In temperate regions the average annual production of dry ligneous material is 10 tons per hectare, with the maxima reaching 20 t/ha. This corresponds to a gross resource between 3.6 and 7.2 toe/ha, i. e. between 40 and 80 MWh. As compared with the average annual insolation of 1.5 x 104MWh/ha this corresponds to an efficiency between 0.2 and 0.5%. Taking into account the thermodynamical efficiency for electricity production, the maximum efficiency for electricity production is 0.2%. A facility producing 7 TWh per year would require a cultivated area of about 2500 km2, in the best cases. This surface could be halved in tropical conditions.

It is generally considered that the use of biomass is neutral as far as CO2 emissions are concerned. However, this is only true if it is ensured that all incinerated biomass is compensated by adequate replantating. This is, presently, not the case in most developing countries where deforestation contributes to greenhouse gas emission.

Today’s world biomass energy production amounts to approximately 70 GToe/year. Humans use about 4% of this production either for producing food (2GToe) or for energy production (1 Gtoe). In the most biomass intensive scenarios given at the 1992 UN Rio Conference, biomass energy production would be as high as 5 GToe, and the total human use would amount to 13 GToe, i. e. around 20% of the available resources. Because of its large volume, biomass has to be transformed into high energy content material close to its production location. Aside from local uses, the transfor­mation of biomass into gas (methane), alcohol (ethanol, ETBE) or vegetable oil ester is considered. At present, electricity production using biogas is only marginally competitive when the cost of the biomass is negligible. Otherwise the cost of biogas electricity is three times more than that which can be obtained with fossil fuels. The cost of biofuels is about three times that of fossil fuels.