In a period of increasing awareness about climate changes and environmental protection, it is important to focus on the development of cleaner energy sources, to reduce the environmental impact of fossil fuels combustion plants. One of the possible solutions is the use of biofuels-fed high efficiency and zero emissions cogeneration systems like fuel cells. The purpose of this thesis is to study the performance of the Solid Oxide Fuel Cell (SOFC) cogeneration plant installed in the framework of the DEMOSOFC European project. The modules are based on the SOFC technology and are fed by biogas locally produced by the SMAT wastewater treatment plant in Collegno, Italy.