Biofuel

Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial bio waste. Biofuels are mostly used for transportation, but can also be used for heating and electricity. Biofuels (and bioenergy in general) are regarded as a renewable energy source. The use of biofuel has been subject to criticism regarding the "food vs fuel" debate, varied assessments of their sustainability, and ongoing deforestation and biodiversity loss as a result of biofuel production.

In general, biofuels emit fewer greenhouse gas emissions when burned in an engine and are generally considered carbon-neutral fuels as the carbon emitted has been captured from the atmosphere by the crops used in production. However, life-cycle assessments of biofuels have shown large emissions associated with the potential land-use change required to produce additional biofuel feedstocks. The outcomes of lifecycle assessments (LCAs) for biofuels are highly situational and dependent on many factors including the type of feedstock, production routes, data variations, and methodological choices. Estimates about the climate impact from biofuels vary widely based on the methodology and exact situation examined. Therefore, the climate change mitigation potential of biofuel varies considerably: in some scenarios biofuel emission levels are comparable to fossil fuels, and in other scenarios the use of biofuel results in negative emissions.

Global demand for biofuels is predicted to increase by 56% over 2022–2027. By 2027 worldwide biofuel production is expected to supply 5.4% of the world's fuels for transport including 1% of aviation fuel. Demand for aviation biofuel is forecast to increase. However some policy has been criticised for favoring ground transportation over aviation.

The IEA says that biofuel should particularly be used for applications which are difficult to electrify, such as shipping and aviation. The two most common types of biofuel are bioethanol and biodiesel. The United States is the largest producer of bioethanol, while the EU is the largest producer of biodiesel. Meanwhile, Brazil produces and uses large amounts of bioethanol in vehicles, including in some flex-fuel cars exclusively available in Brazil. The energy content in the global production of bioethanol and biodiesel is 2.2 and 1.8 EJ per year, respectively.