What are the three main biofuels?

The three main biofuels are bioethanol, biodiesel, and biogas (often upgraded to biomethane). These fuels are produced from biological materials such as crops, agricultural residues, and organic waste, and are used primarily in transportation, electricity generation, and heating. Below, we explain how each is made, where it’s used, and what its environmental impacts are.

At a glance

The following points summarize the core characteristics of the three main biofuels, including their production pathways and typical end uses.

• Bioethanol: An alcohol made by fermenting sugars and starches (e.g., sugarcane, corn) or cellulosic biomass; blended with gasoline (e.g., E10, E15, E85) to boost octane and cut tailpipe carbon intensity.
• Biodiesel (FAME): Produced by transesterifying vegetable oils or animal fats; commonly blended with petroleum diesel (e.g., B5, B20) for use in compression-ignition engines. A related diesel-range biofuel, renewable diesel (HVO), is chemically different but serves a similar role as a drop-in fuel.
• Biogas/biomethane: Generated via anaerobic digestion of organic waste (manure, food waste, wastewater sludge); used for heat and power, or upgraded to pipeline-quality biomethane (renewable natural gas) for grid injection or transport as CNG/LNG.

Together, these fuels dominate today’s bioenergy use in transport and distributed energy, with rapidly growing contributions from waste-based pathways that improve greenhouse gas (GHG) performance and reduce methane emissions.

How each fuel is made and used

Bioethanol

Bioethanol is produced by fermenting sugars from crops like sugarcane and sugar beet or converting starches from corn and wheat into sugars before fermentation. Advanced “cellulosic” ethanol uses enzymes and microbes to break down non-food biomass such as agricultural residues (corn stover, wheat straw) and energy grasses, then distills the resulting alcohol. Ethanol is primarily a gasoline substitute or blendstock: E10 (10% ethanol) is ubiquitous in many countries; E15 and E85 are used where vehicles and infrastructure permit. It raises octane, can lower carbon intensity versus gasoline, and is governed by standards such as ASTM D4806 (U.S.) and EN 15376 (EU). The United States and Brazil are the largest producers, with sugarcane ethanol in Brazil generally offering higher GHG reductions than grain-based ethanol due to feedstock and energy inputs.

Biodiesel (FAME) and renewable diesel (HVO)

Biodiesel—chemically fatty acid methyl esters (FAME)—is made by transesterifying vegetable oils (soy, canola/rapeseed), used cooking oil, or animal fats with methanol and a catalyst. It blends readily with petroleum diesel as B5 (5% biodiesel), B20, or even B100 in some applications, improving lubricity and reducing particulate matter and carbon monoxide emissions. Standards include ASTM D6751 (U.S.) and EN 14214 (EU). Cold-flow properties and storage stability can require additives or blend adjustments in colder climates. Renewable diesel (hydrotreated vegetable oil, or HVO) is a separate, paraffinic diesel-range biofuel produced via hydrotreating lipids; while not the same as biodiesel, it is compatible with diesel infrastructure and can be used at high blends, offering similar or better emissions benefits depending on feedstock.

Biogas and biomethane (renewable natural gas)

Biogas forms when microorganisms break down organic matter without oxygen in anaerobic digesters or landfills. Raw biogas typically contains 50–65% methane plus carbon dioxide and trace gases (e.g., hydrogen sulfide). After cleaning and upgrading to remove CO₂ and contaminants, it becomes biomethane—also called renewable natural gas (RNG)—which meets pipeline or vehicle-fuel specifications. It is used for onsite heat and power, injected into gas grids, or compressed/liquefied (CNG/LNG) for heavy-duty vehicles and buses. Because it captures methane that would otherwise escape from manure or waste, RNG from these sources can achieve very low—or even net-negative—lifecycle GHG emissions.

Environmental performance and constraints

The environmental benefits and trade-offs of biofuels vary by feedstock, technology, and supply chain practices. The items below summarize typical patterns seen in recent lifecycle assessments.

• GHG reductions: Corn/grain ethanol often shows about 20–50% lower GHGs than gasoline; sugarcane ethanol can achieve roughly 60–90% reductions; cellulosic ethanol typically exceeds 80%. FAME biodiesel from soy/rapeseed can deliver about 50–70% reductions, while waste-based biodiesel can exceed 80%. Biomethane derived from manure or food waste frequently delivers 80%+ reductions and can be net-negative when avoided methane emissions are counted.
• Air quality: Biodiesel usually reduces particulate matter, hydrocarbons, and carbon monoxide; some engine-fuel combinations may see slight NOx increases, mitigated by modern aftertreatment. Ethanol blending reduces certain toxics and CO but can increase acetaldehyde emissions; overall impacts depend on vehicle technology and blend levels.
• Land use and sustainability: Using residues and wastes generally improves sustainability. Crop-based fuels can raise concerns about indirect land-use change, biodiversity, soil carbon, and water use; certification schemes and better agronomy can help mitigate risks.
• Operational considerations: Biodiesel has higher cold filter plugging points and may require winterization. Ethanol has lower energy density than gasoline and can be hygroscopic, influencing storage and distribution. For biogas, methane leakage must be tightly controlled to preserve climate benefits.

In practice, the strongest climate and environmental performance comes from waste- and residue-based pathways, robust methane control for biogas systems, and careful feedstock sourcing backed by certification and monitoring.

Where you’ll encounter them

Biofuels are integrated into everyday energy systems, with distinct roles depending on infrastructure and policy frameworks.

• Road transport: Ethanol-gasoline blends (E10/E15/E85) for spark-ignition engines; biodiesel and renewable diesel blends (B5–B20 and higher, or drop-in HVO) for diesel fleets.
• Freight and buses: Biomethane as CNG/LNG fuel, especially for refuse trucks and transit buses with depot fueling or grid access.
• Heat and power: Biogas for combined heat and power at wastewater plants, farms, and food-processing facilities; biomethane injected into gas grids to decarbonize building heat.
• Marine and aviation (emerging): Marine engines increasingly test biodiesel/HVO blends. Aviation relies on sustainable aviation fuel (SAF)—often made from similar lipids or alcohol-to-jet routes—though SAF is categorized separately from the three main biofuels commonly cited.

Policy incentives, fuel standards, and infrastructure compatibility largely determine which biofuel a region uses most, with waste-based options gaining momentum due to stronger GHG performance.

Outlook

Demand for the three main biofuels is expected to stay robust where blending mandates and carbon-intensity targets persist. Growth areas include residue- and waste-based ethanol and biodiesel, expanded biogas capture from organics, and biomethane deployment in heavy-duty transport and industry. Advanced pathways—such as cellulosic ethanol, gasification-to-liquids, and alcohol-to-jet—are scaling, complementing the established trio while targeting sectors that are harder to decarbonize with direct electrification.

Summary

Bioethanol, biodiesel, and biogas/biomethane are the three main biofuels used today. Ethanol substitutes for gasoline, biodiesel blends with diesel (alongside drop-in renewable diesel), and biogas/biomethane fuels engines or grids while capturing methane from waste. Their climate benefits depend on feedstock and production practices, with waste- and residue-based pathways delivering the strongest emissions reductions and growing as policy and technology advance.