Generally the fuels which are sourced from plants or waste products and are known as alternative or bio-fuels. Pure Plant Oil (PPO) is also known as SVO – straight vegetable oil. It is not a bio diesel. Bio methanol is the product of the trans esterification of vegetable/waste oil or animal fats. Bio ethanol is mainly used in petrol engines to deliver higher performance and reduced emissions. Natural gas, a fossil fuel comprised mostly of methane, is one of the cleanest burning alternative fuels.