How efficient is the conversion process?
About 60% of the carbon in the organic matter is converted to methane and the other 40% ends up as carbon dioxide. However, not all of the organic matter can be converted in the anaerobic digestion process. Lignin is not attacked by the bacteria present, and some of the cellulose is difficult to digest. Overall, I would expect 30 – 50% of the organic matter is not converted in the process. This will vary depending on how long the material is allowed to digest. If the biogas is used to fuel an engine/generator system, the efficiency of energy conversion would probably be about 25%; i.e., based on the energy of the fuel entering the engine, the energy output from the generator is about 25% of that.
