US low-carbon fuel standard (LCFS) programs are rumbling toward their steepest targets yet with little of the fuel powering them in the tank.
West coast regulators and lawmakers have approved ambitious reductions in carbon levels for automotive fuel following a four-year deluge of renewable diesel production. The fuel grew over that time into the largest source of new credits needed to meet California, Oregon and Washington regulatory obligations. But federal uncertainty and feedstock challenges this year have left renewable diesel producers spinning their wheels.
West coast states have claimed up to 90pc of all US renewable diesel consumption in recent quarters. Made from seed oils, animal fats or used cooking oil, and in some of the same equipment used to produce petroleum diesel, the lower-carbon alternative remains chemically identical to its conventional cousin. This means it can move seamlessly in the same supply systems and engines, leaving customers to manage only the higher price.
Renewable diesel accounted for nearly three-quarters of California's total liquid diesel pool early this year, up from just a quarter of state supply in 2020. Programs in Oregon and Washington lured the fuel further north to account for around 25pc of the total diesel in those markets during recent peaks.
That consumption produced a torrent of credits for the state LCFS programs. The fuel has generated as much as 40pc of new California quarterly credits in recent years, helping credits grow to 1.8 times more than new deficits in 2024. Inundated by supply and concerned about biofuel reliance, California regulators finalized much tougher carbon targets that also limit the types of feedstocks, including for renewable diesels, eligible to meet them.
LCFS programs reshaped both the domestic refining sector and the west coast road fuel markets with incentives driving lowest-carbon alternatives. But this year demonstrated that federal policy remains the heaviest hand on the wheel steering fuel decisions. Federal proposals to favor US producers and domestic oilseeds with tax and other incentives, alongside hostility toward foreign lower-carbon feedstocks and fuels, stifled renewable diesel output. Total renewable diesel supplied in the US during the first 10 months of the year fell by 19pc compared with the same period of 2024, the first year-over-year drop in supplies since 2018.
Diamond Green Diesel, the largest US renewable diesel producer, left one of its production units idled for most of an unprofitable 2025. Phillips 66 and Marathon Petroleum reduced runs at California facilities converted to produce renewable diesel, while CVR Energy will convert units from renewable to conventional diesel production at its Wynnewood, Oklahoma refinery.
Oregon demonstrated the west coast's diesel dependency earlier this year. When facility downtime and other factors cut renewable diesel deliveries in late 2024 and early 2025, credits available for LCFS compliance began to shrink. Credit prices more than doubled from May to July in response to data reporting the supply drop.
California's gasoline carbon intensity limit will start next year 12pc lower than the targets in place in January 2025. Previous years have fallen by 1-2pc. The state will also soon limit credit generation from crop-based diesels to just 20pc of the volume supplied, and require verification standards that agribusiness groups have decried as overly onerous.
Washington state lawmakers early this year adopted a 5pc tougher carbon intensity targetfor 2026 to rekindle alternative fuel incentives in the state. Credit generation has slowed amid declining renewable diesel supplies this year.
The right price can inspire the right supplies, yet the cost of these state incentives ultimately adds to what drivers pay at the pump. Fears of retail price hikes helped slow the adoption of changes to the California LCFS programs this year. Growing national sensitivity to costs could add scrutiny to rising low-carbon incentives in 2026.
