There are considerable incentives to use intermittent electricity generation for production of stporable energy carriers. Upgrading biogas to pipeline quality gas by methanation of the CO₂ content in the biogas with hydrogen from electrolysis is one option.

Solid Oxide electrolysis (SOEC) offer strong synergy with the methanation plant, as the steam produced by the exothermal methanation reaction can be used directly as feedstock for the SOEC thus eliminating water evaporation by electricity.

A pilot plant to demonstrate the concept has been constructed and was operational mid 2016. The design capacity is 10 Nm3/h of upgraded biogas. This capacity requires approx. 50 kW SOEC, which is provided by two Fuel Cores, each consisting of 4 SOEC stacks. Haldor Topsøe A/S has also designed the biogas cleaning unit and the methantion plant which is located at the Agricultural Research Centre of Aarhus University at Foulum, Jutland.

 The paper will outline the design of the pilot as well as full scale plants including exergy analyses. Experimental data from the SOEC unit(s) as well as the biogas cleanup and methanation pilot will be presented.