The U.S. Environmental Protection Agency has unveiled a proposal to reduce greenhouse gas emissions from existing powerplants by 30% below 2005 levels by 2030.

EPA says that the proposed rule, which it released on June 2, could lead to upgrades at fossil-fuel-fired powerplants and has the potential to create thousands of construction and electric-power-transmission jobs. 

The ambitious plan would reduce carbon pollution from the power sector by about 730 million metric tons and help mitigate some of climate change's worst effects, EPA Administrator Gina McCarthy said at a press conference.

The rule, expected to be finalized in June 2015, will cover about 3,000 units at the 1,000 existing fossil-fired powerplants in the U.S. and cost approximately $7.3 billion to $8.8 billion annually starting in 2030. But those expenses will be more than outweighed by an estimated $55 billion to $93 billion annual savings in public health and climate benefits, McCarthy said.

States will play a key role in implementing the the administration's “Clean Power Plan.” They will be required to submit plans to EPA by June 2016 outlining how they would achieve the target reductions.

It will be up to each state to determine how it will hit the goals. Possible solutions include requiring upgrades to improve the efficiency of fossil-fuel plants; implementing energy-efficiency resource standards or renewable portfolio standards; or joining a multi-state market based program, such as New England's regional greenhouse gas initiative.

States' timelines have flexibility; if states are unable to submit a plan by the 2016 deadline, they can request extensions.

The National Association of Clean Air Agencies (NACAA), whose members will be responsible for developing the required compliance plans, expressed some reservations. 

NACAA Executive Director William Becker said the group generally is supportive of the proposal and its flexible approach. But he added, “The regulatory and resource challenges that lie ahead are daunting. Overcoming these challenges will require a heavy lift by all levels of government, particularly state and local.”

Congressional Republicans and power industry advocates criticized the proposal, saying it would prove costly for the power sector and taxpayers.

Sue Kelly, American Public Power Association president and CEO, says that the Clean Air Act is ill-suited as a framework to regulate greenhouse gas emissions. She would rather see congressional action.

Kelly said, “If the EPA moves forward with regulations that call for too much change too fast, we will likely see unnecessary coal-plant retirements without long-term plans for viable, cost-effective alternatives; higher electricity prices; and potential shortage of electrical supply.”

Environmental and climate-focused organizations praised EPA's plan. Eileen Claussen, president of the non-profit Center for Climate and Energy Solutions, called it a “good starting point” and said, “What’s especially important is that the rule would allow states to build on the existing cap-and-trade programs in California and the Northeast and allow other market-based approaches.”

She added, “Letting states use carbon pricing is the best way to cut emissions cost-effectively.”

McCarthy dismissed critics who “will deliberately ignore the risk, overestimate the costs and undervalue the benefits.”

The facts are clear, she said, adding, “For over four decades, EPA has cut air pollution by 70%, and the economy has more than tripled.”

The public will have 120 days to comment on the proposal after it is published in the Federal Register.

The long-awaited proposal is the second major piece of the administration’s plan to reduce carbon emissions from the power sector. EPA published a proposal to reduce emissions from new powerplants in January 2014. Both proposals use EPA’s authority under the Clean Air Act to issue regulations to reduce greenhouse gas emissions.