The US Environmental Protection Agency proposed Friday to limit carbon dioxide emissions from new power plants, in a bid to implement President Barack Obama's plan to fight climate change.
The move marks the "first milestone" of a major part of the Climate Action Plan announced in June by the US leader, the agency said in a statement.
"Climate change is one of the most significant public health challenges of our time," EPA Administrator Gina McCarthy said.
"By taking commonsense action to limit carbon pollution from new power plants, we can slow the effects of climate change and fulfill our obligation to ensure a safe and healthy environment for our children."
The plan foresees that new, large natural gas-fired turbines emit no more than 1,000 pounds (454 kilograms) of carbon dioxide per megawatt hour, while new, small natural gas-fired turbines would have to emit no more than 1,100 pounds of carbon dioxide during that same timeframe.
New coal-fired units, meanwhile, would not be allowed to exceed 1,100 pounds of carbon dioxide per megawatt hour, with "the option to meet a somewhat tighter limit if they choose to average emissions over multiple years."
Together, natural gas and coal-fired power plants account for roughly a third of all US greenhouse gas emissions.
The average advanced coal plant currently emits about 1,800 pounds of carbon per hour, according to industry figures.
Mixed reaction from environmentalists, industry
The proposed new standards, which will undergo a 60-day public comment period, also seek to ensure that new power plants are built with clean technology to keep carbon pollution to a minimum, according to the EPA.
"These standards will also spark the innovation we need to build the next generation of power plants, helping grow a more sustainable clean energy economy," McCarthy said.
The proposal has been warmly received by environmental groups and a number of his fellow Democrats -- but decried by groups that represent industry interests.
"It sets achievable standards for new power plants that will spur innovation in clean coal technologies like carbon capture and sequestration," said Congressman Henry Waxman, the top Democrat on the House Energy and Commerce Committee.
"And the proposal will clean up the air and make the US a world leader in advanced pollution-control technology," he added.
World Resources Institute director Kevin Kennedy agreed that the EPA's announcement delivered "a strong signal that the administration will use its authority to tackle climate change."
And Rachel Cleetus, an economist with the Union of Concerned Scientists, cheered that "these rules pave the way for EPA to achieve truly significant emissions reductions from existing plants."
But she said more must still be done "to cut emissions, including putting a price on carbon" in order to reach Obama's emissions cuts targets.
Far less enthusiastic was the US Chamber of Commerce, which represents more than three million businesses.
The group said the new proposal would be "yet another major regulation that will hamper economic growth and job creation, and could lead to higher energy costs."
The powerful pro-business group said the regulation would end up "essentially outlawing the construction of new coal plants," the biggest power source in the US.
And the Edison Electric Institute, which represents power companies, said the EPA's plan "likely will affect the price of electricity for all Americans and our industry's ability to enhance the electric generation fleet and grid."
In June, Obama laid out a broad new plan to fight climate change, using executive powers to get around what he termed "flat Earth" science deniers who have blocked action in Congress.
Officials said at the time that the plan would allow the United States to meet a goal of cutting greenhouse gas emissions by 17 percent below 2005 levels by 2020, a pledge Obama made at the inconclusive Copenhagen summit in 2009.