Abstract The input and output of energy are two important factors used to determine the energetic and ecological usefulness of a fuel or its production technology. In this paper, a number of different methods for the production of five biofuels which can be produced in agriculture and forestry are analysed and energetic balances are presented. The results show that the energetic input is relatively low compared to the output, especially for by-products and residual substances such as cereal straw and forest pruning timber (thinning). Whenever fuel crops are cultivated, the energetic efficiency is critically determined by the quantity of nitrogen applied. Depending on the crop and technology, each gigajoule of energy input can provide 7–30 GJ or with by-products up to 50 GJ of thermally utilizable energy without any additional CO 2 pollution.