Originally published August 24, 2015. Updated September 22, 2026.
The Clean Power Plan was a 2015 EPA rule built to cut carbon dioxide from US power plants roughly 32% below 2005 levels by 2030. It never got the chance to try. The Supreme Court put the rule on hold in February 2016, before a single power plant had to comply with it, and EPA repealed it in 2019. The rules covering power-plant carbon have kept shifting since, through a 2022 Supreme Court ruling, a tougher 2024 standard, and a partial repeal taking effect in November 2026. The emissions cut it promised happened anyway.
What the 2015 rule asked states to do
The rule didn’t set one national standard. It gave each state its own carbon dioxide target for existing fossil-fuel power plants, built around emission-rate goals of 1,305 pounds of CO2 per megawatt-hour for fossil steam units and 771 pounds for combustion turbines. States could hit those numbers with a rate-based limit on pollution per unit of power, or convert it into a mass-based cap on total tons, the same basic design behind state carbon-pricing programs. Compliance was set to run in stages, with interim steps from 2022 to 2029 ahead of a final 2030 deadline, and EPA projected the rule would deliver $25 billion to $45 billion in net climate and health benefits by 2030.
An Energy Collective piece from 2015 summed up that design in its headline, arguing the rule put states, not Washington, in the driver’s seat. A press release from the same period pointed out what that flexibility meant in practice. States already running a carbon market, like the Northeast’s Regional Greenhouse Gas Initiative, had a head start on compliance that other states didn’t.
The Supreme Court stopped it before it took effect
EPA published the final rule on October 23, 2015, with an effective date of December 22, 2015. Twenty-four states sued to block it almost immediately, and the fight reached the Supreme Court within months. On February 9, 2016, the Court stayed the rule while the challenge worked through a lower court, with Justices Ginsburg, Breyer, Sotomayor and Kagan noted as dissenting from that order. That made it the first time the Supreme Court had stayed a major EPA rule before any lower court ruled on whether the rule was even lawful. The rule never applied to a single plant. If your state had drafted a compliance plan for the Clean Power Plan, that plan never had to take effect.
EPA swapped it for a narrower rule in 2019
EPA repealed the Clean Power Plan and replaced it with the Affordable Clean Energy rule on June 19, 2019. The new rule dropped the state-by-state targets and the option to shift generation toward gas or renewables across an entire grid. In their place, it asked existing coal plants to improve their own efficiency, one plant at a time. That was a much narrower ask than the rule it replaced, and it left the bigger structural question, whether EPA could push utilities to shift generation away from coal at all, for the courts to settle. That same gap, a nationwide generation-shifting target against a plant-by-plant efficiency rule, was at the center of the case the Supreme Court decided three years later.
The Supreme Court curbed EPA’s carbon authority in 2022
On June 30, 2022, the Supreme Court ruled 6-3 in West Virginia v. EPA that the Clean Power Plan’s method, shifting power generation away from coal and toward gas and renewables across a state’s whole grid, went beyond what Section 111(d) of the Clean Air Act lets EPA do. The ruling didn’t touch the Affordable Clean Energy rule directly, since that rule had already dropped the generation-shifting approach. It closed the door on EPA reviving the Clean Power Plan’s original design without new authority from Congress. Any future rule would have to work the way the Affordable Clean Energy rule already did, by setting standards for equipment at specific plants instead of reshaping the grid as a whole. The rule EPA wrote two years later took exactly that shape.
Biden’s EPA tried a tougher, technology-based rule in 2024
EPA came back with a different approach two years later, under the Biden administration. The agency signed a new rule on April 25, 2024, and published it in the Federal Register on May 9. It took effect that July 8, repealing the Affordable Clean Energy rule at the same time. Instead of shifting generation across the grid, this one required specific equipment at specific plants. Existing coal units still expected to run past 2039 had to cut their emission rate 88.4% by January 1, 2032, mainly by capturing 90% of their carbon dioxide. Coal units planning to retire before 2039 got an easier path, co-firing 40% natural gas for a 16% emission-rate cut by 2030, and units already set to close before 2032 were exempt. New gas plants built to run around the clock faced the same 90% carbon-capture requirement by January 1, 2032. Which deadline applied to which coal plant came down to that plant’s own retirement plans, and those plans keep changing. For a closer look at how that timeline has played out, see coal decline.
The 32% target got hit years early, without the rule ever running
The reduction the Clean Power Plan promised never had to be forced on anyone. US electric-sector CO2 emissions stood at 2,411.5 million metric tons in 2005, the baseline year the rule used to set its target. By 2019, they had already fallen to 1,617.6 million metric tons, a 32.9% drop that beat the plan’s 32%-by-2030 goal eleven years early, without the rule ever taking effect. Emissions kept falling from there. By 2024, emissions were down to 1,427.4 million metric tons, a 40.8% cut from 2005. 2025 brought a 4% increase from the year before, to 1,485.4 million metric tons, but that still left emissions 38.4% below the 2005 baseline. The rollback in Washington hasn’t undone that. Power plants kept cutting carbon on their own, years ahead of any deadline, while the rule that was supposed to require it never got the chance to work as planned.
The 2026 rollback goes further, and one big question is still open
EPA Administrator Zeldin proposed repealing the 2024 rule on June 17, 2025, calling it a rollback of what his agency labeled “Clean Power Plan 2.0.” That proposal turned into the Partial Repeal of the Carbon Pollution Standards, signed September 14, 2026, and published three days later. It’s set to take effect November 16, 2026. It drops the 2024 rule’s existing-source guidelines and its 2032 carbon-capture standard for new baseload gas turbines, while keeping that rule’s efficiency standards for new turbines in place. EPA justified the change by calling 90% carbon capture “not adequately demonstrated” and its cost “not reasonable,” a claim made in the rule itself. That’s the agency’s own characterization of the technology.
The same day, EPA proposed rescinding the 2015 finding that gives it the legal basis to regulate power-plant carbon dioxide at all, the “significant contribution” finding under the Clean Air Act. That proposal goes further than repealing one rule. If it’s finalized, EPA would give up the legal basis to regulate power-plant carbon dioxide altogether. Comments on that proposal are due November 2, 2026, with a hearing scheduled for October 1, so whether EPA keeps that authority is still unresolved.
