Summary

The biogas technology in the market today is fully engineered and established. Besides, biogas systems can operate at a low emission level and a high standard of operating safety if the equipment and the mode of operation are chosen with know-how and selected carefully. Latest developments in technology, in addition to making ever more efficient use of renewable primary products, also exploit residual material and biowaste in better ways. Waste heat from the combustion of biogas can be used in engines by available and frequently demonstrated technologies if the site of the system permits this. It can be expected that large biogas plants will take advantage of the possibility of feeding upgraded Biogas (Biomethan) into the local and district distribution natural gas grid which already exists today. Besides, the integration of biogas technology in virtual power plants replacing conventional energy sources can become important.The energy source biogas is produced when organic matter is digested in the absence of oxygen (anaerobic process). This is comparable to the natural process occurring in the rumen of ruminants. In the digestion tank, which is the very core of every biogas plant, manure, organic waste or energy crops are converted into a methane-containing gas. The heating value of biogas amounts on average to 5.5 kWh per cubic metre. It serves as an energy carrier that can be used in several applications. The fully digested substrate is a high-quality fertilizer that is spread on the farmland again. Biogas is currently mostly used to generate heat and electricity in engine based co-generators. The electricity is fed into the national grid and paid for according to agreements with local power suppliers or legal parameters (e.g. the Renewable Energy Sources Act in Germany). Some of the generated heat is used to ensure that the digestion tank has the required temperature. The remaining heat can be used for heating buildings or as process heat. Further applications besides engine based co-generators are made possible by upgrading biogas to natural gas quality. After this refinement it can be fed into the natural gas grid or used directly as vehicle fuel.

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