No abstract

Energy from regenerable raw materials. In the long run, some of the agricultural areas in the Federal Republic of Germany will no longer be needed for food production, and could therefore be used for growing raw material plants in order to provide various sources of energy, such as wood, rape seed oil, ethanol, methanol, and biogas. With this indirect use of the solar power accumulated in the plants, the overall expenditure for fossilized fuel energy to produce these energy sources is lower than the amount of primary energy that can be substituted. Based on the assumption that 20% of farmland will be used to grow regenerable raw materials, it would be possible to replace approximately 7 million tons of coal equivalent (SKE) by wood or approximately 4 million tons of coal equivalent (SKE) by ethanol from sugar beet or methanol from wood. In the case of alcohol production from sugar beet, the total energy efficiency including the regenerative part of energy of about 74%, is lower than in the ethanol synthesis. At present, use of biomasses as an energy source is feasible only in a few rare cases, and can only be achieved if the regenerable raw materials are considered as an alternative to surplus food production or to the strategy of gradually using less acreage for growing food.