Wartsila's Puregas Solutions is to upgrade a US plant to produce biomethane from more than 50,000 US dairy cows.

The work will allow the existing anaerobic digester in Oregon to turn out 3,100 cubic feet per minute (cfm) of the renewable natural gas.

It will use manure from the cattle.

The gas will then be injected into a pipeline for use as transport fuel in California.