At the beginning of March 2025, U.S. senators reintroduced the , a bill aimed at amending the R to allow biodiesel and renewable diesel used in maritime shipping (i.e. cargo ships, tankers and passenger vessels) to generate credits. This proposed legislation could broaden market opportunities for U.S. biofuel producers and accelerate the adoption of low-carbon fuels in the shipping industry.
Under the current RFS framework, only transportation fuels used within the U.S. for on-road, rail, and specific non-road applications (such as locomotives and aircraft) qualify for RIN generation. Biofuels used in vessels are excluded, preventing refiners and blenders from earning RIN credits when supplying these fuels to ships. Instead, they must retire RINs, effectively losing those credits rather than benefiting from them, discouraging biofuels use in maritime shipping.
The bill proposes reclassifying renewable fuels used in the shipping industry, allowing them to generate RIN credits. This change could boost the demand for biofuels in the marine sector, encourage greater investment in production and expand market opportunities for U.S. farmers and biofuel producers.
The maritime industry, which depends on large diesel engines with operational lifespans of 40 to 50 years, faces significant hurdles in adopting alternative propulsion technologies. Unlike other sectors transitioning to electric or hydrogen-powered vehicles, large ships cannot easily replace diesel propulsion with compressed natural gas (CNG) or similar alternatives. In this context, biofuels offer a practical short-term transition solution, providing immediate carbon reduction benefits while longer-term options, such as methanol and ammonia, continue to evolve.
While the bill represents a significant step toward integrating biofuels into maritime fuel regulations, its approval remains uncertain, as it must undergo multiple stages of review, debate and potential amendments before becoming law.
For a deeper understanding of the U.S. Renewable Fuel Standard and the key aspects and market dynamics of Renewable Identification Number credits, please refer to the SGS INSPIRE report