Some fuel comes from plants. 
Some fuel comes from living things. 

Biofuel is a type of energy made from living things. 
There are two main kinds of biofuel. The first is bioethanol. This is an alcohol made through fermentation. Fermentation is a way to change sugars into alcohol using tiny living things. Most bioethanol comes from crops like corn or sugarcane. 
The second kind is biodiesel. This is a liquid made from oils or fats. It can be used in many diesel engines. Some people mix it with regular fuel. Others use it all by itself.
Biofuel helps the air. When burned, it often gives off fewer greenhouse gases. This is because the plants took carbon from the air while they grew. However, making biofuel can cause problems. It may lead to the loss of forests or change how land is used. 
Biofuel is a special kind of energy made from biomass. 
There are two main ways these fuels work. The first is bioethanol, which is an alcohol. 
Scientists and leaders study how these fuels affect our world. Some people worry about the "food vs fuel" debate. This happens when land is used for fuel instead of food. 
Different parts of the world produce different fuels. The United States is the largest producer of bioethanol.
Biofuel connects to the way we move every day. You might see ethanol mixed with gasoline in a car. 
Biofuel is a type of energy produced from biomass. 
There are two main liquid biofuels: bioethanol and biodiesel. Bioethanol is an alcohol produced through fermentation. This process uses microorganisms or enzymes to change sugars or starches into alcohol. Common feedstocks for ethanol include maize, sugarcane, wheat, and sugar beets. To make ethanol, producers use enzyme digestion to release sugars from starch. They then use fermentation, distillation, and drying. Distillation is a step that requires significant energy to generate heat. 
Scientists categorize biofuels into different generations based on their source. First-generation biofuels, or conventional biofuels, are made from food crops grown on arable land. This includes using the sugar, starch, or oil from crops for fuel. This has led to a "food vs fuel" debate. This debate focuses on whether land should be used for energy or for food. To avoid this, researchers develop advanced biofuels. These are second-generation or third-generation biofuels. They are made from feedstocks that do not compete with food. 
Other types of biofuels are also being studied. Methanol is currently made from natural gas, but scientists hope to produce biomethanol from biomass in the future. Butanol is another liquid biofuel. It can be formed through a process called ABE fermentation, which produces acetone, butanol, and ethanol. Some researchers have even engineered Escherichia coli bacteria to produce butanol. Biobutanol is sometimes called "biogasoline." While it is an alcohol rather than a hydrocarbon, it is claimed to be a direct replacement for gasoline. It can be burned in existing engines without modifications. It is also less corrosive and less water-soluble than ethanol.
Biodiesel has specific characteristics when used in engines. It is an oxygenated fuel, meaning it has more hydrogen and oxygen and less carbon than fossil diesel. This can improve combustion and reduce particulate emissions. However, using pure biodiesel may increase NOx emissions. Pure biodiesel is known as B100. It can be used in many diesel engines, but some modern "common rail" systems require biodiesel to be blended with conventional diesel. Biodiesel is also a strong solvent. It can clean old residues from fuel tanks and pipes, which might require more frequent filter changes. 
Global production and demand for these fuels are significant. The United States is the largest producer of bioethanol. The European Union is the largest producer of biodiesel. In 2021, ethanol production used 20% of global sugar supplies and 13% of corn supplies. The energy content for global bioethanol and biodiesel production is 2.2 and 1.8 EJ per year, respectively. Global demand for biofuels is predicted to increase by 56% between 2022 and 2027. By 2027, worldwide production is expected to supply 5.4% of transport fuels. This includes 1% of all aviation fuel.
The environmental impact of biofuels is complex. Biofuels are often considered carbon-neutral. This is because the carbon emitted during burning was recently captured from the atmosphere by the crops. However, life-cycle assessments show that land-use changes can cause large emissions. Using land for biofuels can lead to deforestation and loss of biodiversity. 
🖼️ Images & Media (11)
More to explore
✨ What else?
Related topics you might enjoy
🔬 Go deeper
More advanced topics to explore
🪜 Step back
Simpler topics to build understanding
What is Nepedia?
A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.