Temperatures between 1,300 and 1,500 degrees Celsius prevail in the plasmolysis reactor.
Methane plasma pyrolysis produces low-CO2 hydrogen at high temperatures and – it is hoped – at low cost. The Berlin-based company Graforce is testing the process in Austria, but sees the main market outside Europe.
Text: Fabian Kauschke
Green hydrogen is considered too expensive, too energy-intensive, and therefore not competitive. With this statement, critics often deny the gas its future viability. However, companies are already planning projects with a total capacity that exceeds Germany’s National Hydrogen Strategy target of ten gigawatts (GW). According to the industry association “Die Gas- und Wasserstoffwirtschaft”, 11.3 GW have been announced. However, the reality is that only a fraction of the planned projects will be completed on time, or at all. According to a study by the Potsdam Institute for Climate Impact Research, less than ten percent of the originally announced green hydrogen production was realized in 2023. This is reason enough to focus on technologies that undercut electrolysis in terms of energy intensity while still producing low-emission hydrogen.
Plasma pyrolysis requires twelve kilowatt-hours to produce one kilogram of hydrogen.”
Currently, forty to eighty kilowatt-hours (kWh) of renewable electricity are required to produce one kilogram of green hydrogen. Plasma pyrolysis promises to significantly undercut this value and produce one kilogram of H2 with less than twelve kWh. The Berlin-based company Graforce holds five patents for the application of various plasma processes and builds plants for methane and ammonia plasma pyrolysis.
From methane to H2 and carbon black
Methane plasma pyrolysis decarbonizes methane (CH4) to produce hydrogen, solid carbon, and industrial-grade heat. If you take 200 kilograms of methane and 500 kWh of renewable energy and process them via plasma pyrolysis, you get 50 kilograms of hydrogen, 150 kilograms of carbon black, and 150 kWh of industrial heat. Carbon black is a raw material used in industry, for example in the production of paints, high-performance coatings, plastics, tires, concrete, or asphalt. As activated carbon, carbon black is used in water treatment (fourth purification stage) and for gas separation. In agriculture, it is used to improve soil quality, especially in sandy soils (by increasing water adsorption). Low-carbon carbon black can replace petroleum coke while reducing CO2 emissions and, in the form of graphite, is used in lithium-ion batteries, for example.
The by-product, which occurs here in triple the quantity compared to hydrogen, is already integrated into a wide range of industrial processes. Until now, it has been produced in a CO2-intensive manner by burning oil or natural gas. The waste heat generated by the plasma pyrolysis process can also be used industrially at various temperature levels.
When biomethane is used and the resulting carbon black is stored in product form (C-steel) for the long term (> 35 years), the process acts as a CO2 sink. If raw biogas (consisting equally of biomethane and CO2) is used, the same process can produce CO2-neutral syngas, which, after processing into SAFs (Synthetic Air Fuels), will contribute to the decarbonization of aviation in the medium term. To do this, the methane must first be separated from the other components of the biogas.
Splitting in the reactor
The plasma pyrolysis reactor is three meters long and one meter in diameter. It is mainly filled with thermal insulation. Inside is a graphite tube 2.5 meters long. Within this graphite reactor is a plasma torch, which, with the supply of hydrogen, generates a thermal hydrogen plasma that quickly and energy-efficiently brings the reactor to high temperatures. The required H2 is initially supplied via an external gas bundle and remains after the splitting process.
What unites companies is the necessity to drastically reduce their CO2 emissions as quickly as possible.”
In the reactor, in the absence of oxygen, methane splits at temperatures between 1,300 and 1,500 degrees Celsius into hydrogen and carbon, which is then removed. After the process, the hydrogen has a purity of approximately 98 percent and can therefore be used directly, for example, in an H2 combustion engine (Keyou), an H2 combined heat and power plant, or H2 turbines. However, for applications such as fuel cells, a higher degree of purity is required. To achieve this, pressure swing adsorption is connected downstream of the plasmolysis. This brings the hydrogen to a purity level of nearly 100 percent.
Not green, but climate-friendly?
A plasmolysis reactor has a capacity of 0.5 megawatts. The systems can be combined modularly, making production facilities with 30 megawatts possible. When connected to an industrial operation, all three products – hydrogen, carbon, and waste heat – can be used. In Kremsmünster, Upper Austria, a methane plasmolysis plant has been established in cooperation with Rag Austria, which exploits these characteristics. The hydrogen produced is stored by the project partner in the region and used in a combined heat and power plant or for industrial purposes. The carbon obtained is used in agriculture to enrich the soil.
“We are in discussions with steel mills, energy suppliers, pigment manufacturers, and companies in the oil and gas sector in order to produce significant quantities of hydrogen and carbon from natural gas in the near future. What unites these companies is the need to drastically reduce their CO2 emissions as soon as possible,” says project manager Marc Dünow about the current developments at Graforce.
Hydrogen from methane plasmolysis is defined as low carbon hydrogen according to the regulation to be ratified at the EU level in 2025, taking into account all upstream emissions, and can be certified, subsidized, and traded on this basis. “This enables the breakthrough for our H2 bridging technology,” says the project manager. According to current European legislation, only hydrogen from water electrolysis produced with renewable energy may be referred to as green. The hydrogen produced in plasmolysis is classified as turquoise. Nevertheless, the technology helps to decarbonize industrial processes. Due to the currently limited availability of proven green H2, plasmolysis – like the use of blue hydrogen – could serve as a transitional solution until the electrolysis technology market is fully established. However, it is questionable whether methane plasmolysis will be included in federal funding programs in the future. For this reason, Graforce is also turning its attention to the USA, Saudi Arabia, Australia, Thailand, and Korea, due to increased international demand.
Ammonia plasmolysis
Ammonia plasmolysis is another technology for producing hydrogen. It is used, for example, in the treatment of wastewater in sewage treatment plants. In this process, nitrogen compounds contained in the water (such as urea and ammonium) are broken down into individual N and H atoms. These subsequently recombine to form green hydrogen and nitrogen. What remains is purified water. Using membrane technology, the gases are separated and stored in gas tanks for further use. This technology already represents an energy-efficient method for splitting the future hydrogen carrier ammonia (NH3) and is ready for large-scale industrial implementation today.
