Anaerobic digestion is a biological process where the organic matter is degraded to form biogas and a digestate. Biogas can be fired in combined heat and power (CHP) engines or purified and injected into the gas grid. The total primary energy produced from biogas in Europe was 5.9 million toe in 2007, and there is still growing potential, since the white paper objective for 2010 is 15 million toe ...