Global demand for U.S. ethanol has grown substantially over the last decade, but ongoing trade tensions, policy enforcement, and changing markets could set up potential roadblocks for the industry in the years ahead.

Biofuel groups say a Trump administration plan to account for gallons of renewable fuel waived through small refinery exemptions is unsatisfactory and goes back on commitments offered earlier this month.

The Environmental Protection Agency relied on a faulty analysis by the Department of Energy when it rejected a West Virginia refinery’s request for an exemption from renewable fuel blending requirements, a federal appeals court ruled Friday.

A quartet of pro-biofuel groups, frustrated with the Environmental Protection Agency’s use of waivers that exempt small refineries from certain biofuel blending requirements, have sued the agency in an effort to curb the practice.