The City of Ahlen in North Rhine Westphalia, Germany and RWE Fuel Cells GmbH, Essen, cooperate in order to install a molten carbonate fuel cell in the municipal sewage works of Ahlen in May/June 2005. The MCFC unit, a so-called HotModule made by MTU CFC Solutions, Ottobrunn operates on anaerobic digester gas and provides power and heat for the sewage works. This is the first project of its kind in Europe. This article outlines the experiences of RWE Fuel Cells with planning, installation and operation of MCFC systems and is focussing on the use of digester gas. The engineering and installation phase is described regarding to the special features of digester gas, for example variation in gas composition and impurities as well as different flow rates. The results of the first months of operation are interpreted and influences to the performance of the fuel cell on digester gas composition are compared. One focus of the recent RWE Fuel Cells projects is the use of MCFC systems using different biofuels. With the results from planning, installation and operation of the MCFC in Ahlen a system design for the application of different fuels can be validated and tested. (c) 2006 Elsevier B.V. All rights reserved.