The U.S. Supreme Court put a stay on the plan and a federal appeals court will hear arguments in the case later this year.

Unit No. 3 is buzzing with construction workers who are installing environmental upgrades to make the coal-fired operation run cleaner.

President Obama’s Clean Power Plan enraged many top officials in Oklahoma, who argued the rules were an expensive, unnecessary overreach by the federal government. But the effort to reduce greenhouse gas emissions could create opportunities in Oklahoma, researchers and officials say.

Oklahoma’s largest utility companies say they’re already on track to meet the carbon-reduction goals in the federal plan.