Renewable Diesel Offers Alternative to Fossil-Based Fuels
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 a dramatic increase in supply and demand, according to the State of Sustainable Fleets 2025 Market Brief. More than one-third of fleets responding to the annual survey — 39% — reported that they use renewable diesel. Plus, more fleets are researching and seeking RD after facing hurdles with other technologies.
The Market Brief, sponsored by Penske, found that RD production grew 28% in the first half of 2024 compared to the same period in 2023, with the Energy Information Administration projecting an increase to 7.2 million gallons per day in 2025. RD now comprises over 70% of the diesel fuel consumed in California.
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 60-90%
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.