Hawaii clean fuel standard signed into law aims for 50% carbon intensity cut by 2045

Hawaii Governor Josh Green signed a clean fuel standard into law on July 14, 2026, targeting a 50% reduction in transportation fuel carbon intensity below 2019 levels by 2045. The law makes Hawaii the fifth U.S. state to adopt such a program, joining California, Oregon, Washington, and New Mexico. The standard uses a credit-based system where fuels with lower carbon intensity generate credits, while gasoline and diesel above the annual standard create deficits. The Hawaii Department of Transportation must adopt rules by January 2028 and implement them by January 2029. Exemptions exist for aircraft, railroad locomotives, military vehicles, and interstate waterborne vessels, though those users can opt in to generate credits for alternative fuels. The program uses the DOE's GREET model for lifecycle emissions calculations and is designed as technology neutral, covering any non-fossil fuel used for transportation. Clean Fuels Alliance America supports the move, saying it will boost demand for biodiesel, renewable diesel, and sustainable aviation fuel in the state.