Renewable fuel produced from biomass. It is a broad definition that covers a range of materials, from solid fuels like wood to liquid fuels such as biodiesel. In its narrow sense the term refers to liquid or gaseous biofuels for transport. First generation or conventional biofuels are biofuels produced from food crops, such as sugar, starch and vegetable oils. Second generation or advanced biofuels are biofuels produced from non-food crops and residues.