The Biden administration pledged last year to update how the Department of Energy's Greenhouse Gases, Regulated Emissions and Energy Use in Technologies (GREET) model measures emissions from agricultural practices used by farmers producing biofuel feedstocks.
The revisions were delayed from an initial March 1 timeline after disputes among agencies about the changes, sources told Reuters at the time.
"In the very near future, we will have that model up and running," Regan told the Society for Environmental Journalists conference.
The model is favored by the biofuels industry for measuring ethanol emissions to determine whether the fuel qualifies for a $1.25 per gallon sustainable aviation fuel tax credit passed in the Inflation Reduction Act.
The passage of the tax credit set off a lobbying battle between biofuel and farm groups and environmental organizations who argue producing fuel from crops is counterproductive to combating climate change.
The EPA, DOE, Department of Agriculture, Federal Aviation Administration, and White House have all been involved in discussions about implementing the credit.