Biofuel

Biofuel is a fuel made from plants or organic waste, such as crops, wood, or even kitchen scraps, instead of from ancient fossil fuels like oil and coal. Because plants absorb carbon dioxide from the air as they grow, burning biofuels is often considered better for the environment. It releases carbon dioxide, but the plants used to make the fuel have already taken that carbon out of the air, making it a more balanced process compared to fossil fuels, which add new carbon to the atmosphere.

Biofuels are mainly used to power cars and trucks, but they can also provide heat and electricity. Two common types are bioethanol and biodiesel. The United States produces the most bioethanol, while the European Union leads in biodiesel production. In Brazil, many cars can run on bioethanol, and special flex-fuel vehicles are widely available there.

Even though biofuels can help reduce pollution, they also have challenges. Using land to grow crops for fuel can sometimes take away land needed for food, leading to debates about whether it’s fair to use food resources for fuel. Also, clearing forests to grow more biofuel crops can harm wildlife and increase carbon emissions. Because of these issues, scientists and governments are working to find the best ways to produce biofuels without causing other problems for the planet.

Terminology

The word biofuel means fuel made from plants or plant waste. It can be a liquid or a gas that helps power cars, trucks, and other vehicles. Some people use the term biofuel only for liquid fuels, while others include gases too.

One group, the IPCC Sixth Assessment Report, says a biofuel is a liquid fuel made from plants. Examples include bioethanol from sugarcane or maize, and biodiesel from canola or soybeans. Bioethanol is an alcohol made from sugars in plants like maize or sugarcane. Biodiesel comes from oils in plants and can clean up pollution from diesel engines.

Types

Liquid

Ethanol

Main article: Ethanol fuel

Ethanol is a common biofuel made by fermenting sugars from plants like corn, wheat, or sugar cane. It is often mixed with gasoline to create a cleaner-burning fuel. Ethanol production uses a lot of crops, which can affect food supplies.

Other biofuels

Methanol can be made from natural gas today, but scientists hope to make it from plants in the future. Butanol is another biofuel that can replace gasoline directly in cars without any changes. Biodiesel is made from oils and fats and works well in diesel engines.

Biodiesel

Main article: Biodiesel

Further information: Biodiesel around the world

Biodiesel is very common in Europe. It is made from oils or fats, like vegetable oil or animal fat, and works in diesel engines. It is cleaner than regular diesel and can be used pure or mixed with regular diesel.

Green diesel

Main article: Biodiesel production

Green diesel is made from plant oils and can replace regular diesel without needing new engines or pipelines. It is being developed in places like Louisiana and Singapore.

Straight vegetable oil

Main article: Vegetable oil fuel

Some people use vegetable oil directly as fuel, but it is usually processed into biodiesel first. This oil can be used in diesel engines after cleaning.

Biogasoline

Main article: Biogasoline

Biogasoline can be made from plants using special bacteria. It looks and works just like regular gasoline.

Bioethers

Bioethers are special compounds that help make fuel burn better and cleaner. They are made from plants and can reduce harmful emissions.

Aviation biofuel

Gaseous

Biogas and biomethane

Main article: Biogas

Biogas is a mix of gases made from rotting plants or animal waste. It can be used to make electricity or power vehicles. When cleaned up, it is called biomethane.

Syngas

Main article: Gasification

Syngas is made by heating biomass without burning it completely. It can be used in engines or to make other fuels.

Solid

Main article: Solid fuel § Biomass

Solid biofuels are made from things like wood or crop waste and can be burned for heat or power.

Research into other types

Algae-based biofuels

Main articles: Algaculture and Algae fuel

Scientists study algae as a source for making fuel. Algae can grow in ponds, tanks, or even in the ocean. They need sunlight, water, and carbon dioxide to make fuel. This kind of fuel doesn’t need fresh water or farmland, which is good for the environment. However, making algae fuel uses a lot of energy and can be expensive.

Electrofuels and solar fuels

Electrofuels and solar fuels are special types of fuels that might use living things or not. Electrofuels store electricity in chemicals like butanol, biodiesel, or hydrogen. Solar fuels use sunlight to make energy-rich chemicals, turning light into power by changing water or carbon dioxide into fuels. These ideas are still being tested and studied.

Bio-digesters

A bio-digester is a special toilet that turns human waste into a clean fuel called biogas. This happens through a process where tiny living things break down organic matter without any oxygen. The waste used can come from farms or sewage, and the end result is a useful gas that can be used as energy.

Extent of production and use

Global biofuel production was 81 million tonnes of oil equivalent (Mtoe) in 2017, which was an annual increase of about 3% compared to 2010. The United States was the largest producer, making 37 Mtoe, followed by Brazil and South America at 23 Mtoe, and Europe (mainly Germany) at 12 Mtoe.

In 2021, biofuels provided 4.3% of the world's transport fuels, including a small amount of aviation biofuel. By 2027, this is expected to rise to 5.4% of transport fuels, with 1% of aviation fuel coming from biofuels. The United States, Europe, Brazil, and Indonesia are leading in increasing the use of biofuels.

Issues

Biofuels can help reduce greenhouse gas emissions compared to fossil fuels because the carbon they release was recently taken from the air by plants. However, how much they help depends on many factors, like what plants are used and how they are grown.

Growing crops for biofuels can sometimes create other problems. Using land that could grow food for biofuels can make food harder to get, especially in places that already struggle to have enough food. Clearing forests to make room for biofuel crops harms wildlife and can damage the soil. Some newer types of biofuels try to use parts of plants that aren’t used for food, but they can also have their own challenges.