The US Environmental Protection Agency (EPA) on Wednesday proposed the repeal of CO2 and mercury emissions standards for power plants, its latest steps in an effort to undo many of the regulations enacted by President Donald Trump's predecessors

The agency said the repeals will help bring about an end to the "war on much of our domestic energy supply" waged by previous administrations, while saving consumers money

"We have chosen to both protect the environment and grow the economy," EPA administrator Lee Zeldin said. "There was this false binary choice made before we got here."

Together, the repeals would save more than $1bn/yr for American families, Zeldin said.

The standards, finalized last year by EPA during the administration of former president Joe Biden, cover CO2 emissions from existing and new coal-fired power plants and new natural gas-fired units, as well as mercury emissions from coal- and oil-fired power plants.

At the time, EPA said the CO2 rules will lead to a 90pc reduction in emissions from coal-fired power plants, while it tightened the Mercury and Air Toxics Standards (MATS) for coal- and oil-fired units by 67pc and included new emissions-monitoring requirements. In addition, the MATS for lignite-fired units were tightened by 70pc to put them in line with the standards for other coal plants.

The CO2 rule includes standards for new coal and gas units and guidance for existing coal-fired power plants, the latter of which vary by unit type, size and other factors such as whether a power plant provides baseload or backup power. It does not include standards for existing gas-fired generators, which EPA had proposed in 2023 but last year decided to scrap in favor of a "new, comprehensive approach".

While the CO2 regulation would be fully repealed, Zeldin said the agency is proposing to only undo last year's "gratuitous" changes to MATS, such as the new lignite standards.

"If finalized no power plant will be allowed to emit more than they do now or as much as they did one or two years ago," he said.

In addition to repealing the two Biden regulations, EPA is proposing to undo the Clean Power Plan, developed by the agency during the administration of former president Barack Obama. It would do this in part by reversing a previous agency determination that it could regulate greenhouse gas (GHG) emissions from power plants, and by also finding that those emissions "do not contribute significantly to dangerous air pollution."

The Clean Power Plan has never been enforced, and the US Supreme Court in 2022 ruled the agency lacked the authority to regulate CO2 emissions from power plants in the way envisioned by that approach.

Unlike during Trump's first term, when EPA first sought to repeal the Clean Power Plan, the agency this time around is not proposing any replacement. The previous replacement rule was struck down by the US District of Columbia Circuit Court of Appeals in 2021.

The lack of a new rule could make EPA more vulnerable to legal challenges, which are all but certain to be filed by environmental groups and some states.

"This administration is transparently trading American lives for campaign dollars and the support of fossil fuel companies, and Americans ought to be disgusted and outraged that their government has launched an assault on our health and our future," Sierra Club climate policy director Patrick Drupp said.

Zeldin said he was not concerned about any potential litigation.

"I would say with great enthusiasm and excitement for the future, I know we are absolutely going down the right path," he said.

Coal and electric sector groups cheered EPA's proposal.

"Today's announcement nullifies two of EPA's most consequential air rules, removing deliberately unattainable standards and leveling the playing field for reliable power sources, instead of stacking the deck against them," National Mining Association president Rich Nolan said.

EPA in March included the CO2 and mercury rules among 31 Obama and Biden-era regulations and actions it planned to review and potentially repeal. Since then, the White House has identified more than 60 fossil fuel-fired power plants that will have two extra years to comply with the more-stringent MATS, giving them a reprieve while EPA works to formally repeal the regulations.

The March announcement also included a reconsideration of the 2009 endangerment finding for GHG emissions, which underpins all of the major climate regulations EPA issued in recent years.

"I don't have anything to announce today as it relates to any proposed rulemaking that may be to come on that topic," Zeldin said.

EPA will open a 45-day public comment period on each proposed repeal once they are published in the Federal Register.

By Michael Ball