The US Environmental Protection Agency (EPA) proposed on Friday the first-ever limits on greenhouse gas emissions from new power plants, a move almost certainly to invite opposition or a backlash from the coal industry.

Under the proposal, new large natural gas-fired turbines would need to meet a limit of 1,000 pounds (454 kilograms) of carbon dioxide per megawatt-hour, while new small natural gas-fired turbines would need to meet a limit of 1,100 pounds (499 kilograms) of carbon dioxide per megawatt-hour.

New coal-fired units would need to meet a limit of 1,100 pounds of carbon dioxide per megawatt-hour, and would have the option to meet a somewhat tighter limit if they choose to average emissions over multiple years, giving those units "additional operational flexibility," the EPA said.

Currently, the average US natural gas plant emits 800 to 850 pounds of carbon dioxide per megawatt-hour, while coal plants emit 1,768 pounds.

The EPA originally proposed to limit carbon dioxide emissions from all new power plants to 1,000 pounds per megawatt-hour in March 2012, but decided to rewrite it in April to address the concerns raised by the coal industry, which said the restrictions could not be met using existing technology.

Unlike the previous attempt, the revised version sets separate standards for new gas-fired and coal-fired power plants.

"These carbon pollution standards are flexible and achievable. They pave a path forward for the next generation of power plants," EPA Administrator Gina McCarthy said during a speech at the National Press Club on Friday morning.

"The standards are flexible because they set different standards for different types of power plants. The standards are achievable because they'll secure major public health and environmental protections, and they reflect the demonstrated performance of a variety of efficient, clean, homegrown technologies," McCarthy said.

McCarthy said the new standards set the stage for continued public and private investment in technologies like carbon capture and sequestration (CCS). "With these investments, technologies will eventually mature and become as common for new power plants as scrubbers have become for well-controlled plants today," she said.

Power plants are the largest concentrated source of emissions in the United States, together accounting for roughly one-third of all domestic greenhouse gas emissions, the EPA said. While the country has limits in place for arsenic, mercury and lead pollution that power plants can emit, there are now no national limits on the amount of carbon pollution new power plants can emit.

US President Barack Obama announced a series of executive actions to reduce carbon pollution in June, and McCarthy said EPA's new proposal is "one of those important steps" to implement Obama's Climate Action Plan.

Hal Quinn, president and chief executive of the National Mining Association, however, accused the EPA of setting "a dangerous and far-reaching precedent for the broader economy by failing to base environmental standards on reliable technology."

"The regulation announced today by EPA effectively bans coal from America's power portfolio, leaving new power plants equipped with even the most efficient and environmentally advanced technologies out in the cold," Quinn said in a statement, noting that "EPA is recklessly gambling with the nation's energy and economic future."

The proposed rule does not impact existing power plants. It is now open for comments in the next 60 days. Meanwhile, the EPA said it rescinded the April 2012 proposal and will issue proposed standards for existing power plants by June 1, 2014.