Trying to make sense of the types of biofuels? The main ones are ethanol, biodiesel, renewable diesel, biogas and sustainable aviation fuel, each suited to different engines and uses.
Biofuels are one part of a larger system, and what is the bioeconomy sets out the bigger picture.
| Item | Value |
|---|---|
| Ethanol share in most US gasoline | 10 percent by volume (E10) |
| Common biodiesel blends | 5 percent (B5) or 20 percent (B20) by volume |
| US ethanol production, 2022 | Approximately 15.4 billion gallons |
| US biodiesel plus renewable diesel output, 2022 | About 3.1 billion gallons |
| Biofuels’ share of road transport fuel worldwide | Roughly 4 percent |
| Corn ethanol carbon intensity versus gasoline (life-cycle) | Roughly half |
These figures come from Resources for the Future and the IEEE Technology Navigator. They can change, so check the source before you rely on them.
Ethanol, biodiesel and renewable diesel for road transport
Ethanol is the most widely used biofuel and is generally made from starch and sugar crops such as corn and sugarcane. According to RFF’s explainer of May 12, 2026, it is blended into nearly all gasoline sold in the United States, typically at 10 percent by volume (E10). Higher blends such as E15 suit most gasoline vehicles sold, as of that explainer, though most gasoline is still sold as E10.
Producers make ethanol by fermenting sugars with yeast under anaerobic conditions, then distilling and dehydrating the result to fuel-grade purity. The IEEE Technology Navigator also lists E85 among the ethanol blends used in road transport.
Biodiesel is made from fats and oils such as vegetable oils, animal fats and recycled cooking oil. The usual route is transesterification, a reaction between the oil or fat and an alcohol, typically methanol, which leaves glycerol as a co-product. RFF notes common blends of 5 percent (B5) or 20 percent (B20), and these can be used in most modern diesel engines without engine modification.
Renewable diesel is also made from fats and oils, but unlike biodiesel it is chemically indistinguishable from petroleum diesel. It can fully replace diesel in existing engines and fuel systems, and its use has grown rapidly in recent years, driven in part by policies such as California’s Low Carbon Fuel Standard. Carbon News adds that it is made by hydrotreatment and offers higher energy density and better cold-weather performance than biodiesel.
On scale, the IEEE Technology Navigator reports that US ethanol production totaled approximately 15.4 billion gallons in 2022, while combined biodiesel and renewable diesel output reached about 3.1 billion gallons. Ethanol still dwarfs the diesel-type fuels in volume.
Biogas and biomethane: fuel from waste
Biogas is produced from organic waste such as manure, sewage and food waste through anaerobic digestion. It contains methane and carbon dioxide, and when purified it becomes biomethane, which Carbon News says can serve as a transport fuel or be injected into the gas grid.
Biogas is a different kind of biofuel from the liquids above. It is a gas, it comes mainly from wet waste rather than crops, and it doubles as a waste-management tool.
The IEEE Technology Navigator lists power generation from biogas made by anaerobic digestion of food waste and organic effluents as a key application. That makes it especially relevant in farming regions with large organic waste streams.
Aviation fuel, other alcohols and wood
Sustainable aviation fuel (SAF) refers to alternatives to conventional jet fuel that can be produced from feedstocks such as oils and fats, alcohols and other forms of biomass. RFF says that blended with conventional jet fuel, it can be used in existing aircraft and fueling systems without modification. However, production remains limited by high costs and competition for feedstock supply.
Carbon News cites the International Civil Aviation Organization as saying SAF could deliver over 60% of the emissions reductions needed for aviation to reach net zero by 2050, as set out in its overview of biofuels. Treat that as a projection, not a result.
Some less common fuels round out the picture, as described in a ResourceWise post of June 2, 2025:
- Butanol is an alcohol fuel that contains more energy per ounce than ethanol or methanol, but higher production costs lead many producers to make ethanol instead.
- Methanol is another alcohol fuel, used in specialised areas such as auto racing, and the post calls it mostly obsolete as of its date.
- Wood is the most direct biofuel, burned as pellets, charcoal or sawdust.
The same post separates primary biofuels, which use a resource in unprocessed form (wood pellets heating a stove), from secondary biofuels, which convert biomass into liquids or gas such as ethanol or biogas.
First, second and third generation: what the labels mean
Biofuels are often grouped by generation, according to feedstock and technology maturity. Here is how the IEEE Technology Navigator describes the three groups:
- First generation: made from food crops, with sugar cane and corn for ethanol and soybeans and rapeseed for biodiesel. Feedstocks are readily available, but there are concerns about food competition and land area.
- Second generation: made from lignocellulosic feedstocks such as agricultural straws, forestry residues, energy grasses and food waste.
- Third generation: based on algal lipids, still in research and demonstration phases. Algae can achieve far higher yields per hectare than oilseed crops, but harvesting and dewatering costs remain a barrier to commercial viability.
Second-generation fuels need extra steps. Cellulosic ethanol requires pretreatment to disrupt the lignocellulose matrix and enzymatic hydrolysis to release fermentable sugars, which is where integrated plants matter, as explained in how does a biorefinery work.
Policy discussions often call fuels from non-food feedstocks advanced biofuels. RFF says fuels from agricultural residues, woody biomass and waste oils have seen more limited deployment than crop-based ones.
Comparing the main types side by side
| Fuel | Typical feedstock | Main use |
|---|---|---|
| Ethanol | Corn, sugarcane | Blended into gasoline |
| Biodiesel | Vegetable oils, animal fats, recycled cooking oil | Blended with petroleum diesel |
| Renewable diesel | Fats and oils | Full replacement for diesel |
| Biogas and biomethane | Manure, sewage, food waste | Power, transport fuel, gas grid |
| Sustainable aviation fuel | Oils and fats, alcohols, other biomass | Blended with jet fuel |
Where a fuel is made also matters. RFF calls the United States the world’s largest producer of biofuels and Brazil the second-largest, with a 2024 country-level breakdown in its explainer.
Biomass does not only become fuel. If you want to see what else it becomes, what are biomaterials covers the non-fuel side.
Do biofuels actually cut emissions?
They can, because biofuels recycle carbon that growing organisms recently captured, unlike fossil fuels. Still, the result depends on lifecycle emissions. RFF says it turns on how feedstocks are grown, the emissions from processing and transport, and how demand affects land use.
The IEEE Technology Navigator gives an example: US corn ethanol has a carbon intensity roughly half that of gasoline on a life-cycle basis, though this varies considerably with farming practices. Brazilian sugar cane ethanol does better still because the bagasse residue is burned to power the conversion process.
Several trade-offs remain:
- Competition with food crops, high water use in some feedstock production, and impacts on biodiversity, according to RFF.
- Deforestation and land-use change concerns for some feedstocks, especially palm oil, per Carbon News.
- Limited supply of the waste-based fuels that perform best.
That last point matters because the IEEE page reports an IEA analysis projecting that advanced biofuels from waste feedstocks offer the most significant emission reductions per unit volume while avoiding land-use competition with food. Biofuels also supply roughly 4 percent of road transport fuel worldwide, so they are a complement to other options, not a single fix.
Frequently asked questions
Which biofuel is the most widely used?
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Ethanol. RFF calls it the most widely used biofuel, generally produced from starch and sugar crops such as corn and sugarcane.
Is biodiesel the same as renewable diesel?
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No. Both are made from fats and oils, but renewable diesel is chemically indistinguishable from petroleum diesel, while biodiesel is a different fuel that is usually blended with it.
Can my vehicle run on biofuel blends?
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Often, yes. As of RFF’s explainer of May 12, 2026, E15 is compatible with most gasoline vehicles sold, and B5 and B20 work in most modern diesel engines without modification. Check your vehicle’s manual before switching.
What is biogas made from?
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Organic waste such as manure, sewage and food waste, broken down by anaerobic digestion. Purified, it becomes biomethane, per Carbon News.
Are algae fuels available yet?
Show answer
Not at commercial scale. The IEEE Technology Navigator describes third-generation, algae-based biofuels as still in research and demonstration phases.
