Here’s a current overview of biodiesel use in California — including how it’s regulated, how widely it’s actually used today, and how it fits into broader state fuel policy.
1. What Biodiesel Is (and How It’s Different from Renewable Diesel)
- Biodiesel is a renewable fuel made from vegetable oils or animal fats using a chemical process called transesterification. It can be blended with petroleum diesel at various levels (e.g., B5, B20) or used as pure biodiesel (B100).
- Renewable diesel is also made from renewable oils and fats but processed differently (hydrotreated) so it is chemically identical to petroleum diesel and can be used in any diesel engine without blending limits.
2. Current Use of Biodiesel & Renewable Diesel in California
Biodiesel Adoption
- California historically allowed biodiesel blends like B20 (20% biodiesel) in underground storage tanks and commercial use after regulatory approval.
- However, a very large share of the bio-based diesel consumed today in California is actually renewable diesel, not traditional biodiesel.
Combined Bio-Diesel Usage
- In 2023, renewable diesel plus biodiesel made up about 56 % of on-road diesel fuel use in California — a very high share compared to most of the U.S.
- Renewable diesel dominates this mix due to compatibility and policy incentives.
3. Regulations & Policies Affecting Biodiesel Use
Diesel Fuel Regulations
- California treats biodiesel and other biofuels the same as diesel for fuel tax purposes — they are taxed at the diesel fuel tax rate.
Off-Road Rule Changes
- Recent amendments to CARB’s Off-Road Regulation require most fleets to use R99/R100 renewable diesel fuel, effectively discouraging biodiesel in off-road fleets, with only limited exceptions.
4. Trends & Market Realities
Biodiesel vs. Renewable Diesel
- Although biodiesel is part of the renewable fuel mix, renewable diesel has outpaced biodiesel in growth because:
- It can replace petroleum diesel 1:1 in engines.
- It doesn’t have blend limits like biodiesel (e.g., B20 cap).
Policy Impacts
- California’s Low Carbon Fuel Standard (LCFS) has been a major driver of renewable diesel consumption and has indirectly shifted the market away from traditional biodiesel toward renewable diesel.
- New policy proposals in 2024–2025 may limit the use of certain virgin vegetable oils (like soy & canola) in biofuel feedstocks under the LCFS to reduce land-use emissions.
5. Environmental Context
- Both biodiesel and renewable diesel contribute to greenhouse gas reduction compared with petroleum diesel. Under the LCFS, these fuels have been credited with substantial CO₂ reductions — though renewable diesel accounts for most of the gains due to its large volume used.
Quick Summary
Biodiesel use in California:
- Historically allowed and still part of diesel fuel blends (e.g., up to B20).
- Treated as diesel fuel under state tax law.
- Now a minority of bio-based diesel consumption, with renewable diesel being the dominant renewable diesel fuel consumed.
- Subject to evolving policy pressures (favoring renewable diesel and possible feedstock limits).