The term biofuel is referred to as liquid fuels for the transport sector that are predominantly produced from biomass. Biofuels are important because they replace petroleum fuels. There are many benefits for the environment, economy, and consumers in using biofuels. The advantages of biofuels such as biodiesel, vegetable oil, bioethanol, biomethanol, and biomass pyrolysis oil as engine fuel are liquid nature-portability, ready availability, renewability, higher combustion efficiency, lower sulfur and aromatic content, and biodegradability. The biggest difference between biofuels and petroleum feedstocks is oxygen content. Biofuels have oxygen levels from 10-45% while petroleum has essentially none making the chemical properties of biofuels very different from petroleum. Oxygenates are just pre-used hydrocarbons having structure that provide a reasonable antiknock value. Also, as they contain oxygen, fuel combustion is more efficient, reducing hydrocarbons in exhaust gases. The only disadvantage is that oxygenated fuel has less energy content.