Evonik has developed a biogas upgrading process that makes best use of the membranes' separation properties: Through skillful connection of SEPURAN® Green membranes it is possible to obtain methane with a purity level of up to 99% from the crude gas. Just one compressor is needed.

SEPURAN® Green membranes have the highest CO₂/CH₄ selectivity and are therefore a superior technology for upgrading biogas. This selectivity of the membranes enables the production of high purity biomethane with superior methane recovery. This distinguishes the Evonik membranes from other membranes that are available.

Biogas comes from the biogas plant as a mixture of CO₂, methane and the typical secondary components, and is first desulfurized, filtered and pre-dried with activated carbon. The pre-treated gas is then compressed to 10 - 20 bar, and upgraded to biomethane and a CO₂-rich waste gas flow using several membrane stages.

• Reduced operating costs
• Low Investment
• Easy to operate
• Low space requirement and short installation times
• Flexible and modular Installation
• No chemicals required
• No additional drying stage

Compared with other biogas upgrading processes such as pressurized water scrubbing, pressure swing adsorption, or amine scrubbing, Evonik's membrane technology has significant advantages: It requires comparatively little energy and does not need any auxiliary materials or chemicals. No waste or wastewater is produced that would otherwise have to be treated and disposed of.

Biogas is produced by the fermentation of biomass - an organic substance, for example, from waste such as liquid manure and sewage sludge or from renewable raw materials. The particularly selective SEPURAN® Green hollow-fiber membranes from Evonik easily and efficiently upgrade raw biogas, which consists of the energy carrier biomethane plus carbon dioxide, into high-purity biomethane. The climate-friendly energy source can consequently be used to generate electricity and heat or used as a fuel. The membranes are made of a high-performance polymer specially developed by Evonik that is highly resistant to pressure and temperature.

In addition to the SEPURAN® Green membranes, Evonik has also developed and patented a 3-stage biogas upgrading process that makes optimum use of the membranes' separation properties: Through skillful connection of SEPURAN® Green membranes it is possible to obtain methane with a purity level of up to 99% from the crude gas with one compression step. 

Worldwide, more than 900 biogas upgrading plants are equipped with SEPURAN® Green membranes. Our membrane processing process delivers consistently high biomethane quality with over 99%. This means that almost all methane is obtained in bio natural gas quality.