Energy from Biomass needs highly efficient small-scale energy systems in order to achieve cost effective solutions for decentralized generation. Especially in Mediterranean and southern areas, and for applications without adequate heat consumers highest efficiencies are needed due to the fact that no revenues for heat may be achieved. Thus fuel cells are an attractive option for these decentralized generation from biomass and agricultural residues.
Due to their robustness SOFC fuel cells are applicable above all other concepts for the use of gaseous fuels from biomass. They operate with exhaust gas temperatures between 800°C and 1000°C and are able to convert not only hydrogen but also carbon monoxide and even hydrocarbons.
Other fuel cell concepts, for example the PEM fuel cells, make extremely high demands against the purity of the gaseous fuels. Carbon monoxide, hydrocarbons, dust and tars must be separated restrictively before.
High temperature fuel cells like the SOFC and the MCFC are therefore the
most promising options for upcoming fuel cell systems with integrated gasification. But even if the fuel gas matches the strict requirements of SOFC membranes the main challenge of the conversion of biogeneous fuel gas is to achieve the required efficiency of the fuel cell system. Common biomass fuel cell systems with realistic boundary conditions will hardly reach efficiencies above 30% due to:

• the low hydrogen and methane content of biogenious fuel gases, which reduces the fuel cell efficiency

• the physical limitation of the cold gas efficiency of any gasification system