EP2836575A1

EP2836575A1 - Storing power plant

Info

Publication number: EP2836575A1
Application number: EP13716185.7A
Authority: EP
Inventors: Karl-Werner Dietrich
Original assignee: Individual
Current assignee: SHIFTPOWER UG
Priority date: 2012-04-10
Filing date: 2013-03-12
Publication date: 2015-02-18
Also published as: CN106967467A; CN104334695A; WO2013152748A1; CN107461606A

Abstract

The inevitable surpluses of wind and solar power and the supply shortages that alternate with these surpluses, together with the inadequate suitability of electrical energy for storage, are the greatest obstacles to overcome for the introduction of renewable energy sources. The present application describes a method for generating and storing electrical energy in which synthesis gas is burned in a power plant to generate electrical energy in a power supplying phase and synthesis gas is converted with additional hydrogen into methane in a storage phase and the methane produced is introduced into the natural gas network and stored in the natural gas network, wherein the hydrogen additionally required for forming methane from synthesis gas is obtained by electrolysis of water. The synthesis gas is preferably produced by gasifying coal or coke. The method described uses coal and surplus wind and solar energy to make methane that has little impact on climate change. This methane is a hybrid methane, in which the carbon may be of fossil origin and the hydrogen originates from wind and solar energy. The overall effect is that electrical energy is drawn from the power network, and the methane produced from it with the addition of coal, which has the properties of natural gas, is fed into the gas network. The methane or equivalent thereof of natural gas that is fed in during the storage phase can be drawn again from the natural gas network in the power supplying phase and converted back into electrical energy in a gas power plant.

Description

Power Station

The natural and forcible surpluses of wind and solar power become the biggest problem on the way to the energy transition. Now it is already clear that with 5 electrotechnical means a solution can not be found. As a way out, the production of hydrogen by water electrolysis from excess electrical energy is becoming more and more important.

The hydrogen can be introduced into natural gas and placed on the market in mixture with natural gas. And here comes the next problem: Hydrogen and natural gas differ fundamentally in their physical and fire properties. Natural gas has eight times the density, three times the calorific value, and consumes four times more oxygen during combustion. 5A fluctuating wind or solar current then results in a fluctuating hydrogen flow after electrolysis and, inevitably, after introduction into natural gas, a fluctuating gas mixture. The storage, transport and use of such hydrogen / natural gas mixtures are described in the published patent applications DE 10 2010 020 762 A1 (transport and stabilization of renewable energies) and DE 10 2010 031 777 A1 (hydrogen storage in natural gas deposits). Although there is a viable way to stabilize renewables, there are still significant market barriers for such fluctuating gas mixtures.

Another way of bringing hydrogen into circulation is the chemical conversion of carbon dioxide to methane. Methane is almost identical to natural gas and can be fed into the gas network without any problems. Numerous projects deal with this topic. The carbon dioxide used in this case comes either from the flue gas separation in coal power plants or from the Kohl endioxidabtrennung to biogas plants. The removal of carbon dioxide from biogas does not provide a sufficient raw material basis and the flue gas separation combined with the subsequent storage of carbon dioxide (CCS) has an uncertain future due to a lack of acceptance among the population.

As an economic alternative to the use of excess renewable energy, traditional reactions from coal chemistry have been identified. Thus, coal reacts with water (carbon and water in the molar ratio 1: 1, reaction equation 1) under pressure and heat to carbon monoxide and hydrogen. The equimolar gas mixture of hydrogen and carbon monoxide is used in the called "synthesis gas". If one adds another 2 mol of hydrogen to the synthesis gas, obtained by water electrolysis from wind or solar power (equation 3), then in a reaction named after the chemist "Sabatier" methane and water in a molar ratio of 1: 1 (equation 2).

5

Reaction equation 1.) C + H20 = CO + H2

Reaction equation 2.) (CO + H2) + 2 H2 = CH4 + H20

Reaction Equation 3.) 2 H20 = 2 H2 + 02 The method described converts coal and excess wind and solar energy into climate-friendly methane. This methane is a hybrid methane in which the carbon can be of fossil origin and the hydrogen comes from wind and solar energy. In the balance sheet, electrical energy is taken from the electricity grid and the methane produced therefrom with the addition of coal, which has the properties of natural gas (referred to below as "hybrid methane"),

15 fed the gas network. Carbon is the carrier of stored energy.

As can still be seen, the synthesis of the hybrid methane (reaction Equations 1 to 3) in combination with its power generation / combustion (reaction equation 4) results in a storage power plant. The co-firing of the synthesis gas with natural gas (equation 5) results in important synergies.

Reaction equation 4.) CO + H2 + 02 = CO 2 + H 2 O

Reaction equation 5.) CH4 + 202 = C02 + 2 H20

251 in the following text will be repeated on the reaction equations 1 to 5 shown above with the abbreviations Rk.l. to Rk.5. related (installation at the shot of the description).

Besides coal, it is also possible to use carbon compounds, preferably of vegetable origin, for the preparation of the synthesis gas. Plant materials such as e.g. Wood consists largely of carbohydrates, in which the carbon also reacts with water to form hydrogen and carbon monoxide.

Due to the toxicity of carbon monoxide, the synthesis gas containing carbon monoxide has to be generated in parallel with the electrolysis of water in the amount (stoichiometric) predetermined by reaction equation (2). Larger accumulations of carbon monoxide or even its storage in carrying out reactions 1 and 2 are to be avoided for the protection of the population. The present invention thus provides a process for the production of methane from excess electrical energy and carbon, wherein the electrical energy is removed from the mains and converted into hydrogen by electrolysis of water, the hydrogen 5 mit Carbonmonoxid, by reacting coal or carbon compounds with water vapor in stoichiometric amount is produced directly as synthesis gas, reacting to form methane and the methane is fed into the natural gas network.

To prevent carbon monoxide from entering the gas network, it is important to ensure that all carbon monoxide has reacted to hybrid methane or that carbon monoxide has been separated from the hybrid methane before it is introduced. It is recommended to check the hybrid methane for unreacted carbon monoxide before it is introduced into the network.

Full conversion of carbon monoxide to hybrid methane can also be promoted by using a slight excess of hydrogen. The excess hydrogen could remain in the hybrid methane. Up to 5% (10% are planned in the future) According to the current standard, hydrogen may be introduced into the natural gas grid together with the methane.

The present invention thus further provides that the 20-hybrid methane to be introduced into the gas network is mixed with up to 10% of hydrogen.

With the method according to the invention, large amounts of excess wind or solar power should be taken from the power grid with the addition of coal in methane überfuhrt and this can be introduced into the natural gas grid. This not only requires a correspondingly large system capacity, but also corresponding connections to the electricity and gas grids. Taking into account the required capacity, this would be the high-pressure network (gas grid) for electricity connected to the high-voltage grid and for gas. This in turn requires, in addition to the corresponding supply lines, investments in current transformers and gas compressors.

30This additional investment can be omitted if the plants for the process according to the invention are coupled to a gas-fired power plant. In a gas-fired power plant, there are connections to the high-voltage grid as well as to the natural gas grid. In addition, the transformers can be used to clamp the electrical energy from the turbine into the high-voltage grid, the energy in the other direction, from the high-voltage grid to the electrolysis. Such a "hybrid storage plant with conversion of coal (carbon) into methane" then consists of the following units, in which the reactions in brackets Rk.l. to Rk.5. occur:

1. Power station / gas-fired power station (optional Rk.4 and / or Rk.5.)

2. Plant for coal gasification and production of the synthesis gas (Rk.l.)

3. Electrolyser for converting electrical energy into hydrogen (Rk.3.)

4. System for the hydrogenation of carbon monoxide to hybrid methane (Rk.2.)

5. Connection to the high voltage network with transformer

6. Connection to the natural gas network

With such a system, the two greatest challenges of the energy turnaround can be met alternately in different operating phases: the use of excess electricity and the stabilization of the power grid with unsteady power supply.

• In the one (in the disclosure, the first) phase of operation, the gas power plant (1) is operated to bridge nature supply gaps occurring in wind and solar power or generally for grid stabilization. Hybrid methane or its equivalent of natural gas or synthesis gas is taken from the gas network (6), emitted and electrical energy (via the transformer) in the power grid (5.) initiated. The system components 2 to 4 are not in operation.

• in the other (in the disclosure the second) operating phase (excess) electrical energy is taken from the mains (5.) and converted into 3. in hydrogen. The hydrogen reacts in 4. with that in 2. e.g. Synthesis gas produced from coal for hybrid methane according to the invention. Electricity is taken from the electricity grid (5.) and hybrid methane is fed into the natural gas grid (6.). The plant part 1. (gas power plant) is then not in operation.

In this sequence of operating phases, the hybrid methane, in which the excess electrical energy gives the extra fuel value to the coal, is first stored in the gas network, and its equivalent of natural gas is excreted in the gas power plant when needed. This is the most important feature of a storage power plant to store unused energy and give it back when needed. The entire plant is a hybrid storage power plant; because only half of the hybrid methane stored in the gas network is excess stored energy (the other half comes from the coal). The advantage of the gas network as storage is its enormous storage capacity.

The subject of the present invention is thus a hybrid storage power plant which comprises the abovementioned plant parts 1 to 6 and in which the gas and electricity flow takes place alternately in both directions in the plant parts 5 and 6 and which uses the natural gas network as storage. The system components 1 to 4 are switched on or off depending on the requirements and the resulting operating phase. This requires a high degree of flexibility in the implementations taking place in these plant components. This flexibility is given in the gas-fired power plant (1st) and water electrolysis (3rd). The hydrogenation of carbon monoxide (4.), which proceeds in the 5Gasphase nickel catalysts can be switched on and off according to the requirements.

From experience, flexibility does not apply to coal gasification and the production of carbon monoxide (2.). Although this part of the plant can be throttled in performance, it is not possible to display and switch off, in addition to the electrolysis (3.) and the carbon monoxide hydrogenation (4.). Especially as an accumulation of the most important intermediate, the carbon monoxide, as already mentioned must be avoided.

This shows now another advantage of the coupling according to the invention of the system parts 2 to 4.

15 with a power plant (1.): The synthesis gas produced in 2. has almost the calorific value of fluorescent gas and can there in the operating phase of the gas power plant either alone (Rk.4.) Or together with natural gas (Rk.5.) Are exuded. Thus, the plant part 2, which is used to produce the synthesis gas, can be operated in both operating states mentioned above and used alternately both for producing electrical energy in the gas power plant (Rk.4) and for producing the hybrid methane (Rk.2) ,

In a variation of the first phase of operation, therefore, the gas power plant (1) is operated together with the plant for coal gasification and production of the synthesis gas (2) for network stabilization and the synthesis gas flows out. In addition, you can remove natural gas from the gas network, 25 if necessary mix with the synthesis gas, the mixture flow and introduce the electrical energy into the power grid. The system parts 3. and 4. are not in operation.

Another object of the present invention is therefore the alternative use of the synthesis gas, on the one hand as a fuel gas, optionally together with natural gas or alone for 30 power generation in the gas power plant in the first phase of operation, on the other hand for the production of hybrid methane together with in the electrolyzer from electrical energy recovered hydrogen in the second phase of operation. This means that coal gasification remains in operation in both operating phases.

Another synergetic effect in the coupling of the inventive production of hybrid gas from excess renewable energy and coal with a gas-fired power plant lies in the preparation of the feedwater for the electrolysis: The condensate from the combustion gases of the synthesis Gases is water from the reaction of hydrogen or methane with oxygen (Rk.4 or Rk.5.). This water is naturally salt-free, as it is needed for water electrolysis. One mole of hydrogen produces one mole of water. The second mol of water required for the formation of 2 moles of hydrogen in Equation 3 can be obtained by drying the hybrid methane 5 (Rk.2) as also salt-free condensed water. Purely mathematically, salt-free feed water for the electrolysis and the inventive production of methane from wind and solar power is thus obtained in the overall process. If natural gas is burnt, 2 moles of water can be condensed (Rk.5.), Which give the required amount of water in Rk.3. Depending on the degree of efficiency, water electrolysis produces 200 to 250 cubic meters of hydrogen gas from one megawatt of electrical energy. In this case, 160 to 200 liters of salt-free (distilled) water are consumed. Assuming that a 100 MWh gas-fired power plant is to be coupled to a plant for receiving the same amount of excess electrical energy, a demand of 16,000 to 20,000 liters of distilled water per hour for the electrolysis is calculated. This shows that the procurement of feedwater for electrolysis is a significant cost and energy factor.

The condensate from a gas-fired power plant is a suitable starting product for a cost-effective feedwater treatment for water electrolysis. By nature, it is salt-free but slightly acidic (pH = about 4.5) due to low concentrations of carbonic acid and low sulfuric acid and sulfuric acid. Carbonic acid can be expelled and the (trace) mineral acids can be separated with anion exchangers.

Additional condensate can be obtained from gas heating systems5 (condensing heating) according to the same principle. For heating systems with more than 60 kW of power, depending on local regulations, the condensate may only be discharged into the sewage system after chemical neutralization. It should therefore be worthwhile to collect the condensate from heating systems and to provide for the erfmdungsgemäße process. 0Synthesis gas needs special treatment if it is burned together with natural gas in a gas-fired power station and the condensate is to be treated as feedwater in the same way. The coal, raw material for the synthesis gas contains namely up to 4% of sulfur compounds, which must be separated. Methods for binding sulfur from coal gases are known. An example is the coal gasification in the presence of iron oxides. The purification of the synthesis gas is also important because the hybrid methane produced from it is to be fed into the gas network and the natural gas located there has a high purity standard. It can also be advantageous to separate synthesis gas and natural gas in the gas power plant separately and to use only the condensate (2 mol H20!) Of purer natural gas for electrolysis (see .Rk.3 and Rk.5.)

The present invention thus also relates to the use of collected condensates and condensates of the natural gas combustion in the gas power plant (1) as feed water for the electrolysis of water (3). The condensate (H20) from Rk.2. and Rk.4. or from Rk.5. delivers exactly the amount of water required for electrolysis (Rk.3.) and subsequent hydrogenation (Rk.2.).

With the method according to the invention is in the synthesis part of the plant parts 2nd to 4th from coal or carbon compounds with wind and solar energy, the hybrid methane, which is comparable to the climate-friendly natural gas. With the integration of this process into the energy transition, the hybrid gas gradually displaces the natural gas in the network and becomes independent of gas imports.

15The synergies that occur during the merger of gas power plant with coal gasification, water electrolysis and carbon monoxide hydrogenation are in detail:

• It is advantageous in terms of production technology when coal gasification (production of synthesis gas, Rk.l.) is carried out in a continuous process. This means that the synthesis gas is used both for the production of the hybrid methane in the second operating phase (Rk.2.) And for the power generation in the gas power plant (Rk.4.) In the first operating phase.

• In the electrolysis of water (Rk.3.), In addition to the hydrogen in the synthesis gas, 2 mol of water are required for the required amount of hydrogen in the hydrogenation (Rk.2.). One mole of H 2 O can be separated and stored directly in Rk 2 in the second phase of operation. Another mole can be condensed in the first phase of operation from the flue gases of the gas power plant and stored 5. That the hydrogen for the construction of the hybrid methane comes from condensation of the plant parts of both operating phases. By connecting the plant parts 1 to 4 with each other, the amount of water required for the chemical composition of hybrid methane (stoichiometrically) can be collected and stored

• Both the natural gas connection with supply line and the high-voltage line with connection 30 to the power grid can be used in different operating phases in different directions and thus from all parts of the system. Both the natural gas pipeline and the connection to the high-voltage grid are shared by the plant components.

• Power plants have an extensive capacity of transformers to transform the electricity (in the first phase of operation) from the turbines into the high voltage grid. The same

In the second phase of operation, transformers can be used to convert the electrical energy from the high-voltage network for the electrolysis of the second phase of operation into lower voltage. The result is a hybrid storage power plant. Hybrid storage power plant because part of the energy is introduced by the excess electrical energy and part of the energy through the coal in the hybrid methane. This hybrid methane is fed into the gas network and can be withdrawn from the gas network if necessary. The gas network is a storage of the 5Hybrid storage power plant. Another store is the feedwater tank.

To consider the economics of the hybrid storage power plant according to the invention, e.g. 1 million KW of excess electrical energy with the addition of about 80 tons of coal in about 130000 cubic meters of hybrid methane transferred, which (at 65% efficiency of the gas power plant lOmit condensation) to 850000 kW of electrical energy for peak demand with then corresponding added value to be converted (efficiency without Coal: 85% / see below).

Due to the nature of renewable energies, their continued proliferation will continue to be either too much or too little energy in the electricity grid. Then the two phases of operation will alternate. Inexpensive and abundantly available coal can take over the stabilization of the power grid. However, not coal, but climate-friendly natural gas (hybrid methane) is emitted.

To improve the ecological balance, gradually increasing amounts of hydrogen, which is diverted after electrolysis (3.), can be added to the hybrid gas introduced into the natural gas network. The addition of hydrogen 10% in natural gas is possible according to the latest standard.

Advantageously, the oxygen formed in the electrolysis of water (Rk.3.) Collected, stored and used in the combustion of the synthesis gas (Rk.4.) Or the natural gas / methane (Rk.5.) Instead of 25 combustion air. In the absence of atmospheric nitrogen, this prevents the formation of nitrogen oxides during the combustion process. Nitrogen oxides are far more climate-damaging than carbon dioxide. The oxygen accumulates as a gas in pure form during electrolysis and can be stored for storage e.g. be liquefied.

When pure oxygen is used during combustion, the higher energy density of the combustion gases results in a significantly higher combustion temperature. Although this is favorable for the achievable efficiency, but materials can reach the limit of their thermal capacity. Here, the addition of water, preferably from the condensate, to control the combustion temperature is recommended. Both the water and his

Evaporation energy can be recovered during condensation following combustion. In the same sense can be used as inert gas and separated from flue gases carbon dioxide be used. In this case, carbon monoxide contained in the combustion gases can be recycled.

If the synthesis gas is incinerated in the first phase of operation, then this part of the overall process 5 is coal-fired from the point of view of carbon dioxide emission. However, the life cycle assessment of the process, which claims to convert coal into climate-friendly methane using excess energy, is only marginally deteriorated if predominantly natural gas / hybrid methane is used in the first phase of operation (in the gas-fired power plant). In addition, experience has shown that, in general, the generation of electricity from gases is more efficient than the conversion of solids such as coal.

On the other hand, the life cycle assessment in the process according to the invention can be achieved by the (partial) use of biomass, e.g. Wood, to be improved in coal gasification (2nd). Wood as a carbohydrate can also be converted to Rk.l in synthesis gas. After methanation with hydrogen, biomethane is formed. An improvement in the ecological balance is also caused by the addition of hydrogen to the methane introduced into the network. Hydrogen burns completely emission-free.

The production of climate-friendly hybrid methane from excess renewable energy and coal makes the energy transition more affordable. It makes countries with coal reserves of gas imports more independent. The "hybrid coal-fired power plant with excess electrical energy" is by far the most economical way to stabilize renewable energies.

The economic significance of the method according to the invention can be seen from the following rough approximate estimate; From 1 million KW of excess electrical energy, 135,000 cubic meters of hybrid methane are recovered. Reconverted as hybrid methane or as natural gas equivalent gives about 850000 KW. (see "electrochemical model calculation" at the end).

The carbon for the hybrid methane is 60 to 80 tons of coal. That With the use of approx. 70 30to coal, 1 million KW of surplus energy will time-shifted 850000 KW of higher-value energy for demand peaks.

Excess electrical energy is also generated in all inflexible types of power plants such as coal and nuclear power plants, if the power grid can not absorb any additional power due to excess power from the power plant. A state that suffers from the economic efficiency of large power plants and that becomes even more critical with the spread of renewable energies, as renewable energy sources are becoming increasingly scarce Power grid have priority. It is foreseeable when only too much or too little power is left in the network.

Such inflexible power plants can be replaced by a hybrid storage power plant according to the invention. Then, on the one hand, hybrid methane can be produced from excess energy and introduced into the gas network and, on the other hand, gas can be emitted for peak demand in the gas power plant. The (main) power plant can then go through in the optimum range of effectiveness. Optionally, the synthesis gas can also be burned in the combustion chamber of the (main) power plant.

For existing power plants, the output voltage on the generator is on the order of 5000 volts. The input voltage of conventional devices for water electrolysis is 200 to 300 volts and results from the series connection of several cells, each with 2.2 volts. The number of cells connected in series is limited by the need to switch off and repair the entire device if only one cell is disrupted. A much larger number of electrolysis cells would be permissible if one connects several blocks with the same number of cells in the back and holds an additional block. If one of the blocks in operation then fails, then the prepared additional block can be switched on and the defective block is switched off and repaired. So a water electrolysis can be operated safely even with comparatively high voltage. The input voltage from the electrolyzer is thus adapted to the power plant generator and the transformer to the high voltage network can be used by both devices in both phases of operation. Of course, a voltage difference between generator and electrolyzer (and thus also to the main transformer) can also be bridged by a switched-on transformer.

A particularly advantageous location for a hybrid storage power plant would be in the vicinity of a lignite power plant. There lignite is available directly and in the foreseeable increasing demand for storage power plants, the energy production and thus also the use of lignite from the lignite-fired power station could be shifted train by train to the hybrid storage power plant. This would end the controversial combustion of lignite and still promote and use lignite as the most economical source of energy and would even have an important function in the energy transition. The ecological spell is taken from the coal.

Overview of Chemical Reaction Equations (Rk.1 to Rk.5.)

Rk.1.) C + H20 = CO + H2

Rk.2.) (CO + H2) +2 H2 = CH4 + H20

Rk.3.) 2H20 = 2H2 + 02 Rk.4.) CO + H2 + 02 = C02 + H20

Rk.5.) CH4 + 202 = C02 + 2 H20

Rk.6.) C02 + 4H2 = CH4 + 2H20

Overview of the individual plants of the hybrid storage power station (in parentheses the above reactions Rk.l. to Rk.5 belonging to the respective plant)

1. Power station / gas power plant (Rk.4 and / or Rk.5.)

2. Plant for coal gasification and production of the synthesis gas (Rk.l.)

3. Electrolyser and rectifier for converting electrical energy into hydrogen (Rk.3.)

4. System for the hydrogenation of carbon monoxide (or carbon dioxide) to hybrid methane (Rk.5, u.6.)

5. Connection to the high voltage network and transformer (Rk.4./5. Or Rk.3.)

6. Connection to the natural gas network (Rk.5 or Rk.2.)

Memory and storage media

The most important storage is the gas network with hybrid methane as the storage medium. If necessary, then the stored hybrid methane or its equivalent of natural gas in the gas network can be reconverted. This reconversion takes place preferably in a hybrid power plant associated with the gas power plant. The synergies occurring in this combination of plants are described in detail above. However, the reconversion may also be at a more remote location, with the hybrid methane or its equivalents of natural gas removed from the gas network.

The carbon dioxide can also be separated from the flue gases and stored or sequestered. If oxygen from the electrolysis of water is used instead of air during combustion, the carbon dioxide remains as gas after condensation of the water. If the carbon dioxide is also liquefied, the carbon monoxide which is unavoidable during coal combustion remains, which can be returned to the burner and thus does not escape into the environment. Another storage medium is the feed water for the electrolysis, which is obtained as condensate from the flue gases of / gas power plants. If the gas power plant connected to the hybrid storage power plant, the feedwater can be collected on site, prepared and stored with appropriate capacity in the tank. From more distant gas power plants, the condensed water collected there would then have to be transported to the hybrid storage power plant in tankers. Condensates from condensing boilers could then also be included in these transports. Collection and storage of the condensate from the natural gas / hybrid gas combustion is therefore an object of the invention, because with the amount of decay of the hybrid methane from Synthesis gas is allowed (Rk.2, Rk.3 and Rk.5.). The condensate from the combustion of natural gas is preferable because of its greater purity to the condensate from the combustion of coal-derived syngas to be used according to the invention for water electrolysis.

5

Synthesis gas / manufacture and use

The synthesis gas is produced in the first stage of the "Fischer-Tropsch process" from carbon and water vapor at high temperatures (Rk.l.). Depending on the quality of the coal or carbon compound, it contains as its main component carbon monoxide and hydrogen and optionally lOMethan. It is also possible to heat the coal to 1000 ° C to 1300 ° C in the absence of air to obtain coke, i. purer carbon, which is converted to the synthesis gas. In addition, about 1 to coal each about 300 cubic meters of gas, a gas mixture with about 50% hydrogen and 30% methane as main components, which can be fed directly into the gas network or in Rk.2. As a further byproduct of coking the coal is produced

15sog. "Coal tar", a mixture of aromatics The coal tar was historically the springboard of the chemical industry. If the process according to the invention removes the ecological ban from the coal, numerous chemical intermediates can be recovered in the coal utilization according to the invention and the dependence of the chemistry on the petrochemicals is reduced.

20

In both cases, the production of the synthesis gas, which also includes its purification, a complex, continuously running process in which prohibits a continuous on and off in the changing phases of operation of the storage power plant. It is therefore a particular object of the present invention that the synthesis gas is used in both operating phases in different uses (in the first operating phase according to Rk.3 and in the second operating phase according to Rk.4.).

If the hybrid storage power plant provided a coal power plant, so in the second phase of operation, the syngas can also be injected into the focal point of the coal power plant 0und so exuded. With an additional gaseous fuel, higher power is available much faster for peaks in demand So you can gain flexibility even with a coal-fired power plant.

The reaction of the synthesis gas to hybrid methane (Rk.2.) Is carried out in a reaction according to the chemist 5 "Sabatier", in which carbon monoxide is hydrogenated on nickel or iron catalysts with hydrogen to methane, The chemical reaction is exothermic and can in a Refinement of the method according to the invention can be used thermally, whereby the efficiency of the reconversion can be further increased.

When the reaction procedure in Rk.3 is changed, it is also possible to obtain long-chain hydrocarbons which are suitable as fuels for motor vehicles.

Synthesis gas / electricity / storage of carbon dioxide

Generating electricity from the synthesis gas means its direct or indirect thermal utilization for the purpose of generating electrical energy.

The carbon dioxide formed in the operating phase of the conversion of the synthesis gas can also be stored or sequestered. In this case, for example, after the condensation of the water formed during the combustion of the hydrogen, the carbon dioxide is separated by pressure liquefaction from the flue gases. If the oxygen produced during the electrolysis of water is used instead of air for combustion, carbon dioxide, which can be stored directly, remains as the only gas after the condensation of water.

In the generation of electricity from the synthesis gas, in addition to its direct combustion, the carbon monoxide can also be converted into carbon dioxide and further hydrogen with steam. Then the carbon dioxide is stored and subsequently only hydrogen is burned. This hydrogen can also be methanized in the same way as hydrogen obtained from the electrolysis. This is done by reacting the hydrogen either with stored carbon dioxide (Rk.6.) Or with synthesis gas carbon monoxide (Rk.2.). To the latter, the synthesis gas can be divided, with one part reacting as above to hydrogen and carbon dioxide, and the other part of the synthesis gas then reacting with hydrogen to form methane (Rk.2). This produces also in the operating phase of the power generation of the synthesis gas methane, which can alternatively be stored for direct combustion / electricity generation.

In summary, the synthesis gas can be emitted / burned as such, as hydrogen or as methane. In all three variants, the carbon dioxide can be separated and stored as described.

The transfer of the synthesis gas in methane, even in the operating phase, in which its power is otherwise pending, is recommended when at the site of the hybrid storage power plant electrical energy is not needed and also can not be derived. If the synthesis gas is obtained from biomass (for example wood) in the process according to the invention, the carbon dioxide which the plants had taken from the atmosphere is stored in the soil in the operating phase of the power generation during sequestration and excess in the operating phase of the storage Energy is generated by biomethane.

Detection of the bio-fraction in the gases carbon dioxide and methane

Depending on their origin (biological or fossil), the gases formed as end products carbon dioxide and methane are either taxed or financially supported (for example biomethane). It is therefore important, if e.g. changing proportions of wood with coal are gasified according to the invention, the organic content in o.g. To determine gases.

This can be done by means of the known from archeology Radiocarbon method (C14 method). It is assumed that the biomass used and thus formed biomethane with respect to the C14 isotope content has the initial value, while fossil carbon does not contain C14. The same applies to carbon dioxide. The measurement can be carried out on the gases according to the so-called "counting tube method according to Libby".

Electrochemical model calculation for the production of hybrid methane from (excess) electrical energy and coal:

Starting with Rk.3. (Water electrolysis) are required for one cubic meter of hydrogen (H2) with an assumed efficiency of 80% 4.2 KW. According to Rk.2. In addition to the hydrogen of the synthesis gas further 2 moles of hydrogen (H2) are required for the production of hybrid methane from carbon monoxide. It follows that per cubic meter of synthesis gas produced hybrid methane (CH4) about 8.4 KW of electrical energy are needed.

It is believed that the carbon for the hybrid methane is derived from coal. Methane consists of 75% carbon (molecular weight methane: 16, atomic weight carbon: 12). The gas density of methane is 718g / cubic meter. It is calculated that 1 cubic meter of methane contains 539g of carbon. Coal carbon content of 65% to 90% (depending on the grade of coal) requires 580g to 830g of coal per cubic meter of hybrid methane.

In summary, 8.4 KW (excess) electrical energy and 580 g to 830 g (dry) coal yield one cubic meter of hybrid methane, which is comparable to natural gas of H quality. Back-flowed, the cubic meter of hybrid methane would deliver 7.5 KW (energy content of hybrid methane 11.5 KW / efficiency of the gas power plant 65%). If we exclude the use of (580g) coal, the efficiency of the reconversion is 87%.

Generating the synthesis gas / stabilizing the hydrogenation of carbon monoxide In the power conversion phase, the synthesis gas is converted by combustion in the power plant into electrical energy. The conversion of the synthesis gas can take place in a coal or gas power plant. In the gas power plant, natural gas can also be emitted, depending on the need for electrical energy.

5

The power phase is naturally associated with a stoppage of energy storage. However, the energy storage of the present invention, like coal gasification, is a chemical process involving carbon monoxide. It is therefore advantageous to continue the hydrogenation of carbon monoxide to methane even in the power phase, albeit at a lower power, 10.

This can be achieved without additional hydrogen from the electrolysis of water by hydrogen is separated from the synthesis gas and 2 moles of the separated hydrogen according to equation 2 with one mole of hydrogen and one mole of carbon monoxide from the synthesis gas to methane to be implemented. Thus, in the power conversion phase, the methane formation can be continued in a low power range. Remaining carbon monoxide or carbon monoxide-enriched synthesis gas is then discharged from the power plant according to the invention. Further, when the carbon monoxide hydrogenation is shut down, if unreacted carbon monoxide occurs in the methane, the reaction mixture may be temporarily burned in the power plant. This prevents carbon monoxide from entering the gas network (as a safety precaution, this can generally happen when carbon monoxide is present in the end product methane). Since the shutdown of the carbon monoxide hydrogenation with the beginning of the electricity phase

If it is connected, additional fuel may be welcome. This is another synergy in the coupling of power plant and carbon dioxide hydrogenation.

Electrochemical model calculations / reconversion

Relationships between energy, mass and volume, which result from the chemical laws, are described below. The calculations are based on syngas as an equimolar mixture of hydrogen and carbon monoxide. Depending on the raw materials (coal, biomass) and their gasification method, the mixing ratio may change. In addition, pre-formed methane may be present in the synthesis gas. Storage phase: energy / mass / volume (rounded)

Reference value of the electrical energy to be stored: 1 million KW

By electrolysis of water from 0. 8 1 water and

4.2 KW (80% efficiency) 1 cbm hydrogen.

5 According to Rk.2 u. 3. give 2 H2 (with syngas) 1 CH4.

That one cubic meter of methane binds 8.4 KW / 1 million KW yielded: 120000 cbm Methan be added 600g to 800g coal / cbm Methane: approx. 85 to coal memory

Only the condensation from the flue gas separation must

be stored (second operating phase).

0.8 x 2 x 120000 = 192000 1 water for natural gas combustion: 192 cbm of water

0.8 x 1 x 120000 = 96000 1 water with synthesis gas combustion: 96 cbm of water

The second storage, the gas network has for all conceivable situations

sufficient capacity.

15Rückverstromung

From 120000 cbm of methane will be at 65% efficiency

in the gas power plant about 850000 KW

Efficiency of the reconversion

(to 1 million KW without use of coal) 85%

0

Conclusions

■ Excess energy and coal produce methane, which can be stored in the gas network, transported and reconcooled with an efficiency of approx. 85% (electricity to electricity)

5 ■ In different operating situations, electric power is alternately absorbed and stored or released by the hybrid storage power plant.

■ The hybrid methane corresponds to H-quality natural gas.

■ 1 cubic meter of hybrid methane is made up of approx. 700g of coal and 8 KW of excess energy.

0 "The efficiency of the reconversion of stored energy (with the addition of 60 to 80 kg of coal per MW) Uegt at about 85% (75 to 90%, depending on the efficiency of the back-flow gas power plant).

■ The addition of coal more than doubles the efficiency of water electrolysis

^■ When biomass is used together with the electrical energy to be stored, the entire biological carbon is converted into biomethane (in biogas plants, carbon and methane together form 30 to 50% carbon dioxide). Also stored carbon dioxide can be reconstructed methane with hydrogen. However, compared to synthesis gas, carbon dioxide requires twice the amount of hydrogen for methanation. The mechanism of methane recovery from its flue gases is shown by the following equations:

A.) Combustion of methane CH4 + 2 02> C02 + 2 H20

B.) Electrolysis of water 4 H20> 4 H2 + 2 02

C.) Recovery of methane C02 + 4 H2> CH4 + 2 H20

From C.) it can be seen that in the recovery of methane from carbon dioxide 4 moles of hydrogen are needed, while synthesis gas for methane production only 2 moles of hydrogen are needed. Accordingly, the efficiency of the technology described above is "power to gas." The overall efficiency is then 35 to 40% (current to current).

According to the equations A. to C. can also be a chemical storage power plant. In this case, methane is burned / emitted in an operating phase for energy production (A.) and the carbon dioxide is separated from the flue gases and stored. In another phase of operation, excess energy stored is hydrogen obtained by electrolysis (B.) and the hydrogen hydrogenates the stored carbon dioxide to methane (C). Also the water from equation A. and C. can be separated by condensation and prepared for the feed water for the water electrolysis (B.). If one also stores the oxygen produced in addition to hydrogen in the electrolysis (B.) and uses it in the combustion of methane instead of the combustion air (A.), then the flue gases consist exclusively of carbon dioxide and water vapor and, after condensation of the water vapor, gaseous carbon dioxide can be stored directly , Carbon dioxide and water can also be stored as a mixture.

Another storage power plant is included in Equation B.). In this equation, in one phase of operation, one can run the reaction from right to left and burn / flow the hydrogen. The water formed is collected (after condensation) and stored. In the other phase of operation, the stored water is decomposed into hydrogen and oxygen by electrolysis with electrical energy to be stored, in equation B. the reaction proceeds from left to right. The hydrogen is stored and is available for the other phase of operation, combustion / power generation. Again, the oxygen can be stored and used in place of the combustion air. The use of pure Oxygen during combustion has the advantage that no nitrogen oxides are produced in the absence of atmospheric nitrogen.

Another object of the present invention is thus the electrochemical reconstruction 5von methane from its flue gases, characterized in that in a gas power plant, which is connected to a water electrolysis and hydrogenation of carbon dioxide in a first phase of operation with natural gas / methane removal from the gas network and its combustion in the power plant produces electrical energy and is introduced into the power grid and separated from the flue gases carbon dioxide, collected and stored and in a second lOBetriebsphase electrical energy from the mains of the water electrolysis is absorbed and hydrogen formed in the electrolysis of water in the first Operating phase collected and stored carbon dioxide hydrogenated to methane and the methane is introduced into the gas network.

Furthermore, water vapor can be condensed from the flue gases in the first phase of operation, stored and used as feed water for the electrolysis in the second phase of operation.

Furthermore, the oxygen formed in the second operating phase in the electrolysis of water in addition to hydrogen in the 0passenden amount can be stored and used in the subsequent first phase of operation instead of the combustion air. If pure hydrogen is then burned with pure oxygen, the flue gases consist of pure water, which can be stored and then fed directly to the electrolysis. If methane is burned with pure oxygen, the flue gases consist only of water vapor and carbon dioxide, which are separated, stored and reused.

In general, aqueous condensates which are obtained in the combustion of hydrogen or hydrocarbons from the flue gases (for example in condensing boilers) are suitable as feed water for the electrolysis of water.

30

The use of the oxygen collected and stored in the storage phase during the electrolysis offers the following advantages and possibilities:

1. In methane combustion with pure oxygen instead of the combustion air, the flue gases consist exclusively of water vapor and carbon dioxide. After condensation of the water vapor and separation of the condensate, carbon dioxide which can be stored remains as gas. This creates in the storage phase exactly the amount of oxygen that is required in the power phase for the combustion of methane. 2. As with 1., the combustion of syngas with pure oxygen also produces fumes of water vapor and carbon dioxide, facilitating the separation (and storage or sequestration) of carbon dioxide in the same way. If, after separation of the aqueous condensate, the carbon dioxide is liquefied (eg by pressure),

5 gases contained carbon monoxide, which boils almost 100 ° C lower than carbon dioxide and therefore remains in the gas phase, are returned to the combustion. By circulating carbon monoxide during combustion, it does not get into the environment. This also makes it possible to allow higher temperatures during the combustion of synthesis gas, which is thermo-dynamically desirable, but otherwise due to the then increasingly occurring carbon monoxide overeating is.

3. The use of pure oxygen is also advantageous in the combustion or conversion of hydrogen. The only "flue gas" is then water vapor, which can be stored and used directly in the storage phase as feed water for the electrolysis of water. Pure hydrogen and pure oxygen, as produced by electrolysis, give pure water, which in turn breaks down into pure hydrogen and oxygen, etc. The high energy density of the hydrogen-oxygen mixture may be added to steam during combustion for temperature control, where a steam turbine may be placed directly behind the gas turbine, then relaxed steam is returned to combustion and only the amount of water vapor is condensed, which is considered feedwater needed for the electrolysis.

04. In all three described applications, the pure oxygen during combustion causes (in contrast to the combustion with air) in the absence of atmospheric nitrogen, no nitrogen oxides.

5. If the synthesis gas according to the so-called. Oxy gasification (gasification of coal or carbon compounds with deficit of oxygen) produced, so here also the pure oxygen aus5der water electrolysis can be used. Since the oxygen is then used substoichiometrically, there is still oxygen left for storage for the electricity phase.

If the synthesis gas is obtained from biomass, the following advantages according to the invention result:

1. Upon combustion of synthesis gas from biomass, the carbon dioxide then sequestered was originally taken up by the biomass-forming plants from the atmosphere. That In the use of biomass according to the invention, the carbon dioxide content in the atmosphere is reduced.

2. In the storage phase, the entire bio-carbon of the synfhesase is converted to biomefan. That is almost double the biomethane yield compared to biogas plants.

53. When biomass is gasified in mixture with coal and these mixtures are seasonally fluctuating, the biocarbon in the sequestered carbon dioxide in the produced methane can be determined according to the radiocarbon method known from archeology.

Claims

claims

1. A method for generating and storing electrical energy, in which synthesis gas in a power plant is burned in a power plant for generating electrical energy and synthesis gas in a storage phase with additional hydrogen

5 implemented methane and the methane generated is introduced into the natural gas network and stored in the natural gas network, the hydrogen additionally required for methane formation from synthesis gas is obtained by electrolysis of water.

2. The method of claim 1, wherein the production of synthesis gas continuously passes through and Stromstromphase and storage phase alternate.

103. The method of claim 1 or 2, wherein continued during the Verstromungsphase methane production and for methane production additionally required hydrogen separated from a portion of the synthesis gas and the separated hydrogen reacted with the rest of the synthesis gas, the methane formed in the natural gas network and initiated Hydrogen depleted part of the synthesis gas for generating electrical energy in the

15 power plant is burned.

4. The method according to any one of claims 1 to 3, taken in the stored from the gas network methane or its equivalent of natural gas and reconverted in a power plant.

5. The method according to any one of claims 1 to 4, wherein the synthesis gas is produced by gasification of coal or coke.

206. The method according to any one of claims 1 to 5, wherein the synthesis gas is produced by gasification of biomass and in the storage phase, the biological carbon is converted to biomethane in total.

7. The method of claim 6, wherein in the production of synthesis gas from mixtures of fossil carbon and biomass, the proportion of biological carbon in the storage

25 phase is determined in the generated methane and / or in the power phase in the generated carbon dioxide by the radiocarbon method.

8. The method according to any one of claims 1 to 7, wherein in the combustion of hydrogen or methane formed water vapor is separated by condensation from the flue gases and the condensate is used as feed water for the electrolysis of water.

309. A process according to any one of claims 1 to 8, wherein carbon dioxide formed in the combustion phase of synthesis gas or methane is separated from the flue gases and stored.

10. The method according to any one of claims 1 to 9, wherein in the storage phase, the oxygen formed in addition to hydrogen in the electrolysis is collected and stored and is used in the power phase in the combustion in place of the combustion air.

11. The method of claim 10, wherein the existing exclusively of water vapor and carbon dioxide 5 flue gases are stored together or after removal of aqueous

Condensate remaining carbon dioxide is stored.

12. The method according to any one of claims 1 to 11, wherein in the occurrence of carbon monoxide in the flue gases after separation of the carbon dioxide and the water condensate gaseous carbon monoxide is returned to the gas combustion.

1013. Method for generating and storing electrical energy, in which, in a first operating phase, synthesis gas with additional hydrogen, which is obtained by electrolysis with electrical energy to be stored, is converted into methane and the methane generated is fed into the natural gas network; and in a second phase of operation, the methane fed in or its natural gas equivalent is taken from the natural gas network, and

15 is converted back to a gas power plant.

14. The method of claim 13, wherein the first phase of operation is performed at a different time or at a different location than the second phase of operation.

15. Storage power plant, comprising

1) apparatus for coal gasification ,;

20 2) power plant;

3) device for water electrolysis and rectifier;

4) Device for the hydrogenation of carbon monoxide;

5) Transformer with connection to the high voltage network;

6) Connection to the natural gas network.

2516. Storage power plant according to claim 15, in which the voltage of the device for water electrolysis is adapted to the voltage of the generator in the power plant and the transformer is used to high voltage network of both the electrolysis and the power plant, in which to achieve the voltage in the electrolysis, the electrolysis cells in blocks with the same voltage in series, and a block of electrolysis in reserve

30, which is interposed in the event of a fault in a block while the block with the fault is turned off and put into order.