HI SB2999

Requires the Department of Transportation to adopt rules by January 1, 2028, establishing a clean fuel standard for alternative fuels in Hawaii, with implementation for diesel and gasoline beginning 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

Creates a credit and deficit system where fuels with carbon intensity below annual standards generate credits, while those exceeding standards generate deficits, with credits tradeable and bankable for future compliance

Exempts fuels used by aircraft, railroad locomotives, military vehicles, and interstate waterborne vessels, though these sectors may opt in to generate credits when using alternative fuels

Uses Argonne National Laboratory's GREET model to measure lifecycle greenhouse gas emissions and requires the department to review and update modeling every three years