Biofuels are renewable fuels that are produced from biomass, organisms that were formed and stopped living a short time ago. The energy in the biofuels is called bioenergy. The major constituents of biomass are cellulose, lignin, starch and sugar, but many plants also contain other organic compounds that are beneficial for energy recovery from the material due to their physical structure and chemical composition. The difference between biofuels and fossil fuels is that fossil fuels take millions of years for new formation while new biomass for biofuels is constantly being formed. This means that biofuels can usually be considered carbon neutral as the carbon dioxide emitted during combustion is constantly bound to new biomass in a closed cycle.
