From research conducted at the Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research

CO₂ membranes for biogas

Biogas is one of the most important forms of renewable energy in Germany, but biogas plants have a CO₂ problem: they produce a gas mixture that contains up to 40 percent CO₂. Before biogas is fed into the gas grid, this CO₂ must be removed.

Image module design — Schematic representation of a membrane module designed to remove CO2 from biogas. Photo/Graphic: HZG.

photo membrane pilot installation — Photo/Graphic: HZG.

Researchers at the Helmholtz-Zentrum Geesthacht have developed polymer membranes and membrane processes that are well suited for this task. They consist of several layers of polymer, which allow the CO₂ to preferentially pass through while retaining most of the methane when biogas is fed to the membrane module under elevated pressure. The membranes have undergone extensive tests and can be manufactured on an industrial scale. Even when used continuously under real conditions in a biogas plant run by our industrial partner BORSIG Membrane Technology, the membranes showed their worth as a simpler technical alternative to other CO₂ separation technologies such as gas scrubbing and active carbon filters.

Uta Deffke

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