A U.S. Supreme Court ruling on emissions from power plants reaching other states could affect several electric generating plants in Oklahoma for part of the year.
In a 6-2 ruling, the Supreme Court on Tuesday upheld the Cross-State Air Pollution Rule. Oklahoma is covered by a supplemental part of the rule on nitrogen oxides that can cause ozone in the summer months.
The rule covers upwind emissions from power plants and their downwind effects on other states. Twenty-eight states, mostly in the eastern and central parts of the country, are affected in some way by the Cross-State Air Pollution Rule.
The Supreme Court decision reversed an earlier ruling from an appellate court in the District of Columbia. The ruling sends the case back to the lower court for further action.
The Environmental Protection Agency said it was reviewing the opinion and no immediate action from states or affected plants is expected.
The EPA lists 22 power plants in Oklahoma covered by the Cross-State Air Pollution Rule. In 2011, five of those plants were responsible for three-fourths of the state’s emissions of nitrogen oxides that could cause ozone.
One county in Michigan is affected by nitrogen oxide emissions from Oklahoma coal plants, according to air modeling by the EPA to support the rule.
For Oklahoma, the rule set up a cap-and-trade system for nitrogen oxide emissions during ozone season from May to September. Representatives at the Oklahoma Department of Environmental Quality said the EPA could reinstate nitrogen oxide limits from the rule before it was put on hold by a lower court. Or EPA could finish a pending rulemaking establishing new criteria and deadlines.
“In Oklahoma, we’re just waiting to see how the D.C. circuit court rules, and we will get additional guidance from the circuit court,” said Tom Richardson, an engineer with DEQ’s air quality division. “We’re still not sure how EPA will proceed.”
Oklahoma utilities could install additional emissions controls to comply with the rule, or they could trade emissions credits to come under the limits established by the EPA, Richardson said.
The ruling won’t affect Public Service Co. of Oklahoma, which already has an environmental compliance plan with the EPA to phase out its last coal units in Oklahoma by 2026. Stan Whiteford, PSO spokesman, said the utility’s agreement on the EPA’s Regional Haze rule takes care of the emissions addressed in the Cross-State Air Pollution Rule.
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In Oklahoma, we’re just waiting to see how the DC circuit court rules, and we will get additional guidance from the circuit court. We’re still not sure how EPA will proceed.”
An engineer with DEQ’s air quality division