Abstract:
A system and method for supplying an energy grid with energy from an intermittent renewable energy source having a production unit for producing Hydrogen, Nitrogen, and Oxygen. The production unit is operated by using energy provided by the renewable energy source. An Oxygen storage receives and stores Oxygen produced by the production unit, a mixing unit receives and mixes the Hydrogen and the Nitrogen produced by the production unit to form a Hydrogen-Nitrogen-mixture, an Ammonia source receives and processes the Hydrogen-Nitrogen-mixture for generating a gas mixture containing Ammonia, an Ammonia power generator generates energy for the energy grid. The Ammonia power generator is fluidly connected to the Ammonia storage vessel, is configured to combust the received Ammonia in a combustion chamber to generate the energy, and is fluidly connected to the Oxygen storage to introduce Oxygen into the combustion chamber for combustion of Ammonia.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the US National Stage of International Application No. PCT/EP2014/062581 filed Jun. 16, 2014, and claims the benefit thereof, and is incorporated by reference herein in its entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    The invention relates to a system and method for supplying an energy grid with energy from an intermittent renewable energy source. 
       BACKGROUND OF INVENTION 
       [0003]    The uptake of renewable natural resources (renewables) for energy generation in the last years has been impressive, but there is still the unsolved problem of dealing with the transient nature of the renewables. Both solar and wind power are intermittent by their nature and, therefore, it is not possible to provide a dependable baseload to the energy networks. Since the demand of energy consumers can be irregular, a power supply based on renewables does not match the demand of the consumers. Also, the excess energy, i.e. the amount of energy which would be momentarily available from renewables but which is not demanded by the consumers at that time, strains the energy networks and would get lost in case it is not consumed. 
         [0004]    Thus, conditions exist in which the energy momentarily provided by renewables is not sufficient to cover the demand. However, there would also be conditions in which the energy momentarily provided by renewables is exceeding the current demand. As the proportion of energy from renewable sources increases, the situation will become unsustainable. 
         [0005]    A promising approach for solving these drawbacks would be the use of long term energy buffers or storages which are suitable to store the energy. Such a solution would allow to handle situations in which the demand exceeds the available energy as well as situations in which excess energy is available. 
         [0006]    A variety of buffering solutions for storing electrical energy are known, e.g. Lithium batteries and Vanadium based Redox batteries, but these solutions cannot provide the necessary scale of energy storage. Hydrogen offers another carbon free route for storing energy, but it is difficult and risky to utilize. In gaseous form it has to be compressed to 500 bars in order to achieve a suitable energy density. Liquid Hydrogen requires cryogenic temperatures and the associated complicated infrastructure. Moreover, the use of Hydrogen in either form requires safeguards due to the risk of explosion. For these reasons, Hydrogen is not considered to be a qualified candidate for energy storage. 
         [0007]    Thus, there are currently no reliable and appropriate means for decoupling energy supply and demands for renewable energies on a local or national scale. 
       SUMMARY OF INVENTION 
       [0008]    It is an object of the invention to provide a solution for supplying an energy grid with energy from an intermittent renewable energy source. 
         [0009]    The object is solved by a system and a method according to the independent claims. 
         [0010]    The invention is based on the approach of storing at least parts of the energy generated using renewable. This is achieved by using that energy to produce Hydrogen and Nitrogen. Hydrogen and Nitrogen are subsequently converted into Ammonia (NH3) which is a carbon-free fuel and which can be stored at ambient temperatures. Also, NH3 can be transported effectively and safely using pipelines, railroads, shipping and trucks. Moreover, NH3 offers the advantages that it can be synthesized in a carbon free process and it can be burned without generating green house gases. 
         [0011]    The invention achieves a decoupling of the supply and demand of electricity from fluctuating renewable energy sources by using the renewable energy for the generation of Ammonia which can be stored subsequently. The stored Ammonia can then be used in a NH3 power generator to generate electricity which is fed into the electricity grid. This integrated solution proposed by the invention allows to translate intermittent electricity into a baseload provided by the renewable energy source to the local or national energy grid. 
         [0012]    Moreover, the present invention also makes use of the Oxygen which is generated as a byproduct during the production of Hydrogen and/or Nitrogen. The Oxygen generated therein is directed to an Oxygen storage. The Oxygen storage is fluidly connected to the NH3 power generator such that Oxygen can be provided to the NH3 power generator to achieve an optimized performance of the NH3 power generator. For example, an increased Oxygen concentration during combustion will increase the efficiency and cleanliness of the NH3 burning. 
         [0013]    The flow of Oxygen from the Oxygen storage to the NH3 power generator will be managed by a corresponding Oxygen control system. The Oxygen control system receives as an input the amount of NH3 reaching the NH3 power generator, i.e. the NH3 flow rate to the NH3 power generator, as well as combustion parameters which give information about the combustion status. For example, this might be the temperature in the combustion chamber and the chemical composition of the gas in the combustion chamber. Out of these data, the Oxygen control system determines the optimum flow rate of Oxygen to be provided from the Oxygen storage to the NH3 power generator. 
         [0014]    Thus, the presence of the NH3 storage vessel as a buffer allows a better flexibility of providing energy to the energy grid and, therefore, an improved load balancing. Moreover, the efficiency of the system and method is improved by the usage of Oxygen produced in the system. 
         [0015]    The invention can be applied for operating the energy network based on renewable energies as well as in the local energy supply for heavy industry and rural areas, grid stabilization. 
         [0016]    In more detail, the system for providing energy for an energy grid and for load balancing of an energy input for the energy grid based on intermittent renewable energy provided by a renewable energy source, comprises—an H2-N2-O2-production unit for producing Hydrogen H2, Nitrogen N2 and Oxygen O2, wherein the H2-N2-O2-production unit is operated by using energy provided by the renewable energy source,—an Oxygen storage configured to receive and store the Oxygen produced by the H2-N2-O2-production unit,—a mixing unit configured to receive and mix the Hydrogen and the Nitrogen produced by the H2-N2-O2-production unit to form a Hydrogen-Nitrogen-mixture,—an NH3 source for receiving and processing the Hydrogen-Nitrogen-mixture for generating a gas mixture containing NH3, wherein the NH3 source is fluidly connected to the mixing unit to receive the Hydrogen-Nitrogen mixture from the mixing unit and wherein the NH3 source is configured to generate the gas mixture containing NH3 from the Hydrogen-Nitrogen-mixture, wherein the NH3 source comprises a NH3 storage vessel for storing at least a part of the NH3 of the gas mixture containing NH3,—an NH3 power generator for generating energy for the energy grid, wherein the NH3 power generator—is fluidly connected to the NH3 storage vessel to receive NH3 from the NH3 storage vessel,—is configured to combust the received NH3 in a combustion chamber to generate the energy for the energy grid,—is fluidly connected to the Oxygen storage such that Oxygen from the Oxygen storage can be introduced into the combustion chamber for the combustion of NH3 to increase the efficiency and cleanliness of the burning. 
         [0017]    The system might comprise an Oxygen control system for controlling a flow of Oxygen from the Oxygen storage to the NH3 power generator based on an input data set which contains information about actual working conditions in the combustion chamber. 
         [0018]    The working conditions might include at least one of—a status of combustion in the combustion chamber,—a flow rate of NH3 from the NH3 storage vessel to the NH3 power generator,—a temperature in the combustion chamber,—an actual chemical composition of a gas mixture in the combustion chamber, and/or—an actual chemical composition of combustion exhaust gases of the NH3 power generator. 
         [0019]    This allows to operate the system with optimal parameters and efficiency. 
         [0020]    The system might comprise a main control unit for controlling the generation of the NH3 to be stored in the NH3 storage vessel and/or controlling the generation of energy with the NH3 power generator. For example, the controlling can be achieved by regulating the energy flow provided to the H2-N2-production unit and, therewith, the production of H2 and N2 or by regulating the mass flow in the system via influencing mixers, compressors or other components and/or by regulating the temperature in NH3 reaction chamber. 
         [0021]    The main control unit might be configured and arranged, i.e. connected to corresponding components, such that the controlling of the generation of the NH3 to be stored in the NH3 storage vessel and/or the controlling of the generation of energy with the NH3 power generator at least depends on an actual power demand in the energy grid and/or on an amount of energy currently generated by the renewable energy source. This allows a flexible energy supply which reacts to actual demands in the energy grid and which on the other hand allows to store energy form the renewable energy source in case of low demands. 
         [0022]    The main control unit might be configured—to preferably simultaneously reduce the generation of the NH3 to be stored in the NH3 storage vessel, which can be achieved by controlling the generation of the gas mixture containing NH3, and/or increase the generation of energy during periods of low renewable energy input from the renewable energy source,—to preferably simultaneously increase the generation of the NH3 to be stored in the NH3 storage vessel and/or reduce the generation of energy during periods of high renewable energy input from the renewable energy source. 
         [0023]    This also allows effective load balancing of an energy input for the energy grid and a flexible energy supply which reacts to actual demands in the energy grid and which on the other hand allows to store energy form the renewable energy source in case of low demands. 
         [0024]    Therein, the terms “low” and “high” can be referenced to certain given threshold values. I.e. a low renewable energy input means that the actual renewable energy input is less than a first threshold and a high renewable energy input means that the actual renewable energy input is more than a second threshold. First and second threshold can be identical or different from each other. 
         [0025]    The H2-N2-O2-production unit might comprise—an electrolyzer for producing the Hydrogen and Oxygen, wherein the electrolyzer is configured to receive water and energy produced by the renewable energy source and to produce the Hydrogen and the Oxygen by electrolysis, and—an air separation unit for producing the Nitrogen and Oxygen, wherein the air separation unit is configured to receive air and energy produced by the renewable energy source and to produce the Nitrogen and Oxygen by separating the received air. This allows to produce Hydrogen H2, Nitrogen N2, and Oxygen O2 by utilizing energy from the renewable energy source. 
         [0026]    The mixing unit might be fluidly connected to the H2-N2-production unit to receive the Hydrogen and Nitrogen produced therein, wherein the mixing unit might comprise a mixer for mixing the Hydrogen with the Nitrogen to form a Hydrogen-Nitrogen-mixture and a compressor for compressing the Hydrogen-Nitrogen-mixture from the mixer to form a compressed Hydrogen-Nitrogen-mixture to be directed to the NH3 source. Thus, the mixing unit provides a compressed H2-N2-mixture. 
         [0027]    The mixing unit might further comprises a temporary storage system for buffering the Hydrogen and the Nitrogen from the H2-N2-production unit, wherein the temporary storage system is configured to receive the Hydrogen and the Nitrogen from the H2-N2-production unit, to temporary store the Hydrogen and the Nitrogen for buffering and to subsequently process the buffered Hydrogen and Nitrogen to the mixer. This allows a more efficient mixing process. 
         [0028]    The NH3 source might comprise—an NH3 reaction chamber configured to receive the Hydrogen-Nitrogen-mixture from the mixing unit and to process the received Hydrogen-Nitrogen-mixture to form the gas mixture containing NH3 and—a separator for receiving the gas mixture containing NH3 from the NH3 reaction chamber, wherein—the separator is configured to separate NH3 from the gas mixture containing NH3 such that NH3 and a remaining Hydrogen-Nitrogen-mixture are produced and—the separator is fluidly connected to the NH3 storage vessel to direct the produced NH3 to the NH3 storage vessel. 
         [0029]    The usage of the separator allows an efficient production of NH3. 
         [0030]    In one embodiment, an additional a re-processing unit for re-processing the remaining Hydrogen-Nitrogen-mixture with a re-compressor and a second mixer is available, wherein—the re-compressor is fluidly connected to the separator to receive and compress the remaining Hydrogen-Nitrogen-mixture from the separator,—the second mixer is fluidly connected to the re-compressor to receive the compressed remaining Hydrogen-Nitrogen-mixture from the re-compressor,—the second mixer is fluidly connected to the mixing unit to receive the Hydrogen-Nitrogen-mixture from the mixing unit, and wherein—the second mixer is configured to mix the Hydrogen-Nitrogen-mixture from the mixing unit and the compressed remaining Hydrogen-Nitrogen-mixture from the re-compressor to form the Hydrogen-Nitrogen mixture to be provided to the NH3 source. The use of the re-processing unit allows to re-cycle remaining H2 and N2 to form further NH3. 
         [0031]    In an alternative embodiment, the separator might be fluidly connected to the mixing unit to direct the remaining Hydrogen-Nitrogen-mixture from the separator to the mixing unit, such that the remaining Hydrogen-Nitrogen-mixture is mixed in the mixing unit with the Hydrogen and the Nitrogen from the H2-N2-production unit to form the Hydrogen-Nitrogen-mixture to be received by the NH3 source. This also allows to re-cycle remaining H2 and N2 to form further NH3. 
         [0032]    The system might further comprise an energy distribution unit which is configured to receive the energy provided by the renewable energy source and to distribute the energy to the energy grid and/or to the H2-N2-production unit, wherein the distribution depends on an energy demand situation in the energy grid. For example, in case of a higher energy demand from the energy grid, the fraction of energy provided by the renewable energy source to the energy grid is higher and the remaining fraction which is provided to the system is lower. 
         [0033]    In case of a lower energy demand from the energy grid, the fraction of energy provided by the renewable energy source to the energy grid is lower and the remaining fraction which is provided to the system is higher. This allows an effective operation of the system and, in the consequence, load balancing of an energy input for the energy grid. 
         [0034]    In a corresponding method for providing energy for an energy grid and for load balancing of an energy input for the energy grid based on intermittent renewable energy provided by a renewable energy source,—at least a part of the energy from the renewable energy source is used to produce Hydrogen, Nitrogen and Oxygen in a H2-N2-O2-production unit,—the produced Oxygen is directed to and stored in an Oxygen storage,—the produced Hydrogen and Nitrogen are mixed in a mixing unit to form a Hydrogen-Nitrogen-mixture,—the Hydrogen-Nitrogen-mixture is processed in a NH3 source to generate a gas mixture containing NH3 and NH3 of the gas mixture containing NH3 is stored in a NH3 storage vessel,—NH3 is provided from the NH3 storage vessel to a combustion chamber of a NH3 power generator and the provided NH3 is combusted in the combustion chamber for generating the energy for the energy grid, wherein—Oxygen from the Oxygen storage is introduced into the combustion chamber for the combustion of NH3 to increase the efficiency and cleanliness of the burning. 
         [0035]    An Oxygen control system might control a flow of Oxygen from the Oxygen storage to the NH3 power generator based on an input data set which contains information about actual working conditions in the combustion chamber. This allows to operate the system at an optimal parameter set and correspondingly high efficiency. 
         [0036]    Therein, the working conditions might include at least one of—a status of combustion in the combustion chamber,—a flow rate of NH3 from the NH3 storage vessel to the NH3 power generator,—a temperature in the combustion chamber, and/or—an actual chemical composition of a gas mixture in the combustion chamber,—an actual chemical composition of combustion exhaust gases of the NH3 power generator. 
         [0037]    A main control unit of the system might control the generation of the NH3 to be stored in the NH3 storage vessel and/or the generation of energy with the NH3 power generator. 
         [0038]    The gas mixture containing NH3 might be directed to a separator which separates NH3 from the gas mixture containing NH3 such that the NH3 to be stored in the NH3 storage vessel and a remaining Hydrogen-Nitrogen-mixture are produced. Thus, NH3 without further impurifications can be directed to the storage vessel. 
         [0039]    In one embodiment, the remaining Hydrogen-Nitrogen-mixture is re-compressed and the re-compressed remaining Hydrogen-Nitrogen-mixture is mixed with the Hydrogen-Nitrogen-mixture from the mixing unit to form the Hydrogen-Nitrogen-mixture to be received by the NH3 source. Thus, Hydrogen and Nitrogen can be re-cycled to form further NH3. 
         [0040]    In an alternative embodiment, the remaining Hydrogen-Nitrogen-mixture is mixed in the mixing unit with the Hydrogen and the Nitrogen from the H2-N2-O2-production unit to form the Hydrogen-Nitrogen-mixture to be received by the NH3 source. Thus, Hydrogen and Nitrogen can be re-cycled to form further NH3. 
         [0041]    The main control unit might control the generation of the NH3 to be stored in the NH3 storage vessel and/or the generation of energy with the NH3 power generator at least depending on an actual power demand in the energy grid and/or on an amount of energy currently generated by the renewable energy source. 
         [0042]    Moreover, the main control unit might—preferably simultaneously reduce the generation of the NH3 to be stored in the NH3 storage vessel (can be achieved by . . . ) and/or increases the generation of energy during periods of low renewable energy input from the renewable energy source,—preferably simultaneously increase the generation of the NH3 to be stored in the NH3 storage vessel and/or reduces the generation of energy during periods of high renewable energy input from the renewable energy source. 
         [0043]    Thus, the main control unit controls the generation of NH3 and the generation of energy. For example, during periods in which the renewable energy source generates less energy, for example and in the case of a windmill during phases of low wind, the main control unit would power up the NH3 power generator to supply more energy into the energy grid because the supply by the renewable energy source might not be sufficient. During periods of in which the renewable energy source generates a high amount of energy, for example during phases with strong wind, the main control unit would power down the NH3 power generator because the renewable energy source provides sufficient energy to the grid. However, the main control unit would increase the production and storage of NH3. 
         [0044]    A device being “fluidly connected” to a further device means that a fluid can be transferred via a connection between the devices, e.g. a tube, from the device to the further device. Therein, a fluid can be gaseous as well as liquid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0045]    In the following, the invention is explained in detail on the basis of  FIG. 1 . Like reference numerals in different figures refer to the same components. 
           [0046]      FIG. 1  shows a system for load balancing of an intermittent renewable energy source, 
           [0047]      FIG. 2  shows a further embodiment of the system with a re-cycling of a remaining H2-N2-gas mixture, 
           [0048]      FIG. 3  shows a variation of the further embodiment of the system. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0049]    The system  100  comprises a renewable energy source  10 , for example a windmill or a windfarm with a plurality of individual windmills. Alternatively, the renewable energy source  10  can also be a solar power plant or any other power plant which is suitable for generating energy out of a renewable feedstock like water, wind, or solar energy. In the following, the system  100  is explained under the assumption that the renewable energy source  10  is a windmill. However, this should not have any limiting effect on the invention. 
         [0050]    The windmill  10  is connected to an energy grid  300  to supply energy generated by the windmill  10  to the grid  300 . Therein, an energy amount  1 ″ which is at least a fraction of the energy  1  generated by the windmill  10  is provided to the energy grid  300  to meet the energy demands of the consumers in the energy grid  300 . It might be mentioned that the energy grid  300  would normally also have access to other energy sources. 
         [0051]    However, a remaining energy amount  1 ′ of the generated energy  1  can be used in the system  100  to operate an Hydrogen-Nitrogen-Oxygen-production unit  20  (H2-N2-O2-production unit) of the system  100 . 
         [0052]    Especially when excess energy is available, i.e. when the energy  1  generated by the renewable energy source  10  is exceeding the energy demand of the energy grid  300  to the renewable energy source  10 , this excess energy can be directed to the H2-N2-O2-production unit  20  to operate the unit  20 . The amount of energy  1 ′ which is fed to the H2-N2-O2-production unit  20  depends on the energy demands of consumers to be supplied by the energy grid  300 . I.e. in case of high demands, e.g. during peak times, it might be necessary that 100% of the energy  1  generated by the windmill  10  has to be fed into the electricity grid  300  to cover the demand. In contrast, in case of very low demands, e.g. during night times, 100% of the electricity  1  generated by the windmill  10  might be available for use in the system  100  and can be directed to the H2-N2-O2-production unit  20 . 
         [0053]    Such managing and distribution of energy  1  from the windmill  10  is achieved by an energy distribution unit  11 . The energy distribution unit  11  receives the energy  1  from the windmill  10 . As indicated above, certain ratios of the energy  1  are directed to the energy grid  300  and/or to the system  100  and the H2-N2-O2-production unit  20 , respectively, depending on the energy demand situation in the energy grid  300 . Thus, the energy distribution unit  11  is configured to receive the energy  1  provided by the renewable energy source  10  and to distribute the energy  1  to the energy grid  300  and/or to the H2-N2-O2-production unit  20 , wherein the distribution depends on an energy demand situation in the energy grid  300 . 
         [0054]    For example, in case a high amount of energy is demanded in the grid  300 , most or all of the energy  1  would be directed to the grid  300  and only less energy  1 ′ would be provided to the H2-N2-O2-production unit  20 . In case the demand situation is such that only less energy is demanded in the grid  300 , most or all of the energy  1  provided by the renewable energy source  10  can be used for generation of NH3. Thus, a high amount of energy  1 ′ would be provided to the H2-N2-O2-production unit  20 . 
         [0055]    As mentioned above, the amount  1 ′ of the energy  1  generated by the renewable energy source  10  is supplied to the system  100  and to the H2-N2-O2-production unit  20  to achieve the production of NH3. The H2-N2-O2-production unit  20  comprises an electrolyzer  21  and an air separation unit  22 . 
         [0056]    The electrolyzer  21  is used to generate Hydrogen  4  and Oxygen  6  through the electrolysis of water  2 . The electrolyzer  21  is supplied with water  2  from an arbitrary source (not shown) and it is operated using the energy  1 ′ from the windmill  10 . 
         [0057]    The air separation unit (ASU)  22  of the H2-N2-O2-production unit  20  is used for the generation of Nitrogen  5  and Oxygen  7 . Energy  1 ′ is used to operate the ASU  22  which utilizes conventional air separation techniques to separate Nitrogen  5  and Oxygen  7  from air  3 . The remaining components of the air  3  can be released into the ambient air (not shown). 
         [0058]    Thus, the windmill  10  is utilized to provide the energy  1 ′ for both the electrolysis of water  2  to form Hydrogen  4  and Oxygen  6  with the electrolyzer  21  and for separating Nitrogen  5  and Oxygen  7  from air  3  using the ASU  22 . 
         [0059]    Oxygen  6  from the Electrolyzer  21  and Oxygen  7  from the ASU  22  are directed to and subsequently stored in an Oxygen storage  70  of the system  100  whereas both Hydrogen  4  and Nitrogen  5  are directed to a mixing unit  30  of the system  100 . Therein, established techniques are applied for separating Hydrogen from Oxygen and Nitrogen from Oxygen, respectively, which will not have to be explained in detail. 
         [0060]    The mixing unit  30  comprises a temporary storage unit  31 , a mixer  32  and a compressor  33 . First, Hydrogen  4  and Nitrogen  5  pass the temporary storage unit  31  before being mixed in the mixer  32 . The resulting Hydrogen-Nitrogen-gas mixture  8  (H2-N2-gas mixture) is subsequently compressed to fifty or more atmospheres in the compressor  33 . 
         [0061]    Ammonia NH3 can now be formed by processing the compressed H2-N2-gas mixture  8  in the presence of a catalyst at an elevated temperature. This is achieved in a NH3 reaction chamber  41  of a NH3 source  40  of the system  100 . The compressed H2-N2-gas mixture  8  from the mixing unit  30  and from the compressor  33 , respectively, is directed to the NH3 reaction chamber  41 . The reaction chamber  41  comprises one or more NH3 reaction beds  42  which are operated at an elevated temperature of, for example, 350-450° C. The NH3 reaction chamber  41  produces a mixture of NH3 and, additionally, Nitrogen N2 and Hydrogen H2 out of the H2-N2-gas mixture from the mixer  30 , i.e. the NH3 reaction chamber releases an NH3-H2-N2-gas mixture  9 . 
         [0062]    For example, a suitable catalyst can be based on iron promoted with K2O, CaO, SiO2, and Al2O3 or, rather than the iron based catalyst, ruthenium. 
         [0063]    The NH3-H2-N2-mixture  9  is directed to a separator  43  of the NH3 source  40 , for example a condenser, where NH3 is separated from the NH3-H2-N2-mixture  9 . Thus, the separator  43  produces NH3, which is sent to an NH3 storage vessel  44  of the NH3 source  40 , and a remaining H2-N2-gas mixture  8 ′. 
         [0064]    It can be assumed that an extensive knowledge base exists both on the storage and on the transportation of Ammonia. The same is applicable for the handling and transportation of Hydrogen, Nitrogen, Hydrogen-Nitrogen-mixtures, and Oxygen. Therefore, the NH3 storage vessel  44 , the Oxygen storage  70  as well as the variety of ducts which connect all the components of the system  100  for directing NH3 and other gases or gas mixtures are not described in detail. 
         [0065]    As explained above, the separator  43  generates NH3 out of the NH3-H2-N2-mixture  9  provided by the NH3 reaction chamber  41  and a H2-N2-gas mixture  8 ′ remains. In one embodiment of the invention, for which two variations are shown in  FIGS. 2 and 3 , this remaining H2-N2-gas mixture  8 ′ is re-cycled to be utilized again for the generation of NH3 in the NH3 reaction chamber  41 . 
         [0066]    For this, the system  100  of this embodiment as shown in  FIG. 2  comprises an additional re-processing unit  50  with a re-compressor  51  and a mixer  52 . Moreover, this embodiment of the invention differs from the above described basic embodiment of the invention in that the compressed H2-N2-gas mixture  8  from the compressor  33  is not passed directly to the NH3 reaction chamber  41 , but it reaches the NH3 reaction chamber  41  only via the mixer  52  of the re-processing unit  50 . The remaining H2-N2-gas mixture  8 ′ of the separator  43  is passed to the re-compressor  51  of the re-processing unit  50  of the system  100 . Like the compressor  33 , the re-compressor  51  compresses the remaining H2-N2-gas mixture  8 ′ to fifty or more atmospheres to account for pressure losses during the processing in the NH3 reaction chamber  41  and in the separator  43 . The re-compressed remaining H2-N2-gas mixture  8 ′ is then passed to the mixer  52  where it is mixed with the fresh H2-N2-gas mixture  8  from the mixer  30  and the compressor  33 , respectively. The mixer  52  generates a mixture  8  of the H2-N2-gas mixtures  8 ,  8 ′ which is subsequently directed to the NH3 reaction chamber  41 . In the following, the gas mixture is processed as described above in the NH3 source  40  to produce NH3 and, again, a remaining H2-N2-gas mixture  8 ′. 
         [0067]      FIG. 3  shows a variation of the embodiment shown in  FIG. 2 . The remaining H2-N2-gas mixture  8 ′ is directly fed into the mixer  32  of the mixing unit  30  to be mixed with the incoming Hydrogen and Nitrogen from the temporary storage unit  31 . A separate re-processing unit  50  is not used. 
         [0068]    In the following, reference is made again to  FIG. 1 . However, the details and features described below are also applicable for the embodiments and variations shown in  FIGS. 2 and 3 . 
         [0069]    The NH3 storage vessel  44  is fluidly connected with an NH3 power generator  200 . Ammonia can be used in a number of different combustion cycles, for example in the Brayton cycle or in the Diesel cycle. However, at a power level of a windmill or a windfarm, it would be appropriate to use a gas turbine for combustion of Ammonia for the generation of electrical energy, wherein the Brayton cycle would be applicable for a gas turbine solution. Thus, the NH3 power generator  200  can be a gas turbine which is configured for the combustion of Ammonia. It has been shown earlier that conventional gas turbines with only slight modifications of the burner would be suitable. 
         [0070]    The gas turbine  200  combusts the NH3 from the NH3 storage vessel  44  for the generation of energy  1 ′″ in a combustion chamber  201  of the NH3 power generator  200  and the gas turbine, respectively. This energy  1 ′″ can then be fed into the energy grid  300 . 
         [0071]    However, the performance and efficiency of the NH3 power generator  200  and the gas turbine, respectively, can be optimized by introducing additional Oxygen to the combustion process. For example, an increased Oxygen concentration during combustion will increase the efficiency and cleanliness of the NH3 burning. This can be achieved by making use of the Oxygen  6 ,  7  which is generated as described above as a byproduct during the production of Hydrogen  4  and/or Nitrogen  5  with the H2-N2-O2-production unit  20 . As shown above, the generated Oxygen  6 ,  7  is directed to the Oxygen storage  70 . The Oxygen storage  70  is fluidly connected to the NH3 power generator  200  such that Oxygen O 2  can be provided to the NH3 power generator  200  to achieve an optimized performance. 
         [0072]    The flow of Oxygen O 2  from the Oxygen storage  70  to the NH3 power generator  200  is managed by a corresponding Oxygen control system  71 . The Oxygen control system  71  receives (not shown) as an input a data set which contains information about actual working conditions of the NH3 power generator  200 . These working conditions may include a status of combustion in the combustion chamber  201  of the NH3 power generator  200  and/or the amount of NH3 reaching the NH3 power generator  200  from the NH3 storage vessel  44 , i.e. the NH3 flow rate to the NH3 power generator. Moreover, other combustion parameters which allow conclusions about working conditions in the NH3 power generator  200  can also be included in the data set, for example a temperature and/or an actual chemical composition of the gas in the combustion chamber  201  and/or an actual chemical composition of combustion exhaust gases of the NH3 power generator  200  and the combustion chamber  201 , respectively. Out of these and potentially other data, the Oxygen control system  71  determines and regulates the optimum flow rate of Oxygen O 2  to be provided from the Oxygen storage  70  to the NH3 power generator  200  and to the combustion chamber  201 , respectively. For example, the data might be determined with corresponding sensors (not shown) and sensor data might be transferred to the Oxygen control system  71  wirelessly. Based on the data set, the Oxygen control system  71  controls a plurality of devices  72  like pumps, valves and/or other devices necessary for controlling a flow rate to influence the Oxygen O 2  flow rate from the Oxygen storage  70  to the NH3 power generator  200 . 
         [0073]    The system  100  moreover comprises a main control unit  60  which is configured to control various components of the system  100  (connections of the main control unit  60  with other components of the system  100  are not shown in  FIG. 1  to avoid confusion). Especially, the main control unit  60  controls the process of generating energy  1 ′″ for the energy grid  300  and the production of NH3. 
         [0074]    In case the energy supply from the windmill  10  and the energy managing unit  11 , respectively, to the system  100  is too low, for example due to high energy demands in the energy grid  300 , the main control unit  60  reduces the production of NH3 by reducing the gas mass flow in the system  100  by powering down the compressors  33 ,  51  and/or the H2-N2-O2-production unit  20  with the electrolyzer  21  and the ASU  22 . Thus, less energy  1 ′ is directed from the windmill  10  to the system  100  and more energy  1 ″ is available for the energy grid  300 . Moreover, the main control unit  60  increases the NH3 mass flow from the NH3 storage vessel  44  to the NH3 power generator  200 . Consequently, the NH3 power generator  200  increases the generation of energy  1 ′″ required for the energy grid  300  in order to guarantee a stable energy supply in the grid  300  to achieve a balanced load. 
         [0075]    In case the energy supply from the windmill  10  and the electricity managing unit  11 , respectively, to the system  100  is too high, for example when the windmill  10  generates more energy than required by the energy grid  300 , the main control unit  60  intensifies the production of NH3 in the system  100  by increasing the gas mass flow in the system  100  by providing more power to the compressors  33 ,  51 , to the electrolyzer  21  and/or to the ASU  22 . This results in an increased production of NH3 which is stored in the NH3 storage vessel  44 . However, the generation of energy  1 ′″ from the NH3 power generator  200  for the energy grid  300  is not increased, but it might be decreased. 
         [0076]    Moreover, the main control unit  60  controls the generation of power in the NH3 power generator  200  based on the energy consumption and demand in the electricity grid  300  and based on the available power supply by any energy sources available for the grid  300 . Thus, in case the available power supply in the grid  300  is less than the demand, the main control unit  60  would power up the NH3 power generator  200  to cover the demand. In case the available power supply in the grid  300  is higher than the demand, the main control unit  60  would power down the NH3 power generator  200  and the NH3 generation would be intensified by supplying more energy to the H2-N2-O2-production unit  20  and by increasing the mass flow in the system  100  so that the NH3 storage vessel  44  can be filled up again. 
         [0077]    In other words, the main control unit  60  is configured to reduce the generation of NH3 to be directed to the NH3 storage vessel  44  and/or increase the generation of energy  1 ′″ during periods of too low renewable energy input  1 , e.g. during periods of low wind and/or high energy demands in the energy grid  300 . Also, the main control unit  60  is configured to increase the generation of NH3 to be directed to the NH3 storage vessel  44  and/or reduce the generation of energy  1 ′″ during periods of too high renewable energy input  1 , e.g. during periods of strong winds and/or low energy demands in the grid  300 . 
         [0078]    Thus, the controlling performed by the main control unit  60  may depend on the actual power demand in the energy grid  300 , the energy  1  generated by the renewable energy source  10 , and/or the actual amount of energy  1 ′ from the renewable energy source  10  available for the system  100 . 
         [0079]    Correspondingly, the main control unit  60  has to be connected to the energy grid  300  to receive information about the current energy demand and coverage in the grid  300 . Moreover, the main control unit  60  would be connected to the energy distribution unit  11  and/or to the windmill  10  directly to receive information about energy  1 ,  1 ′,  1 ″ provided by the windmill  10  and available for usage in the system  100  and in the grid  300 . The main control unit  60  would have to be connected to the H2-N2-O2-production unit  20  to control the amount of produced Hydrogen and Nitrogen and to the various mixers and compressors, if applicable, to regulate the mass flow in the system. With this, the main control unit  60  can regulate the production of NH3 to be directed to the NH3 storage vessel  44 . In addition to this, the main control unit  60  is connected to the NH3 storage vessel  44  to regulate the supply of NH3 to the NH3 power generator  200  and to the NH3 power generator  200  itself to regulate the energy generation by NH3 combustion. Finally, the main control unit  60  can be connected to the Oxygen control system  71  such that the Oxygen O 2  flow rate from the Oxygen storage  70  to the NH3 power generator  200  can also be influenced centrally by the main control unit  60 .