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 meet a limit of 1,000 pounds of carbon dioxide per megawatt hour, while new small natural gas-fired turbines would have to meet a limit of 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.
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.
In a speech on June 25, 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 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.
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