The term "biofuels" refers to biomass, bioethanol and biodiesel fuels produced by different methods from different materials. Biomass fuel generally converts plant matter via biochemical, thermal or chemical reaction into a fuel. One form of biochemical biomass fuel is bioethanol, a type of alcohol made from fermenting processed crops high in sugar or starch. Another is biodiesel, produced from used oils and fats. A biochemical reaction called transesterification exchanges lipids from the materials for alcohol.
Biodiesel is commonly used as an additive for petroleum-based diesel fuel, effectively reducing emissions of hydrocarbons and carbon monoxide. It is Europe's most widely produced and used biofuel, made from vegetable oils, animal fats and algae.
The United States uses energy crops such as corn and soybeans to produce bioethanol fuel, typically used as an additive for petroleum-derived gasoline. In comparison, Brazil ferments sugarcane waste material to produce ethanol, the most commonly used fuel source in the country.
Although biofuels are advantageous because they are a renewable resource, as of 2015 it's still being debated whether the cost of raising energy crops yields a net energy gain. The process of growing, maintaining via pesticides and fertilizers, and processing the plant matter for biofuel is an energy-intensive process that doesn't necessarily remove non-renewable energy source demands.