Yes, biodiesel is a biofuel. It is a renewable, biodegradable fuel made from biological sources like vegetable oils, animal fats, or recycled cooking grease. Under the U.S. Renewable Fuel Standard, biodiesel qualifies as both a biomass-based diesel and an advanced biofuel, placing it firmly within the biofuel family alongside ethanol and renewable diesel.
What Makes Biodiesel a Biofuel
A biofuel is any fuel derived from living organisms or their byproducts rather than from fossil deposits. Biodiesel fits this definition because its energy comes from recently grown plants or recently produced animal fats, not from petroleum that formed millions of years ago. The carbon in biodiesel was pulled from the atmosphere by plants during their lifetime, which is why burning it releases far less net carbon dioxide than burning fossil diesel.
Biofuels are typically grouped into generations based on their feedstock. First-generation biofuels come from food crops like soybean oil, rapeseed, or palm oil. Second-generation biofuels use non-food sources such as agricultural waste or forestry residues. Third-generation biofuels are made from algae. Biodiesel can span all three categories depending on the raw material. Most commercial biodiesel today is first-generation, produced from soybean or canola oil, but researchers are actively producing it from waste cooking oil (which blurs into second generation) and from algae oils.
How Biodiesel Is Made
Biodiesel production relies on a chemical reaction called transesterification. In simple terms, fats or oils are mixed with an alcohol, and a catalyst triggers a reaction that breaks the fat molecules apart and rearranges them into two products: biodiesel and glycerol (a thick, syrupy byproduct used in soap and cosmetics).
Methanol is the most common alcohol used because it’s inexpensive, reacts quickly, and pairs well with the fat molecules. The catalyst is usually a strong base like sodium hydroxide or potassium hydroxide, though acids and even enzymes can do the job. The result is a clear, amber liquid that burns cleanly in diesel engines.
Biodiesel vs. Renewable Diesel
Both biodiesel and renewable diesel are biofuels made from similar raw materials, but they’re chemically different products. Biodiesel is produced through transesterification and contains oxygen in its molecular structure. Renewable diesel is produced through a hydrogenation process that strips out the oxygen, making it chemically identical to petroleum diesel.
That chemical difference matters in practice. Renewable diesel is a “drop-in” fuel, meaning it can travel through existing petroleum pipelines, blend at any ratio with regular diesel, and work in any diesel engine without modification. Biodiesel, by contrast, is typically blended at lower percentages and can gel in cold temperatures at high concentrations. Both reduce emissions compared to fossil diesel, but they reach that goal through different chemistry.
Environmental Benefits
Lifecycle analysis by Argonne National Laboratory found that pure biodiesel (B100) produces 74% fewer greenhouse gas emissions than petroleum diesel when you account for the entire supply chain, from growing the feedstock to burning the fuel. This is one of the largest emission reductions among commercially available biofuels.
Biodiesel also sharply reduces most toxic tailpipe pollutants, including particulate matter and carbon monoxide. One tradeoff: pure biodiesel can slightly increase nitrogen oxide emissions, which contribute to smog. Lower blends minimize this effect while still delivering meaningful emission cuts.
Blend Levels and Engine Compatibility
Biodiesel is sold in blends identified by the letter “B” followed by the percentage of biodiesel in the mix. B5 means 5% biodiesel and 95% petroleum diesel. B20 is 20% biodiesel. B100 is pure biodiesel.
- B5: Approved for use in any diesel engine without modification. This is the most common blend at retail fuel stations.
- B20: Compatible with most current diesel engines without modification. Many original equipment manufacturers explicitly approve B20, and it’s the most popular blend for fleets looking to cut emissions without special equipment changes.
- B100: Requires biodiesel-compatible hoses, gaskets, and seals. Some engines built since 1994 can handle it. Pure biodiesel contains less energy per gallon than petroleum diesel, so fuel economy drops slightly. It also gels more easily in cold weather and needs careful storage.
To meet quality standards, biodiesel sold in the U.S. must conform to ASTM D6751, which sets minimum thresholds for flash point (93°C), cetane number (45, comparable to premium petroleum diesel), and maximum limits on residual glycerol. These specs ensure the fuel burns predictably and won’t leave deposits in your engine.
Global Production and Market Scale
Biofuel demand hit a record 170 billion liters in 2022, surpassing pre-pandemic levels. Biodiesel and its close relative renewable diesel make up a significant share of that total. The International Energy Agency projects that biofuel demand will need to grow by about 11% per year to meet net-zero targets by 2030, more than doubling current production. Near-term growth is driven by energy security policies in the U.S., EU, Brazil, and Indonesia, all of which mandate minimum biofuel blending levels for transportation fuel.
Indonesia and the U.S. are the world’s largest biodiesel producers, with Indonesia relying primarily on palm oil and the U.S. on soybean oil. The EU remains a major market as well, with rapeseed oil as its dominant feedstock. Recycled cooking oil is growing as a preferred source globally because it avoids the food-vs.-fuel debate that has dogged first-generation biofuels.