. heat, which may come from the collectors.

[0065] However, according to the invention, a configuration of the solar energy source as a solar thermal collector 23 is preferably used such that the electrolysis system 11 is only supplied with thermal energy when no wind energy can be tapped. This can be the case, for example, in the event of a defect, an emergency stop of the wind generator, or simply when there is no wind.

[0066] The electrical energy provided by the photovoltaic module 22 can also be used to operate an air conditioning system of the wind turbine 30 and / or the electrolysis system 11.

[0067] Finally, the electrical energy provided by the photovoltaic module 22 can alternatively or additionally be used to charge a battery storage unit (not explicitly marked) of the wind turbine 30 (only) when needed.

[0068] Reference numeral 24 schematically and by way of example indicates a reservoir for a heat transfer medium. Reservoir 24 may further be part of energy supply system 20 and is accordingly expediently functionally coupled to the corresponding solar thermal collector. Accordingly, in an inventive embodiment of the energy supply method, solar thermal collector 23 can transfer heat from a heat-absorbing surface thereof to a heat transfer medium (also not explicitly identified here) during operation. This heat can then be used step by step to heat the electrolysis units, as needed.

[0069] In Figure 2, a heat pump or an electric heating device 25 is also indicated schematically in dashed lines (optional), which can be provided in order to use electrical energy obtained via photovoltaics (PV) for thermal use for heating purposes.

[0070] Figure 3 shows the platform 34 of a wind turbine 30 described herein, which is equipped with the energy supply system 20 according to the invention; similar to the illustration in Figure 1. It can be seen that each roof of the containers 12 shown is provided with a solar energy source, be it a photovoltaic module 22 or a solar thermal collector 23.

[0071] Preferably, the energy supply system comprises 20 photovoltaic modules 22 with a module area of ​​at least 50 m 2 per electrolysis unit. The specified module area does not have to be present per container; the available solar-active roof area of ​​those containers can, of course, also be equipped with photovoltaic modules that only contain "balance-of-plant" components or auxiliary systems.

[0072] Furthermore, approximately or at least three electrolysis units can be present per platform 34 or system 10. The increasing electrical output of an electrolysis unit can amount to approximately 4 to 5 MW. Alternatively or additionally, a photovoltaic module or a solar thermal collector can be mounted on the tower 33 of the wind turbine.

[0073] In other words, in summary and possibly including further features applicable to all embodiments of the present invention, the present invention can be described in the following words.

[0074] Solar energy is harnessed at the wind turbine through the use of photovoltaic modules or solar thermal collectors to protect the electrolysis system from freezing during calm winds and cold outside temperatures. The advantage of this is that when there is no wind, the sky is often cloudless, allowing direct sunlight to be used during the day.

[0075] In principle, all solar cell technologies are suitable for photovoltaic applications. Thick-film cells made of monocrystalline (c-Si) or polycrystalline silicon have the highest efficiency to date and therefore require the smallest footprint for the required electrical power. With these modules, one can generate approximately 200W / m² in direct sunlight. 2 generate. Thus, the module area described above (40 to 50 m 2 ) are already sufficient for a minimal supply of the electrolysis containers.

[0076] As described, the photovoltaic modules 22 can, for example, be placed on the roof of the electrolysis container 12 and provide electrical power whenever there is no wind. This electrical power can be used directly for the measurement technology and control system or the HVAC air conditioning system of the electrolysis units when they are not in operation. In addition, a backup battery can be charged in order to provide electrical power (only) at night, for example. Thin-film solar cells such as amorphous (a-Si), microcrystalline (pm-Si) silicon, CIS / CIGS (copper indium (gallium) (di) selenide, CdTe (cadmium telluride) or organic solar cells can also be used for this purpose. Modules using these technologies can, for example, be applied to flexible films and thus attached to the round tower of the wind turbine 30.

[0077] Perovskite solar cells can also be used. These thin-film technologies are capable of efficiently converting even dim light, thus making the back of the tower (facing away from the sun) usable.

[0078] The use of concentrated photovoltaics (CPV) is also conceivable. However, since these modules require direct sunlight and thus must track the sun's path, such an installation appears more complex.

[0079] The electrical energy of the installed photovoltaic modules does not have to be used only at low temperatures and when there is no wind, but can instead be used to supply the electrolysis unit at any time.

[0080] In addition to the use of photovoltaic modules, solar thermal collectors can also be installed for hot water production (see above). The heat can be temporarily stored in tanks along with the collected heat.

[0081] These tanks can be placed, for example, beneath the platform or in the wind turbine tower. This heat can then be used gradually, for example, to bridge the night.

[0082] Figure 4 also indicates a further design and installation of the photovoltaic modules (or solar thermal collectors) using a schematic view. It can be seen that with offshore platforms - in addition to placing the solar modules on the electrolysis platform or directly on the wind turbine tower - it is also possible according to the invention to provide solar modules floating on the sea, located near the tower 34. With so-called onshore platforms, these could then instead be installed on land or on the ground. The electricity generated there can then be fed to the platform and used for the purposes described.

[0083] Figure 5 shows an example of a specific design of a solar thermal collector. Both flat-plate collectors and evacuated-tube collectors are suitable for use as solar thermal collectors. With both technologies, solar radiation heats a heat-absorbing surface, which transfers the heat to the heat transfer medium. The warm water thus generated can be used to heat the interior of the container and, as described, to protect it from freezing.

[0084] Figure 6 shows an electrolysis cell 10, in particular a PEM electrolysis cell for water electrolysis. The core of such a polymer electrolyte membrane electrolysis cell 10 is typically formed by a membrane electrode assembly (MEA), which is indicated in the center. The MEA has a membrane 3 coated with catalysts.

[0085] A first catalyst material is identified by the reference numeral 2. In contrast, a second catalyst material, different from the first catalyst material, is shown with the reference numeral 4. The respective cell reaction of the electrolysis takes place in the region of the layer formed by the respective catalyst material. During normal operation, electrons are diverted via the respective catalyst material and a gas diffusion layer to the contact or bipolar plates 5. For this reason, a high electrical conductivity of the catalyst layers is also desired. It can also be seen that reactant water (H2O) is generally provided on the anode side, which can be released and obtained during the electrolysis process into oxygen (O2) at the anode and hydrogen (H2) at the cathode.

[0086] The membrane 3 or a starting material, which is usually to be coated for the coating of the membrane 1 with the "catalyst", usually contains a perfluorosulfonic acid material (PFSA), polymer or ionomer 2.

[0087] As an alternative to the present embodiment of a PEM water electrolysis, another electrolysis variant, for example an alkaline water electrolysis, can also be used in the context of the invention, without limiting the generality.

Claims

Patent claims 1. Energy supply system (20) for coupling to a wind turbine (30) used in island operation, wherein the wind turbine (30) is designed to have an electrolysis system (11) for producing green hydrogen with wind energy, wherein the energy supply system (20) has a solar energy source (21) comprising a photovoltaic module (22) and / or a solar thermal collector (23), which is designed to supply the electrolysis plant (11), in particular a housing (12) and water-carrying lines of electrolysis units of the electrolysis plant (11), with thermal energy in the event of a lack of wind energy.

2. System (20) according to claim 1, wherein the photovoltaic module (22) is configured to supply a controller (14) and / or a water treatment system (13) of the electrolysis system with electrical energy.

3. System (20) according to claim 1 or 2, wherein the energy supply system (20) comprises photovoltaic modules (22) with a module area of ​​at least 50 m 2 per electrolysis unit.

4. System (20) according to claim 3, wherein a photovoltaic module (22) is arranged to be mounted on the roof of an electrolysis unit.

5. System (20) according to claim 3 or 4, wherein the photovoltaic module (22) is arranged to be installed on the tower (33) of the wind turbine (30) during operation.

6. System (20) according to one of the preceding claims, wherein the wind turbine (30) is an offshore wind turbine and the photovoltaic module (22) and / or the Solar thermal collector (23) during operation of the Wind turbine (30) is designed to float on the sea and is accordingly coupled to the electrolysis plant (11).

7. System (20) according to one of the preceding claims, wherein the solar thermal collector (23) comprises a reservoir (24) for a heat transfer medium and is designed as a flat collector or as a vacuum tube collector, wherein a heat-absorbing surface of the solar thermal collector (23) transfers heat to the heat transfer medium during operation of the system.

8. System (20) according to claim 7, wherein the reservoir (24) is installed under a platform (34) supporting the electrolysis plant or in the tower (33) of the wind turbine (30).

9. Method for supplying a wind turbine (30) used in island operation with solar energy, in particular using the energy supply system (20) according to one of the preceding claims, wherein the wind turbine (30) supplies wind energy to operate the electrolysis plant (11) for producing green hydrogen, and wherein a solar energy source (21), comprising a photovoltaic module (22) and / or a solar thermal collector (23), is used to supply the electrolysis plant with thermal energy in the event of a lack of wind energy.

10. The method according to claim 9, wherein the photovoltaic module (22) and / or the solar thermal collector (23) are used to supply a housing (12) and water-carrying lines of the electrolysis units (11) with thermal energy.

11. The method according to claim 9 or 10, wherein the photovoltaic module (22) is additionally used to Control (14) and / or a water treatment (13) of the electrolysis plant, with electrical energy.

12. Method according to one of claims 9 to 11, wherein the solar thermal collector (23) supplies the electrolysis plant (11) with thermal energy only when no wind energy can be tapped.

13. Method according to one of claims 9 to 12, wherein the solar thermal collector (23) transfers heat from a heat-absorbing surface thereof to a heat transfer medium during operation, and wherein this heat is used step by step to heat the electrolysis units as needed.

14. The method according to any one of claims 9 to 13, wherein the electrical energy provided by the photovoltaic module (22) is used to operate an air conditioning system of the wind turbine (30) and / or the electrolysis system (11).

15. The method according to any one of claims 9 to 14, wherein the electrical energy provided by the photovoltaic module (22) is used to charge a battery storage unit of the wind turbine (30) when required.

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