Methane-rich biogas is generated on farms, landfills and wastewater treatment plants in anaerobic digestion of biological material. Until now, the processing of such gas into biomethane has only been viable on large biogas-producing sites; small biogas sources such as farms have remained largely unexploited.

The method developed by VTT would reduce emissions, increase the use of biogas and improve protein self-sufficiency.

It is based on the ability of methanotrophic bacteria to grow in aerobic conditions in gas fermentors, using methane as the source for carbon and energy.

The process is as follows: The methane gas generated by anaerobic digestion is fed into a gas fermentor. A growth medium containing the methanotrophic bacteria circulates through the pipes of the gas fermentor, creating a protein biomass with a protein content of around 60 per cent. The cell mass is filtered, pasteurised and dried.

Based on previous studies, proteins produced using micro-organisms can be substituted for ingredients such as meat, soya, egg whites or fish in food and feed.

Finland is import-dependent with respect to soya: a fluctuating worldwide crop causes price fluctuations and uncertainty about the availability of this foodstuff. In Europe and Finland, attempts are being made to meet the challenge of protein feed for domesticated animals by improving protein self-sufficiency.