HI SB1120

Requires the Department of Transportation to conduct a feasibility study on implementing clean fuel standards for alternative fuels, with a report due to the legislature 60 days before the 2027 session

Mandates adoption of rules for a clean fuel standard by January 1, 2028, with implementation for diesel and gasoline beginning no later than January 1, 2029

Sets carbon intensity reduction targets of at least 10% below 2019 levels by 2035 and at least 50% below 2019 levels by 2045

Establishes a credit and deficit system where fuels below the annual carbon intensity standard generate credits, while fuels above the standard generate deficits

Exempts fuels used by aircraft, railroad locomotives, military vehicles, and interstate waterborne vessels from the clean fuel standard requirements