Anaerobic Digestion (AD) offers one of the few methods of energy and nutrient recovery from organic wastes. These wastes can come from various sources, eg farm wastes, food processing, retail sales and sewage. It is also one of the most efficient ways of producing a renewable fuel from energy crops, including grass, maize, sugar beet, etc.

AD is a biological process which runs more efficiently at elevated temperatures of 35 - 55 degrees C in an enclosed vessel. It releases about 35% Carbon Dioxide and 65% Methane and a trace of sulphur, so only carbon and the elements of water are removed, leaving all the "fertilizer" elements more available.