A biogas plant is a container of a slurry of anaerobic methanogenic bacteria and wet organic matter that produces methane and carbon dioxide. Cattle dung is often used as feedstock as it contains the right bacteria. The bacteria work best at 35°C (mesophylic), although some also work at 55°C (thermophyllic). The container must be gas tight to retain the gas and to exclude air.
Biogas technology has a long history, in China, India and Nepal. there has been a strong revival of interest in Germany, Sweden, Denmark, Austria and elsewhere. The UK has been slow but has an ongoing programme.
Biogas is a fuel gas that can be used in gas burners, for cooking and heating, or in internal (and external) combustion engines to give shaft power or to drive an electric generator.
Raw biomass materials will generate more biogas per kg than animal dung, but needs to be pre-processed. Pre-processing can improve the process of digestion and allow a much wider range of materials to be digested.
