The U.S. Department of Agriculture will spend up to $400,000 to adjust a federal greenhouse gas (GHG) emissions model to ensure that aviation fuel made from corn-based ethanol is eligible for hefty subsidies, Agriculture Secretary Tom Vilsack said at a conference on Tuesday.

"We’re working on the modeling to make sure that there’s a broad array of feedstocks that can qualify, including ethanol," he said at a conference hosted by biofuels lobby group Growth Energy.

Vilsack's comments are his latest effort to calm a biofuel industry concerned it will be left out of the multibillion-dollar market for sustainable aviation fuel (SAF) airlines and the administration of President Joe Biden see as key to reducing transportation emissions.

Last year's Inflation Reduction Act included lucrative tax credits for SAF producers who can show with an approved scientific model that their fuel emits 50% less greenhouse gas than gasoline.

The Biden administration is divided over whether to grant a request from the biofuels industry to allow the use of the U.S. Department of Energy’s Greenhouse Gases, Regulated Emissions and Energy Use in Technologies (GREET) model.

Environmental groups say it underestimates emissions from the displacement of farmland or vegetation to grow crops for biofuels.

Vilsack, who supports the use of GREET, said the USDA is making adjustments to the model.

"We’re spending our own resources at USDA to make sure the GREET model is where it needs to be," he said.

The agency has identified between $300,000 and $400,000 in funds for the effort, which will be done by the end of the year, Vilsack said.

The USDA did not respond to questions about what specific adjustments the agency is making to GREET.

Vilsack also emphasized his efforts to build support for the GREET model in meetings with the secretaries of transportation, environment, and treasury.

A decision on the modeling issue is expected from the Treasury Department in December, Reuters reported on Sept. 6.

Reporting by Leah Douglas; Editing by Mark Porter