Biofuels are fuels produced from recently living biological material, or biomass, such as crops, plant waste and animal waste. Their main advantage is that they can be renewable and may reduce net carbon dioxide emissions; however, their production can compete with food crops, damage ecosystems and still cause pollution.
This is part of Reactivity 1.3: Energy from fuels and is required at both SL and HL.
Biofuels include bioethanol made by fermenting plant sugars, biodiesel made from vegetable oils or animal fats, and biogas produced through the decomposition of organic matter. Plants used to make biofuels remove carbon dioxide from the atmosphere by photosynthesis.
When the fuel burns, carbon dioxide is returned to the atmosphere. This creates a short carbon cycle because the carbon was fixed biologically over a relatively short period, unlike the carbon in fossil fuels, which was stored for millions of years.
| Advantages | Disadvantages |
|---|---|
| Biomass can be replaced, making biofuels potentially renewable. | Crops grown for fuel may compete with food production and increase food prices. |
| Growing biomass absorbs atmospheric carbon dioxide. | Farming, processing and transporting biofuels require energy and may use fossil fuels. |
| Agricultural waste can be converted into useful fuel. | Land clearance can cause deforestation, habitat loss and reduced biodiversity. |
| Local production may improve energy security and reduce dependence on imported fossil fuels. | Fertilizers, pesticides and irrigation may cause pollution or place pressure on water supplies. |
| Some biofuels produce less sulfur pollution than fossil fuels. | Combustion still releases carbon dioxide and may release other air pollutants. |
A common misconception is that biofuels are automatically carbon neutral. Their net carbon dioxide emissions may be lower than those of fossil fuels, but the complete must include cultivation, fertilizer production, processing, transport and land-use change.