Renewable natural gas (RNG) used by commercial fleets in California remained carbon-negative for the sixth straight year in 2025, according to a new report from The Transport Project, RNG Coalition, and the California Renewable Transportation Alliance. RNG made up 98% of the natural gas used by on-road natural gas vehicles in the state and posted an average carbon intensity score of -198.32 gCO2e/MJ, the lowest of any transportation fuel under California's Low Carbon Fuel Standard (LCFS). Although RNG accounted for only 6% of alternative fuel use under the LCFS program, it generated over 25% of all greenhouse gas emission reductions. Nearly 22% of the RNG used by California fleets was produced in-state, up from less than 7% in 2021. The report argues RNG is a lower-cost, scalable option for heavy-duty applications that are hard to electrify, such as long-haul trucking and refuse collection.
