The use of thermoelectric converters for the production of electricity from biomass

The role of renewable sources of energy to replace fossil fuels and in reducing carbon dioxide emissions and conserving natural resources has been widely realised. Among the renewable sources of energy bioenergy appears to have at the present the greatest potential. The use of biofuels for heating purposes in rural areas has been developed extensively in the past years especially in the Nordic countries and Austria. In these countries the contribution of biofuels to the total energy demand has reached 12 to 15%. Efforts to produce electricity from biomass have been less successful although this would be for great interest for small scale decentralised power production in remote rural areas. Three technologies have been suggested: steam engines, gasification of biomass combined with gas motors and Stirling engines. All the technologies mentioned involve the use of elaborate mechanical equipment and, therefore, need for their operation and for their maintenance highly trained personnel. During the past 25 years thermoelectric converters have been developed mainly for space applications. This technology is now also being applied to supply electricity in remote places such as light houses or on mountains but appear also possible in bioenergy applications. These installations are normally supplying hot water for space heating. Low conversion efficiencies to electricity are no problem as heat can also be utilised. First tests of the technology have been performed in a bench scale unit in the laboratory. It has a capacity of about 0.45 kW electricity and 6.8 kW of heat in form of hot water.