In this work, the use of fuel cells for valorising agricultural derived biogas in Switzerland is studied. The Swiss agricultural case is characterised by farms with small numbers of animals (20 cows) and high feed-in tariffs for biogas derived electricity. Thus, small-scale biogas installations are reviewed and the possibility to couple them with SOFCs and photovoltaic panels is analysed. To date, less than 5% of the Swiss agricultural biogas potential is used. It is possible to increase this value significantly up to 86% through the deployment of 2 kWel engines. Small-scale biogas facilities are not profitable yet: the main challenge is to bring down the lifetime cost of the SOFCs to 11,000 CHF/kWel (considering a lifetime of 10 years) and to reduce the investment cost of small-scale biogas facilities to around 9,500 CHF/kWch. It is shown that SOFCs become competitive over engines if the investment cost of the former decreases below 13,000 CHF/kWel for a lifetime of 11 years. Combining the biogas facility with a PV-battery system, which covers the digester’s electricity needs, is found to be beneficial. A considerable reduction in the feed-in tariffs would make small to medium scale biogas installations unprofitable, at current cost. In order to reach a break-even under these conditions, the investment cost of the biogas plant needs to drop below 4,000 CHF/kWch, whereas the investment cost of the SOFC needs to drop below 3,400 CHF/kWel.

Majerus, S., Lauinger, D., & Herle, J. V. (2017). Cost Requirements for a Small-Scale SOFC fed from Agricultural Derived Biogas. Journal of Electrochemical Energy Conversion and Storage. doi:10.1115/1.4035891