Renewable diesel and biodiesel get used as if they were the same thing, but they are two distinct fuels. They start from similar feedstocks, then go through different processes and behave differently in the tank and the cold. For a jobber deciding whether to carry them, the differences are worth knowing.
The core difference
Both can come from vegetable oils, animal fats, and used cooking oil, but the processing splits them. Biodiesel is made by transesterification into fatty acid methyl esters (FAME), and it has to be blended with petroleum diesel. Renewable diesel is made by hydrotreating into pure hydrocarbons, chemically much like petroleum diesel, so it can run as a drop-in fuel on its own.
Reading the blend numbers
Biodiesel blends use a B number for the percentage of biodiesel:
- B5 (5%) generally meets the standard diesel spec, ASTM D975.
- B6 to B20 fall under ASTM D7467; B20 is common in fleets.
- B100 (pure biodiesel) must meet ASTM D6751 before blending.
Renewable diesel uses an R number the same way, so R99 is 99% renewable diesel and R100 is pure. Nearly everything sold is R99, and the reason is tax law. The federal blender's tax credit paid $1.00 per gallon and required a trace of petroleum diesel in the mix, as little as 0.1%, so producers blended to 99% to capture it. The credit moved to a producer-side credit (Section 45Z) in 2025, but R99 stuck as the standard product.
The cold-weather story
Cold weather is where the two fuels split. Biodiesel, especially B100, gels at higher temperatures, roughly 30 to 40°F depending on feedstock, so it needs cold-weather care. Renewable diesel handles cold as well as petroleum diesel or better. Producers can tune its cold-flow during manufacturing, and arctic grades are rated to roughly -40°F, which makes it the easier of the two in cold climates.
What it means for a jobber
These are more products to source, blend, store, price, and track, each with its own spec and blend level. Renewable diesel handles like regular diesel; biodiesel blends add blending and cold-weather considerations. Carrying them well means treating them as tracked products, right alongside your DEF and conventional fuel. It is one more way the product mix keeps expanding.
Where FastDragon fits
FastDragon Fuel Jobber tracks renewable diesel and biodiesel blends as distinct products with their own cost, pricing, and tax treatment, so adding a low-carbon line does not muddy your numbers.
Questions we hear a lot
Can renewable diesel run in existing diesel engines and tanks?
Yes. It meets the same ASTM D975 spec as petroleum diesel, so existing engines, dispensers, and storage tanks take it without modification. Fleets often make the switch with no change beyond the fuel order.
Does biodiesel need different storage and handling?
It needs more attention than petroleum diesel. Biodiesel attracts water and oxidizes over time, so tanks must stay clean and dry, and long storage usually calls for stability additives. Higher blends can also soften older gaskets and hoses, which is worth checking before carrying B20 and up.
Which states drive renewable diesel demand?
California, Oregon, and Washington, through their low-carbon fuel programs. California's LCFS pays credits for low-carbon fuels, which is why the bulk of U.S. renewable diesel is sold there and why West Coast jobbers see it far more often than the rest of the country.
Do renewable diesel and biodiesel generate RINs?
Yes, both qualify as biomass-based diesel under the Renewable Fuel Standard. EIA figures put RIN generation at 1.5 RINs per gallon for biodiesel and 1.6 to 1.7 for renewable diesel, depending on the production pathway. Those credits are a big part of the economics that bring these fuels to the rack.