(Villigen / Switzerland) – The Paul Scherrer Institute (PSI) and the startup Alphasynt have signed a cooperation and licensing agreement to market a process called “Power-to-Methane”. Background: In order to efficiently convert biogas from agricultural and forestry waste into gaseous or liquid fuels, it must have a high degree of purity with a methane content of at least 96 percent, according to the companies. According to the information, biogas from the fermentation of biomass such as manure and plants consists of around 40 percent carbon dioxide (CO2) and must therefore be processed.
Direct methanation in a two-stage process
In the standard procedure, the contaminants would be separated from the methane (CH4) and released into the air. However, additional methane can be obtained using the “direct methanation” process developed at PSI, says Tilman Schildhauer, scientific head of methanation research at PSI.
Schematic representation of the process of direct methanation in a fluidized bed reactor. © Paul Scherrer Institute / Mahir Dzambegovic
This requires a two-stage process: First, hydrogen must be produced using electrolysis and electricity from renewable energies (power-to-hydrogen). In a second stage, the hydrogen is added to the biogas to convert the CO2 it contains into methane and water. The electrical energy is “ultimately converted into chemical energy in the methane” (power-to-methane).
The energy required for this can be obtained from green electricity that cannot be used elsewhere - for example from photovoltaic systems, some of which have to be taken off the grid in summer if the output is too high. In the future, this electricity should no longer be lost, but rather be stored seasonally in the form of methane gas through the methanation process - like a battery, only in the long term. If necessary, the gas can be converted back into electricity, used in industry as high-temperature heat or used as fuel in the transport sector.
“Hydrogen is a very light gas and requires an enormous storage volume. The conversion into methane is therefore more space-saving because methane only takes up a third of the volume of hydrogen with the same energy content,” says Tilman Schildhauer, explaining the advantage of this process. In addition, methane can be used and stored in the existing gas network infrastructure. “Methane is a long-term battery that we can already benefit from today.”
Marketing to energy suppliers
PSI now wants to bring the new methanation process onto the market together with Alphasynt. The target groups are primarily larger energy suppliers that have gas networks or biogas or wastewater treatment plants. “Investors must be found, customers must be acquired and the construction of certified fluidized bed reactors and the associated infrastructure must be commissioned,” says Tilman Schildhauer.
In this way, according to the plan, “fossil gases should be gradually replaced by renewable methane gas”. The electricity stored in this way from renewable energy sources also contributes to the stabilization of the power grid because it “can also be used outside of the season,” says Andreas Aeschimann, managing director of Alphasynt GmbH, which was founded in 2020.
Photo above
From left: Andreas Aeschimann and Luca Schmidlin, founders of Alphasynt, and Tilman Schildhauer from PSI in front of the GanyMeth pilot plant at PSI. © Paul Scherrer Institute / Markus Fischer
