What Is Biofuel?

Biofuel is a renewable fuel made from recently living biological material—such as plants, organic waste, or algae—used to power vehicles, aircraft, ships, heat systems, and sometimes electricity generation. It differs from fossil fuels because its carbon originally comes from atmospheric CO2 captured by biomass, offering the potential for lower lifecycle greenhouse-gas emissions when produced sustainably.

Definition and Scope

Biofuels are liquid, gaseous, or solid fuels derived from biomass feedstocks including crops (sugar, starch, and oilseeds), agricultural and forestry residues, animal fats, used cooking oil, municipal organics, and algae. They include ethanol, biodiesel, renewable diesel, sustainable aviation fuel (SAF), and biomethane (renewable natural gas). Unlike “e-fuels” made from captured CO2 and renewable electricity, biofuels rely on biological carbon. Their climate impact is assessed on a lifecycle basis—considering cultivation, processing, transport, and combustion—with sustainability safeguards aimed at minimizing land-use change, biodiversity loss, and other externalities.

Main Types of Biofuels and Where They’re Used

The following list outlines the primary categories of biofuels, their typical applications, and how they integrate with today’s engines and infrastructure.

• Ethanol: An alcohol produced mainly by fermenting sugars and starches (e.g., sugarcane, corn, wheat). Commonly blended into gasoline as E10 or E15 for most modern cars; flex-fuel vehicles can use higher blends like E85. It has high octane but lower energy density than gasoline.
• Biodiesel (FAME): A diesel substitute made by transesterifying vegetable oils or animal fats. Used in blends such as B5, B7, or B20; some fleets run B100 with engine and climate considerations. It can improve lubricity but may have cold-flow and NOx challenges depending on feedstock and engine.
• Renewable diesel (HVO/HEFA): A “drop-in” diesel fuel produced by hydrotreating oils and fats. Chemically similar to fossil diesel, it can be used at any blend ratio (often R99/R100) without engine modification and typically offers better cold-flow and NOx performance than biodiesel.
• Sustainable aviation fuel (SAF): Jet fuel alternatives from biomass via pathways such as HEFA, Fischer–Tropsch (FT), or Alcohol-to-Jet (ATJ). Certified for blends up to 50% with conventional jet fuel under current standards; airlines and airports are scaling supply to cut aviation emissions.
• Biogas/biomethane (renewable natural gas): Produced by anaerobic digestion of organic waste or upgraded landfill gas. Used as compressed or liquefied biomethane in vehicles, fed into gas grids, or for combined heat and power.
• Advanced/cellulosic fuels: Made from non-food biomass (agricultural residues, forestry waste, energy grasses). Examples include cellulosic ethanol, FT-diesel/jet from syngas, and fuels from hydrothermal liquefaction or pyrolysis oils after upgrading.

Together, these fuels cover road, aviation, marine, and off-road uses. Some require blending (ethanol, biodiesel), while others are drop-in (renewable diesel, many SAF pathways) that integrate seamlessly with existing engines and supply chains.

Common Feedstocks

Feedstocks determine fuel properties, costs, and sustainability. Below are the major sources used in commercial production and development.

• Sugar and starch crops: Sugarcane, corn, wheat, and sorghum for ethanol production.
• Oils and fats: Soy, rapeseed/canola, sunflower, used cooking oil (UCO), and animal fats for biodiesel and renewable diesel; palm oil is controversial due to deforestation risks and is restricted in some regions.
• Lignocellulosic residues: Corn stover, wheat straw, rice husks, bagasse, and forestry residues for advanced biofuels.
• Energy crops: Perennials like miscanthus and switchgrass, and short-rotation woody crops (e.g., willow, poplar) for cellulosic pathways.
• Organic wastes: Source-separated municipal organic waste and food waste for biogas or advanced liquid fuels.
• Algae: High-potential, still emerging for oils and novel pathways; not yet widely commercial at scale.
• Manure and wastewater sludge: Feedstocks for biogas/biomethane with strong methane abatement benefits.

Using wastes and residues generally delivers better climate and land-use outcomes than dedicating food crops. Many jurisdictions cap crop-based biofuels and incentivize advanced feedstocks to prioritize sustainability.

How Biofuels Are Made

Production technologies span biochemical and thermochemical routes, each suited to specific feedstocks and end-use fuels.

• Fermentation and distillation: Microbes convert sugars/starches into ethanol; residues may fuel the plant or be sold as animal feed (e.g., DDGS).
• Transesterification: Oils/fats react with an alcohol to make fatty acid methyl esters (FAME), i.e., biodiesel, plus glycerin.
• Hydrotreating/isomerization (HVO/HEFA): Oils/fats are deoxygenated and refined into renewable diesel and SAF blending components.
• Anaerobic digestion and upgrading: Organic matter decomposes without oxygen to biogas (CH4 + CO2), then upgraded to pipeline-quality biomethane.
• Gasification + Fischer–Tropsch: Biomass converted to syngas and catalytically synthesized into diesel/jet-range hydrocarbons.
• Alcohol-to-Jet (ATJ): Ethanol or isobutanol upgraded to jet fuel blending components.
• Hydrothermal liquefaction/pyrolysis: Wet or dry biomass thermally converted to bio-crude, then hydroprocessed into fuels.
• Co-processing: Biogenic oils co-refined with petroleum in existing refineries to produce partially renewable fuels.

Commercial maturity varies: fermentation, transesterification, and hydrotreating are well-established; cellulosic and thermochemical routes are scaling with ongoing cost and technology improvements.

Climate Impact and Performance

Biofuels’ climate benefits depend on lifecycle emissions and land-use effects. When feedstocks are responsibly sourced and production uses low-carbon energy, biofuels can significantly cut greenhouse gases versus fossil fuels. They can also reduce particulate matter and CO; effects on NOx vary by fuel and engine. Energy density and cold-flow properties differ: ethanol has lower energy density but high octane; biodiesel can gel in cold weather; renewable diesel and many SAF pathways closely match petroleum fuels’ properties.

The indicative lifecycle greenhouse-gas (GHG) reductions versus fossil fuels are as follows, contingent on feedstock and process:

• Corn ethanol: roughly 20–40% in typical U.S. conditions; up to 50–60% with climate-smart farming, efficient plants, and low-carbon electricity.
• Sugarcane ethanol: about 50–90%, reflecting high-yield crops and use of bagasse for process energy.
• Soy or rapeseed biodiesel (FAME): around 50–65%, with variation by region and cultivation practices.
• Renewable diesel (HEFA) from used cooking oil or tallow: typically 60–90%, benefiting from waste feedstocks and efficient hydrotreating.
• Cellulosic fuels and biomethane from manure/landfill: 80% to over 100% (net negative) when methane capture and displacement are credited.
• SAF: commonly 50–80% today for HEFA, with potential for higher reductions via FT or ATJ using low-carbon hydrogen and power.

Actual results depend on certified carbon-intensity scores under programs like the U.S. LCFS and IRA credits, EU sustainability criteria, or aviation schemes such as CORSIA.

Benefits and Limitations

The points below summarize why biofuels are being deployed now and the key challenges that shape their future role.

• Benefits: Use of existing engines and infrastructure (especially drop-in fuels), potential for deep GHG cuts with waste/residue feedstocks, rural income diversification, energy security, and methane abatement via biomethane.
• Limitations: Land-use change and biodiversity risks, “food vs. fuel” concerns, water and fertilizer impacts (including N2O emissions), feedstock supply constraints, cost volatility, and infrastructure compatibility for certain fuels (e.g., ethanol in pipelines).

Maximizing climate value means prioritizing high-integrity feedstocks, minimizing land conversion, improving agricultural practices, and deploying transparent certification and monitoring.

Sustainability Standards and Safeguards

To ensure real emissions savings and protect ecosystems, many markets require sustainability certification and set guardrails. The European Union’s renewable energy directives mandate minimum GHG savings, traceability, and no-go areas for sourcing; high indirect land-use change (ILUC) risk feedstocks, notably certain palm-oil routes, are being phased out. Voluntary schemes such as ISCC, RSB, and crop-specific programs (e.g., Bonsucro for sugarcane) audit supply chains. Aviation uses CORSIA sustainability criteria, and airports/airlines often apply additional due-diligence to prioritize waste and residue-based SAF.

Policy Landscape and Market Outlook (2024–2025)

As of 2025, biofuels supply a small but material share of transport energy worldwide and are growing where policy support is strong. Expansion is fastest in renewable diesel and SAF, while advanced/cellulosic fuels continue to scale from a smaller base. Feedstock availability—particularly used cooking oil and animal fats—is a strategic bottleneck, steering investment toward residues, energy crops, and biogas pathways.

The following highlights show how policy is shaping biofuel deployment:

• United States: The Renewable Fuel Standard (RFS) sets annual volume obligations. State Low Carbon Fuel Standards (e.g., California) reward lower carbon-intensity fuels. The Inflation Reduction Act provides a SAF tax credit through 2024 and a technology-neutral clean fuel production credit (45Z) for 2025–2027, both tied to lifecycle carbon intensity.
• European Union: RED III targets a 14.5% reduction in transport fuel GHG intensity or a 29% renewable share by 2030, caps crop-based biofuels at 7%, and sets subtargets for advanced biofuels and renewable fuels of non-biological origin. ReFuelEU Aviation introduces a SAF mandate starting at 2% in 2025, rising steadily to 70% by 2050, with minimum shares for synthetic aviation fuels.
• Brazil: RenovaBio establishes decarbonization targets with tradable CBIO credits; ethanol use is widespread and biodiesel blending is increasing toward B15 by mid-decade.
• India: Accelerating ethanol blending with a policy push toward E20 around 2025–2026, alongside programs to expand compressed biogas.
• International aviation: ICAO’s CORSIA scheme entered its first phase in 2024; SAF that meets CORSIA criteria can generate compliance credits, helping airlines scale lower-carbon fuel use.

Policy remains the primary driver of investment and adoption. Near term, SAF demand is set to grow fastest due to mandates, while renewable diesel expands in road freight where LCFS-type incentives exist. Longer term, advanced and waste-based pathways are expected to dominate new capacity to meet stricter sustainability rules.

How Biofuels Compare to Other Low-Carbon Options

Biofuels complement electrification and hydrogen. Battery-electric solutions are efficient for light-duty road transport, while biofuels can quickly decarbonize existing internal-combustion fleets, long-haul trucking (with renewable diesel), and especially aviation and some marine applications where energy-density and infrastructure constraints favor liquid drop-in fuels. Over time, biofuels are likely to focus on sectors that are hardest to electrify, using waste/residue feedstocks first.

Real-World Use and Fuel Labels

Consumers and fleets encounter biofuels mainly through blends and specific labels at the pump or via supplier contracts in aviation and gas networks.

• E10/E15 gasoline: 10–15% ethanol; compatible with most modern gasoline vehicles. E85 is for flex-fuel vehicles only.
• B5/B7/B20 diesel: 5–20% biodiesel; check OEM approvals and local climate guidance. B100 requires dedicated engines or warm conditions.
• Renewable diesel (R99/R100): A drop-in diesel replacement; generally compatible with existing diesel engines and emissions systems.
• SAF: Supplied via airport fueling systems; airlines use approved blends (commonly up to 50%) without passenger-facing labeling.
• Biomethane (CNG/LNG): Used in fleets with natural-gas engines; often marketed as renewable natural gas or biomethane.

Always consult vehicle manuals and national labeling standards for approved blends, seasonal specifications, and warranty coverage.

Key Takeaways

Biofuels are renewable fuels made from biomass that can cut transport emissions today, especially when sourced from wastes and residues. They include ethanol, biodiesel, renewable diesel, SAF, and biomethane, produced via biochemical and thermochemical routes with varying maturity. Their real climate value depends on lifecycle carbon intensity, land-use impacts, and robust sustainability governance. In 2024–2025, growth is strongest in renewable diesel and SAF under policies in the U.S., EU, Brazil, India, and international aviation. Over the long term, biofuels are poised to play a targeted role where electrification is hardest, with advanced, waste-based pathways leading the way.

How is biofuel made?

Biofuel is made through processes like fermentation, which converts sugars and starches from crops (like corn, sugarcane, and potatoes) into bioalcohols (such as ethanol), and transesterification, a chemical reaction that turns vegetable oils and animal fats into biodiesel. Advanced biofuels are also produced from non-food crops using thermochemical processes like pyrolysis and gasification to break down plant matter, while biogas is created through the anaerobic digestion of organic materials like waste and manure.
 
Fermentation (for Bioalcohols like Ethanol) 

1. Feedstocks: Opens in new tabSugarcane, sugar beets, corn, potatoes, and other starchy or sugary crops are used. 
2. Process: Opens in new tabYeast or other microorganisms break down the sugars in the feedstock in a process called fermentation. 
3. Product: Opens in new tabThis process produces bioalcohols, primarily ethanol, which can be used as a fuel or gasoline blend. 

This video explains the process of making bioalcohols through fermentation: 34sFuseSchool – Global EducationYouTube · Sep 24, 2019
Transesterification (for Biodiesel)

1. Feedstocks: Opens in new tabVegetable oils (like soybean, sunflower, or palm oil), animal fats, or recycled cooking oil are used. 
2. Process: Opens in new tabThe oil or fat is reacted with an alcohol (like methanol) in the presence of a catalyst. 
3. Product: Opens in new tabThis chemical reaction separates the oil into biodiesel (a fatty acid methyl ester) and a co-product called glycerin, which can be used for soap. 

You can watch this video to learn how biodiesel is made through transesterification: 53sBiodiesel EducationYouTube · Aug 21, 2018
Thermochemical Processes (for Advanced Biofuels) 

1. Feedstocks: Tough, non-food plant materials like wood, grasses, and crop residues are used.
2. Processes:
   • Pyrolysis: Biomass is rapidly heated at high temperatures (500–700°C) in an oxygen-free environment to produce a liquid bio-crude.
   • Gasification: Biomass is exposed to higher temperatures with some oxygen to create a synthesis gas (syngas).
3. Product: These processes create intermediate products that are further processed into usable fuels.

Anaerobic Digestion (for Biogas) 

1. Feedstocks: Opens in new tabOrganic waste such as food scraps, yard waste, animal manure, and sewage sludge is used.
2. Process: Opens in new tabBacteria and other microorganisms break down the organic material in the absence of oxygen in a sealed tank called a digester.
3. Product: Opens in new tabThe process produces biogas, a mixture of methane and carbon dioxide that can be used for energy.

What are the two examples of bio fuels?

Unlike other renewable energy sources, biomass can be converted directly into liquid fuels, called “biofuels,” to help meet transportation fuel needs. The two most common types of biofuels in use today are ethanol and biodiesel, both of which represent the first generation of biofuel technology.

What is biofuel in short answer?

Biofuels are liquid fuels produced from renewable biological sources, including plants and algae. Biofuels offer a solution to one of the challenges of solar, wind, and other alternative energy sources.

What are the pros & cons of biofuels?

Advantages include sourcing, renewability. The disadvantages covered include production costs and resources. Biomass and biofuels have been used to generate energy since ancient times. Examples include ancient people burning wood and branches to generate fire.