PG Blog Exclusive: The Affordable Clean Energy Rule Attempts to Rewrite PSD

(Editor’s Note: This is an exclusive opinion piece written for Power Engineering. The views are the author’s).

On August 20, EPA released the Affordable Clean Energy (ACE) rule, the proposed replacement to the Clean Power plan. But buried beneath the headlines of heat rate improvements, longer coal plant lives, and predictions of 1400 additional premature deaths, EPA reattempts a mechanism to modify the Prevention of Significant Deterioration (PSD) rule that has previously failed to survive court challenge.

PSD has historically held power plants back from making efficiency improvements since a modification to a coal-fired boiler can trigger PSD permitting and thus require adding on pollution control devices.

Contrast how the current and under proposed PSD rules treat a heat rate improvement modification (such as a blade path upgrade at a steam turbine):

Most heat rate improvements will not increase emissions on a pound per hour basis. However, most heat rate improvements will increase emissions on a ton per year basis. It is only logical that a more efficient unit will be dispatched more, its capacity factor will increase, and therefore its annual emissions will increase. The ACE rule would stop most heat rate improvement projects from tripping PSD at the new Step 2.

In 2005, EPA tried to change the PSD rules to use a pound per hour increase test instead of a ton per year test. The proposed hourly emissions test was similar to the hourly emissions test in the New Source Performance Standards (NSPS) program. The U.S. Court of Appeals for the Fourth Circuit Court in United States v. Duke Energy Corp. agreed with EPA; however, the Supreme Court vacated the decision. The hourly test was thus never implemented.

I don’t claim to be a lawyer and I acknowledge there is currently a different Supreme Court, but inertia controls environmental regulations. What one admiration tries, another undoes. And court cases can take more time to resolve than the four to eight years that an administration might last.

Utilities should consult their own legal staff before betting on that the draft ACE rule’s PSD change will become final.

About the author: Robynn Andracsek is a regular contributing editor and P.E., Burns & McDonnell.


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