The U.S. Environmental Protection Agency is said to be planning a replacement for the Clean Power Plan that would require power plants to become more efficient, and utilities appear to be supportive of this approach — so long as the agency keeps within the bounds of the Clean Air Act and cannot tighten the standards later on.

Responding to a request for comment on a regulatory docket addressing the Trump administration's de-regulatory efforts, a number of utilities and industry groups said any replacement of the Clean Power Plan must be firmly within the bounds of the Clean Air Act.

Any new rule must be based on a "best system of emission reduction" that can be applied at individual generators subject to the rule, wrote the Utility Air Regulatory Group, or UARG, a mostly anonymous coalition of utility companies and related groups. UARG also asked the EPA to acknowledge that it lacks authority to tighten standards set under Section 111(d) of the Clean Air Act once they are promulgated.

Several utility members of UARG submitted additional comments to the record concurring with the group's opinion, including the Tennessee Valley Authority, Southern Co., Kansas City Power & Light Co., Consumers Energy and American Electric Power Co. Inc.

In supplemental comments, Southern Co. said that the EPA's original Clean Power Plan was "fundamentally flawed" because it was "not based on emission control technologies at all." The agency instead based the rule on shifting electricity generation from coal- and gas-fired power plants to renewable sources, rather than physical changes that could be made at the plant level, the company said. The Clean Power Plan did allow generators to shift to less- or nonemitting resources; however, it did not require any specific action to be built into state plans.

"Southern Co. encourages the agency to reaffirm the longstanding principle that standards of performance must be achievable based on available control technologies at the source," Southern Co. wrote.

AEP asked the EPA to develop a replacement rule that reflects "achievable standards and guidelines based on commercially available and cost-effective technologies that can be utilized by individual generators at the affected sources."