WASHINGTON (CN) — The D.C. Circuit ordered the Environmental Protection Agency on Friday to reconsider the exemptions regarding hazardous air pollutants that it gives to coal- and oil-burning power plants.
Regulators carved out the exemptions as part of Mercury and Air Toxics Standards, otherwise known as the MATS Rule, finalized in 2014.
Though the rule set specific numerical emission limits for power plants to meet at all times, it said the plants would face “work-practice standards” —considered less stringent because they are non-numerical — during periods of starting up and shutting down the boilers.
In explaining why, the EPA said numerical emission limits would not be feasible at start-up since they are production-based, and there is no production by definition at start-up. Shut-down and start-up periods occur some 100 times annually, according to the EPA’s estimates.
Petitioning for the rule to be reconsidered, the Chesapeake Climate Action Network and other groups took issue with the EPA’s conclusion that the power plants that perform best would be unable to reliably measure emissions until four hours after they generate electricity. They accused the agency of waiting until after the rule had been finalized to disclose that it based the best-performance analysis on an assumption.
The D.C. Circuit sided with the challengers Friday, saying their “objections provide substantial support for the argument that the regulation should be revised.”
“What is clear is that if different best performers are selected, the extended startup definition’s end point would have to be recalculated,” U.S. Circuit Judge Robert Wilkins wrote for a three-judge panel.
Appointed to the circuit by President Barack Obama, Wilkins said the EPA cannot apply work-practice standards without first demonstrating that measurability is infeasible until air pollution control devices become operational.
The challengers’ two objections are both relevant and could not have been raised during the notice-and comment period, the court found.
Representatives from the Chesapeake Climate Action Network did not immediately respond to a request for comment.
Wilkins was joined in his opinion by Judge Cornelia Pillard, a fellow Obama appointee, and the Clinton-appointed Judge David Tatel.