A method and a system for handling waste heat generated by at least one component of a wind turbine generator

Abstract

A method (200) for handling a waste heat generated by at least one component of a wind turbine generator is presented. The method (200) comprises: - determining (210) that an inflow of thermal energy to at least one electrolyzer (121) is needed to control the at least one electrolyzer (121) to operate in a specific electrolyzer state; and - transferring (220) a turbine thermal energy TEturbine associated with at least a part of the waste heat from the wind turbine generator (101) to the at least one electrolyzer (121), by transferring the turbine thermal energy TEturbine from a turbine temperature controlling arrangement (310) to at least one electrolyzer temperature controlling arrangement (320) of the at least one electrolyzer (121) via a connection (322, 330, 340) between the turbine temperature controlling arrangement (310) and the at least one electrolyzer temperature controlling arrangement (320), respectively.

Description

[0001] A METHOD AND A SYSTEM FOR HANDLING WASTE HEAT GENERATED BY AT LEAST ONE COMPONENT OF A WIND TURBINE GENERATOR

[0002] Technical field

[0003] Aspects of the present invention relate to a method and a system for handling a waste heat generated by at least one component of a wind turbine generator. Further aspects of the invention relate to a power plant comprising the system, and to a computer program or a computer-readable medium implementing the method.

[0004] Background

[0005] Power plants, such as so-called renewable power plants, rely on renewable energy sources such as wind and / or sun to produce electricity by usage of wind turbine generators and / or photovoltaic power generators. The power plants may also comprise one or more power-to-gas units, and may then also be known as power-to-x plants. Besides electricity, the power plants may then produce additional energy vectors, such as green hydrogen, produced from water, and other green synthetic fuels, produced by mixing green hydrogen with additional chemical compounds and / or elements. Byproducts of renewable power plants may include oxygen, also resulting from the electrolysis of water.

[0006] The power plant may be connected via one or more interfaces to an external electricity grid, an external hydrogen or natural gas grid, and / or a grid for industrial products, such as e-fuels.

[0007] Summary

[0008] Wind turbine generators generate heat, also known as waste heat, in one or more of its components during operation, primarily due to for example friction in the gearbox, electrical resistance in the generator, and jawing. This generated waste heat may, if not being handled, decrease an efficiency of the wind turbine generator, may cause damages and wear, and / or may cause safety hazards. Therefore, cooling of these one or more components is crucial. Conventional cooling solutions for wind turbine generators include utilization of air cooling, liquid cooling, and heat exchangers. These conventional solutions must be sized to match the specific platform of the windturbine generator, and represent a significant cost for development and operation of the wind turbine generators.

[0009] Water electrolysis is a process that uses electricity to split water into hydrogen and oxygen. This is achieved using an electrolyzer, which comprises an anode and a cathode separated by an electrolyte. When a voltage is applied, water at the anode is oxidized to produce oxygen and protons, while at the cathode, protons are reduced to produce hydrogen. The thermodynamics of water electrolysis is governed by the Gibbs free energy change of the reaction, which is related to the cell voltage. A thermoneutral voltage for an electrolyzer is the cell voltage at which the Gibbs free energy change is zero.

[0010] Conventionally, the electrolyzers have been operated at steady state, above the thermoneutral voltage. Above the thermoneutral voltage, the electrolyzer reaction is exothermic, which means that it releases heat. In this case, the electrical energy provided to the electrolyzer is more than what is needed to break the bonds in the water molecules, and the excess energy is released as heat into its surroundings. Thus, in conventional solutions, the electrolyzers also generates excessive heat and therefore require cooling arrangements being expensive and adding to a complexity of the electrolyzers.

[0011] An object of the invention is to provide a solution which mitigates or solves such heat associated problems of the wind turbine generators and the electrolyzers.

[0012] An object of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

[0013] The above and further objects are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

[0014] According to a first aspect of the invention, a method for handling a waste heat generated by at least one component of a wind turbine generator is presented, wherein- the wind turbine generator is configured to provide electric power to one or more electrolyzers;

[0015] - the wind turbine generator comprises a turbine temperature controlling arrangement;

[0016] - the one or more electrolyzers comprise one or more electrolyzer temperature controlling arrangements, respectively; and

[0017] - the turbine temperature controlling arrangement and the one or more electrolyzer temperature controlling arrangements are connected such that thermal energy can be transferred between the turbine temperature controlling arrangement and the one or more electrolyzer temperature controlling arrangements.

[0018] The method comprises:

[0019] - determining that an inflow of thermal energy to at least one of the one or more electrolyzers is needed to control the at least one electrolyzer to operate in a specific electrolyzer state; and

[0020] - transferring a turbine thermal energy TEturbine associated with at least a part of the waste heat from the wind turbine generator to the at least one electrolyzer, by transferring the turbine thermal energy TEturbine from the turbine temperature controlling arrangement to at least one electrolyzer temperature controlling arrangement of the at least one electrolyzer via the connection between the turbine temperature controlling arrangement and the at least one electrolyzer temperature controlling arrangement, respectively.

[0021] The connection between the turbine temperature controlling arrangement and the one or more electrolyzer temperature controlling arrangements provides for an interconnection of these two temperature regulation systems. Hereby, it becomes possible to efficiently and robustly operate the at least one electrolyzer in an endothermic state, a hot standby state and / or a start-up state, since thermal energy may now be transferred from the wind turbine generator to the at least one electrolyzer when needed.

[0022] When the presented solution is utilized, the electrolyzer may be controlled to ramp up and down its operation to follow the fluctuations of the electric power supplied by the wind turbine generator. When the wind speed is high and a lot of electricity is beingproduced, the electrolyzer may be controlled to ramp up its operation to consume this excess electricity, thus producing a higher hydrogen flow. Conversely, when the wind speed is low and less electricity is being produced, the electrolyzer may be controlled to ramp down its operation, thus producing a lower hydrogen flow. This ramping principle can thus allow for both endothermic and exothermic operation of the at least one electrolyzer, and for a more flexible utilization of the at least one electrolyzer. Below the thermoneutral voltage, the reactions in the at least one electrolyzer are endothermic, which means that the at least one electrolyzer absorbs heat from its surroundings. The reason for this is that the electrical energy provided to the electrolyzer by the wind turbine generator is not sufficient to break the bonds in the water molecules, and additional energy is required in the form of heat for the electrolyzer to operate properly. The endothermic nature of the electrolyzer reactions below the thermoneutral voltage indicates that the electrolyzer needs to be heated to achieve efficient operation.

[0023] The presented solution utilizes the at least one electrolyzer, for example when it is operating in the endothermic regime, as a temperature regulation system, which draws thermal energy from the surroundings. Thus, the at least one electrolyzer is here intelligently utilized as a cooling element for cooling the wind turbine generator, by transferring thermal energy of the waste heat generated by the wind turbine generator to the at least one electrolyzer, which then needs thermal energy.

[0024] The presented solution modifies the conventional cooling of the wind turbine generator in order to facilitate directing of the waste heat towards the at least one electrolyzer. Since the at least one electrolyzer needs to be heated at lower operation setpoints, the waste heat from the wind turbine generator can be used for prewarming the incoming electrolyte to the at least one electrolyzer, which in turn is utilized for cooling down the components of the wind turbine generator. It is anticipated that the modification of the turbine temperature controlling arrangement may be performed without unnecessarily adding to the technical complexity of the wind turbine generator. Also, the utilization of the electrolyzer temperature controlling arrangement for cooling of the wind turbine generator may result in a reduction of the number of cooling elements in the turbine temperature controlling arrangement.Thus, the presented solution reduces the costs for both development and operation of the wind turbine generators.

[0025] Further, a known characteristic of renewable energy sources is their intermittency. Upon integrating and powering the electrolyzer with renewable energy, the hydrogen generator may enter into various distinct states during operation. The herein presented solution manages to integrate and utilize the waste heat from the at least one components of the wind turbine generator as a heat supply for the water electrolyzers when operating in these distinct states.

[0026] The presented solution thus makes it possible to utilize ramping of the at least one electrolyzer down to a point of limited hydrogen production, at which the at least one electrolyzers starts to function as a cooling element for the wind turbine generator. Such a utilization of the at least one electrolyzer may be favorable for example if generation of electricity is favored over hydrogen production due to higher energy prices. Such a utilization of the at least one electrolyzer may also be favorable if there is a limited amount of power available for an ensemble of electrolyzers, e.g. for two or more stacks of electrolyzers, which requires one of the electrolyzers to be shut off or operate at a lower setpoint. The disclosed solution thus makes an intelligent utilization of the endothermic operation of the electrolyzer possible, which is also easily adaptable to the current operating conditions.

[0027] According to an embodiment of the first aspect, the determination comprises one in the group of:

[0028] - determining that the inflow of thermal energy is needed to maintain an operational temperature Teof the at least one electrolyzer when the at least one wind turbine generator is controlled to operate in a power overdrive state;

[0029] - determining that the inflow of thermal energy is needed to maintain an operational temperature Teof the at least one electrolyzer when the at least one electrolyzer is controlled to operate in an endothermic state;

[0030] - determining that the inflow of thermal energy is needed to maintain an operational temperature Teof the at least one electrolyzer when the at least one electrolyzer is controlled to be in a hot standby state; and

[0031] - determining that the inflow of thermal energy is needed to increase an operationaltemperature Teof the at least one electrolyzer when the at least one electrolyzer is in a start-up state.

[0032] Thus, the herein presented solution facilitates maintaining an operational temperature Teof the at least one electrolyzer when it is in its endothermic state, such that a partial / limited hydrogen production may continue to take place. It also facilitates maintaining an operational temperature Teof the at least one electrolyzer when it is in its hot standby state, such that the at least one electrolyzer is prepared to be quickly brought to a hydrogen productive state. It further facilitates increasing an operational temperature Teof the at least one electrolyzer when the at least one electrolyzer is in a start-up state, such that the at least one electrolyzer may be brought to a normal hydrogen productive state. It also makes it possible to control the at least one wind turbine generator to operate in a power overdrive state, since the surplus thermal energy generated in the power overdrive state may be used to maintain an operational temperature Teof the at least one electrolyzer. Hereby, a more flexible utilization of the at least one electrolyzer is provided, at the same time as an efficient cooling of the wind turbine generator is provided.

[0033] An endothermic state of an electrolyzer is a state in which the chemical reactions taking place in the electrolyzer when producing hydrogen are endothermic. Thus, the chemical reactions absorb heat from its surroundings because the electrical energy provided to the electrolyzer by the wind turbine generator is not sufficient to break the bonds in the water molecules. Thus, additional energy is required in the form of heat for the electrolyzer to operate properly.

[0034] A power overdrive state of the wind turbine generator is a state in which the wind turbine generator produces more electric power than a nominal electric power for that wind turbine generator.

[0035] A hot standby state of an electrolyzer is a state in which the electrolyzer is not producing hydrogen, but is ready to start producing hydrogen. Thus, the electrolyzer has a suitable temperature and is also otherwise prepared for start breaking bonds of water molecules if needed.A start-up state of an electrolyzer is a state in which the electrolyzer is off, i.e. a state in which the electrolyzer is not producing hydrogen and is also not prepared to start producing hydrogen. In the start-up state, a temperature of the electrolyzer considerably lower than a suitable operation temperature for producing hydrogen.

[0036] According to an embodiment of the first aspect, the determination that the at least one electrolyzer needs an inflow of thermal energy is based on one or more in the group of:

[0037] - operation information provided by a control system configured to control the at least one electrolyzer;

[0038] - an operational temperature Teof the at least one electrolyzer;

[0039] - an electric power consumption of the at least one electrolyzer; and

[0040] - a production of hydrogen of the at least one electrolyzer.

[0041] Hereby, a reliable determination of the thermal energy needs of the at least one electrolyzer is provided. It should be noted that the control system configured to control the at least one electrolyzer may be centrally located, e.g. in a plant controller, or may be distributed over multiple, and possibly also independent, control arrangements, possibly arranged adjacent to the respective at least one electrolyzer.

[0042] According to an embodiment of the first aspect, the transfer of the turbine thermal energy TEturbine comprises:

[0043] - transferring the turbine thermal energy TEturbine from a coolant loop of the turbine temperature controlling arrangement to the connection between the turbine temperature controlling arrangement and the at least one electrolyzer temperature controlling arrangement.

[0044] Hereby, an efficient and reliable interconnection of the turbine temperature controlling arrangement and the at least one electrolyzer temperature controlling arrangement is provided, such that thermal energy may be transferred from the wind turbine generator to the at least one electrolyzer.According to an embodiment of the first aspect, the transfer of the turbine thermal energy TEturbine comprises:

[0045] - transferring the turbine thermal energy TEturbine from the connection between the turbine temperature controlling arrangement and the at least one electrolyzer temperature controlling arrangement to a lye loop of the at least one electrolyzer temperature controlling arrangement.

[0046] Hereby, an efficient and reliable interconnection of the turbine temperature controlling arrangement and the lye loop of the at least one electrolyzer temperature controlling arrangement is provided, such that efficient cooling of the wind turbine generator and heating of the at least one electrolyzer is made possible.

[0047] According to an embodiment of the first aspect, the transfer of the turbine thermal energy TEturbine is utilized for at least one in the group of:

[0048] - maintaining an operational temperature Teof the at least one electrolyzer; and - increasing an operational temperature Teof the at least one electrolyzer.

[0049] Hereby, the at least one electrolyzer may be controlled to stay in an endothermic state and thereby continue to produce hydrogen at a lower level, or to keep the at least one electrolyzer in a hot standby state. The at least one electrolyzer may also be controlled to increase its operational temperature Tesuch that it goes into a hydrogen production state.

[0050] According to an embodiment of the first aspect, the transfer of the turbine thermal energy TEturbine is utilized for:

[0051] - decreasing a temperature Tt of the at least one component of the wind turbine generator.

[0052] Thus, the integration of the wind turbine generator ant the electrolyzers according to the presented solution may be used as a cooling element, which efficiently cools down the components of the wind turbine generator that become warm during operation.According to an embodiment of the first aspect, the one or more electrolyzers comprise:

[0053] - a first electrolyzer comprising a first electrolyzer temperature controlling arrangement; and

[0054] - a second electrolyzer comprising a second electrolyzer temperature controlling arrangement; wherein

[0055] - the first electrolyzer temperature controlling arrangement and the second electrolyzer temperature controlling arrangement are connected such that thermal energy can be transferred between the first electrolyzer temperature controlling arrangement and the second electrolyzer temperature controlling arrangement; the method further comprising:

[0056] - determining that an inflow of thermal energy to the second electrolyzer is needed to control the second electrolyzer to operate in a specific electrolyzer state; and

[0057] - transferring a first thermal energy TEist from the first electrolyzer temperature controlling arrangement to the second electrolyzer temperature controlling arrangement via the connection between the first electrolyzer temperature controlling arrangement and the second electrolyzer temperature controlling arrangement.

[0058] Hereby, heat generated by a first electrolyzer may be used for heating a second electrolyzer, which may be favourable in many situations. Waste heat generated in the first electrolyzer is then utilized as a heat supply for the second electrolyzer, for example during hot standby or during electrolyzer start-up, to optimize the synergistic production of green hydrogen during value adding opportunities. Therefore, excessive heat generated during specific value adding windows of operations is efficiently made use of.

[0059] According to an embodiment of the first aspect, the determination comprises one in the group of:

[0060] - determining that the inflow of thermal energy is needed to maintain an operational temperature Te2 of the second electrolyzer when the wind turbine generator is controlled to operate in a power overdrive state;

[0061] - determining that the inflow of thermal energy is needed to maintain an operational temperature Te2 of the second electrolyzer when the second electrolyzer is controlledto operate in an endothermic state;

[0062] - determining that the inflow of thermal energy is needed to maintain an operational temperature Te2 of the second electrolyzer when the second electrolyzer is controlled to be in a hot standby state; and

[0063] - determining that the inflow of thermal energy is needed to increase an operational temperature Te2 of the second electrolyzer when the second electrolyzer is in a startup state.

[0064] Hereby, it is possible to maintain an operational temperature Te2 of the second electrolyzer when it is in its hot standby state, such that the second electrolyzer is prepared to be quickly brought to a hydrogen productive state. It further facilitates increasing an operational temperature Te2 of the second electrolyzer when the second electrolyzer is in a start-up state, such that the second electrolyzer may be brought to a hydrogen productive state. It also makes it possible to control the at least one wind turbine generator to operate in a power overdrive state, since the surplus thermal energy generated in the power overdrive state may be used to maintain an operational temperature Te2 of the second electrolyzer.

[0065] According to an embodiment of the first aspect, the method further comprises:

[0066] - determining that the first electrolyzer is in an exothermic state; and

[0067] - transferring the first thermal energy TEist created in the exothermic state of the first electrolyzer from the first electrolyzer temperature controlling arrangement to the second electrolyzer temperature controlling arrangement.

[0068] Hereby, the excessive heat from the exothermic reactions of the first electrolyzer is efficiently made use of in the second electrolyzer.

[0069] According to an embodiment of the first aspect, the transfer of the first thermal energy TEist from the first electrolyzer temperature controlling arrangement to the second electrolyzer temperature controlling arrangement comprises:

[0070] - transferring the first thermal energy TEist from a first lye loop of the first electrolyzer temperature controlling arrangement to the connection between the first electrolyzertemperature controlling arrangement and the second electrolyzer temperature controlling arrangement.

[0071] Hereby a reliable interconnection of the first lye loop with the second electrolyzer temperature controlling arrangement is provided via the connection.

[0072] According to an embodiment of the first aspect, the transfer of the first thermal energy TEist from the first electrolyzer temperature controlling arrangement to the second electrolyzer temperature controlling arrangement comprises:

[0073] - transferring the first thermal energy TEist from the connection between the first electrolyzer temperature controlling arrangement and the second electrolyzer temperature controlling arrangement to a second lye loop of the second electrolyzer temperature controlling arrangement.

[0074] Hereby a reliable interconnection of the first second electrolyzer temperature controlling arrangement and the second lye loop is provided via the connection.

[0075] According to an embodiment of the first aspect, the wherein the transfer of the first thermal energy TEist is utilized for at least one in the group of:

[0076] - maintaining an operational temperature Te2 of the second electrolyzer; and

[0077] - increasing an operational temperature Te2 of the second electrolyzer.

[0078] Hereby, the second electrolyzer may be controlled to stay in an endothermic state and continue to produce hydrogen at a sub-maximum level, or to keep the second electrolyzer in a hot standby state. The second electrolyzer may also be controlled to increase its operational temperature Te2 such that it goes into a hydrogen production state.

[0079] According to an embodiment of the first aspect, the method further comprises:

[0080] - controlling the wind turbine generator to run in an overdrive mode when the turbine thermal energy TEturbine is transferred from the wind turbine generator to the at least one electrolyzer.Hereby, more electric power may safely be generated by the wind turbine generator, without any risk of overheating the one or more components of the wind turbine generator, since the waste heat is efficiently utilized for maintaining or increasing the temperature of the at least one electrolyzer, such that the one or more components of the wind turbine generator are cooled down.

[0081] According to a second aspect of the invention, a system for handling waste heat generated by at least one component of a wind turbine generator configured to provide electric power to one or more electrolyzers is presented. The system comprises:

[0082] - a turbine temperature controlling arrangement configured to control a temperature of the wind turbine generator;

[0083] - one or more electrolyzer temperature controlling arrangements configured to control the temperature of the one or more electrolyzers, respectively;

[0084] - a connection arranged between the turbine temperature controlling arrangement and at least one of the one or more electrolyzer temperature controlling arrangements; and

[0085] - a control unit configured to transfer a turbine thermal energy TEturbine associated with at least a part of the waste heat from the wind turbine generator to at least one electrolyzer when an inflow of thermal energy to the at least one electrolyzer is needed to control the at least one electrolyzer to operate in a specific electrolyzer state, the turbine thermal energy TEturbine being transferred from the turbine temperature controlling arrangement to the at least one electrolyzer temperature controlling arrangement of the at least one electrolyzer via the connection between the turbine temperature controlling arrangement and the at least one electrolyzer temperature controlling arrangement, respectively .

[0086] The system may carry out any one of the method aspects and embodiments disclosed above or below. The system has corresponding advantages as the ones mentioned above for the method for handling a waste heat generated by at least one component of a wind turbine generator according to the first aspect of the invention and its embodiments.According to an embodiment of the second aspect, the connection arranged between the turbine temperature controlling arrangement and the at least one electrolyzer temperature controlling arrangement comprises a heat exchanger.

[0087] The heat exchanger efficiently interconnects the turbine temperature controlling arrangement and the at least one electrolyzer temperature controlling arrangement, such that thermal energy may be transferred between them.

[0088] According to an embodiment of the second aspect, the one or more electrolyzers comprise:

[0089] - a first electrolyzer comprising a first electrolyzer temperature controlling arrangement; and

[0090] - a second electrolyzer comprising a second electrolyzer temperature controlling arrangement;

[0091] the system further comprising:

[0092] - a connection arranged between the first electrolyzer temperature controlling arrangement and the second electrolyzer temperature controlling arrangement, the connection being configured to transfer a first thermal energy TEist from the first electrolyzer temperature controlling arrangement to the second electrolyzer temperature controlling arrangement.

[0093] Hereby, excessive heat generated by the first electrolyzer may be used for heating the second electrolyzer, which may be favourable in many situations.

[0094] According to an embodiment of the second aspect, the connection arranged between the first electrolyzer temperature controlling arrangement and the second electrolyzer temperature controlling arrangement comprises a heat exchanger.

[0095] The heat exchanger provides for an efficient interconnection of the first electrolyzer temperature controlling arrangement and the second electrolyzer temperature controlling arrangement.According to an embodiment of the second aspect, the at least one waste heat generating component comprises one or more in the group of:

[0096] - at least one power electronics component;

[0097] - at least one converter;

[0098] - at least one rectifier; and

[0099] - at least one inverter.

[0100] Thus, the proposed solution is useful for cooling down the components of the wind turbine generator being most prone to generating excessive / waste heat during operation.

[0101] According to a third aspect of the invention, a power plant is presented. The power plant comprises:

[0102] - at least one wind turbine generator;

[0103] - one or more electrolyzers; and

[0104] - a herein described system for handling waste heat.

[0105] The renewable power plant of the third aspect has corresponding advantages as the ones mentioned above for the method for handling a waste heat generated by at least one component of a wind turbine generator according to the first aspect of the invention and its embodiments.

[0106] According to an embodiment of the third aspect,

[0107] - the power plant is a decentralized power plant; and

[0108] - one or more electrolyzers are connected to each one of the at least one wind turbine generator.

[0109] Here, the power generated by a single wind turbine generator is used directly to supply one or more electrolyzer systems. For the decentralized solution, the generator of the electric power and the consumer of the electric power are closely integrated in terms of operation, controls, and location. This is also known as a decentralized power-to-x plant architecture, in which the electrolyzer is intimately integrated with the wind turbine generator through control, operation, and proximity. Itshould be noted that the wind turbine generator may still be connected to the grid, enabling dual revenue generation either from selling electrons to the power market or from producing green hydrogen.

[0110] According to a fourth aspect of the invention, the above mentioned and other objects are achieved with a computer program or a computer-readable medium comprising instructions which, when the program or the instructions is / are executed by a computer, cause the computer to carry out one or more of the methods according to any one of the aspects and embodiments disclosed above or below. Advantages of the computer program or the computer-readable medium according to the fourth aspect correspond to advantages of the method according to the first aspect and its embodiments mentioned above or below.

[0111] According to an aspect of the present invention, the above-mentioned computer program and / or the computer-readable medium are / is configured to implement the method and its embodiments described herein.

[0112] The above-mentioned features and embodiments of the method, the computer program, the computer-readable medium, the control arrangement and the power plant, respectively, may be combined in various possible ways providing further advantageous embodiments.

[0113] Further advantageous embodiments of the method for handling a waste heat generated by at least one component of a wind turbine generator and the system, and further advantages of the embodiments of the present invention, emerge from the detailed description of embodiments.

[0114] Brief Description of the Drawings

[0115] Embodiments of the invention will now be illustrated, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, where similar references are used for similar parts, in which:Figure 1 is a schematic diagram illustrating an embodiment of a power plant, to which herein described embodiments may be applied;

[0116] Figure 2 is a schematic diagram illustrating an embodiment of a wind turbine generator of the power plant of figure 1 ;

[0117] Figure 3 is a schematic diagram illustrating an embodiment of a Power-to-X unit of the power plant of figure 1 ;

[0118] Figure 4 is a schematic flow chart illustrating methods according to various aspects and embodiments of the invention;

[0119] Figure 5 is a schematic presentation of a system according to various aspects and embodiments of the invention;

[0120] Figure 6 is a schematic presentation of a system according to various aspects and embodiments of the invention; and

[0121] Figure 7 is a schematic diagram illustrating an embodiment of a control arrangement according to the second aspect of the invention, in which a method according to any one of the herein described aspects and embodiments may be implemented.

[0122] Detailed Description

[0123] Figure 1 schematically illustrates a non-limiting example of a power plant 100, also known as a renewable power plant, in which aspects and embodiments of the present invention may be implemented. The aspects and embodiments of the present invention may, of course be implemented in any suitable power plant, in which one or more wind turbine generators and one or more electrolyzers are utilized. The aspects and embodiments of the present invention are thus not limited to implementation in the power plant example shown in figure 1.

[0124] The power plant 100 is arranged for providing electric power, or electrical energy, to an electric power grid 116. The power plant 100 includes one or more renewable electric power generating units 103, such as wind turbine generators 101. According to some embodiments, the power plant 100 may also comprise one or more other renewable electric power generating units / assets 103, for example a photo-voltaic generator 102, such as a photo-voltaic panel, a solar panel, or a solar cell panel. The wind turbine generators 101 and the photo-voltaic generator 102 may also begenerally described as renewable power sources 103 of the power plant 100, or as renewable power generators 103 of the power plant 100. Other renewable electric power generating units 103, such as e.g. one or more fuel cells 104, may according to some embodiments also be comprised in the power plant 100. The one or more fuel cells 104 may for example comprise one or more hydrogen fuel cell, and may be configured for converting hydrogen and oxygen into electric power by utilizing redox reactions.

[0125] The power plant 100 may, according to some embodiments, also comprise one or more additional renewable power sources or power generators 103, such as one or more electric battery energy storage systems 106, which may comprise an electric battery energy storage system, possibly including one or more electric battery units.

[0126] The power plant 100 may also comprise further assets / units / components, such as for example one or more harmonic filters and / or one or more reactive power compensation units. Such further assets / units / components are schematically referred to as further assets / units / components 107 in figure 1.

[0127] The power plant 100 may be connected, or connectable, possibly via an internal grid 110 of the power plant 100, to the electric power grid 116 via a point of common coupling (PCC) 115. The renewable electric power generating units 103 feed / provide electric power produced by them to the internal grid 110, which is connected via the point of common coupling 115 to the external electric power grid 116. For some embodiments, the electric power grid 116 may be referred to as a utility grid, an electrical grid, a power grid, or an electric power network.

[0128] The power plant 100 further comprises one or more power-to-x units, including one or more power-to-gas units 120, 120’. The power-to-x units are configured to convert electric power from the power plant 100 to x, i.e. to hydrogen in this case. Each power-to-gas (P2G) unit 120, 120’ includes an electrolyzer 121, 12T configured to convert electric power from the power plant 100 to hydrogen. The one or more electrolyzers 121, 12T are arranged to break down water molecules into its constituents, i.e. into hydrogen and oxygen, by consuming electricity. The one ormore electrolyzers 121, 12T may be commonly controlled by a centralized control arrangement 150, or may be independently controlled by distributed and / or independent control arrangements / stacks / modules. The hydrogen used in conversions in a fuel cell 104 may for example be produced by one or more power-to-gas (P2G) units 120, 120’ of the power plant 100. The hydrogen may possibly be stored in an internal hydrogen storage 122 of the power plant 100.

[0129] Optionally, the renewable power plant 100 may, according to some embodiments, also comprise one or more plant extension units 130 that can transform hydrogen produced by the one or more power-to-gas units 120, i.e. produced by the one or more electrolyzers 121, respectively, into other products by consuming electricity. The plant extension units 130 may for example comprise one or more chemical units / plants that utilize hydrogen and possibly other compounds or elements, such as e.g. nitrogen or carbon dioxide, to produce other industrial products, such as e.g. e-fuels. The plant extension units 130 may also comprise e.g. an ammonia production plant and / or a methanol production plant. The produced industrial products, e.g. e-fuels, may be stored locally in a product storage 131 , or may be provided for direct onward transportation.

[0130] One or more interfaces, such as the point of common coupling, 115 to the external electricity grid 116, may provide the possibility to export surplus power produced by the renewable electrical generators 103 of the power plant, which is not used by the one or more power-to-gas units 120, including the electrolyzer 121, and the downstream plant extension units 130, to the electricity grid 116. Corresponding one or more external interfaces 125 may be implemented to export hydrogen produced by the power-to-gas units 120, i.e. by the electrolyzs 121, in the renewable power plant 100 to a hydrogen or natural gas grid 126, i.e. to a gas transmission / distribution network / grid 126. Also, one or more interfaces 135 may be implemented to export industrial products, such as for example e-fuels, produced by the plant extension units 130 to a grid 136 for industrial products such as e.g. e-fuels.

[0131] The power plant 100 may include a control arrangement 150 configured to control the power plant 100. According to some embodiments, the control arrangement 150 maycomprise, or be referred to as, a power plant controller (PPC). As schematically illustrated in figure 1, the control arrangement 150 in form of a power plant controller controls the renewable power generating units 103, the battery system 106, the further assets / units / components 107, the internal grid 110, the one or more power-togas units 120, the plant extension units 130 and / or the product storage 131. The power plant controller 150 may also communicate with the external electric power grid 116, the gas transmission network 126, and / or the grid 136 for industrial products, and / or their respective interfaces 115, 125, 135. Also, measurements, for example of electric power or other system parameters and / or attributes, are provided to the control arrangement 150 from one or more of the renewable power generating units 103, the battery system 106, further assets / units / components 107, the internal grid 110, the one or more power-to-gas units 120, the plant extension units 130, and the product storage 131. Measurements may also be provided by one or more of the external electric power grid 116, the gas transmission network 126, and the grid 136 for industrial products, and / or from their respective interfaces 115, 125, 135.

[0132] The power plant 100, which may be called a power-to-x plant, thus utilizes renewable energy sources, such as wind and sun, for producing electricity by the use of renewable electrical generators 103, such as the wind turbine generators 101 and / or the photovoltaic power generators 102. The produced electricity may be provided to the external electricity grid 116 and / or may be used for producing hydrogen, natural gas, and / or industrial products such as for example e-fuels. The produced electricity, hydrogen, natural gas, and / or industrial products may then be exported to the external electric power grid 116, the external gas transmission network 126, and / or an external industrial product grid 136, respectively.

[0133] In figure 2, an embodiment of the wind turbine generator 101 of the power plant 100 of figure 1 is schematically illustrated. The wind turbine generator 101 may comprise a rotor 161 including one or more blades 162, or rotor blades 162, for example two or more blades 162, such as three blades, or more. The wind turbine generator 101 may comprise a tower 163 and a nacelle 164 mounted to the top of the tower 163. The rotor 161 may be connected, such as rotatably connected or mounted, to the nacelle 164. The wind turbine generator 101 may comprise an electric generator 165to which the rotor 161 is connected. The rotor 161 is configured to drive the electric generator 165. The nacelle 164 may house the electric generator 165.

[0134] The rotor 161 is rotatable by action of the wind. The wind-induced rotational energy of the blades 162 and rotor 161 may be transferred via a coupling 166, for example including one or more shafts, to the electric generator 165. Thus, the wind turbine generator 101 may be described to be configured to convert kinetic energy of the wind to mechanical energy, or rotational energy, by way of the blades 162 and, subsequently, to electric power by way of the electric generator 165.

[0135] The wind turbine generator 101 may comprise at least one power electronics component, commonly denoted as 169 in figure 2, comprising for example one or more power converters 167 connected to the electric generator 165. The wind turbine generator 101 and / or the electric generator 165 may be connected to the electric power grid 116 via the one or more power converters 167. The one or more power converters 167 may comprise a first power converter for converting AC power from the electric generator 165 to DC power. The one or more power converters 167 may comprise a second power converter for converting DC power from the first power converter to AC power to be provided to the electric power grid 116. Thus, the one or more power converters 167 may comprise one or more rectifiers and / or one or more inverters. The nacelle 164 may house the one or more power converters 167, or the one or more power converters 167 may be located elsewhere.

[0136] The wind turbine generator 101 may be controlled by, or may comprise, a control arrangement 168 for controlling the wind turbine generator 101. The control arrangement 168 of the wind turbine generator 101 may comprise a wind turbine generator controller. The control arrangement 168 of the wind turbine generator 101 may be configured to communicate with and / or be connected to, or be part of, the control arrangement 150 of the power plant 100. For some embodiments, the wind turbine generator 101 may be referred to as a variable-speed wind turbine generator. It is to be understood that the wind turbine generator 101 may include further units, components and / or devices, such as for example sensors, required for a wind turbine generator 101.For some embodiments, and as schematically illustrated in figure 2, the power-to-x units 120, comprising the electrolyzers 121, may be comprised in the nacelle 164 and may be connected to the one or more power converters, such that it may draw electric power produced by the wind turbine generator 101 for producing hydrogen. Thus, for some embodiments of the power plant, the wind turbine generators 101 and the one or more power-to-x units 120 may be arranged together as a unit, i.e. the one or more power-to-x units 120 are positioned on a wind turbine generator level. This is also known as a decentralized power supply, where the electrolyzer is intimately integrated with the wind turbine generator through control, operation, and proximity. The power generated by a single wind turbine generator is here utilized directly to supply one or more electrolyzers 121. Thus, for the decentralized power supply solution, the electric power generator, i.e. the wind turbine generator 101, and the consumer of the electric power, i.e. the one or more electrolyzers 121, are closely integrated in terms of operation, controls, and location. The wind turbine generator 101 may still be connected to the grid 116, enabling dual revenue generation, either from selling electric power to the power market or from producing green hydrogen.

[0137] However, for some embodiments of the power plant 100, the power-to-x units 120, and thus the electrolyzers 121 , may be located and / or connected elsewhere in the power plant 100 than where the wind turbine generator is located. Thus, the wind turbine generator and the electrolyzers are not located adjacent to each other. This is also known as the electrolyzers being positioned on a plant level. Thus, a number of wind turbine generators may here be utilized to provide a centralized power supply to a group / set of one or more electrolyzers 121 separately arranged on a plant level position.

[0138] The herein presented solution is applicable both on solutions comprising a centralized power supply to electrolyzers arranged separate from the wind turbine generator, and on solutions comprising a decentralized power supply to electrolyzers arranged integrated with or adjacent to the wind turbine generator.

[0139] Figure 3 schematically discloses an embodiment of a power-to-x (P2X) unit, here being a power-to-gas unit (P2G) 120 of the power plant 100 of figure 1, which isconfigured to convert electric power from the renewable power plant 100 to hydrogen. According to various herein described embodiments, the power-to-gas unit 120 is configured to convert electric power produced by the power plant 100 itself to produce a gas or gas mixture comprising hydrogen and oxygen. The power-to-gas unit 120 may be described to be configured to use electricity to break water into hydrogen and oxygen in a process called electrolysis in an electrolyzer 121. Thus, through the electrolysis, hydrogen is created, which may be used for example as a fuel. The power-to-gas unit 120 may include a container 422 configured to hold or contain water. The power-to-gas unit 120, i.e. the electrolyzer 121, may include one or more anodes 423 and one or more cathodes 424 separated from one another by a membrane 425. The container 422 may include an outlet 426 for hydrogen and an outlet 427 for oxygen.

[0140] With reference to figure 3, for some embodiments, the power-to-gas unit 120 comprises one or more electrolyzers 121 in the of the group of:

[0141] - an alkaline electrolyzer;

[0142] - a proton exchange membrane electrolyzer; and

[0143] - a polymer electrolyte membrane electrolyzer.

[0144] As illustrated in figures 1, 2 and 3, for some embodiments, the power-to-gas unit 120 may be connected, more specifically electrically connected, to a connection point of the wind turbine generator 101. For some embodiments, the power-to-gas unit 120 may be connected, more specifically electrically connected, to a connection point of the power plant 100, and thus to the wind turbine generator 101. For some embodiments, the power-to-gas unit 120 may be connected, more specifically electrically connected, to a connection point / external interface, such as the point of common coupling 115, between the power plant 100 and the electric power network / grid 116, and to a connection point / external interface 125 between the renewable power plant 100 and the gas transmission / distribution network 126.

[0145] It is to be understood that the power-to-gas unit 120 may include further units than the ones herein described, such as e.g. other components and / or devices, for example pumps, vents, storage tanks and / or separators, required for the power-to-gas unit 120 to work efficiently. It is to be understood that other embodiments of the power-to-gas unit 120 than the one disclosed in figure 3 are possible.

[0146] The wind turbine generator 101 of the power plant 100 is configured to provide electric power to one or more electrolyzers 121 of the power plant 100. When generating electric power, the wind turbine generator 101 generates waste heat in one or more of its components. These one or more components may for example comprise at least one power electronics component 169, at least one converter 167, at least one rectifier and / or at least one inverter. This generated waste heat may decrease an efficiency of the wind turbine generator, may cause damages and wear, and / or may cause safety hazards. Therefore, cooling of the wind turbine generator 101, i.e. cooling of the at least one component 169, 167 is needed.

[0147] According to a first aspect of the invention, a method 200 for handling a waste heat generated by at least one component 169, 167 of a wind turbine generator 101 is presented. Figure 4 shows a flow chart diagram for the method 200.

[0148] According to a second aspect of the invention, a system 400 for handling waste heat generated by at least one component 169, 167 of a wind turbine generator 101 is presented. Figure 5 schematically illustrates the system 400.

[0149] The wind turbine generator 101 is configured to provide electric power to one or more electrolyzers 121, 12T. The wind turbine generator 101 further comprises a turbine temperature controlling arrangement 310, schematically illustrated in figure 5.

[0150] The one or more electrolyzers 121 , 12T comprise one or more electrolyzer temperature controlling arrangements 320, 320’, respectively. Thus, each of the one or more electrolyzers 121, 12T comprises an electrolyzer temperature controlling arrangement 320, 320’ to regulate its temperature. Figure 5 schematically illustrates one such electrolyzer 121 and its electrolyzer temperature controlling arrangement 320.According to the herein presented solution, the turbine temperature controlling arrangement 310 and the one or more electrolyzer temperature controlling arrangements 320, 320’ are connected 322, 330, 340, as is described more in detail below, such that thermal energy can be transferred between the turbine temperature controlling arrangement 310 and the one or more electrolyzer temperature controlling arrangements 320, 320’.

[0151] In a first step 210 of the method 200, illustrated by the flow chart diagram of figure 4, it is determined that an inflow of thermal energy to at least one 121 of the one or more electrolyzers 121 , 12T is needed to control the at least one electrolyzer 121 to operate in a specific electrolyzer state.

[0152] In a second step 220, a turbine thermal energy TEturbine associated with at least a part of the waste heat from the wind turbine generator 101 is transferred to the at least one electrolyzer 121. This is achieved by transferring the turbine thermal energy TEturbine from the turbine temperature controlling arrangement 310 to at least one electrolyzer temperature controlling arrangement 320 of the at least one electrolyzer 121 via the connection 322, 330, 340 between the turbine temperature controlling arrangement 310 and the at least one electrolyzer temperature controlling arrangement 320, respectively.

[0153] The system 400 for handling waste heat generated by at least one component 169, 167 of a wind turbine generator 101 is schematically illustrated in figure 5.

[0154] The system 400 comprises a turbine temperature controlling arrangement 310 configured to control a temperature of the wind turbine generator 101. The turbine temperature controlling arrangement 310 may, according to various embodiments, comprise a coolant loop 311 , 312, 316, in which a coolant medium, for example glycol, is circulated. The coolant loop may comprise a conduit 311 between the wind turbine generator 101 and a heat exchanger 312, the heat exchanger 312, and a conduit 316 from the heat exchanger 312 back to the wind turbine generator 101 again. A cooling device 314 is thermally connected to the heat exchanger 312 by thermal connections 313, 315, such that heat being provided to the heat exchanger312 from the wind turbine generator 101 is transferred to the cooling device 314, and is circulated back to the heat exchanger 312 at a lower temperature. Hereby, the wind turbine generator 101 is cooled down by the turbine temperature controlling arrangement 310.

[0155] The system 400 further comprises one or more electrolyzer temperature controlling arrangements 320, 320’ configured to control the temperature of the one or more electrolyzers 121, 12T, respectively. One such electrolyzer temperature controlling arrangements 320 is shown in figure 5.

[0156] According to various embodiments, the electrolyzer temperature controlling arrangement 320 of an electrolyzer 121 comprises a lye loop 321, 323, as illustrated in figure 5. The lye loop may comprise a conduit 321 from the electrolyzer 121 to a heat exchanger 322, and a conduit 323 from the heat exchanger 322 back to the electrolyzer 121. Lye is, by the circulation of the lye in the lye loop 321 , 323, provided as a medium to the electrolyzer. Hereby, the lye being circulated in the lye loop 321, 323 may be utilized for controlling a temperature of the electrolyzer 121.

[0157] The system 400 further comprises a connection 322, 330, 340 arranged between the turbine temperature controlling arrangement 310 and at least one 320 of the one or more electrolyzer temperature controlling arrangements 320, 320’. The connection 322, 330, 340 may, according to some embodiments, comprise a heat exchanger 322. As schematically illustrated in figure 5, the connection 322, 330, 340 may, according to various embodiments, also comprise a first connection conduit 330 connected from the coolant conduit 311 of the coolant loop 311 , 312, 316 of the turbine temperature controlling arrangement 310 to the heat exchanger 322 of the electrolyzer temperature controlling arrangement 320. The connection 322, 330, 340 may further comprise a second connection conduit 340 from the heat exchanger 322 of the electrolyzer temperature controlling arrangement 320 to the coolant conduit 311 of the coolant loop 311, 312, 316 of the turbine temperature controlling arrangement 310. A flow of coolant through the first connection conduit 330 may be controlled by a controllable first valve 331 , and flow of coolant through the second connection conduit 340 may be controlled by a controllable second valve 341.The system 400 comprises a control unit 150 (disclosed above and below), which is configured to transfer 220 a turbine thermal energy TEturbine associated with at least a part of the waste heat from the wind turbine generator 101 to at least one electrolyzer 121 when an inflow of thermal energy to the at least one electrolyzer 121 is needed to control the at least one electrolyzer 121 to operate in a specific electrolyzer state. The turbine thermal energy TEturbine is then transferred from the turbine temperature controlling arrangement 310 to the at least one electrolyzer temperature controlling arrangement 320 of the at least one electrolyzer 121 via the connection 322, 330, 340 between the turbine temperature controlling arrangement 310 and the at least one electrolyzer temperature controlling arrangement 320, respectively.

[0158] Thus, the control unit 150 is configured to open the first valve 331 of the first connection conduit 330 and to open the second valve 341 of the second connection conduit 340, such that the warm coolant is circulated through the connection 322, 330, 340, and thereby is circulated through the heat exchanger 322 of the electrolyzer temperature controlling arrangement 320. Hereby, a temperature of the lye being circulated in the lye loop 321 , 323 of the electrolyzer temperature controlling arrangement 320, and thus also being circulated through the heat exchanger 322 is increased, which increases the temperature of the electrolyzer 121.

[0159] As mentioned above, water electrolysis is a process that uses electricity to split water into hydrogen and oxygen. Conventionally, the electrolyzers have been operated at steady state, above the thermoneutral voltage, where the electrolyzer reaction is exothermic, which means that it releases heat. In this case, the electrical energy provided to the electrolyzer is more than what is needed to break the bonds in the water molecules, and the excess energy is released as heat into its surroundings.

[0160] However, a water electrolyzer 121 operates based on a state-machine description throughout its lifecycle, where the electrolyzer may transition into various states such as ‘ON’ (in operation), ‘Standby’ (hot and warm), or ‘OFF’ (shut-down / start-up). The balance of heat inflow and outflow is a critical aspect of the electrolyzer during a typical lifecycle. During operation (‘ON’), water is electrochemically converted intohydrogen and oxygen when powered by an electrical source. The chemical reaction is more favourable at higher temperatures, but heat-sensitive components of the electrolyzer prevent alkaline and proton exchange membranes from operating above 100 degrees Celsius. Consequently, the operating temperature ranges between 70-90 degrees, depending on the supplier.

[0161] Operation of the electrolyzer at nameplate capacity generates excessive heat due to inefficiencies, necessitating cooling equipment to prevent overheating and system failure. During for example hot standby, however the electrolyzer is kept warm through an external heat source. Further, turning the electrolyzer ON requires an external heat source to reach a suitable operating temperature. As explained for the herein presented embodiments, heating of the electrolyzer may be performed by warming up the lye supply to the electrolyzer.

[0162] A known characteristic of renewable energy sources is their intermittency. Upon integrating and powering the electrolyzer with renewable energy, the hydrogen generator may enter the various distinct states during operation. Hence, there is a need for providing heat to the electrolyzer during specific scenarios and for specific operating states. The herein presented solution manages to integrate and utilize the waste heat from the at least one components of the wind turbine generator as a heat supply for the water electrolyzers 121.

[0163] Thus, an electrolyzer 121 of today may ramp up and down its operation to follow the fluctuations of the wind turbine generator 101. When the wind speed is high and a lot of electricity is being produced, the electrolyzer 121 may ramp up its operation to consume this excess electricity, thus producing a higher hydrogen flow.

[0164] Conversely, when the wind speed is low and less electricity is being produced, the electrolyzer 121 may ramp down its operation, thus producing a lower hydrogen flow. Below the thermoneutral voltage, the reaction in the electrolyzer 121 is endothermic, which means that it absorbs heat from its surroundings. This is because the electrical energy provided to the electrolyzer is not sufficient to break the bonds in the water molecules, and additional energy is required in the form of heat. The ramping principle can thus allow for both endothermic and exothermic operation of theelectrolyzer 121. The endothermic nature of the reaction below the thermoneutral voltage means that the electrolyzer 121 needs to be heated to achieve efficient operation. When operating in the endothermic regime, the electrolyzer 121 thus draws energy from the surroundings. This is by the presented solution utilized as a cooling element for the wind turbine generator 101.

[0165] According to an embodiment, the determination 210 that the at least one electrolyzer 121 needs an inflow of thermal energy to operate in a specific electrolyzer state comprises determining 211 that the inflow of thermal energy is needed to maintain an operational temperature Teof the at least one electrolyzer 121 when the at least one wind turbine generator 101 is controlled to operate in a power overdrive state. Thus, the waste heat generated when operating the wind turbine generator 101 in a power overdrive state is here utilized for maintain an operational temperature Teof the at least one electrolyzer 121.

[0166] According to an embodiment, the determination 210 that the at least one electrolyzer 121 needs an inflow of thermal energy to operate in a specific electrolyzer state comprises determining 212 that the inflow of thermal energy is needed to maintain an operational temperature Teof the at least one electrolyzer 121 when the at least one electrolyzer 121 is controlled to operate in an endothermic state. Here, the additive thermal energy is needed for keeping the endothermic reactions in the electrolyzer going by maintaining operational temperature Te.

[0167] According to an embodiment, the determination 210 that the at least one electrolyzer 121 needs an inflow of thermal energy to operate in a specific electrolyzer state comprises determining 213 that the inflow of thermal energy is needed to maintain an operational temperature Teof the at least one electrolyzer 121 when the at least one electrolyzer 121 is controlled to be in a hot standby state. In the hot standby state, the additive thermal energy is needed due to thermal losses to the surroundings of the electrolyzer 121.

[0168] According to an embodiment, the determination 210 that the at least one electrolyzer 121 needs an inflow of thermal energy to operate in a specific electrolyzer statecomprises determining 214 that the inflow of thermal energy is needed to increase an operational temperature Teof the at least one electrolyzer 121 when the at least one electrolyzer 121 is in a start-up state. In the start-up state, the additive thermal energy is needed due to thermal losses to the surroundings of the electrolyzer 121, and the electrolyzer 121 needs a temperature increase in order to reach a suitable operation temperature.

[0169] According to an embodiment, the wind turbine generator 101 may be controlled to run in an overdrive mode when the turbine thermal energy TEturbine is transferred 220 from the wind turbine generator 101 to the at least one electrolyzer 121, 12T. Thus, since the waste heat being generated by the overdrive mode is efficiently taken care of, the wind turbine generator may be driven / utilized harder, and may thereby produce more electric power.

[0170] According to an embodiment, the determination 210 that the at least one electrolyzer 121 needs an inflow of thermal energy is based on operation information provided by a control system 150 configured to control the at least one electrolyzer 121 , the operational temperature Teof the at least one electrolyzer 121 , an electric power consumption of the at least one electrolyzer 121 , and / or a production of hydrogen of the at least one electrolyzer 121. Hereby, the thermal needs of the at least one electrolyzer 121 is reliably and accurately determined.

[0171] According to an embodiment, the transfer 220 of the turbine thermal energy TEturbine comprises a transfer 221 of the turbine thermal energy TEturbine from the coolant loop 311, 312, 316 of the turbine temperature controlling arrangement 310 to the connection 322, 330, 340 between the turbine temperature controlling arrangement 310 and the at least one electrolyzer temperature controlling arrangement 320, where the connection 322, 330, 340 may e.g. comprise the first 330 and second 340 connection conduits and the heat exchanger 322 of the electrolyzer temperature controlling arrangement 320.

[0172] According to an embodiment, the transfer 220 of the turbine thermal energy TEturbine further comprises a transfer 222 of the turbine thermal energy TEturbine from theconnection 322, 330, 340 between the turbine temperature controlling arrangement 310 and the at least one electrolyzer temperature controlling arrangement 320 to the lye loop 321 , 323 of the at least one electrolyzer temperature controlling arrangement 320.

[0173] Thus, the turbine thermal energy TEturbine is transferred from the coolant loop 311 , 312, 316 of the turbine temperature controlling arrangement 310 to the lye loop 321, 323 of the electrolyzer temperature controlling arrangement 320. The transferred turbine thermal energy TEturbine may then be utilized for maintaining 223 an operational temperature Teof the at least one electrolyzer 121 , for example when the at least one electrolyzer is in an endothermic state or in a hot standby state, or may be utilized for increasing 224 an operational temperature Teof the at least one electrolyzer 121 , for example when the electrolyzer 121 is in a start-up state.

[0174] The transfer of the turbine thermal energy TEturbine from the coolant loop 311 , 312, 316 of the turbine temperature controlling arrangement 310 to the lye loop 321, 323 of the electrolyzer temperature controlling arrangement 320 may also be utilized for decreasing 225 a temperature Tt of the at least one component 167, 169 of the wind turbine generator 101 generating the waste heat.

[0175] According to some embodiments, the system 400 comprises two or more electrolyzers, schematically illustrated in figure 6 as a first electrolyzer 121a and a second electrolyzer 121b.

[0176] An electrical front-end of each of the first 121 a and second 121b electrolyzer transforms and rectifies the alternating current supplied to each electrolyzer into a direct current being suitable for the electrolyzer, which is critical for the operation of the hydrogen generator. During the transformation and rectification, the power electronic components performing the transformation and rectification generate heat due to their inefficiencies during operation. To prevent critical damage, a cooling system is needed, which may comprise for example by liquid-to-liquid or liquid-to-air cooling units.According to the embodiment, the first electrolyzer 121a thus comprises a first electrolyzer temperature controlling arrangement 320a, and the second electrolyzer 121b comprises a second electrolyzer temperature controlling arrangement 320b. The system 400 further comprises a connection 322b arranged between the first electrolyzer temperature controlling arrangement 320a and the second electrolyzer temperature controlling arrangement 320b. The connection 322b is then configured to transfer 250 a first thermal energy TEist from the first electrolyzer temperature controlling arrangement 320a to the second electrolyzer temperature controlling arrangement 320b when needed.

[0177] According to an embodiment, the connection 322b arranged between the first electrolyzer temperature controlling arrangement 320a and the second electrolyzer temperature controlling arrangement 320b comprises a heat exchanger 322b. The heat exchanger is configured to interconnect a first lye loop 321a, 323a of the first electrolyzer 121a with a second lye loop 321b, 323b of the second electrolyzer 121b.

[0178] For such an embodiment, as illustrated in in figure 4, the method may further comprise the further step of determining 230 that an inflow of thermal energy to the second electrolyzer 121b is needed to control the second electrolyzer 121b to operate in a specific electrolyzer state.

[0179] The method may then comprise the step of transferring 250 a first thermal energy TEist from the first electrolyzer temperature controlling arrangement 320a to the second electrolyzer temperature controlling arrangement 320b via the connection 322b between the first electrolyzer temperature controlling arrangement 320a and the second electrolyzer temperature controlling arrangement 320b, i.e. via the heat exchanger 322b.

[0180] According to an embodiment, the method 200 may comprise the further step of determining 240 that the first electrolyzer 121a is in an exothermic state. The method 200 then also comprises the step of transferring 250 the first thermal energy TEist created in the exothermic state of the first electrolyzer 121a from the first electrolyzertemperature controlling arrangement 320a to the second electrolyzer temperature controlling arrangement 320b, via the connection 322b.

[0181] Thus, the first thermal energy TEist being transferred 250 to the second electrolyzer may be created in an exothermic state of the first electrolyzer 121a and / or may be generated by power electronic components of the first electrolyzer during transformation and rectification of the electric power.

[0182] According to an embodiment, the determination 230 that the second electrolyzer 121 b needs an inflow of thermal energy to operate in a specific electrolyzer state comprises determining 231 that the inflow of thermal energy is needed to maintain an operational temperature Te2 of the second electrolyzer 121 b when the wind turbine generator 101 is controlled to operate in a power overdrive state.

[0183] According to an embodiment, the determination 230 that the second electrolyzer 121 b needs an inflow of thermal energy to operate in a specific electrolyzer state comprises determining 232 that the inflow of thermal energy is needed to maintain an operational temperature Te2 of the second electrolyzer 121b when the second electrolyzer 121b is controlled to operate in an endothermic state or when the second electrolyzer 121b is controlled to be in a hot standby state.

[0184] According to an embodiment, the determination 230 that the second electrolyzer 121 b needs an inflow of thermal energy to operate in a specific electrolyzer state comprises determining 234 that the inflow of thermal energy is needed to increase an operational temperature Te2 of the second electrolyzer 121b when the second electrolyzer 121b is in a start-up state.

[0185] According to an embodiment, the transfer 250 of the first thermal energy TEist from the first electrolyzer temperature controlling arrangement 320a to the second electrolyzer temperature controlling arrangement 320b comprises the step of transferring 251 the first thermal energy TEist from a first lye loop 321a, 323a of the first electrolyzer temperature controlling arrangement 320a to the connection 322b between the first electrolyzer temperature controlling arrangement 320a and thesecond electrolyzer temperature controlling arrangement 320b, i.e. to the heat exchanger 322b.

[0186] According to an embodiment, the transfer 250 of the first thermal energy TEist from the first electrolyzer temperature controlling arrangement 320a to the second electrolyzer temperature controlling arrangement 320b comprises the step of transferring 252 the first thermal energy TEist from the connection 322b between the first electrolyzer temperature controlling arrangement 320a and the second electrolyzer temperature controlling arrangement 320b, i.e. from the heat exchanger 322b, to a second lye loop 321b, 323b of the second electrolyzer temperature controlling arrangement 320b.

[0187] In the second electrolyzer temperature controlling arrangement 320b, the first thermal energy TEist may be utilized for maintaining 253 an operational temperature Te2 of the second electrolyzer 121b and / or for increasing 254 an operational temperature Te2 of the second electrolyzer 121b.

[0188] According to an embodiment, the turbine thermal energy TEturbine from the wind turbine generator 101 is received by the first electrolyzer temperature controlling arrangement 320a of the first electrolyzer 121a. At least a portion of this received turbine thermal energy TEturbine is then transferred as the first thermal energy TEist from the first electrolyzer temperature controlling arrangement 320a to the second electrolyzer temperature controlling arrangement 320b. Thus, the first thermal energy TEist being transferred from the first electrolyzer temperature controlling arrangement 320a to the second electrolyzer temperature controlling arrangement 320b is then originating from the waste energy generated by the wind turbine generator 101.

[0189] To give an illustration of advantages of the herein presented solution, the following simple thermodynamic example calculations are presented.

[0190] A wind turbine generator with a power rating of 4.5 MW may produce roughly 200 kW of waste heat, which needs to be removed. An implementation of the presented solution may theoretically remove approximately 10 percent of the excessive heat.An electrolyzer can operate in an endothermic state, in which heat is extracted from its surroundings while producing hydrogen. If standard conditions of ambient pressure and temperature are assumed, then the amount of heat adsorbed (q) can be calculated theoretical by:

[0191] q = H° — G. (eq. 1) Here, H0is the change in enthalpy at standard conditions, roughly 285.5 kJ / mol and AG is the change of Gibs free energy. The change of the Gibs free energy can be related to the operating cell voltage (Vcen) by:

[0192] AG = zFVceu. (eq. 2)

[0193] Here, z is the number of electrons transferred for the electrolyzer reactions and F is Faraday’s constant.

[0194] As a non-limiting numeric example, a high efficiency electrolyzer stack may operate at a cell voltage of Vcen = 1.45 V while producing a current of 0.1 A / cm2It should be noted that the current density is directly proportional to the flow. Utilizing the dimensions of a conventional alkaline electrolyzer with a power capacity of roughly 4-5 MW will lead roughly to a hydrogen production of 2-3 g / s. It should be further noted that this will depend on the efficiency of the system and the system dimensions. The heat of adsorption becomes q « 5.6 kJ / mol, while the theoretical power by which the electrolyzer stack can cool the wind turbine generator with may be as high as 16 kW. This represents a substantial fraction of the generated turbine waste heat. Thus, the electrolyzer can be actively utilized for cooling the wind turbine generator, and therefore also for removing one or more expensive parts of the conventional cooling equipment.

[0195] According to a third aspect and with reference to figure 1, a power plant 100 is presented. The power plant 100 comprises at least one wind turbine generator 101 , one or more electrolyzers 121, 12T, and a herein described system 400. The power plant 100 may further comprise any herein disclosed components. The power plant 100 may further comprise a control arrangement 150 as herein described. The control arrangement 150 is configured for controlling the power plant 100 accordingto any one of the aspects and / or embodiments disclosed herein. The control arrangement 150 may comprise, or be referred to as, a power plant controller (PPC). The control arrangement 150 may also comprise, or be comprised in, one or more control arrangements of the one or more electrolyzers. Thus, the herein disclosed method 200 and its embodiments, may at least partly be controlled by a centralized control arrangement 150, such as a power plant controller, and / or may at least partly be controlled by one or more distributed control arrangements 150, possibly each being configured for controlling one or more electrolyzers.

[0196] The control arrangement 150 may further be configured to, e.g. it comprises units / means / devices 610, 611, 612, 613, 614, 620, 621, 622, 623, 624, 625, 630, 631, 632, 633, 634, 640, 650, 651, 652, 653, 654 to, execute / provide / implement the further herein mentioned method steps 210, 211, 212, 213, 214, 220, 221, 222, 223, 224, 225, 230, 231 , 232, 233, 234, 240, 250, 251 , 252, 253, 254 according to various above-described embodiments.

[0197] The person skilled in the art will appreciate that the herein described method aspects and embodiments of the control arrangement controlling a power plant 100 may also be implemented in a computer program, which, when it is executed in a computer, instructs the computer to execute the method. The computer program is usually constituted by a computer program product 503 (shown in figure 7) stored on a non-transitory / non-volatile digital storage medium, in which the computer program is incorporated in the computer-readable medium of the computer program product. The computer-readable medium comprises a suitable memory, such as, for example: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit, etc.

[0198] Figure 7 shows in schematic representation an embodiment of the control arrangement 150 according to an aspect of the invention, which may include a control unit 500, which may be arranged / configured for perform ing / executing one or more of the above-mentioned method steps 210, 211 , 212, 213, 214, 220, 221 , 222, 223, 224, 225, 230, 231 , 232, 233, 234, 240, 250, 251 , 252, 253, 254. The controlunit 500 may comprise a computing unit 501, which can be constituted by essentially any suitable type of processor or microcomputer, for example a circuit for digital signal processing (Digital Signal Processor, DSP), or a circuit having a predetermined specific function (Application Specific Integrated Circuit, ASIC). The computing unit 501 is connected to a memory unit 502 arranged in the control unit 500. The memory unit 502 provides the computing unit 501 with, for example, the stored program code and / or the stored data which the computing unit 501 requires to be able to perform computations. The computing unit 501 is also arranged to store partial or final results of computations in the memory unit 502.

[0199] In addition, the control unit 500 may be provided with devices 511, 512, 513, 514 for receiving and transmitting input and output signals. These input and output signals may comprise waveforms, impulses, or other attributes which, by means of the devices 511 , 513 for the reception of input signals, can be detected as information and can be converted into signals which can be processed by the computing unit 501. These signals are then made available to the computing unit 501. The devices 512, 514 for the transmission of output signals are arranged to convert signals received from the computing unit 501 in order to create output signals by, for example, modulating the signals, which, for example, can be transmitted to other parts and / or systems of, or associated with, the electric power grid 116, the gas transmission network 126, the grid 136 for industrial products and / or the renewable power plant 100 (see figure 1 ). Each of the connections to the devices for receiving and transmitting input and output signals can be constituted by one or more of a cable, a data bus, and a wireless connection.

[0200] Here and in this document, control units are often described as being provided for performing steps of the method according to herein described aspects and embodiments of the invention. This also includes that the units are designed to and / or configured to perform these method steps. For example, the control units may comprise one or more control entities arranged for performing one or more of the herein described method steps 210, 211, 212, 213, 214, 220, 221, 222, 223, 224, 225, 230, 231 , 232, 233, 234, 240, 250, 251 , 252, 253, 254, respectively. These control entities may for example correspond to groups of instructions, which may bein the form of programming code, that are input into, and are utilized / executed by the processor / computing unit 501 of the control unit 500 when the entities are active and / or are utilized for performing their method steps, respectively. Such control entities may be implemented as separate entities in multiple control units, or may be logically separated but physically implemented in the same control unit, or may be both logically and physically arranged together.

[0201] With reference to figure 1, the control arrangement 150, which may include one or more control units or control entities 610, 611 , 612, 613, 614, 620, 621 , 622, 623, 624, 625, 630, 631 , 632, 633, 634, 640, 650, 651 , 652, 653, 654, such as for example one or more devices, controllers or control devices, may be arranged to perform all of the method steps mentioned above, in the claims, and in connection with the herein described aspects and embodiments. The control arrangement 150 is associated with the above-described advantages for each respective embodiment of the method.

[0202] The herein described aspects and embodiments may be applied also in other power plant domains than the renewable / power-to-x plant domains mentioned herein. For example, the one or more electolyzers 120, 120’ may be provided with electric power from one or more renewable electric power generating units 103 other than a wind turbine generator. Thus, the power plant 100 may not have to comprise a wind turbine generator at all. In this case, the waste heat utilized for heating the electrolyzer may be generated in one or more components of the one or more other renewable electric power generating units 103.

[0203] The present invention is not limited to the above-described embodiments. Instead, the present invention relates to, and encompasses all different embodiments being included within the scope of the independent claims.

Claims

Claims1. A method (200) for handling a waste heat generated by at least one component (169, 167) of a wind turbine generator (101); wherein- the wind turbine generator (101) is configured to provide electric power to one or more electrolyzers (121, 121’);- the wind turbine generator (101) comprises a turbine temperature controlling arrangement (310);- the one or more electrolyzers (121, 12T) comprise one or more electrolyzer temperature controlling arrangements (320, 320’), respectively; and- the turbine temperature controlling arrangement (310) and the one or more electrolyzer temperature controlling arrangements (320, 320’) are connected (322, 330, 340) such that thermal energy can be transferred between the turbine temperature controlling arrangement (310) and the one or more electrolyzer temperature controlling arrangements (320, 320’);the method (200) comprising:- determining (210) that an inflow of thermal energy to at least one (121) of the one or more electrolyzers (121, 12T) is needed to control the at least one electrolyzer (121) to operate in a specific electrolyzer state; and- transferring (220) a turbine thermal energy TEturbine associated with at least a part of the waste heat from the wind turbine generator (101 ) to the at least one electrolyzer (121), by transferring the turbine thermal energy TEturbine from the turbine temperature controlling arrangement (310) to at least one electrolyzer temperature controlling arrangement (320) of the at least one electrolyzer (121) via the connection (322, 330, 340) between the turbine temperature controlling arrangement (310) and the at least one electrolyzer temperature controlling arrangement (320), respectively.

2. The method (200) according to claim 1 , wherein the determination (210) comprises one in the group of:- determining (211 ) that the inflow of thermal energy is needed to maintain an operational temperature Teof the at least one electrolyzer (121 ) when the at least one wind turbine generator (101) is controlled to operate in a power overdrive state; - determining (212) that the inflow of thermal energy is needed to maintain anoperational temperature Teof the at least one electrolyzer (121 ) when the at least one electrolyzer (121) is controlled to operate in an endothermic state;- determining (213) that the inflow of thermal energy is needed to maintain an operational temperature Teof the at least one electrolyzer (121 ) when the at least one electrolyzer (121) is controlled to be in a hot standby state; and- determining (214) that the inflow of thermal energy is needed to increase an operational temperature Teof the at least one electrolyzer (121 ) when the at least one electrolyzer (121) is in a start-up state.

3. The method (200) according to any one of claims 1-2, wherein the determination (210) that the at least one electrolyzer (121) needs an inflow of thermal energy is based on one or more in the group of:- operation information provided by a control system (150) configured to control the at least one electrolyzer (121);- an operational temperature Teof the at least one electrolyzer (121);- an electric power consumption of the at least one electrolyzer (121 ); and- a production of hydrogen of the at least one electrolyzer (121 ).

4. The method (200) according to any one of claims 1-3, wherein the transfer (220) of the turbine thermal energy TEturbine comprises:- transferring (221 ) the turbine thermal energy TEturbine from a coolant loop (311 , 312, 316) of the turbine temperature controlling arrangement (310) to the connection (322, 330, 340) between the turbine temperature controlling arrangement (310) and the at least one electrolyzer temperature controlling arrangement (320).

5. The method (200) according to any one of claims 1-4, wherein the transfer (220) of the turbine thermal energy TEturbine comprises:- transferring (222) the turbine thermal energy TEturbine from the connection (322, 330, 340) between the turbine temperature controlling arrangement (310) and the at least one electrolyzer temperature controlling arrangement (320) to a lye loop (321 , 323) of the at least one electrolyzer temperature controlling arrangement (320).

6. The method (200) according to any one of claims 1-5, wherein the transfer (220) of the turbine thermal energy TEturbine is utilized for at least one in the group of: - maintaining (223) an operational temperature Teof the at least one electrolyzer (121); and- increasing (224) an operational temperature Teof the at least one electrolyzer (121).

7. The method (200) according to any one of claims 1-5, wherein the transfer (220) of the turbine thermal energy TEturbine is utilized for:- decreasing (225) a temperature Tt of the at least one component (169, 167) of the wind turbine generator (101).

8. The method (200) according to any one of claims 1-6, wherein the one or more electrolyzers comprise:- a first electrolyzer (121a) comprising a first electrolyzer temperature controlling arrangement (320a); and- a second electrolyzer (121b) comprising a second electrolyzer temperature controlling arrangement (320b); wherein- the first electrolyzer temperature controlling arrangement (320a) and the second electrolyzer temperature controlling arrangement (320b) are connected such that thermal energy can be transferred between the first electrolyzer temperature controlling arrangement (320a) and the second electrolyzer temperature controlling arrangement (320b);the method further comprising:- determining (230) that an inflow of thermal energy to the second electrolyzer (121b) is needed to control the second electrolyzer (121b) to operate in a specific electrolyzer state; and- transferring (250) a first thermal energy TEist from the first electrolyzer temperature controlling arrangement (320a) to the second electrolyzer temperature controlling arrangement (320b) via the connection (322b) between the first electrolyzer temperature controlling arrangement (320a) and the second electrolyzer temperature controlling arrangement (320b).

9. The method (200) according to claim 8, wherein the determination (230) comprises one in the group of:- determining (231 ) that the inflow of thermal energy is needed to maintain an operational temperature Te2 of the second electrolyzer (121b) when the wind turbine generator (101) is controlled to operate in a power overdrive state;- determining (232) that the inflow of thermal energy is needed to maintain an operational temperature Te2 of the second electrolyzer (121b) when the second electrolyzer (121b) is controlled to operate in an endothermic state;- determining (233) that the inflow of thermal energy is needed to maintain an operational temperature Te2 of the second electrolyzer (121b) when the second electrolyzer (121b) is controlled to be in a hot standby state; and- determining (234) that the inflow of thermal energy is needed to increase an operational temperature Te2 of the second electrolyzer (121b) when the second electrolyzer (121b) is in a start-up state.

10. The method (200) according to any one of claims 8-9, further comprising: - determining (240) that the first electrolyzer (121a) is in an exothermic state; and - transferring (250) the first thermal energy TEist created in the exothermic state of the first electrolyzer (121a) from the first electrolyzer temperature controlling arrangement (320a) to the second electrolyzer temperature controlling arrangement (320b).

11. The method (200) according to any one of claims 8-10, wherein the transfer (250) of the first thermal energy TEist from the first electrolyzer temperature controlling arrangement (320a) to the second electrolyzer temperature controlling arrangement (320b) comprises:- transferring (252) the first thermal energy TEist from the connection (322b) between the first electrolyzer temperature controlling arrangement (320a) and the second electrolyzer temperature controlling arrangement (320b) to a second lye loop (321b, 323b) of the second electrolyzer temperature controlling arrangement (320b).

12. The method (200) according to any one of claims 8-11 , wherein the transfer (250) of the first thermal energy TEist is utilized for at least one in the group of:- maintaining (253) an operational temperature Te2 of the second electrolyzer (121b); and- increasing (254) an operational temperature Te2 of the second electrolyzer (121b).

13. A computer program (703) or a computer-readable medium comprising instructions which, when the program or the instructions is / are executed by a computer, cause the computer to carry out the method according to any one of the claims 1 to 12.

14. A system (400) for handling waste heat generated by at least one component (169, 167) of a wind turbine generator (101 ) configured to provide electric power to one or more electrolyzers (121, 121’);the system (400) comprising:- a turbine temperature controlling arrangement (310) configured to control a temperature of the wind turbine generator (101);- one or more electrolyzer temperature controlling arrangements (320, 320’) configured to control the temperature of the one or more electrolyzers (121, 121’), respectively;- a connection (322, 330, 340) arranged between the turbine temperature controlling arrangement (310) and at least one (320) of the one or more electrolyzer temperature controlling arrangements (320, 320’); and- a control unit (150) configured to transfer (220) a turbine thermal energy TEturbine associated with at least a part of the waste heat from the wind turbine generator (101 ) to at least one electrolyzer (121) when an inflow of thermal energy to the at least one electrolyzer (121) is needed to control the at least one electrolyzer (121) to operate in a specific electrolyzer state, the turbine thermal energy TEturbine being transferred from the turbine temperature controlling arrangement (310) to the at least one electrolyzer temperature controlling arrangement (320) of the at least one electrolyzer (121) via the connection (322, 330, 340) between the turbine temperature controlling arrangement (310) and the at least one electrolyzer temperature controlling arrangement (320), respectively.

15. A power plant (100) comprising:- at least one wind turbine generator (101); - one or more electrolyzers (121, 121’); and - a system (400) according to claim 14.

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