A coalition of 26 states, counties and cities led by New York Attorney General Letitia James told the U.S. Environmental Protection Agency (EPA) on October 1 that it intends to sue over the agency's failure to set greenhouse gas guidelines for existing gas-fired power plants. The same coalition filed a separate challenge in the U.S. Court of Appeals for the D.C. Circuit to EPA's September repeal of most of its 2024 Carbon Pollution Standards.
The two filings arrive as utilities lean on gas to meet rising demand. Electricity use grew about 1.7% a year from 2020 through 2025, compared with 0.1% a year from 2005 to 2019, according to the U.S. Energy Information Administration (EIA), which attributes the acceleration to data centers. EIA's March analysis found that faster data center growth would push more gas generation, a trend already straining corporate efficiency programs.
Coalition Says 2015 Standards Obligate EPA to Regulate Existing Turbines
The notice of intent to sue argues that EPA's 2015 performance standards for new fossil fuel power plants triggered a duty under Clean Air Act Section 111(d) to issue guidelines for existing ones. The 2024 standards covered new gas turbines but left the existing fleet unaddressed. The coalition quotes EPA's own 2024 finding that existing combustion turbines could produce the largest share of power-sector greenhouse gas emissions as soon as 2030. After the required 180-day notice period, the coalition plans to sue in federal district court in Washington, D.C.
The notice also targets peaker plants. Citing EPA's earlier description, it says these units are often less efficient, less controlled for nitrogen oxides and more likely to sit near population centers and communities with environmental justice concerns. It names battery storage at peaker sites as one way to cut emissions.
EPA's Partial Repeal Takes Effect November 16
EPA is moving the other way. The final rule signed September 14 removes guidelines for existing coal, oil and gas steam units, carbon capture requirements for modified coal units and carbon capture standards for new baseload gas turbines. EPA estimates the rule will save the power sector and the public up to $310 billion, without stating a time period. A supplemental proposal would repeal all remaining power-plant greenhouse gas standards under Section 111, which would also undercut the coalition's legal theory if finalized.
Neither filing imposes requirements on any plant today, and the turbine suit cannot be filed until the 180-day window closes in late March 2027. For utilities and large power buyers, the open question is how durable today's rules will be for gas assets built to run for decades, alongside the grid congestion costs and litigation exposure already showing up in planning.
