(Reuters) -The U.S. Environmental Protection Agency said it will issue on Friday decisions on 16 petitions by small refineries for exemptions to the nation's biofuel blending mandates.

The decisions could effectively clear the remainder of the agency's huge backlog of such requests that had built up under former President Joe Biden's administration.

The EPA had approved 140 petitions in part or in full earlier this year, and denied just 28, leaving just a handful remaining under review.

The agency has 20 pending applications, including 11 for the 2025 compliance year.

Under the Renewable Fuel Standard, refiners are required to blend billions of gallons of ethanol and other biofuels into the nation's fuel pool each year. 

But small refiners can seek exemptions if they show the obligations would cause them significant financial hardship.

The waivers have been a lightning rod of contention between oil refiners who want to avoid costly blending obligations and biofuel advocates concerned that they eat into their market.