WO2016169744A1

WO2016169744A1 - Method for generating electric energy by means of fluctuating renewable energy sources

Info

Publication number: WO2016169744A1
Application number: PCT/EP2016/057125
Authority: WO
Inventors: Ina Hahndorf; Triin TAMRA
Original assignee: Younicos Ag
Priority date: 2015-04-23
Filing date: 2016-03-31
Publication date: 2016-10-27
Also published as: DE102015207478A1; EP3286282A1

Abstract

In a method for generating electric energy by means of fluctuating renewable energy sources the excess energy obtained during the generation of energy is utilized for the long-time storage, in particular for the seasonal storage, by conversion of water and/or carbon sources into storable energy carriers in the form of chemical media for the generation of backup energy to be fed into an electric energy supply network as required.

Description

Method for Generating Electric Energy

by Means of Fluctuating Renewable Energy Sources

Description

This invention relates to a method for generating electric energy by means of fluctuating renewable energy sources according to the generic part of claim 1 .

The feed-in of electric energy from the fluctuating renewable energy sources such as photovoltaic and wind energy plants into an electric energy supply network considerably is subject to daily and weather-related fluctuations, which to cover the electric energy demand of the consumers connected to the electric energy supply network must be compensated by electric and mechanical storage facilities as well as conventional facilities for generating electric energy. For reasons of environmental protection and a C0₂-neutral generation of electric energy, conventional energy generators such as nuclear power plants and power plants processing fossil energy carriers for the generation of electric energy are not suitable for compensating a fluctuating output of energy by photovoltaic and wind energy plants. C0₂-neutral mechanical storage facilities such as pumped or compressed air storage plants or flywheel accumulators require a certain infrastructure which is not present everywhere or must be set up with considerable costs. Electric or electrochemical storage facilities such as capacitors or battery accumulators are optimally suitable as short-time accumulators for compensating daily or load-related fluctuations and for the frequency and voltage stabilization of an electric energy supply network, but for the long-time storage of electric energy over days and weeks require a considerable amount of equipment and hence financial expenditure. As can be taken from the graphical representation of the costs per kilowatt hour (€/kW) in dependence on the amount of renewable energies RE without seasonal storage as shown in Fig. 1 , the costs for the use of fluctuating, renewable electric energy sources possibly by including existing constant renewable energy sources such as hydroelectric and geothermal power plants in combination with a short-time energy accumulator such as a battery power plant as electrochemical accumulator with a capacity of 1 to 12 hours decrease continuously down to an amount of about 65% of renewable energies in the energy generation, but then increase exponentially up to an amount of 100% fluctuating, renewable energy sources RE because of the high costs of electric and mechanical energy accmulators dimensioned correspondingly large.

Another problem in the use of fluctuating, renewable energy sources consists in that during strong sunlight and/or optimum wind conditions an excess of electric energy is generated by the fluctuating, renewable energy sources, which without corresponding storage facilities is discarded by throttling the photovoltaic and wind energy plants. With a high amount of fluctuating, renewable energy sources in the generation of electric energy, the excess energy therefore always is part of the energy supply, so that with an optimization for competitive energy generation costs with an amount of fluctuating, renewable energy sources of more than 60% in the generation of electric energy an amount of more than 30% of excess energy usually is generated, which can neither be consumed nor be stored in a short-time energy accumulator with a capacity of 1 to 12 hours.

From DE 199 56 560 C2 a method for generating renewable combustibles and fuels from renewable raw materials or other biomasses, water and regenerative energy is known, in which the carbon monoxide-hydrogen mixture required for the synthesis is produced by mixing hydrogen obtained by electrolysis of water with carbon monoxide. The carbon monoxide is produced by gasification of coke with oxygen from the electrolysis of water, the coke being obtained by heating or partial oxidation of biomass.

It is the object underlying the present invention to indicate a method for generating electric energy by means of fluctuating, renewable energy sources, which provides for an amount of fluctuating, renewable energy sources in the generation of electric energy of more than 60% with competitive energy generation costs. According to the invention, this object is solved by a method for generating electric energy by means of fluctuating, renewable energy sources, which renders excess energy obtained in the generation of energy usable for long-time storage, in particular for seasonal storage, by converting water and/or carbon sources into storable energy carriers in the form of chemical media for generating backup energy to be fed into an electric energy supply network as required.

The solution according to the invention provides for the generation of electric energy for an electric energy supply network with an amount of fluctuating, renewable energy sources of more than 60% with competitive energy generation costs, in that for the long-time or seasonal storage the excess energy obtained during the generation of electric energy by means of fluctuating, renewable energy sources is converted into a storable energy carrier in the form of chemical media, is stored, and days, weeks or months later the stored energy carrier is consumed for generating backup energy for the electric energy supply network, so that an energy supply with an amount of up to 100% of fluctuating, renewable energy sources is possible for the electric energy supply network.

The excess energy always obtained during the generation of electric energy by means of fluctuating, renewable energy sources as a result of daily and weather-related fluctuations is not stored directly in electric or electrochemical form, but is integrated into an energy supply concept with 100% of fluctuating, renewable energy sources by using the same for operating substance conversion processes such as for example electrolysis or pyrolysis methods or for supporting substance conversion processes by an optimum preparation of the substances to be converted for the subsequent substance conversion process.

The use of excess energy in storable form during the generation of electric energy by means of fluctuating, renewable energy sources is effected by transfer into storable energy carriers in the form of chemical media with additionally provided carbon sources such as biomass and/or provided water by utilizing the existing infrastructure for the combustion of hydrocarbon fuel sources and for generating the electric backup energy required for compensating the energy output of the fluctuating, renewable energy sources reduced over an extended period, in order to achieve a 100% electric energy supply by means of fluctuating, renewable energy sources. In the storable energy carriers of chemical nature a distinction is made according to the features of claim 2 between carbonaceous and non-carbonaceous energy carriers and a refinement of hydrocarbonaceous energy carriers by means of hydrogen, depending on whether or not a carbon source, for example biomass, is available in the energy supply area for the energetic utilization.

The sole utilization of excess energy for the conversion of carbon sources into backup energy and the utilization of excess energy for combining water electrolysis and conversion of carbon sources provides for generating a C0₂-neutral energy carrier which can be stored in storable form and can be used for generating electric energy, when no excess energy is available over an extended period. The efficiency in use of the two energetic bases excess energy and carbon source is of particular importance, as corresponding to its meaning the excess energy is available in excess and therefore can still be used with small degrees of efficiency, while carbon sources from carbon present in concentrated form or usable directly usually are available to a very limited extent and therefore must be utilized highly efficiently.

Preferably, an alkaline electrolyser, an acid or PEM electrolyser, or a high-temperature electrolyser are used for the electrolysis of water

The hydrogen generated by means of water electrolysis by utilizing the excess energy likewise is improved qualitatively by utilizing excess energy, in that it is compressed, dried and purified.

The quality improvement of the hydrogen generated by means of water electrolysis can be optimized in particular in that the hydrogen is temporarily stored in a buffer tank, thereafter compressed with low pressure, dried and purified, again temporarily stored in a buffer tank and subsequently compressed with high pressure, dried, purified and stored. To increase the utilization efficiency of the carbon source according to another feature of the method according to the invention, the carbon source is prepared for the further processing before the conversion by comminution, drying and compression by utilizing the excess energy or by means of filtration techniques based on absorption and desorption and temporarily stored for the conversion. As another possibility of obtaining a C0₂-neutral energy carrier, the recovery of C0₂ from the air by means of electrodialysis can be taken into account.

By utilizing excess energy, the prepared carbon source is converted into a liquid or gaseous hydrocarbonaceous energy carrier by means of physical, thermal or chemical methods of the carbon and/or C0₂ conversion, in particular by means of flash, ablation and turbulent- flow pyrolysis, biomass gasification, biomass liquefaction, Sabatier method, Fischer- Tropsch synthesis and the like, into a liquid or gaseous, hydrocarbonaceous fuel.

To further increase the utilization efficiency of the carbon source, the liquid or gaseous, hydrocarbonaceous fuel is treated further by means of physical methods by utilizing excess energy, in particular compressed, stored, heated, cooled, filtered and dried.

In a preferred embodiment, the liquid or gaseous hydrocarbonaceous energy carrier is refined by means of hydrocarbon synthesis by using the treated hydrogen and by utilizing the excess energy to obtain a higher-quality hydrocarbonaceous energy carrier such that it is easily storable and usable in an existing energy generation infrastructure. According to another feature of the invention, the refinement of the hydrocarbonaceous energy carrier is effected by

balance improvement and hence increase of the hydrocarbon content of a biogas process by supplying hydrogen,

balance improvement and hence decrease of the carbon dioxide content of biomass gasification to synthesis gas as well as a balance improvement of the fuel obtained by applying the Sabatier method or the Fischer-Tropsch synthesis by supplying hydrogen,

refinement of a pyrolytically obtained bio-oil by means of a hydrogenation method or a hydrogenation. The treated and possibly refined hydrogen is compressed by utilizing excess energy and stored cooled, and after decompression and heating by means of excess energy is supplied to a gas engine or fuel cells for the generation of backup energy.

A method according to the invention for operating an electric energy supply network, which is connected with fluctuating renewable energy sources, a unit for generating backup energy, an electric or electrochemical energy accumulator, a long-time or seasonal accumulator and an electric load, is characterized in that the electric energy supply network outputs excess energy from the fluctuating renewable energy sources not consumed by the active and reactive electric loads to the electric or electrochemical energy accumulator for the short-time storage and/or for the long-time storage to the long-time or seasonal storage facility for the conversion of water and/or carbon sources into storable energy carriers in the form of chemical media, and that as required backup energy for a short time generated by the electric or electrochemical energy accumulator and generated by the facility for generating backup energy from the storable energy carriers in the form of chemical media is fed into the electric energy supply network for a long time or seasonally.

With reference to several diagrams shown in the Figures of the drawing the idea underlying the invention as well as the advantages of a method for generating electric energy by means of fluctuating, renewable energy sources, which can be achieved with the solution according to the invention, will be explained in detail. In the drawing: Fig. 1 shows a schematic representation of the energy generation costs over the amount of fluctuating, renewable energy sources in the generation of electric energy for an energy supply network;

Fig. 2 shows a schematic block diagram representation of the energy generation and energy consumer systems connected to an electric energy supply network; Fig. 3 shows a schematic representation of the temporal course of cumulative excess energy of an electric energy supply network with fluctuating, renewable energy sources and cumulative backup energy supplied to the energy supply network.

Fig. 4 shows a schematic flow diagram of the various methods for preparing and converting water and/or carbon sources into storable energy carriers as well as their aftertreatment for the generation of backup energy by using excess energy;

Fig. 5 shows a detailed schematic flow diagram of the water electrolysis of water and the aftertreatment of the hydrogen generated and its use in fuel cells for the generation of backup energy; Fig. 6 shows a representation of the temporal course of the hydrogen produced by means of water electrolysis, of the hydrogen consumed for the generation of backup energy, and of the stored hydrogen of an energy supply network;

Fig. 7 shows a schematic representation of the preparation and conversion of a carbon source and of the generated hydrocarbonaceous fuel for the generation of backup energy in a flow diagram; and

Fig. 8 shows a schematic representation of the temporal course of hydrocarbonaceous fuel produced with interruptions, of the consumption of the hydrocarbonaceous fuel for the generation of backup energy, and of the hydrocarbonaceous fuel stored with interruptions of an energy supply network.

Fig. 2 shows a block circuit diagram of an electric energy supply network 1 with the energy generators and energy consumers connected to the energy supply network 1 . The energy generators include a photovoltaic system 2, a wind energy plant 3 and a facility for feeding in backup energy 4, in particular a diesel generator or fuel cells. The energy consumers include active and reactive electric loads 5 as well as a long-time or seasonal storage facility 6 for the variable withdrawal of excess energy. A short-time or battery storage system 7 serves for the short-time storage of electric energy and hence for the temporary withdrawal of electric energy from the energy supply network 1 and for the temporary feed- in of energy into the energy supply network 1 over a period of maximally 1 to 12 hours. In the case of a variable feed-in and withdrawal of energy, the energy supply network 1 compensates short-time differences between feed-in and withdrawal via the battery storage system 7 and supplies excess energy to the long-time or seasonal storage facility 6, with which it exchanges backup energy as required for the longer-term compensation of differences between energy generation and energy consumption. With reference to the example of an island energy supply network, Fig. 3 shows the accumulated course of the excess energy generated in the island network in curve A and the accumulated course of the backup energy output to the island network in curve B.

In a flow diagram, Fig. 4 shows three variants for the production of backup energy BE by including excess energy EE in the generation of electric energy by means of fluctuating, renewable energy sources. The backup energy BE is obtained by converting water W and/or carbon sources C into storable energy carriers in the form of chemical media such as hydrogen H₂ and/or hydrocarbonaceous energy carriers CH and their seasonal storage.

In a first variant no carbon source C for example in the form of biomass or atmospheric C0₂ is available, so that pure hydrogen H₂ is obtained as final energy carrier. In step A1 , hydrogen H₂ is electrolytically generated from the existing water W with the aid of excess energy EE, wherein as possible electrolysis methods an alkaline electrolysis, an acid or PEM electrolysis or a high-temperature electrolysis can be used. The electrolysis chiefly is operated from the excess energy EE during the generation of electric energy by means of fluctuating, renewable energy sources. In the following step A2 the hydrogen H₂ generated by means of the electrolysis method is prepared or treated further, wherein for the further preparation and treatment steps such as for example compression, storage, cooling, heating, decompression and/or drying of the hydrogen H₂ excess energy EE likewise is utilized. In the following process step, the treated and prepared hydrogen H_2N is further used directly or stored. In step A3, the possibly temporarily stored, treated and prepared hydrogen H_2N is supplied to special gas engines, fuel cells or alternative combustion technologies as energy carrier for the generation of backup energy BE.

In a second variant, excess energy EE is included into a seasonal storage concept which is based on a chemical medium in the form of a hydrocarbonaceous energy carrier CH in liquid or gaseous form.

In this variant, it should be considered from which source the required carbon C for generating the hydrocarbonaceous energy carrier CH originates. Since the generation of electric energy exclusively should be based on the use of fluctuating, renewable energies, the required carbon does not originate from fossil carbon sources C such as coal or petroleum, so that methods for converting fossil carbon sources based thereon will not be employed. Correspondingly, two carbon sources C can be used in principle, namely carbon from renewable raw materials or carbon from atmospheric C0₂. In principle, C0₂ from geothermal water might also be taken into account, which however would not correspond to the exclusive use of fluctuating, renewable energy sources, as this C0₂ originally had been stored underground and when accessing to the energy form of geothermal energy is additionally supplied to the atmosphere and correspondingly contributes to global warming like CO2 from fossil energy carriers.

A suitable carbon source C in particular is carbon in the form of biomass, biomass waste, fresh wood, wood-like biomass waste, domestic waste, sewage plant sludge and atmospheric C0₂. The carbon source C initially is prepared in step B 1 in suitable form by utilizing the excess energy before the conversion by comminution, drying and compression or by means of filtration techniques based on absorption and desorption. In step B2, the prepared carbon source C subsequently is converted into a liquid or gaseous hydrocarbonaceous energy carrier CH with the aid of the existing excess energy EE. As conversion methods, physical or thermal methods of the biomass conversion or CO2 conversion are used, such as for example flash, ablation and turbulent-flow pyrolysis, biomass gasification, biomass liquefaction, Sabatier method, Fischer-Tropsch synthesis or the like.

Subsequent to the conversion of the prepared carbon source C into a liquid or gaseous hydrocarbonaceous energy carrier CH , the same is aftertreated in step B3 by means of physical methods such as compression, heating, cooling, filtration or drying and possibly stored temporarily in the existing infrastructure for the further utilization as aftertreated, hydrocarbonaceous energy carrier CH _N in the form of fuel, wherein the necessary process energy is provided in the form of excess energy EE. The aftertreated liquid or gaseous hydrocarbonaceous energy carrier CH_N, for example in the form of pyrolysis oil, then can be used for driving an existing or modified diesel generator.

In a third, preferred variant with existing carbon source C hydrogen H₂ generated by means of an electrolysis method is used for refining the liquid or gaseous hydrocarbonaceous energy carrier CH generated from the carbon source C by means of pyrolysis. In this variant, parallel to the production of the hydrogen H₂ by means of electrolysis in step C1 and its preparation in step C2, the carbon C prepared in step C3 is pyrolytically converted into a hydrocarbonaceous energy carrier CH in step C4, which is aftertreated in step C5. In step C6, the generated products hydrogen H₂ and aftertreated hydrogen H₂N and aftertreated hydrocarbonaceous energy carrier CH _N are taken as starting substances of a hydrocarbon synthesis or hydrocarbon preparation, wherein these conversion processes for example represent a refinement of the aftertreated hydrocarbonaceous energy carrier CH_N to obtain a liquid or gaseous, refined hydrocarbonaceous energy carrier CHv, such as for example bio-oil, biodiesel, synthetic methane or synthetic hydrocarbon.

The objective of the refinement is to synthesize a liquid or gaseous energy carrier CH_V, which both can be stored easily and can be utilized in an existing energy generation infrastructure. For this purpose, hydrogen H₂ or aftertreated hydrogen H₂N and excess energy EE in the form of process energy is utilized and the refined, liquid or gaseous energy carrier CH_V is stored. The methods suitable for this purpose for example include the following:

a balance improvement and hence increase of the hydrocarbon content of a biogas process by supplying hydrogen,

a balance improvement and hence decrease of the carbon dioxide content of the biomass gasification to synthesis gas by supplying hydrogen, or

a refinement of a pyrolytically obtained bio-oil by means of a hydrogenation method or a hydrogenation. Since many energy supply systems are based on the utilization of fossil fuels for the generation of electric energy, i.e. employ generators for the generation of electric energy, which are coupled with combustion machines for the combustion of hydrocarbonaceous fuels, the liquid or gaseous and possibly stored energy carrier CH_V refined in step C6 is used for the generation of electric energy in the existing infrastructure or in an infrastructure to be newly installed. The existing infrastructure, such as e.g. diesel generators, gas turbines or gas engines, for the combustion of hydrocarbonaceous fuels in the liquid or gaseous state therefore is used as present or after corresponding modification. The corresponding modifications are changes which provide for or improve the utilization of the biofuels generated in step C6 for example by

- the incorporation of particularly corrosion-resistant or acid-resistant components made of special alloys,

the use of special additives such as engine oils for more corrosion resistance, or a change of the combustion parameters. The aftertreatment of the hydrogen H₂ generated by means of electrolysis in steps A2 and C2 can be varied by utilizing excess energy EE - as will be explained below with reference to the flow diagram shown in Fig. 5. Fig. 5 schematically shows the production of hydrogen H₂ in step 5.1 by means of electrolysis from existing water W by using excess energy EE and the temporary storage of the generated hydrogen H₂ in a buffer tank in step 5.2. In step. 5.3, an aftertreatment of the generated hydrogen H₂ subsequently is effected at low pressure in the form of the compression, drying and purification of the generated hydrogen H₂ likewise by using excess energy EE. The aftertreated hydrogen H₂ again stored temporarily in step 5.4 subsequently is treated further by compression, drying and purification at high pressure likewise by using excess energy EE. The hydrogen H_2N aftertreated and treated further in this way is stored in step 5.6 and in step 5.7 converted into electric energy for the generation of backup energy BE for example in fuel cells or a gas engine.

Fig. 6 shows the temporal course of the generation of hydrogen (curve H₂), the hydrogen consumed for the generation of backup energy (curve BE), and the stored generated hydrogen (curve S) in an island energy supply network. The curves illustrate that with an approximately linearly rising generation of hydrogen H₂ with less generation of backup energy BE larger amounts of hydrogen H₂ are stored and with rising generation of backup energy BE the storage of hydrogen H₂ is reduced distinctly, in order to again rise distinctly with an only slight deviation between generated hydrogen H₂ and hydrogen H₂ consumed for the generation of backup energy BE.

Fig. 7 shows a schematic flow diagram of the generation of bio-oil as hydrocarbonaceous energy carrier from fresh wood and the use of the bio-oil for the generation of backup energy.

In step 7.1 the fresh wood C is shredded and dried by using excess energy EE, in step 7.2 the dried wood is processed to wood chips likewise by using excess energy and in step 7.3 stored temporarily. In step 7.4 the wood chips are pyrolytically converted into a hydrocarbonaceous energy carrier CH by using excess energy, and in step 7.5 said energy carrier is aftertreated for the generation of bio-oil. The aftertreated liquid or gaseous hydrocarbonaceous energy carrier CH_N is stored in step 7.6 and in step 7.7 supplied to a modified diesel generator for the generation of backup energy BE.

Fig. 8 schematically shows the accumulated production of bio-oil with interruptions corresponding to curve A, the bio-oil consumed for the generation of backup energy in curve B, and in curve C with interruptions the course of the storage of bio-oil. The curves A, B and C each show the linear rise of the generation of bio-oil with individual interruptions, the approximately constant consumption of bio-oil for the generation of backup energy, and the fluctuations of the stored bio-oil as a result of the interruptions of the generation of bio-oil with a respective increase of the stored bio-oil in the case of a resumed generation of bio-oil and purchase of the stored bio-oil during the interruptions of the bio-oil generation.

List of Reference Numerals

1 electric energy supply network

2 photovoltaic system

3 wind energy plant

4 diesel generator or fuel cells

5 active and reactive electric loads

6 long-time or seasonal storage facility

7 short-time or battery storage system

BE backup energy

C carbon source (biomass or atmospheric C0₂)

CH hydrocarbonaceous energy carrier

CH N aftertreated hydrocarbonaceous energy carrier

CHv refined hydrocarbonaceous energy carrier

EE excess energy

H₂ hydrogen

H2N aftertreated hydrogen

W water

Claims

A method for generating electric energy by means of fluctuating renewable energy sources, characterized in that excess energy (EE) obtained during the generation of energy is utilized for the longtime storage, in particular for the seasonal storage, by conversion of water (W) and/or carbon sources (C) into storable energy carriers in the form of chemical media (H₂, CH) for the generation of backup energy (BE) to be fed in as required into an electric energy supply network (1 ).

The method according to claim 1 , characterized in that for the generation of the backup energy (BE)

A) by using water (W) without availability of a carbon source (C)

A1 hydrogen (H₂) is generated from the water (W) by means of water electrolysis by utilizing the excess energy (EE),

A2 the generated hydrogen (H₂) is aftertreated by utilizing the excess energy (EE) and possibly stored, and

A3 the aftertreated hydrogen (H₂) is supplied to a facility for generating backup energy (BE) by utilizing the excess energy (EE);

B) with availability of a carbon source (C)

B1 the carbon source (C) is prepared for the further processing by utilizing the excess energy (EE),

B2 the prepared carbon source (C) is converted into a liquid or gaseous hydrocarbonaceous energy carrier (CH) by utilizing the excess energy (EE),

B3 the liquid or gaseous hydrocarbonaceous energy carrier (CH) is aftertreated and possibly stored, and

B4 the liquid or gaseous hydrocarbonaceous energy carrier (CH) is supplied to a drive of a generator for the generation of backup energy (BE);

C) with availability of a carbon source (C) by including water (W)

C1 hydrogen (H₂) is generated from the water (W) by means of water electrolysis by utilizing the excess energy (EE), C2 the generated hydrogen (H₂) is aftertreated by utilizing the excess energy (EE) and possibly stored,

C3 the carbon source (C) is prepared for the further processing by utilizing the excess energy (EE),

C4 the prepared carbon source (C) is converted into a liquid or gaseous, hydrocarbonaceous energy carrier (CH), in particular into a fuel, by utilizing the excess energy (EE) or its balance is improved by supplying hydrogen,

C5 the liquid or gaseous hydrocarbonaceous energy carrier is aftertreated and possibly stored,

C6 the aftertreated liquid or gaseous hydrocarbonaceous energy carrier (CH) is refined by means of hydrocarbon synthesis by using the treated hydrogen (H₂) and by utilizing the excess energy (EE) to obtain a higher-quality hydrocarbonaceous energy carrier (CH) , in particular biodiesel, and

C7 the higher-quality hydrocarbonaceous energy carrier (CH), possibly after temporary storage, is supplied to a drive of a generator for the generation of backup energy (BE).

3. The method according to claim 2, characterized in that in steps B1 and C3 biomass is prepared by comminution, drying and compression or by means of filtration techniques based on absorption and desorption or carbon is obtained from atmospheric C0₂, by utilizing the excess energy (EE).

4. The method according to claim 2 or 3, characterized in that for the water electrolysis an alkaline electrolyser, an acid or PEM electrolyser or a high-temperature electrolyser is used.

5. The method according to claim 2 or 3, characterized in that in steps A2 and C2 the hydrogen (H₂) generated by means of water electrolysis is treated, in particular compressed, dried and purified by utilizing the excess energy (EE).

6. The method according to claim 5, characterized in that in step A3 the treated hydrogen (H₂N) is supplied to a gas engine or fuel cells by utilizing the excess energy (EE).

7. The method according to claim 5, characterized in that the hydrogen (H₂) generated by means of water electrolysis is temporarily stored in a buffer tank, thereafter compressed with low pressure, dried and purified by utilizing the excess energy (EE), temporarily stored again and subsequently compressed with high pressure, dried, purified and stored.

8. The method according to at least one of the preceding claims, characterized in that in steps B1 and C3 the carbon source (C) is prepared, in particular comminuted, dried, compressed and temporarily stored, by utilizing the excess energy (EE).

9. The method according to at least one of the preceding claims, characterized in that the carbon source (C) consists of atmospheric C0₂, biomass, biomass waste, in particular wood-like biomass waste, domestic waste, sewage plant sludge and the like.

10. The method according to claim 8 or 9, characterized in that by utilizing the excess energy (EE) in steps B2 and C4 the prepared carbon source (C) is converted into a liquid or gaseous hydrocarbonaceous energy carrier (CH) by means of physical, thermal or chemical methods of the carbon and/or C0₂ conversion, in particular by means of flash pyrolysis, ablation pyrolysis and turbulent-flow pyrolysis, biomass gasification, biomass liquefaction, Sabatier method, Fischer-Tropsch synthesis and the like.

1 1 . The method according to claim 10, characterized in that in steps B3 and C5 the liquid or gaseous, hydrocarbonaceous energy carrier (CH) is aftertreated by means of physical methods by utilizing the excess energy (EE), in particular compressed, stored, heated, cooled, filtered and/or dried.

12. The method according to claim 1 1 , characterized in that the hydrocarbonaceous energy carrier (CH_N) aftertreated in steps B3 and C5 is synthesized such that it is easily storable and usable in an existing energy generation infrastructure.

13. The method according to claim 1 1 or 12, characterized in that the hydrocarbonaceous energy carrier (CH_N) aftertreated in steps B3 and C5 is refined in step C6 by adding hydrogen (H₂), in particular by adding aftertreated hydrogen

14. The method according to claim 13, characterized in that the refinement of the aftertreated hydrocarbonaceous energy carrier (CH_N) is carried out by

balance improvement and hence decrease of the carbon dioxide content of the biomass gasification to synthesis gas by supplying hydrogen,

refinement of a pyrolytically obtained bio-oil by means of a hydrogenation method or a hydrogenation.

15. The method according to claim 14, characterized in that the hydrocarbonaceous energy carrier (CH_N) refined in step C6 is stored and in step C7 supplied to a diesel generator for the generation of backup energy (BE).

16. A method for operating an electric energy supply network which is connected with fluctuating renewable energy sources, a facility for generating backup energy, an electric or electrochemical energy accumulator, a long-time or seasonal storage facility and active and reactive electric loads, characterized in that the electric energy supply network (1 ) outputs excess energy (EE) not consumed by the active and reactive electric loads (5) from the fluctuating renewable energy sources (2, 3) to the electric or electrochemical energy accumulator (7) for the short- time storage and/or for the long-time storage to the long-time or seasonal storage facility (6) for the conversion of water (W) and/or carbon sources (C) into storable energy carriers in the form of chemical media (H₂, CH) and that as required backup energy (BE) from the electric or electrochemical energy accumulator (7) for a short time is fed into the electric energy supply network (1 ) and backup energy (BE) generated by the facility for generating backup energy (BE) from the storable energy carriers in the form of chemical media (H₂, CH) for a long time or seasonally is fed into the electric energy supply network (1 ).