With this investment, we’re systematically strengthening our activities in the area of gas separation membranes proving our commitment to renewable energies by producing biomethane that can be fed directly into the grid. By contrast to other processes, our membrane technology needs no auxiliary chemicals; nor does it generate any solid wastes or effluents that would need to be disposed of.

—Dr. Axel Kobus, head of the growth segment Fibres & Membranes

The Evonik process is offered on the market by leading plant engineering and construction partners, and works cost effectively, even in relatively small plants.

Close-up view of a hollow fiber membrane module. Click to enlarge.

The technology is based on membranes produced from high-performance polymers that in the past have been processed into fibers and used in hot-gas filtration. At pressures of up to 25 bar, such membranes allow significantly improved separation of carbon dioxide and methane with stable selectivity in a single process step. The method yields methane of purity higher than 99%.

Neither energy-intensive recycle streams nor costly downstream processing steps are required, which significantly distinguishes the Evonik method from the technologies currently available on the market, according to the company.

At present, biogas is still largely converted to electricity at its production site, with a maximum of 40% of its energy being utilized by the conversion to power. In such local power generation the waste heat often remains largely unused. When fed into the natural gas grid, however, the raw material can be stored much more efficiently, and more than 90% of its energy utilized as power and heat, Evonik says.