Pyrolysis is the thermo-chemical decomposition of organic material, at elevated temperatures without the participation of oxygen. The process involves the simultaneous change of chemical composition and physical phase that is irreversible. Pyrolysis occurs at temperatures >750°F (400°C) in a complete lack of oxygen atmosphere. The syn-gas that is produced during the reaction is generally converted to liquid hydrocarbons, such as biodiesel. Byproducts from the process are generally unconverted carbon and/or charcoal and ash.