Biofuels are gaseous, liquid or solid fuels containing carbon derived from a biological source or from natural and renewable sources such as vegetable oils, animal fats or even cooking oils. In the search for alternative sources and renewable forms of energy with no net impact on atmospheric carbon dioxide (CO2), there is growing interest in the use of biofuels (such as biogas, plant-based biodiesel and bioethanol from crops such as maize and sugar beet).

With the rise in oil prices and the growing concern about global warming caused by CO2 emissions, biofuels are currently the renewable energy sources being blended with conventional road fuels. In Portugal, biodiesel and bioethanol are the most sought after, both depending on the policy of mandatory incorporation and consequent reduction of greenhouse gas emissions.