Is Biodiesel Better for the Environment Than Gasoline?

In general, yes—when produced from waste oils or sustainably sourced feedstocks and used in modern diesel engines, biodiesel typically delivers lower lifecycle greenhouse gas emissions and fewer toxic pollutants than gasoline. However, the advantage depends heavily on the biodiesel’s feedstock and supply chain; some pathways (notably those linked to deforestation) can erase or even reverse the climate benefits, and certain engines may see slight increases in nitrogen oxides (NOx).

What We’re Comparing

Biodiesel is a fatty acid methyl ester (FAME) fuel made from vegetable oils, used cooking oils, or animal fats. It is designed for compression-ignition (diesel) engines and is commonly blended as B5 (5% biodiesel), B20 (20%), or used as B100 (pure biodiesel). Gasoline, by contrast, powers spark-ignition engines. Any comparison therefore spans both fuel properties and typical engine differences: diesel engines are usually more efficient per mile than gasoline engines, which affects total emissions per distance traveled.

The Bottom Line by Environmental Metric

Climate Impact (Lifecycle Greenhouse Gases)

On a full “well-to-wheels” basis, biodiesel from waste oils or animal fats often cuts greenhouse gas emissions by roughly 70–90% versus petroleum fuels, while biodiesel from soy or rapeseed typically delivers around 40–60% reductions. California’s Low Carbon Fuel Standard reports carbon intensities around 10–30 gCO2e/MJ for used-cooking-oil biodiesel, about 50–60 gCO2e/MJ for soy-based biodiesel, compared with roughly ~99 gCO2e/MJ for gasoline. However, biodiesel tied to tropical deforestation or peatland conversion (e.g., some palm oil pathways) can exceed gasoline’s carbon intensity, sometimes by a wide margin when land-use change is included.

Air-Quality Pollutants

Relative to petroleum diesel, biodiesel generally lowers particulate matter (PM), carbon monoxide (CO), hydrocarbons (HC), and essentially eliminates sulfur oxides (SOx) due to its very low sulfur content. Compared to gasoline vehicles, biodiesel in diesel engines typically results in lower CO and aromatics and fewer toxic air toxics, but NOx can rise slightly (more so with B100) in some engines and duty cycles. Modern diesel vehicles equipped with selective catalytic reduction (SCR) and diesel particulate filters (DPFs) largely control NOx and PM, making biodiesel’s air-quality profile favorable in most real-world applications.

Energy Use and Efficiency per Mile

Diesel engines are typically 15–25% more efficient than comparable gasoline engines. B100 has about 8–12% less energy per gallon than petroleum diesel, so fuel economy can drop somewhat with higher blends; B20 typically results in roughly a 1–2% mileage penalty. Even after this, a biodiesel-powered diesel vehicle often emits less CO2 per mile than a similar gasoline vehicle, assuming sustainable feedstocks.

Land, Water, and Biodiversity

Biodiesel’s sustainability hinges on feedstock. Used cooking oil and waste fats have minimal land-use impacts and the best environmental performance. Oil crops like soy, rapeseed, or palm require farmland; if production drives deforestation or peat drainage, the carbon and biodiversity costs can be severe and long-lasting. Water use, fertilizer runoff, and pesticide impacts also vary by crop and region. Certification schemes and strong land-use safeguards substantially improve outcomes.

Spills and Toxicity

Biodiesel is readily biodegradable and far less toxic than petroleum fuels, reducing harm from spills. Gasoline’s volatility leads to evaporative emissions and exposure to carcinogenic aromatics (e.g., benzene), which biodiesel avoids.

When Biodiesel Is Clearly Greener

The environmental case for biodiesel is strongest under specific conditions that limit land-use pressures and leverage modern emission controls. The points below highlight contexts where biodiesel typically outperforms gasoline.

• Feedstocks are waste-based (used cooking oil, animal fats, distillers corn oil), avoiding new land conversion.
• Engines are modern diesels with DPF and SCR, minimizing NOx and PM.
• Short, transparent supply chains with sustainability certifications and robust traceability.
• Regional production that limits transport emissions and supports circular waste management.
• Moderate blends (e.g., B20) that balance emissions gains with reliable cold-weather performance.

Under these conditions, biodiesel commonly delivers large lifecycle GHG cuts and cleaner local air than gasoline, while also lowering spill risks and toxic exposure.

When Biodiesel May Not Be Better Than Gasoline

Some biodiesel pathways can underperform gasoline on climate or local air quality, especially when land-use change is significant or emissions controls are lacking. The scenarios below illustrate when advantages can erode.

• Feedstocks linked to deforestation or peatland drainage (e.g., certain palm oil expansions), which can push lifecycle emissions above gasoline for decades.
• Older diesel engines without effective NOx controls operating in urban areas prone to ozone formation.
• Cold climates without appropriate cold-flow additives or blending, leading to operability issues and higher upstream energy use for mitigation.
• Long, opaque supply chains with uncertain sustainability, increasing transport emissions and ILUC risk.
• Comparisons against highly efficient gasoline hybrids in clean-air cities may narrow or, in some cases, surpass the benefits of poorly sourced biodiesel.

In these cases, the climate edge can diminish and local air-quality concerns can rise, making feedstock sourcing and technology choices decisive.

Practical Guidance for Drivers and Fleets

Choosing biodiesel wisely can maximize environmental benefits while avoiding common pitfalls. Consider the following steps to ensure a better outcome than gasoline.

1. Know the feedstock: prioritize used cooking oil and waste fats; seek documentation on origin.
2. Use certified suppliers: look for compliance with programs like the U.S. RFS pathways, California LCFS documentation, or recognized sustainability certifications.
3. Match blend to climate and equipment: B5–B20 is widely compatible; verify OEM approvals and winter specifications.
4. Maintain aftertreatment systems: ensure DPF/SCR are functioning to control NOx and PM.
5. Localize supply when possible: shorter logistics reduce emissions and improve traceability.
6. Monitor performance: track fuel economy, emissions inspections, and maintenance to confirm expected benefits.

These practices help lock in lower lifecycle emissions and reduce local pollutants compared with gasoline, without sacrificing reliability.

Key Numbers at a Glance

The figures below summarize typical, policy-vetted values used by regulators and researchers for quick comparison. Actual results vary by feedstock, region, and technology.

• Carbon intensity (gCO2e/MJ): gasoline ~99; soy biodiesel ~50–60; used-cooking-oil biodiesel ~10–30; palm with land-use change can exceed 100.
• Lifecycle GHG reduction vs fossil fuels: waste-oil biodiesel ~70–90%; soy/rapeseed ~40–60%.
• Tailpipe pollutants vs petroleum diesel: PM, CO, HC down; SOx near zero; NOx unchanged to slightly higher without SCR, controlled with SCR.
• Fuel economy impact: B20 ~1–2% lower than petroleum diesel; B100 ~8–12% lower; diesel engines remain more efficient than gasoline overall.
• Spill/biodegradability: biodiesel biodegrades faster and is less toxic than gasoline or petroleum diesel.

Taken together, these benchmarks show why biodiesel—especially from waste streams—often undercuts gasoline on climate and public-health metrics.

Summary

Biodiesel can be better for the environment than gasoline—often substantially so—when it’s produced from waste or sustainably managed feedstocks and used in modern diesel vehicles. It typically delivers sizable lifecycle greenhouse gas reductions and cleaner toxic-emissions profiles. The main caveats are feedstocks tied to land-use change and NOx control in older engines. With responsible sourcing and contemporary emissions technology, biodiesel generally outperforms gasoline on both climate and air-quality grounds.

Are biodiesel fuels more toxic to the environment than petroleum fuels?

Safety. Biodiesel in its pure, unblended form causes far less damage than petroleum diesel if spilled or released to the environment.

What is the downside of biodiesel?

Disadvantages of biodiesel include higher costs than petroleum diesel, poor cold-weather performance (thickening and gelling), increased NOx emissions leading to smog and acid rain, and the potential for engine clogging due to poor fuel quality, high viscosity, or contamination. Environmental drawbacks can also arise from its production, including land use competition with food crops, soil erosion, water pollution, and biodiversity loss, in addition to the energy required for farming and processing. 
Performance & Engine Issues

• Cold weather problems: Opens in new tabBiodiesel tends to gel in cold temperatures, obstructing fuel flow in engines and requiring more energy-intensive infrastructure for storage and transportation. 
• Engine clogging: Opens in new tabIssues with fuel quality, such as high viscosity or incomplete processing, can lead to deposits in fuel lines and filter clogs. 
• Lower energy content: Opens in new tabBiodiesel has a lower energy content than petro-diesel, meaning more fuel is needed to produce the same amount of energy. 

Emissions Concerns

• Increased NOx emissions: Biodiesel combustion can result in a significant increase in nitrogen oxides (NOx) emissions, contributing to smog and acid rain. 
• Tailpipe emissions: While often considered a clean alternative, biodiesel-fueled vehicles still produce tailpipe emissions, including a small amount of greenhouse gases. 

Production & Environmental Drawbacks

• Cost of production: Opens in new tabThe overall high cost of production, linked to feedstock and processing costs, makes biodiesel more expensive than petroleum diesel. 
• Food vs. Fuel: Opens in new tabProduction of biodiesel requires agricultural land and crops, which can compete with food production, driving up food prices. 
• Environmental pollution: Opens in new tabThe farming and processing of crops for biodiesel can lead to soil erosion, water pollution from fertilizer runoff, and harm to biodiversity. 
• Fossil fuel reliance in production: Opens in new tabThe energy-intensive process of growing and refining feedstock, as well as processing, often still relies on fossil fuels. 

Fuel Quality & Storage

• Poor fuel quality: Incomplete processing can leave contaminants like methanol, lye, or excess water in the fuel. 
• Instability: Biodiesel can degrade over time, especially with improper storage or prolonged exposure to moderate to high temperatures. 
• Specialized storage needs: Biodiesel needs to be stored at the correct temperature to prevent microbial growth or thickening, often requiring specialized tanks. 

Is biodiesel more environmentally friendly?

Biodiesel is also non toxic and biodegardable. Using biodiesel lowers particulate matter by 47%, reduces hydrocarbon emissions by up to 67%, and reduces smog. It’s environmental benefits don’t stop there. The production of biodiesel, in lieu of petroleum diesel, reduces wastewater by 79% and hazardous waste by 96%.

Why are we not using biodiesel?

Biodiesel isn’t widely used because of its high cost, lower energy content, and susceptibility to cold weather, which causes gelling. Significant infrastructure is also missing, which makes it unavailable everywhere, and production often requires large amounts of land and water, potentially impacting food prices and security. Additionally, while some emissions are reduced, it doesn’t eliminate tailpipe pollutants and can contribute to other environmental issues.
 
Technical & Performance Drawbacks

• Cold Weather Gelling: Opens in new tabBiodiesel’s “cloud point” is higher than petrodiesel, meaning it freezes and solidifies in colder temperatures, making it unreliable for use in colder regions. 
• Lower Energy Content: Opens in new tabBiodiesel has less energy per gallon than petroleum diesel, so more fuel is needed for the same amount of work. 
• Corrosive Nature: Opens in new tabSome components in older diesel engines, made from natural rubber, can degrade upon contact with biodiesel. 
• Fuel Quality: Opens in new tabPoor quality biodiesel can lead to problems like oxidation and microbial fouling, which can damage storage tanks and clog fuel lines. 

Economic & Infrastructure Challenges

• High Cost: Biodiesel is often more expensive to produce than petroleum-based diesel, and market demand may not support the higher price. 
• Limited Availability: There isn’t widespread availability of biodiesel at all fuel stations, creating a barrier for consumers and fleets. 
• Fossil Fuel Infrastructure: The current energy infrastructure is built for fossil fuels, and a massive investment would be needed to transition to biodiesel. 

Environmental & Resource Concerns

• Land and Water Use: Opens in new tabGrowing crops for biodiesel requires significant amounts of land and water, which can compete with food production. 
• Food Prices and Security: Opens in new tabUsing more land for biofuel crops can reduce food crop availability, potentially increasing food prices and impacting food security. 
• Environmental Impact of Production: Opens in new tabThe entire process of producing biodiesel can release greenhouse gases and cause air and water pollution. 

Other Considerations

• Tailpipe Emissions: Biodiesel still produces tailpipe emissions, including nitrogen oxides (NOx), which contribute to smog. 
• Lobbying: The powerful oil industry actively resists the transition to alternative fuels like biodiesel.