What Exactly Is Biofuel?

Biofuel is fuel made from recent biological material—such as plants, agricultural residues, algae, and organic waste—rather than from fossilized remains. It can be produced as liquids (like ethanol, biodiesel, and renewable diesel), gases (biogas/biomethane), or solids, and is used to power cars, trucks, planes, ships, and industrial processes. Because the carbon in biofuels originates from contemporary biomass, their lifecycle greenhouse-gas footprint can be lower than that of fossil fuels, depending on what they’re made from and how they’re produced.

Defining Biofuel

At its core, biofuel is any energy-dense fuel derived from biomass that has grown or been generated in the relatively recent past. Unlike fossil fuels, which release carbon that has been locked underground for millions of years, biofuels recycle carbon already active in today’s biosphere. That distinction does not automatically make biofuels “carbon neutral”—real-world impacts vary by feedstock, farming practices, land-use changes, processing energy, and transport. Modern assessments use lifecycle analysis to quantify benefits and trade-offs.

Main Types of Biofuels

Biofuels come in several forms, each suited to different engines and infrastructure. Below are the principal categories consumers, fleets, and utilities encounter today.

• Ethanol (bioethanol): An alcohol made by fermenting sugars or starches (e.g., sugarcane, corn). Commonly blended into gasoline (E10–E15); higher blends like E85 are used in flex-fuel vehicles.
• Biodiesel (FAME): Fatty acid methyl ester produced via transesterification of vegetable oils or waste fats. Used in diesel engines typically at blends like B5–B20; has different properties from fossil diesel.
• Renewable diesel (HVO/HEFA): A hydrotreated fuel chemically similar to petroleum diesel. It is “drop-in,” meaning it can fully replace or mix with diesel without engine modifications.
• Sustainable aviation fuel (SAF): Aviation-grade biofuels made via pathways such as HEFA, alcohol-to-jet (ATJ), or Fischer–Tropsch (FT) from biomass. Certified to meet jet-fuel specifications and blended for commercial flights.
• Biogas and biomethane (renewable natural gas, RNG): Methane-rich gas from anaerobic digestion of organic waste. When purified to pipeline quality, it can substitute for fossil natural gas.
• Advanced/”second-generation” fuels: Fuels made from lignocellulosic residues (e.g., corn stover, straw, forestry slash) or municipal solid waste, including cellulosic ethanol and FT or ATJ drop-in fuels.

Together, these fuels address a spectrum of energy needs, with “drop-in” options like renewable diesel and SAF offering the smoothest integration into existing engines and fuel logistics.

Common Feedstocks

The sustainability and performance of a biofuel largely depend on its feedstock—the raw material used to make it. Below are the most prevalent sources and why they matter.

• Sugar and starch crops: Sugarcane, corn, wheat—primarily for ethanol via fermentation.
• Oil crops: Soybean, rapeseed/canola, palm—used to make biodiesel and renewable diesel; sustainability varies widely by region and practice.
• Waste oils and fats: Used cooking oil, tallow, greases—highly valued for low lifecycle emissions and avoiding land-use impacts.
• Agricultural residues: Corn stover, wheat straw—cellulosic ethanol or thermochemical fuels without expanding cropland.
• Forestry residues: Slash, thinnings—used in advanced fuels and for biogas; careful management is needed to protect forest health.
• Dedicated energy crops: Switchgrass, miscanthus, short-rotation woody crops—grown for high biomass yields and soil benefits.
• Algae: High-potential lipid or carbohydrate source; still largely pre-commercial due to cost.
• Organic waste streams: Manure, food waste, sewage sludge—feed anaerobic digesters to produce biogas/RNG.

Shifting from food crops to wastes, residues, and dedicated energy crops generally improves climate outcomes and reduces pressure on land and food markets.

How Biofuels Are Made

Multiple biochemical and thermochemical pathways convert biomass into usable fuels. The choice of process depends on the feedstock and the target fuel.

• Fermentation: Microbes convert sugars/starches (and, with pre-treatment, cellulose) into ethanol or other alcohols.
• Transesterification: Oils/fats react with methanol to make biodiesel (FAME) and glycerin byproduct.
• Hydrotreating/isomerization: Oils/fats processed with hydrogen to produce renewable diesel or SAF (HEFA).
• Anaerobic digestion: Microbes break down wet organic matter to biogas (methane and CO₂), which can be upgraded to RNG.
• Gasification + Fischer–Tropsch: Biomass converted to synthesis gas (CO and H₂) and then to liquid fuels (diesel/jet-range hydrocarbons).
• Pyrolysis + upgrading: Thermal decomposition of biomass into bio-oil, then refined into transportation fuels.
• Alcohol-to-jet (ATJ): Converts alcohols (ethanol, isobutanol) into synthetic jet fuel components.

Each pathway has trade-offs in cost, scalability, and emissions. Processes powered by renewable electricity and paired with carbon capture can significantly improve lifecycle performance.

Generations of Biofuels

Biofuels are often grouped by “generation,” reflecting feedstock choice and technology maturity.

• First generation: Made from food crops (corn, sugarcane, vegetable oils). Mature, widely deployed, but can raise land-use concerns.
• Second generation (advanced): From non-food lignocellulosic biomass and wastes; better sustainability profile but more complex and costly.
• Third generation: Algae-based routes with high theoretical yields; still early-stage for mass fuel production.
• Fourth generation: Encompasses engineered organisms and bioenergy with carbon capture and storage (BECCS), aiming for net-negative emissions.

Policy and investment are increasingly steering markets toward advanced and waste-based options with stronger climate benefits.

Climate Impact and Sustainability

The climate value of biofuels is measured across their full lifecycle—from cultivation through processing, transport, and combustion. Results vary widely: using wastes and residues, renewable energy, precision agriculture, and carbon capture generally lowers emissions, while indirect land-use change, fertilizer use, and deforestation erode benefits.

To illustrate performance, the following ranges summarize typical lifecycle greenhouse-gas reductions versus fossil counterparts, assuming good practices and verified supply chains.

• Sugarcane ethanol: Approximately 60–90% lower emissions than gasoline, depending on mill efficiency and electricity co-generation.
• Corn ethanol: Roughly 20–50% lower on average, with higher savings possible when plants use low-carbon power and carbon capture.
• Biodiesel (soy/rapeseed): Often 40–60% lower than diesel; from waste oils, reductions can reach 60–85%.
• Renewable diesel (from waste lipids): Typically 60–80%+ lower than diesel; performance varies with hydrogen source and energy inputs.
• SAF (HEFA, ATJ, FT from residues/wastes): Commonly 50–80% lower than conventional jet fuel; some advanced routes can exceed this when powered by clean energy.
• Biomethane/RNG from waste: 50% lower to net-negative in some cases when methane capture of otherwise-emitting waste is credited.

Robust certification (e.g., RSB, ISCC) and jurisdictional safeguards are increasingly required to ensure traceability, prevent deforestation, and limit food-based expansion.

Benefits

Well-designed biofuel systems can deliver multiple energy, climate, and economic gains. The points below capture the most cited advantages.

• Lower lifecycle emissions: Especially from wastes, residues, and advanced pathways.
• Energy security: Diversifies supply and reduces dependence on imported fossil fuels.
• Waste reduction: Turns organic waste streams into useful energy while curbing methane.
• Rural development: Creates markets for residues and new crops, supporting jobs.
• Infrastructure compatibility: Drop-in fuels like renewable diesel and SAF integrate with existing engines and pipelines.
• Near-term decarbonization: Helps cut emissions in sectors that are hard to electrify, notably aviation and long-haul transport.

These benefits are most robust when biofuels avoid land-use conversion, use low-carbon power, and follow verified sustainability standards.

Drawbacks and Risks

Biofuels are not a one-size-fits-all climate solution. The following issues must be managed for credible benefits.

• Land-use and food competition: Expanding cropland for fuel can displace food production and natural ecosystems.
• Biodiversity impacts: Poor practices (e.g., palm expansion into forests) cause habitat loss.
• Water and soil pressures: Irrigation, fertilizer, and erosion can degrade local environments.
• Air pollutants: Some blends and engines may increase certain pollutants without proper controls.
• Feedstock constraints: Waste oils and residues are limited; scaling supply sustainably is challenging.
• Cost and policy dependence: Many advanced fuels rely on incentives and stable regulations to compete.
• Engine/material compatibility: High biodiesel or ethanol blends require suitable engines and handling.

Mitigation strategies include stricter sourcing rules, advanced agronomy, better conversion efficiency, and prioritizing non-food, waste-based inputs.

Where Biofuels Are Used Today

Biofuels already play a visible role in transport and heating, with growth focused on hard-to-electrify sectors. Here’s where they are most commonly deployed.

• Road transport: Ethanol blends (E10–E15) are standard in many markets; E85 is used in flex-fuel cars. Biodiesel (B5–B20) and renewable diesel power diesel fleets and municipal buses.
• Aviation: SAF is being blended into jet fuel on selected routes; airlines and regulators are ramping mandates and offtake agreements through the 2030s and beyond.
• Maritime: Trials and early deployments of bio-methanol, FAME blends, and HVO are underway as the sector seeks lower-carbon fuels.
• Buildings and industry: Biomethane/RNG substitutes for fossil gas in boilers, combined heat and power, and some process heat.
• Off-grid and backup power: Generators increasingly use HVO/renewable diesel to cut local emissions.
• Household energy: Small-scale biogas digesters provide clean cooking fuel in many rural communities.

As electrification accelerates in light-duty transport, biofuels are expected to concentrate where high energy density and existing engines dominate—aviation, shipping, heavy-duty road, and certain industrial uses.

Policy and Market Snapshot (2025)

Policies shape biofuel markets. In the United States, the Renewable Fuel Standard and state Low-Carbon Fuel Standards (e.g., California) drive demand via lifecycle-based credits; new federal clean fuel production incentives begin in 2025. The European Union’s updated Renewable Energy Directive tightens sustainability criteria, caps food-based biofuels, and boosts advanced fuels, while ReFuelEU Aviation initiates mandatory SAF blending that rises over time. Other notable programs include Brazil’s RenovaBio, the UK’s Renewable Transport Fuel Obligation, India’s accelerated ethanol blending targets, and emerging mandates in parts of Asia and Latin America. Across regions, regulators are prioritizing advanced, waste-derived, and high-integrity supply chains.

How Biofuels Differ from Fossil Fuels—and From E‑Fuels

Fossil fuels release carbon that has been geologically stored, adding net CO₂ to the atmosphere. Biofuels recycle contemporary carbon, offering potential reductions when sustainably sourced and processed. By contrast, e‑fuels (synthetic fuels made from captured CO₂ and green hydrogen) are not bio-based; they can be very low carbon but currently face high costs and limited supply of renewable hydrogen and CO₂.

Bottom Line

Biofuels are fuels derived from modern biomass and organic wastes, available as liquids and gases that can power existing engines. When sourced from wastes and residues and produced with clean energy, they can significantly cut lifecycle emissions, especially in aviation, shipping, and heavy-duty transport. Their real-world value hinges on rigorous sustainability, careful land-use management, and smart policy that prioritizes the highest-impact pathways.

Summary

Biofuel is a fuel made from recent biological material, not ancient fossil carbon. Major types include ethanol, biodiesel, renewable diesel, sustainable aviation fuel, and biogas/biomethane, produced via fermentation, hydrotreating, anaerobic digestion, and thermochemical routes. Advanced, waste-based biofuels generally deliver the strongest climate benefits, while challenges include land-use pressures, feedstock limits, and costs. With tighter sustainability standards and targeted policies, biofuels are set to play a pivotal role in decarbonizing sectors that are difficult to electrify.

What are the three main biofuels?

There are three main types of biofuel– ethanol, biodiesel and biojet fuel. Ethanol is used in engines that burn gasoline, like most cars, biodiesel is used in engines that burn diesel fuel, like trucks and tractors and biojet fuel is used in planes.

What are biofuels in simple terms?

biofuel, any fuel that is derived from biomass—that is, plant or algae material or animal waste. Since such feedstock material can be replenished readily, biofuel is considered to be a source of renewable energy, unlike fossil fuels such as petroleum, coal, and natural gas.

What are the negatives of biofuels?

Disadvantages of biofuels include deforestation, loss of biodiversity, increased food prices and potential food shortages, significant land and water requirements, high production costs, and the release of air pollutants like nitrogen oxides and fine particles that negatively impact public health and contribute to smog. Furthermore, the energy required for biofuel production and transport can be substantial, sometimes even exceeding the energy content of the fuel itself, and the quality and efficiency of these fuels can vary. 
Environmental & Land Use Concerns

• Deforestation and Habitat Loss: Opens in new tabGrowing crops for biofuels requires large amounts of land, which can lead to deforestation and destruction of natural habitats, reducing biodiversity. 
• Water Consumption: Opens in new tabBiofuel crop production often demands substantial water resources for irrigation, potentially straining local water supplies and disrupting ecosystems. 
• Soil Erosion: Opens in new tabLarge-scale monoculture farming for biofuels can lead to soil erosion and degradation. 
• Air Pollution: Opens in new tabBurning biofuels releases air pollutants, including fine particulate matter, ozone, and nitrogen dioxide, which can trigger respiratory problems, heart attacks, and contribute to smog. 

Socioeconomic Impacts

• Food Prices and Shortages: Opens in new tabUsing land to grow biofuel crops reduces the amount of land available for food production, which can drive up food prices and potentially lead to food shortages. 
• High Production Costs: Opens in new tabSignificant investments in infrastructure and technology are needed to produce biofuels, making them more expensive than traditional fossil fuels. 

Energy and Production Issues

• Production Energy Use: The process of producing, transporting, and refining biofuels can consume a large amount of energy, sometimes to the point where the energy input is not significantly less than the energy output. 
• Variable Quality and Efficiency: The quality of biofuels can vary depending on the feedstock and production process. Additionally, some biofuels are less efficient than other fuels, releasing more heat and less usable energy. 
• Technical Challenges: High-ethanol biofuels may require modifications to car engines, and higher blends of biodiesel can gel in cold weather, limiting their use. 

Why don’t cars run on biofuel?

Adding a higher percentage of ethanol beyond this point would cancel out any of the environmental benefits of using it in the first place, because vehicles would use more fuel. While some vehicles, even conventional ones, can run on 100 percent biofuel, they never run as efficiently as they would with petroleum.