US20190024002A1

US20190024002A1 - A combined system for producing fuel and thermal energy and a method for poduction of fuel and thermal energy

Info

Publication number: US20190024002A1
Application number: US15/752,259
Authority: US
Inventors: Tadeusz BAK
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-08-14
Filing date: 2016-08-11
Publication date: 2019-01-24
Also published as: IL257459A; WO2017029189A1; PL231889B1; PL413518A1

Abstract

A combined system for producing fuel and thermal energy, comprising: an electrolyser (150) for producing oxygen and hydrogen in the process of water electrolysis; a gasifier (110) for producing synthesis gas in a process of gasification of carbon-based fuel in the presence of a gasifying agent; a methane synthesis reactor (130) for producing methane in a process of synthesis of carbon oxide from the gasifier (110) and hydrogen from a water electrolyser (150); a reactor (120) with a catalytic packing for producing carbon dioxide in a process of combustion of synthesis gas from the gasifier (110) and/or methane; wherein the electrolyser (150) comprises a heat exchange system connected with a heat exchanger (160).

Description

TECHNICAL FIELD

The present invention relates to a combined system for producing fuel and thermal energy and a method for producing fuel and thermal energy from renewable energy resources and carbon-based fuels.

BACKGROUND

There are known combined systems for producing heat that allow combined production of electrical and thermal energy. The systems can be used at power plants with gas turbine and a heat recovery steam generator allowing production of electrical energy and heat. The advantage of cogeneration systems is a continuous energy supply that is guaranteed by the possibility of supplying a single device with various fuels, for example: natural gas, heating oil, gas mixtures obtained from recycling of waste or biogas.
There are also known cogeneration systems operating on biomass, equipped with gas engine or a steam turbine and adapted accordingly to a thermal gasification, an anaerobic gasification or atmospheric combustion of biomass producing electrical and thermal energy in the final stage.
Other typical combined systems for producing electrical energy and heat are adapted for utilizing various renewable energy sources, for example geothermal energy sources. This type of systems are by default equipped with geothermal heat exchangers, wherein the heat is exchanged between the geothermal energy, a working fluid of the system and the steam generator. The main advantage of the currently known combined systems for producing heat and electrical energy is a decreased emission of pollutants to the environment.
There are also known systems that allow producing fuel and heat in a combined process. For example, a US patent application US20100187822 presents a combined heat and power/combined-cycle electricity generation method and gasification method utilizing a multi-process method of producing, methane, biodiesel, and ethanol production. The waste heat from the combined heat and power generation/combined-cycle method and gasification method is utilized by these multiple methods in such a manner that the waste heat of each successive method serves directly as the heat reservoir for the succeeding method before it is reclaimed at the back-end of the combined-cycle method.
Moreover, a US patent application US20150089919 presents a system for the production and storage of surplus energy from regenerative power sources in the form of hydrocarbons, which can be used in a closed cycle for renewed environment-friendly power production by the recycling of waste gas products. The system has a facility for the production of power by the combustion of hydrocarbons, a facility for the production of hydrocarbons from hydrogen and carbon dioxide a repository with carbon dioxide a repository with hydrocarbons.
The known combined systems for producing fuel and heat allow production of electrical and/or thermal energy and hydrocarbon fuel for example in the form of methane or biodiesel, simultaneously reducing the emission of hazardous compounds being by-products of fuel combustion.
However, the known combined systems for heat and fuel production are not adapted to continuously adjust the operating mode to the excess of electrical energy supply, which may vary daily and/or annually and originates from the renewable energy sources, which can be converted to fuel which is possible to be stored—with a continuously maintained reduced emission of the environmentally hazardous products of carbon-based fuels combustion/oxidation.
There is a need to develop an alternative combined system for producing thermal energy and fuel, which would allow to absorb periodic excess of electrical energy and to synchronize with the thermal energy and/or fuel supply demands, with simultaneous reduction of the environmentally hazardous products of carbon-based fuels combustion/oxidation.

SUMMARY

There is disclosed herein a combined system for producing fuel and thermal energy, comprising: an electrolyser (150) for producing oxygen and hydrogen in the process of water electrolysis; a gasifier (110) for producing synthesis gas in a process of gasification of carbon-based fuel in the presence of a gasifying agent; a methane synthesis reactor (130) for producing methane in a process of synthesis of carbon oxide from the gasifier (110) and hydrogen from a water electrolyser (150); a reactor (120) with a catalytic packing for producing carbon dioxide in a process of combustion of synthesis gas from the gasifier (110) and/or methane; wherein the electrolyser (150) comprises a heat exchange system connected with a heat exchanger (160).
The system may further comprise a storage tank (121) for carbon dioxide emitted in the combustion process in the reactor (120) with the catalytic packing.
The methane synthesis reactor (130) can be further configured to produce methane in a process of synthesis of carbon oxide from the gasifier (110), carbon dioxide from a carbon dioxide tank (121) and hydrogen from the water electrolyser (150).
The system may further comprise an additional methane synthesis reactor (140) for producing methane in a process of synthesis of carbon dioxide from the carbon dioxide tank (121) and hydrogen from the water electrolyser (150).
The system may further comprise a storage tank (151) for oxygen and a storage tank (152) for hydrogen produced in the water electrolyser (150).
The heat exchanger (160) may comprise an electrical heater (161) for conversion of electrical current into thermal energy.
There is also disclosed a method for producing fuel and thermal energy, the method comprising: providing a system comprising: an electrolyser (150) for producing oxygen and hydrogen in a process of water electrolysis; a gasifier (110) for producing synthesis gas in a process of gasification of carbon-based fuel in the presence of a gasifying agent; a methane synthesis reactor (130) for producing methane in a process of synthesis of carbon oxide from the gasifier (110) and hydrogen from a water electrolyser (150); a reactor (120) with a catalytic packing for producing carbon dioxide in a process of combustion of synthesis gas from the gasifier (110) and/or methane; wherein the electrolyser (150) comprises a heat exchange system connected with a heat exchanger (160); producing fuel and thermal energy in at least one of at least two operating modes: in a first operating mode, conducting a process of carbon-based fuel gasification in the gasifier (110) with emission of synthesis gas, which is combusted in the reactor (120) with the catalytic packing with emission of carbon dioxide and water, wherein the heat from the combustion process in the reactor (120) with the catalytic packing is delivered to a heating network by means of the heat exchanger (160); in a second operating mode, enriching carbon oxide from the gasifier (110) with hydrogen produced in the electrolyser (150) and producing methane in the methane synthesis reactor (130).
The method may further comprise producing fuel and thermal energy in a third operating mode by combusting methane produced in the methane synthesis reactor (130) in the reactor (120) with the catalytic packing, wherein the heat from the combustion process is delivered to the district heating by means of the heat exchanger (160).
The method may further comprise producing fuel and thermal energy in a fourth operating mode by supplying the electrical heater (161) of the heat exchanger (160) with electrical power from electrical grid.
The method may further comprise producing methane in the additional methane synthesis reactor (140) in a process of synthesis of carbon dioxide produced in the reactor (120) with the catalytic packing and hydrogen from the water electrolyser (150).
The method may further comprise supplying the electrolyser (150) with electrical power from renewable sources.
The method may further comprise supplying the electrolyser (150) with excess electrical power occurring in electrical grids due to the operation of uncontrollable renewable energy sources.

BRIEF DESCRIPTION OF DRAWINGS

The present invention is shown by means of example embodiments in a drawing, in which:

FIG. 1 shows a schematic of a combined system for producing thermal energy and fuel.

FIG. 2 shows an example schematic of gasifier for mineralization (gasification) of carbon-based fuel.

DETAILED DESCRIPTION

FIG. 1 shows a schematic of a combined system 100 for producing thermal energy and fuel. The combined system 100 comprises a gasifier 110 for gasification (mineralization) of various organic fuels, such as coal, lignite, wastes or biomass. The system structure allows to use syngas produced in the gasifier 110 in two ways: as a source for producing methane—after previously enriching it with hydrogen in a first methane synthesis reactor 130, or as a source for producing thermal energy with emission of carbon dioxide and water by catalytic oxidation of the syngas in reactors 120. Carbon dioxide produced as a result of the syngas oxidation may be stored in a storage tank 121 and utilized for producing methane in an additional methane synthesis reactor 140, operating independently with respect to the first synthesis reactor 130, after prior enrichment of carbon dioxide with hydrogen. Alternatively, in the synthesis reactor 130, the synthesis of methane may be conducted both from carbon oxide as well as from carbon dioxide. Methane produced from carbon oxide and/or carbon dioxide in the synthesis reactors 130 and 140, respectively, may be accumulated in the storage tanks or delivered to a pipeline 170. The heat from the methane synthesis reactors 130, 140 may be transferred by appropriate heat exchange systems to a heat exchanger 160.
The gas mixture from the gasifier 110 is delivered to the synthesis reactor 130 by means of a compressor 110A.
The synthesis process in the synthesis reactors 130, 140 is preferably performed under high pressure, of about 4 MPa.
The synthesis products in the synthesis reactors 130, 140, apart from methane, are higher hydrocarbons such as ethane, propane, butane and others, which should be eliminated before introducing gas from the reaction to the pipeline 170. This can be achieved by freezing them in systems 131, 141. The chill needed for the freezing may be acquired for example from nearby LNG regasification installations. The wastes that are obtained may be a by-product for sale or may be directed to the reactor 120 for combustion.
The structure of the system 100 allows to redirect methane to the system: depending on the needs, methane may be periodically introduced to the reactor 120 and combusted in the chamber of the reactor 120 in order to obtain energy. Carbon dioxide emitted as a result of methane combustion may be stored in the carbon dioxide tank 121 or may be emitted to the atmosphere. The system 100 further comprises an independent system for supplying hydrogen for the process of methane production in the form of an electrolyser 150, wherein the process of H₂O electrolysis is performed. Methane emitted in the process may be directly delivered to the one or more methane synthesis reactors 130, 140 or may be stored in a hydrogen tank 152 from where, depending on the needs, it can be delivered to the selected synthesis reactor 130, 140 when the electrolyser 150 is not operating. Oxygen, emitted during the electrolysis process, may be delivered to the gasifier 110 as the sole gasifying agent, or can be mixed with other gasifying agents such as air or water vapor, in case of oxygen deficiency in the system during the operating mode of energy production. The gasifier 110 may be also powered solely by air, in case when the electrolysis process is not conducted in the system. Moreover, when the gasifier is not operating, oxygen may be stored in a storage tank 151.
The system utilizes the gasifier 110 for carbon-based fuel mineralization having a structure as for example the gasifier described in the European patent application EP2860450A1, the contents of which are incorporated by reference herein. The structure of such the gasifier is schematically shown in FIG. 2. The gasifier 110 utilized in the combined system 100 has a substantially horizontal rotatable pipe 111 with still or/and adjustable elements 112, 113, 114 distributed inside, for pouring the material during the rotation of the pipe 111. In the gasifier 110 there is performed the continuous mineralization (gasification) process of a batch (carbon-based fuel) introduced to the chamber of the gasifier 110 with the production of the gaseous combustion products—syngas, inorganic solid products and heat—according to the process described in the document EP2860450A1. The gasifier 110 comprises nozzles, delivering the gasifying agent to the chamber 110, for example in the form of one or more inlet fittings with flow adjustment. The gasifying agent may be air, air enriched with oxygen, or pure oxygen, water vapor, which additionally increases the efficiency of the reactions comprising the mineralization (gasification) process occurring during mineralization, wherein the greater the amount of oxygen in the gasifying agent, the greater the gasifying efficiency is. Carbon-based fuel in the process of mineralization can be any fuel comprising one or more carbon compounds or elemental carbon—capable of gasification under the process conditions with production of the gaseous products—syngas comprising carbon oxide (CO), hydrogen H₂and various hydrocarbons: C_xH_yand depending on the process parameters, also small amounts of carbon dioxide (CO₂). Carbon-based fuel may therefore be coal, brown coal or alternative fuels such as biomass.
The synthesis gas leaving the chamber 111 of the gasifier 110, depending on the needs, may be directed to the reactors 120 with the catalytic oxidizer, for example a platinum catalyzer for catalyzing the oxidation reaction, including oxidation of CO, H₂, C_xH_yto CO₂and H₂O. The oxidation process in the gasifier is conducted under a pressure that is close to the atmospheric pressure. The oxidation products: CO₂and H₂O, after collecting heat inside the heat exchanger and their further purification, are emitted to the atmosphere, or CO₂is emitted and stored in the storage tank 121. The gaseous products (the syngas) leaving the gasifier 110 may be also delivered to methane synthesis reactor 130. For example, the outlet of the gaseous products from the gasifier chamber 110 may have a form of piping equipped with a valve-distributer allowing to close the inflow of gases to the reactor 120 with a catalytic packing and to open the flow of gases to methane synthesis reactor 130. Alternatively, the gasifier 110 may be equipped with two separate outflows of the gaseous products: the first one delivering the gaseous products to the reactor 120 with the catalytic packing and the second one delivering the syngas to methane synthesis reactor 130. The structure of the system delivering the synthesis gas out may also allow simultaneous delivery of the gaseous products to the reactor 120 and methane synthesis reactor 130.
The methane synthesis reactor 130 may have a form of a conventional reactor for methane synthesis under conditions enabling the synthesis of CH₄with CO/CO₂and H₂. For example, methane may be produced in the synthesis reactor 130 in the Fischer-Tropsch (FTS) process enabling conversion of CO/CO₂into methane with a high selectivity.
The combined system 100 may comprise an additional methane synthesis reactor 140 operating independently with respect to the deliveries of the syngas from the gasifier 110, enabling the synthesis of methane with carbon dioxide accumulated in the storage tank 121, which may be delivered by means of a compressor 122. The conversion process of carbon dioxide into methane may be conducted conventionally, for example as in the first synthesis reactor 130, according to the Fischer-Tropsch process. The obtained methane may be stored in storage tanks, transferred to the pipeline 170 or, depending on the needs, it may be introduced to the reactor 120 and combusted in the reaction chamber in order to produce heat subsequently transferred to a heating network, such as a district heating network.
The system 100 is equipped with a system for producing hydrogen for supplying the methane synthesis reactors 130, 140 with hydrogen, which may have the form of a conventional electrolyser 150 for H₂O electrolysis with emission of oxygen and hydrogen.
Various conventional systems enabling water electrolysis may be used as the electrolyser. Hydrogen obtained in the process, according to the needs, is delivered directly to the selected methane synthesis reactors 130, 140 or is accumulated in hydrogen tanks and stored for utilizing it when the electrolyser 150 is not operating, what provides methane synthesis independency with respect to the electrolyser 150. Oxygen obtained during the electrolysis is preferably utilized as a gasifying agent in the mineralization process, wherein oxygen may be directly delivered to the gasifier chamber 110 in a pure form or as a mixture with another gasifying agent. During the periods when the gasifier is not operating, oxygen may be accumulated in the storage tank 151.
The electrolyser 150 is electrically powered, preferably by electrical current from renewable sources, for example produced by solar cells or wind farms. The most preferably, the electrolyser 150 is supplied with electrical power during power excess, produced by solar cells or wind farms, which cannot be consumed by means of other typical method. Such solution enables optimal utilization of power excess produced by renewable sources for producing fuel in the form of methane, which can for example be stored, transferred to the pipeline 170 or utilized for electrical or thermal energy production during the increased requirement for power or during power deficiency from renewable resources, for example at night or during winter. Optionally, produced methane may be also utilized in other industrial processes.
The structure of the combined system 100 is adapted to operate in at least two operating modes in which the produced syngas is combusted in order to obtain thermal energy or it is converted into methane, wherein the system 100 may operate in two additional operating modes in which the synthesis gas is not produced, what provides the possibility of continuous adjustment of the operating mode of the system to the daily or/and annually varying demand for heat or/and electrical energy or fuel and also optimal utilization of accumulated fuel material and electrical energy from renewable sources.
Therefore the structure of the system enables the system 100 to operate in four operating modes. The structure of the system 100 enables the adjustment of the operating mode according to the environmental and economy parameters such as: season of the year, time of day, weather conditions, current temperature, actual price of solid fuels, actual price for carbon dioxide emission, value of product preferences set by law, value of emission preferences set by law, actual electrical energy price, actual gas purchase price, actual gas selling price, and also other factors such as for example noise level.
The system 100, depending on the demands, preferably with the inclusion of the aforementioned environmental and economy parameters, may operate in one of the four operating modes, or the system 100 may operate in several operating modes simultaneously: for example in the operating mode of syngas combustion in the reactor 120 or in the operating mode of methane production.
In the first operating mode, the system enables production of thermal energy from coal or alternative fuels, for example from biomass. In order to run the first operating mode, the fuel is introduced to the gasifier 110 and the mineralization process is conducted according to the process described in the patent application EP2860450, wherein, preferably oxygen supply stored in the oxygen tank 151 after the process of electrolysis is used as a gasifying agent, what decreases the nitrogen ballast load of the system. In case the oxygen supply tank 151 is exhausted, air is introduced as a gasifying agent to the mineralization chamber 110, obtaining as a result of the gasification the mixture of the gaseous products including: CO, H₂, C_xH_yand small amount of CO₂.
The synthesis gas produced in the continuous process is removed from the gasifier chamber 110 to the reactors 120 with the catalytic packing, wherein CO, H₂and C_xH_yis oxidized into CO₂and H₂O. The carbon dioxide obtained as a result of the reaction on the catalyst 120 is extracted from the gas mixture and is stored in the carbon dioxide tank 121 or is released to the atmosphere.
Heat obtained in the process of catalytic oxidation is collected from the process by means of the heat exchanger 160, by which heat is delivered to the heating network or to a steam circuit of a turbo generator. Therefore, the first operating mode enables production of thermal energy delivered for example to the a heating network, for example from alternative fuels such as biomass, in the process in which the whole amount of the produced carbon dioxide is accumulated in the storage tank, therefore eliminating the emission of the carbon dioxide to the atmosphere.
In the second operating mode, the combined system 100 enables collecting excess electrical energy coming from the renewable sources, including solar cells or wind farms, and production of methane. In this operating mode, the process of mineralization in the gasifier 110 and the process of electrolysis of H₂O by means of the electrically powered electrolyser 150, preferably powered by energy excess from renewable sources, are conducted simultaneously. The second operating mode includes collecting the synthesis gas produced in the gasifier chamber 110, enriching the synthesis gas with hydrogen produced in the electrolysis process, converting carbon oxide into methane in the synthesis reactor 130 and transferring H₂O created in the synthesis reactor to the electrolyser 150. Optionally, in case of carbon dioxide presence in the storage tank 121, simultaneously may be conducted the synthesis reaction of methane and carbon dioxide in the additional methane synthesis reactor 140, in the process comprising delivering of carbon dioxide from the storage tank 121 to the synthesis reactor, delivering hydrogen from the electrolyser 150 to the additional methane synthesis reactor 140, collecting methane and recirculating H₂O to the electrolyser 150 being a by-product of the conversion of carbon dioxide into methane. Oxygen emitted in the electrolysis process may be directed directly to the gasifier chamber 110 (as the gasifying agent) or accumulated in the storage tank 151.
Therefore, the second operating mode of the system enables transformation of excess electrical energy from the renewable sources into hydrocarbon fuel such as methane, which can be stored and used for producing electrical or thermal energy according to needs. Moreover, application of such circulation enables transformation of environmentally harmful carbon dioxide into useful fuel (methane), therefore it assures reduction of carbon dioxide emission to the atmosphere.
The third operating mode allows production of heat for the purposes of district heating in case of lack of other source of fuel, such as biomass or coal. In the third operating mode the gasifier 110 is not operating, whereas the heat is generated in the process of combustion of methane in the reactor 120. The third operating mode comprises: delivering methane and oxygen (if it is present in the storage tank 151) to the chamber of the reactor 120 with the catalytic packing or (in case of lack of oxygen in the storage tank 151) delivering air to the reactor chamber, methane combustion and optionally accumulation of heat generated in the process of carbon dioxide combustion in the storage tank 121. The combustion heat is collected from the reactor heat exchange system and is transferred for example to the district heating network by means of the main heat exchanger 160.
The operation of the system in the third operating mode provides reduction of carbon dioxide emission. Carbon dioxide, which is emitted in the process of methane combustion, may be in this operating mode partially or fully stored in the storage tank 121, depending on the needs of the system 100, whereas the remaining part of carbon dioxide that is not stored is emitted to the atmosphere. Therefore, the third operating mode enables the system 100 to operate in reduced or complete lack of carbon dioxide emission to the atmosphere.
In the fourth operating mode of the system, the gasifier 110, the reactors 120 with the catalytic packing and the methane synthesis reactors 130, 140 are not operating. Heat in the amount of approximately 30% of supply energy is obtained in the process of H₂O electrolysis powered by electrical energy obtained for example from renewable sources. Heat from the electrolysis process is collected by means of the electrolyser heat exchanger cooperating with, for example, the main heat exchanger 160, enabling delivery of thermal energy to the district heating network, whereas oxygen and hydrogen is accumulated in the storage tanks 151, 152. When the oxygen and hydrogen tanks 151, 152 are completely filled, the excess electrical energy from the renewable sources may be directly transferred to the main heat exchanger 160 and transformed into thermal energy by means of electrical heaters 161 of the main heat exchanger 160. The thermal energy produced in this way is directly transferred to the district heating network. The fourth operating mode may be used in case of a smog hazard, due to lack of carbon dioxide generation in this mode. Moreover, the process provides economically and environmentally sensible utilization of excess electrical energy generated during increased electrical energy production periods by solar cells or wind farms or other, not easily power-controllable sources, such as water power plants, of fermenters producing biogas.
Therefore the advantage of the combined system is the possibility of adjusting the operation of the system to the varying atmospheric conditions, varying thermal energy demands and hydrocarbon fuel (methane), with simultaneous constant reduction of carbon dioxide emission to the atmosphere.
Additionally, the combined system enables safe periodical stoppages of the gasifier, providing delivery of thermal energy during this period according to the operating modes of the system 100, which do not require its operation, which has a particular meaning during maintenance and cleaning of the device.
Moreover, the combined system according to the invention does not require to be stopped during the periods in which there is a lack of thermal energy demand—for example during summer months. During these periods, the system 100 may conduct methane production process, without the necessity to stop the operation of the system.

Claims

1. A combined system for producing fuel and thermal energy, the system comprising:

an a water electrolyser for producing oxygen and hydrogen in a process of water electrolysis;

a gasifier for producing a synthesis gas in a process of a gasification of carbon-based fuel in a presence of a gasifying agent;

a methane synthesis reactor for producing methane in a process of synthesis of carbon oxide produced by the gasifier and hydrogen produced by the water electrolyser;

a reactor with a catalytic packing for producing carbon dioxide in a process of a combustion of the synthesis gas produced b the gasifier and/or methane;

wherein the electrolyser comprises a heat exchange system connected with a heat exchanger.

2. The system according to claim 1, further comprising a carbon dioxide storage tank for carbon dioxide emitted in the process of combustion in the reactor with the catalytic packing.

3. The system according to claim 1, wherein the methane synthesis reactor (130) is further configured to produce methane in a process of synthesis of carbon oxide from the gasifier, carbon dioxide from a carbon dioxide tank and hydrogen from the water electrolyser;

4. The system according to claim 2, further comprising an additional methane synthesis reactor for producing methane in a process of synthesis of carbon dioxide from the carbon dioxide tank and hydrogen from the water electrolyser.

5. The system according to claim 1, further comprising an oxygen storage tank for oxygen and a hydrogen storage tank for hydrogen produced in the water electrolyser.

6. The system according to claim 1, wherein the heat exchanger comprises an electrical heater for converting electrical current into thermal energy.

7. A method for producing fuel and thermal energy, the method comprising:

providing a system comprising:

a water electrolyser for producing oxygen and hydrogen in a process of water electrolysis;

a methane synthesis reactor for producing methane in a process of a synthesis of carbon oxide produced by the gasifier and hydrogen produced by the water electrolyser;

a reactor with a catalytic packing for producing carbon dioxide in a process of a combustion of the synthesis gas produced by the gasifier and/or methane;

wherein the electrolyser comprises a heat exchange system connected with a heat exchanger;

producing fuel and thermal energy in at least one of at least two operating modes:

in a first operating mode, comprising conducting a process of carbon-based fuel gasification in the gasifier with emission of the synthesis gas, which is combusted in the reactor with the catalytic packing with the emission of carbon dioxide and water, wherein heat resulting from the process of the combustion taking place the reactor with the catalytic packing is delivered to a heating network by means of the heat exchanger;

in a second operating mode, comprising enriching carbon oxide from the gasifier with hydrogen produced in the electrolyser and producing methane in the methane synthesis reactor.

8. The method according to claim 7, further comprising producing fuel and thermal energy in a third operating mode by combusting methane produced in the methane synthesis reactor in the reactor with the catalytic packing, wherein the heat from the process of the combustion is delivered to a district heating by means of the heat exchanger.

9. The method according to claim 7, further comprising producing fuel and thermal energy in a fourth operating mode by supplying the electrical heater of the heat exchanger with electrical power from an electrical grid.

10. The method according to claim 7, comprising producing methane in an additional methane synthesis reactor in a process of a synthesis of carbon dioxide produced in the reactor with the catalytic packing and hydrogen produced by the water electrolyser.

11. The method according to claim 7, comprising supplying the electrolyser with electrical power from renewable sources.

12. The method according to claim 7, comprising supplying the electrolyser with excess electrical power occurring in electrical grids due to the operation of uncontrollable renewable energy sources.