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Biofuel

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Biofuel is a type of energy produced from biomass.

Types and generation of biofuels
Types and generation of biofuels

Biomass refers to organic material that is not fossilized. This includes living plants, wood, and agricultural residues like molasses or bagasse. Unlike fossil fuels, which take millions of years to form underground, biofuels are produced over short time spans. They are considered a renewable energy source. Biofuels are primarily used for transportation. However, they can also be used to generate electricity or provide heating.

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.

Sao Paulo ethanol pump 04 2008 74 zoom
Sao Paulo ethanol pump 04 2008 74 zoom

Biodiesel is produced from oils or fats through a process called transesterification. This chemical process creates a liquid composed mostly of fatty acid methyl or ethyl esters. Feedstocks for biodiesel include vegetable oils like soy, rapeseed, or sunflower, as well as animal fats.

Biodiesel
Biodiesel

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.

Wheat harvest
Wheat harvest

These include waste products like rice straw, wood chips, sawdust, or municipal solid waste. Some are grown on marginal land that is not suitable for 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.

Targray Biodiesel Railcar
Targray Biodiesel Railcar

Despite these details, biodiesel is very safe. It has a high flash point of about 300 °F, which is much higher than petroleum diesel.

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.

Biofuel production by region, OWID
Biofuel production by region, OWID

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.

Deforestation near Bukit Tiga Puluh NP
Deforestation near Bukit Tiga Puluh NP

Because of these factors, the climate impact varies. In some cases, biofuels result in negative emissions. In other cases, their emission levels are comparable to fossil fuels. Because of this, the International Energy Agency suggests using biofuels for sectors that are difficult to electrify, such as shipping and aviation.

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🖼️ Images & Media (11)
File:Biodiesel.JPG
Biodiesel.JPG
File:Types and generation of biofuels.png
Types and generation of biofuels.png
File:Biofuel pumps DCA 07 2010 9834.JPG
Biofuel pumps DCA 07 2010 9834.JPG
File:Targray Biodiesel Railcar.png
Targray Biodiesel Railcar.png
File:Walmart’s Grease Fuel Truck (2).jpg
Walmart’s Grease Fuel Truck (2).jpg
File:Sao Paulo ethanol pump 04 2008 74 zoom.jpg
Sao Paulo ethanol pump 04 2008 74 zoom.jpg
File:Biogas.jpg
Biogas.jpg
File:Biofuel energy production.png
Biofuel energy production.png
File:Biofuel production by region, OWID.svg
Biofuel production by region, OWID.svg
File:Wheat harvest.jpg
Wheat harvest.jpg
File:Deforestation near Bukit Tiga Puluh NP.jpg
Deforestation near Bukit Tiga Puluh NP.jpg
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