Biodiesel: the blend hiding in ordinary diesel
Biodiesel is a diesel substitute made from vegetable oils, used cooking oil or animal fats, blended into ordinary diesel at a percentage set by national regulation, most commonly B5 to B20. It rarely appears as a separate fuel at the pump.
In this entry
What biodiesel is — definition, types, and biodiesel blends
Biodiesel is a diesel substitute made from vegetable oils, used cooking oil or animal fats, chemically processed into a fuel that can run in a diesel engine. It is rarely sold on its own; almost everywhere it is blended into ordinary petroleum diesel at a set percentage — producing what the industry calls biodiesel blends.
The blend level is written with a B and a number: B5 is 5% biodiesel, B20 is 20%, and B100 is pure biodiesel with no petroleum diesel at all. Different types of biodiesel exist depending on the feedstock: soy-based biodiesel (SME) is dominant in North America, rapeseed methyl ester (RME/FAME) is common across Europe, and palm methyl ester (PME) is widely used in South-East Asia. Used cooking oil (UCO) and animal tallow are also common second-generation feedstocks. All are chemically processed through a reaction called transesterification, which converts triglycerides into fatty acid methyl esters (FAME) — the chemical family that covers most commercial biodiesel. Despite the different feedstocks, all FAME biodiesel can be blended into conventional petroleum diesel by the same B-number system.
Because biodiesel blends such as B5 and B7 are almost always sold simply as "diesel" at the pump, most drivers fill up on a biodiesel blend without realising it. National mandates — for example, B7 in the EU and B5–B20 in many US states — define the minimum blend percentage refiners and distributors must meet.
Blend levels: B5 to B100
Common blend levels range from a small percentage that most drivers never notice to fuels that are entirely biodiesel.
Typical named blends. Exact blend levels are set by national or regional regulation and vary by market.
Unlike E85, low-level biodiesel blends such as B5, B7 or B20 are almost always sold simply as "diesel," with no separate pump or price. The blend level is set by national or regional regulation, not chosen by the driver.
Which vehicles can use it
How much biodiesel an engine can safely run varies by vehicle and by how much biodiesel is blended in.
Where biodiesel blending is common
Biodiesel blending is largely driven by government policy rather than by driver choice, so how common it is depends heavily on where you are.
Why governments mandate it
Biodiesel is usually cited as producing lower lifecycle greenhouse gas emissions than petroleum diesel, since the carbon in the vegetable oil or fat was recently absorbed from the atmosphere by the plants it came from, rather than released from long-buried carbon. The size of that benefit depends heavily on how the feedstock was grown and processed, and is a genuinely debated area, not a settled figure we can state precisely here.
How this shows up on FuelTheGuide
We show diesel and premium diesel as single grades, whatever blend a country's regulations set, rather than a separate biodiesel price.
Because low-level biodiesel blends are sold as ordinary diesel almost everywhere, our diesel and premium diesel prices already reflect whatever blend a country's regulations require. We don't break out a separate biodiesel price.
Questions and answers
What are the different types of biodiesel?
The main different types of biodiesel are classified by feedstock: soy methyl ester (SME) from soybean oil is dominant in North America; rapeseed methyl ester (RME) from rapeseed oil is common in Europe; palm methyl ester (PME) is widely used in South-East Asia; and biodiesel from used cooking oil (UCO) or animal tallow is a growing second-generation category. All are produced by a chemical reaction called transesterification and belong to the fatty acid methyl ester (FAME) family. All FAME biodiesel uses the same B-number blend system regardless of feedstock.
What biodiesel blend levels are most common?
The most common biodiesel blends are B5 (5% biodiesel, 95% petroleum diesel), B7 (the standard blend mandated across the EU under EN 590), B10, B20, and B100 (pure biodiesel). B5–B7 are compatible with essentially all modern diesel engines. B20 and above may require manufacturer approval. B100 is mainly used in dedicated fleet vehicles rather than sold at public pumps. See the US DOE AFDC overview of biodiesel blends for details on compatibility.
Does biodiesel damage a regular diesel engine?
At the low blend levels sold as ordinary diesel in most regulated markets, no: modern diesel engines and fuel systems are built to handle them. Higher blends, especially B100, need a compatible engine and sometimes modified seals and fuel lines.
Is biodiesel the same as "renewable diesel"?
No. Biodiesel (FAME) is made by reacting vegetable oil or fat with alcohol, and it has a different chemical structure from petroleum diesel. Renewable diesel (HVO) is made through a different process and is chemically closer to petroleum diesel, so it is often a drop-in replacement. They are both biofuels but they are not the same product. The US DOE Alternative Fuels Data Center explains the difference between biodiesel and renewable diesel.
Why do some diesel prices seem to rise with vegetable oil markets?
Because biodiesel feedstocks — palm oil, soybean oil, rapeseed oil — are commodity markets of their own. When those feedstocks get expensive, the cost of meeting a blending mandate rises, and that can push retail diesel prices up slightly, particularly in markets with high blend requirements. The FAO Food Price Index tracks vegetable oil price movements that feed directly into biodiesel production costs.
Does biodiesel reduce range compared with regular diesel?
Slightly, at higher blends. Biodiesel has a lower energy density per litre than petroleum diesel, so B100 vehicles see a small reduction in range. At B5 to B20, the effect is small enough that most drivers don't notice it.
Understanding biodiesel blend levels and what they mean at the pump
What is biodiesel in the context of everyday fuelling? For most drivers, it is invisible — the diesel at the pump already contains a mandated percentage of biodiesel blend levels such as B5 or B7. The "B" number tells you the percentage of fatty acid methyl ester (FAME) biodiesel in the blend: B7 means 7% biodiesel and 93% petroleum diesel. The U.S. EIA biodiesel page provides data on American biodiesel production and consumption, while the European Commission's biofuels overview explains the EU's Renewable Energy Directive that underpins B7 mandates across member states.
Higher biodiesel blend levels — B20, B50 and B100 — are used mainly by commercial fleets with manufacturer approval. At these concentrations, the lower energy density of biodiesel becomes noticeable (approximately 8% less energy per litre for B100 compared to petroleum diesel), and cold-weather performance can suffer because FAME biodiesel has a higher cloud point than petroleum diesel. The IEA biofuels tracking page monitors how blending mandates are evolving worldwide as countries pursue transport decarbonisation targets.
More questions
What are the most common biodiesel blend levels at the pump?
The most common biodiesel blend levels at public pumps are B5 (5% biodiesel) and B7 (7% biodiesel, the EU standard under EN 590). These are sold simply as "diesel" — no separate pump or label. B20 is available at some stations in the US and is popular with fleets. B100 (pure biodiesel) is rarely sold at retail and is mainly used by municipal or commercial fleets with compatible equipment.
Sources and further reading
- Biodiesel basics US Department of Energy, Alternative Fuels Data Center, afdc.energy.gov
- Renewable Energy Directive, transport fuel blending European Commission, energy.ec.europa.eu
- Fuel prices tool and grade lists OpenVan.camp, openvan.camp/compare/fuels/fuel-prices