Renewable Diesel Offers Low-Carbon, Drop-In Alternative to Fossil-Based Fuels

Yellow roof to a fuel station with FUEL written on it.

Renewable diesel — an advanced fuel option that reduces greenhouse gas emissions while meeting the same specifications as petroleum diesel — can be added to existing fuel truck systems to help lower a fleet’s carbon footprint. As a drop-in fuel that can be used in place of ultra-low-sulfur diesel (ULSD), renewable diesel is helping bridge the gap as the trucking industry moves toward zero-emission vehicles without extra equipment or infrastructure cost related to battery-electric vehicles.


Renewable diesel is refined just like regular fossil petroleum but comes from refining plant-based oils up to R-99. It is identical to ULSD but has a well-to-wheel differential of 60-90+% in greenhouse gas production.

Renewable diesel has experienced dramatic increase in supply and demand, according to the State of Sustainable Fleets 2023report. Erik Neandross, CEO of Gladstein, Neandross & Associates, which created the report, said that in 2022, domestic RD production doubled from 800 million gallons in 2021 to more than 1.7 billion gallons. On the demand side, consumption increased by more than 45% for the second year in a row, and it represented 83% of all bio-based diesel consumed in transportation in California for the first three quarters of 2023.

Penske currently offers R-99 — 99% renewable diesel fuel — at multiple locations on the West Coast.

Renewable diesel can be produced from crop residues, wood and sawdust, animal fats, used cooking oil, vegetable oil, fish fat and switchgrass. It qualifies as an advanced biofuel under the U.S. Environmental Protection Agency’s (EPA) Renewable Fuel Standard (RFS) Program.

Renewable diesel significantly reduces emissions compared to fossil-fuel-based diesel. More specifically, renewable diesel reduces:

  • Particulate matter by more than 40%
  • Carbon monoxide by more than 25%
  • Total hydrocarbons by more than 20%
  • NOx by 10%
  • Lifecycle GHG emissions by up to 90%

There are also performance benefits due to higher cetane, lower aromatics for improved public health, and excellent cloud point for cold-weather use.

Penske sells neat R-99 and does not blend it with biodiesel. Unlike biodiesel, renewable diesel doesn’t contain oxygen, as it is refined just like carb diesel, so users will not encounter the challenges biodiesel presents relating to freezing temperatures and short storage life. As a result, it remains operable at temperatures as low as -34°C. Plus, renewable diesel burns cleaner than biodiesel and does not require any blending. This cleaner burn means fewer regens and longer diesel particulate matter filter life.

Due to California’s low carbon fuel standard (LCFS) credits, the cost is comparable to ULSD. Since renewable diesel currently has a more expensive feedstock than petroleum-based diesel products, Penske focuses on supplying renewable diesel to locations in states with LCFS programs. As the refining capacity expands, the product should be more readily available and the price more competitive.