The Paul Scherrer Institute (PSI) and Energie 360° have achieved an important milestone in the production of renewable gas from biogas plants. Thanks to the innovative fluidized bed methanation technology, the production of biogas can be increased by 60%. In future, CO2 in a biogas processing plant is not to be separated as before, but converted into methane. The suitability for the industrial application has been confirmed in a 1000 hour test at Werdhölzli. The demonstration container now returns to the PSI and shall be used for further research projects.

Original article published by Energie 360° on July 25, 2017; Translated by SCCER BIOSWEET

The power-to-gas technology has proven itself and has yielded the following research results

Production increase: With the power-to-gas technology, 60% more renewable gas can be produced in existing biogas plants. As expected, significantly more than 90% of the carbon dioxide (CO2) contained in the raw biogas can be converted directly from raw biogas into methane by the addition of renewable hydrogen instead of being separated and released into the atmosphere. This enables almost 100% recycling of the raw gas.

Interim storage of electrical energy in the form of gas: The direct methanation of raw biogas counteracts the problem of the production of surplus electricity from renewable sources of energy: With the conversion of electricity into additional gas, the energy in the gas line system can be temporarily stored and used as required.

Control of gas quality is crucial: The impurities contained in the raw biogas, in particular organic sulfur compounds, can only be tolerated by the methanation catalyst in small amounts and must be removed beforehand. A detailed analysis of raw biogas quality is indispensable in order for the filter device to be set correctly. The findings obtained with complex diagnostic methods from the 1000 hour long-term test, can now also serve other methanation applications.

The entire process chain is stable: The fluidized-bed methanation used works from A to Z. The technology is robust in operation and therefore suitable for everyday use. It can be quickly adapted to changing raw gas compositions and provides heat at a high-quality temperature level.

Contribution to the Swiss energy transition: If the existing Swiss sewage treatment plants, which now produce biogas, are converted to power-to-gas technology with a feed into a gas network, the feed-in of renewable gas in Switzerland can be increased fivefold from the current 308 gigawatt hours to 1,400 gigawatt hours.

Peter Dietiker, Senior Vice President of Renewable Energies at Energy 360°, is delighted: “A climate friendly energy future is our goal. The research results of the power-to-gas plant show that we are on the right track into a sustainable energy future“.

With the innovative fluidized bed technology for the production of methane, the PSI and Energy 360° prove that the production of standardized feedable biogas can be significantly increased. With the demonstration plant built at the PSI, it has been demonstrated during the 1000 hour operating test that this technology is suitable for continuous use under real conditions.

The renewable methane generated has been fed into the gas network on site. With the data obtained from the test facility, the process simulations carried out beforehand were validated. This has created a solid foundation for a future economic deployment of a power-to-gas plant.

Rising biogas production is the motivation

The share of renewable gas in Switzerland’s gas network has been steadily increased over the past few years by biogas feeds from the fermentation process. This development is to be continued. The Swiss gas industry wants to increase the share of renewable gases in the heat market to 30% by 2030. Here, the Energy 360° and the PSI have established: raw biogas, which is produced by the fermentation of biogenic waste and in sewage treatment plants consists, to a large extent, of methane. However, it also contains about 40% CO2, which is separated in conventional biogas processing plants by means of appropriate processes prior to feeding it into the gas network. The CO2 contained in the raw biogas can be directly converted into additional methane by means of the power-to-gas technology by adding hydrogen, thus increasing the national production of renewable gas by 60%.

Peter Jansohn, Head of the PSI Thermal Processes and Combustion Laboratory, emphasizes: “The long-term experiment with real raw biogas has shown that the methanation technology developed at the PSI is ready to be used in commercial applications. We are pleased to have demonstrated the practicality of the technology and are ready for the next step, i.e. the up-scaling of the technology to a commercial scale (200 m3 / h raw biogas)”.

The test facility is now being dismantled and returned to the PSI research center, where it shall be used for further research purposes. The cooperation between research (PSI) and business (Energy 360°) has proven itself once again and brings us one step closer to the future of energy.

Direct methanation of biogas. Demonstration plant «CoSyMa»; Picture by Paul Scherrer Institute