DE102019005672A1 - Process for the emission-free generation of useful energy (electrical power, heating) by burning natural gas (methane) using a closed carbon cycle. - Google Patents

Abstract

Using natural gas (methane), useful energy is conventionally generated in CHPs. (el. electricity, heating). The CO2 is washed out of the engine exhaust gases and concentrated. This CO2 is used for the dry reforming of CH4. (1 mol CO 2/1 mol CH4). The resulting synthesis gas (2 CO +2 H2) is catalytically converted using a process named after Carl Bosch at 400 ° C C + H2O. The solid carbon is separated with hot gas filters, transported to sunny regions and hydrogenated there in two stages to methane. 2C + ½ O2 + H2O → ~ 2CO + H22CO + 6 H2 → 2 CH4 + 2 H2O + E The required hydrogen and oxygen are generated by electrolytic splitting of desalinated seawater, the required electrical power is generated by solar power plants developed by DESERTEC. The methane is liquefied and returned to the starting point with liquefied gas tankers.

Description

It is undisputed that fossil carbon dioxide is a major contributor to man-made climate change. On the other hand, it is wrong to conclude that fossil fuels should no longer be used. You do without the reactive properties of the carbon atom and thus a lot of flexibility. It is only correct that no more fossil CO2 is allowed to enter the atmosphere. It is therefore correct that fossil carbon must be recycled.

Even the energy system favored today, based on sun and wind, cannot do without carbon if synthetic methane is to be used to cover the residual load. However, there is no sufficient source for the required CO2, which must be of biogenic origin. Consideration is given to using the CO2 from biogas plants. This is not enough in terms of quantity, as the necessary arable land is not available (plates or electricity) and is cost-prohibitive. According to current planning, there will also be no more biogas plants in 2040.

The subject of this invention is therefore an energy system with a completely closed carbon cycle. It consists of essentially known individual processes which, according to the invention, are interconnected to form this cycle. In individual cases, they are technically optimized. The principle of this cycle is shown in Figure 1.

1. BHKW operated with natural gas (methane) to generate useful energy (el. Electricity, heating). 2 Gas engines and a radial steam turbine generate preferably 10 MWel with an efficiency of 50%. (Fig. 2)

2. Gas scrubbing to separate the CO2 from the engine exhaust gases and concentrate it. Energy requirement approx. 5% of the electrical output of the CHP

3. Dry reforming of the same molar volume of CH4 with this CO2. This creates a synthesis gas (2 CO + 2 H2). The reaction is endothermic. The additional heating takes place allothermally with flue gas, which is generated by burning biochar.

The reactor conditions are chosen in such a way that the gas cooling with expansion machines can take place in a matter of seconds (15-20 bar, 1200 ° C) and thus a reverse reaction (2 CO → CO2 + C) does not occur. At the same time electrical power is generated.

4. With a process named after Carl Bosch (Nobel Prize Winner) (catalytic, 400 ° C), solid carbon is formed (CO + H2 → C + H2O) It can be dumped without any problems. Here a shortened carbon cycle closes (from the earth into the earth)

On the complete cycle, C is hydrogenated to CH4.) Steps 5-8.

5. Transporting the carbon by bulk carriers to sunny regions. (Africa, Middle East.)

6. Oxidation of C to CO 2 C +1/2 O2 + H2O → 2 CO + H2 Oxygen is obtained from the electrolytic splitting of water

7. The splitting (desalinated seawater) also generates the hydrogen for the hydrogenation. The electricity is produced by solar power plants as developed by DESERTEC in Andalusia and brought to operational readiness in Morocco

8. With the Sabatier process, C is hydrogenated to CH4 CO + 3 H2 → CH4 + H2O

The complete carbon cycle no longer requires natural gas Compared to the current energy system and the current concept of an energy transition based on wind energy and photovoltaics and synthetic methane to cover the residual load, the cycle process described has significant advantages:

• Lower operating costs: The consistent use of combined heat and power reduces the consumption of fossil fuels significantly more than the additional consumption to reduce CO2 (with a shortened cycle) The complete carbon cycle requires practically no fossil fuels.
• b.Lower investment costs The existing natural gas infrastructure (pipelines, storage facilities) can continue to be used in full. In the case of the alternatives, electricity and H2, a largely new infrastructure must be built, whereby considerable resistance from the population must always be overcome.
• c. The carbon cycle is capable of residual loads
• d. Since significantly less has to be invested, the time required for construction is significantly lower. This is the only way to achieve a time horizon of 2050 for the goal of "0 emissions".
• e.The concept requires decentralized energy production. To control them, 50 10 MW systems are combined to form a virtual power plant, which controls the individual systems. A central system is built for this, which also takes on other tasks centrally. Workshops and planning office Spare parts warehouse Storage for auxiliary and operating materials VE water generation administration i.a.
• f. The concept can be marketed on the world market and essential points can also be protected by patent law.
• G. Thousands of industrial jobs in machine and apparatus construction can arise. An international group must be created
• That is, in Germany alone, 5000-7000 1 0 MW systems are required. They each include the CHP unit and carbon capture.

Salt for Dubai

BASF is a contract partner in the world's largest solar project "Noor Energy 1" in Dubai. The company will deliver over 100,000 tons of sodium nitrate to the emirate on the Persian Gulf over the next three years.

For a long time, Dubai was one of the cities with the highest water and electricity consumption. For some time now, however, the city has been making great efforts to reduce its energy consumption on the one hand, but at the same time to tap energy from renewable sources. By 2050, 75% of Dubai's electricity is to be generated from renewable energies. With the currently largest solar project worldwide, "Noor Energy 1", Dubai is taking a big step in this direction. A total of 950 MW are to be generated from the end of 2020. The project operators are relying on modern solar thermal power plants; a solar tower power plant, three parabolic power plants and a photovoltaic system only BASF sodium nitrate.

BASF is one of the few companies that chemically produces sodium nitrate. An alternative extraction is possible through mining. The great advantage of the chemically produced salt, however, is its purity. The less magnesium or chlorine components there are in the salt, the better it is suitable for use in a solar thermal power plant.

In such a power station, solar radiation is bundled in order to heat the sodium nitrate until it melts. When the sun is shining, hundreds to thousands of mirrors align themselves in such a way that they reflect the sunlight onto a central absorber. In the project, this is a 260 m high tower - also a superlative. The strong concentration of solar radiation causes temperatures of up to 1000 ° C at the top of the tower. The nitrate salt liquefied and pumped in this way is used to transfer the thermal energy of the sunlight via a heat exchanger into a water cycle, the steam of which drives a turbine and thus generates electrical energy.

This makes it easy to understand why the purity of the salt plays such an important role. The inorganic heat transfer fluid is heated to over 500 ° C. Impurities in the liquefied sodium nitrate can partially promote the decomposition into sodium nitrite and, for example, magnesium or chlorides. These decomposition products can in turn damage the systems through corrosion and the formation of deposits. The more impurities there are in the salt, the more this damage is caused, explains Manuel Atarriba, Sales Manager at BASF Inorganics, E-CMI.

"We have strict quality control and carry out close-knit sampling in our laboratories to ensure seamless quality assurance of the entire delivery quantity."
In addition to product quality, the project's engineering partner, Shanghai Electric Group CO. Ltd another factor is important: "Delivery reliability" The project in Dubai is a global project. In order for it to be successful, we have to be able to rely on our business partners. At BASF, we are convinced that all agreements made will be fulfilled, said Yin Haisheng, the company's Vice Project Director.
Our cooperation shows that there are also new and innovative applications for products that already have a long tradition at BASF, adds Michael Wind, Vice President "Inorganics" (E-CMI / B) in Ludwigshafen

Claims (1)

Process for generating useful energy (el. Electricity, heating) characterized in that the following individual processes known per se are optimized and switched one after the other. a.BHKW operated with natural gas (methane) It consists of 2 gas engines (4.4 MWel x2) and a radial gas turbine (1.2 MW) b. Separation of the CO2 from the engine exhaust gases and concentration according to known processes. c. Use of CO2 for dry reforming of the same standard volume CH4 at a final reaction pressure of 15-20 bar and a final reaction temperature of 1200 ° C. Under these conditions, CO is the stable oxidation form of C. A synthesis gas with the composition (2 CO + 2H2) is produced. Cooling of the gas by means of an expansion machine (turbine or piston machine) within seconds. This creates a disproportionation (2 CO → CO2 + C) avoided and the free energy of the gas converted into electricity. e. The exit temperature from the machine should be around 400 ° C and be fed directly into another reactor, in which solid carbon is split off by means of a reaction named after Carl Bosch (Nobel Prize Winner) (steel catalyst, other metals also possible). CO + H2 → C + H2O The process is exothermic. The reaction temperature is controlled by direct water injection. C is deposited using a hot gas filter. f. Transport of C with bulk cargo ships to sunny regions g Electricity generation with solar power plants, as developed by DESERTEC in Andalusia and brought to operational readiness in Morocco. H. Generation of hydrogen and oxygen by electrolytic splitting of desalinated seawater. i.Oxidation of C by means of the oxygen generated at h. Control of the final temperature by adding water vapor cooling as under d. described k. Synthesis of methane using the Sabatier process. CO + 3 H2 → CH4 + H2O 1. Liquefaction of methane and transport with liquid gas tankers to the starting point.

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