What Is Renewable Diesel? A Plain-English Guide for 2026

Renewable diesel is diesel fuel made from renewable feedstocks — used cooking oil, animal fat, and plant oils — that's been chemically processed until it matches petroleum diesel molecule for molecule. That's the short version. The longer version explains why it's not the same as biodiesel, why it works in your engine without modification, and why it's showing up at more pumps every year.

If you've seen "R99" or "R100" on a fuel pump, or your fleet manager mentioned switching to "renewable diesel" instead of biodiesel, this guide covers what's actually different, what it costs, and whether it's worth switching to.

What Is Renewable Diesel, Exactly?

Renewable diesel is a hydrocarbon fuel refined from fats, oils, and greases through a process called hydroprocessing. The result is chemically identical to petroleum diesel — same molecules, same structure — just made from a different starting material.

That's the key difference from biodiesel. Biodiesel is a fatty acid methyl ester (FAME), a different chemical compound that behaves differently in cold weather and storage. Renewable diesel isn't an ester at all. It meets the same ASTM D975 spec as regular petroleum diesel, which is why it's called a "drop-in" fuel — it runs in existing diesel engines and fuel systems with no blending, no modification, and no separate fuel lines.

You'll also see it labeled HVO (hydrotreated vegetable oil) or HDRD (hydroprocessed renewable diesel). Same fuel, different names depending on the supplier.

How Is Renewable Diesel Made?

Refiners take feedstocks like used cooking oil, tallow (animal fat), soybean oil, or canola oil and run them through a hydroprocessing unit. Hydrogen strips out oxygen and breaks down the fat molecules, leaving pure hydrocarbon chains that match the structure of petroleum diesel.

This differs from biodiesel production, which uses a chemical reaction called transesterification instead of hydrogen treatment. That's why biodiesel keeps some oxygen in its molecule and renewable diesel doesn't — and why the two fuels behave so differently once they're in your tank.

Renewable Diesel vs Biodiesel vs Petroleum Diesel: What's the Difference?

Here's how the three stack up on the specs that matter to owners and shops:

Notice the cetane number. Renewable diesel usually rates 70 to 90, well above the typical petroleum diesel range. Higher cetane means faster, more complete combustion — often translating to smoother cold starts and slightly better fuel economy.

If you want the full breakdown of cetane, gelling, and storage life for regular diesel, see Diesel Fuel Explained: Cetane, Gelling and Storage Life.

Does Renewable Diesel Work in Cold Weather?

Yes — usually better than regular diesel or biodiesel. Renewable diesel has no oxygen-bearing esters, so it doesn't cloud or gel as early as biodiesel does. Some renewable diesel blends hold a cloud point several degrees lower than a #2 petroleum diesel of the same season grade.

That said, it's not gel-proof. Cold-weather performance still depends on the specific feedstock and refining process, so check the supplier's cold flow spec before winter. For general cold-weather prep, see Preventing Diesel Fuel Gelling in Winter: A Practical Guide and At What Temperature Does Diesel Freeze? (Gel Point Explained).

Is Renewable Diesel Safe for Your Engine and Warranty?

Most major OEMs — Cummins, Ford, GM's Duramax line, and Detroit Diesel — approve renewable diesel that meets ASTM D975, including R100 (100% renewable, no petroleum blend). Check your owner's manual or ask your dealer, since approval language varies by model year.

Warning: Not every fuel labeled "renewable diesel" meets the same spec. Confirm the supplier's fuel meets ASTM D975 before running it at 100%, especially in older engines built before renewable diesel became common.

Because renewable diesel is chemically the same as petroleum diesel, it doesn't need the fuel system upgrades biodiesel sometimes requires — no special seals, no shortened fuel filter intervals in most cases. If you're due for service anyway, the standard fuel filter and water separator schedule still applies. For Ford 6.7 Powerstroke owners, see the 6.7 Powerstroke Fuel Filter Service Guide for OEM-published intervals.

How Much Does Renewable Diesel Cost?

Pricing depends heavily on region and state incentive programs. In California, renewable diesel — often sold as R99 or R100 — usually prices within $0.05 to $0.20 per gallon of petroleum diesel, thanks to credits under California's Low Carbon Fuel Standard (LCFS).

Outside California and a handful of other incentive states, expect a premium of roughly $0.20 to $0.60 per gallon over standard diesel, since feedstock and processing costs run higher without the credit offset. Prices as of 2026 — verify locally, since fuel taxes and state programs shift year to year.

For a broader look at what drives diesel pricing nationally, see Is Diesel Cheaper Than Gas? 2026 Price Comparison Guide.

Where Can You Buy Renewable Diesel?

Renewable diesel is most widely available in California, Oregon, and Washington, where state low-carbon fuel programs make it cost-competitive. It's also showing up at truck stops and fleet fueling stations in parts of the Pacific Northwest and select Midwest markets tied to soybean and tallow processing plants.

Decision framework: if you fuel mostly in California or the Pacific Northwest, ask your supplier for R99 or R100 renewable diesel as a direct swap. If you're outside those regions, biodiesel blends (B5-B20) remain the more common and cheaper renewable option at most truck stops.

Renewable Diesel and Emissions Rules — What Regulators Say

Renewable diesel qualifies under the EPA's Renewable Fuel Standard (RFS2) as an advanced biofuel, and it's a recognized pathway fuel under California's LCFS. Neither program requires or allows tampering with a vehicle's emissions equipment — renewable diesel is a fuel swap, not an emissions delete.

Warning: Switching fuel types never justifies removing or bypassing a DPF, EGR, or SCR system. Deleting or defeating emissions equipment is illegal under the federal Clean Air Act, regardless of what fuel you run. If your emissions system needs service, a proper shop visit is the only legal path — see Diesel Emissions Rules by State for what applies where you operate.

Should You Switch to Renewable Diesel?

If your engine's OEM approves it and it's available near your routes, renewable diesel is a low-risk switch — same tank, same fuel lines, usually better cold flow and cleaner combustion. The main hurdle is availability outside a few West Coast states.

Fleets running mixed routes through California often split fueling strategy: renewable diesel where it's priced competitively, standard diesel elsewhere. Owner-operators fueling mostly in the Midwest or East Coast will find biodiesel blends more common for now.

Not sure whether your engine or fuel system needs attention before making the switch? Find a diesel shop near you on USA Diesel Finder for a fuel system check, or get a free diesel repair quote before you commit to a new fuel supplier.

FAQ: Renewable Diesel

What does "R99" or "R100" mean at the pump?

R100 means 100% renewable diesel with no petroleum blend. R99 means 99% renewable diesel blended with a small amount of petroleum diesel, often used to meet certain state fuel tax or labeling rules.

Can I put renewable diesel in an older diesel engine without modification?

In most cases, yes — because it's chemically identical to petroleum diesel, it needs no fuel system changes. Still, confirm with your engine's OEM or a diesel shop before running it at 100% in pre-2007 engines, since approval language varies by manufacturer.

Does renewable diesel reduce my truck's fuel economy?

No — most drivers see fuel economy that's about the same or slightly better than petroleum diesel, thanks to renewable diesel's higher cetane rating and cleaner combustion.

Is renewable diesel available nationwide, or just certain states?

It's most widely available in California, Oregon, and Washington. Other states have limited or growing supply, so check with local truck stops or bulk fuel suppliers before planning a route around it.

Do OEMs like Cummins, Ford, and GM approve renewable diesel use?

Most current diesel engine makers approve renewable diesel meeting ASTM D975, including R100. Check your owner's manual, since coverage can vary by model year and engine family — see our guide to Diesel Engine Families: Power Stroke, Cummins & 3.0 Duramax for platform-specific notes.