Environmental Protection Agency Administrator Scott Pruitt warned Wednesday that taking coal out of the nation's fuel mix would make the U.S. much more vulnerable if attacked, especially as natural gas dominates much of the market.

"What would happen if we had an attack on our infrastructure when you've diverted to natural gas almost exclusively and you don't have coal there as a safeguard to preserve the grid?" Pruitt asked in an interview with Fox Business's Varney and Co.

"Utility companies across this country need fuel diversity. You need solid hydrocarbons on-site that you can store, so when peak demand rises, you've got solid hydrocarbons to draw on," Pruitt told the program's host Charles Payne.

The North American Electric Reliability Corporation, the congressionally mandated grid watchdog that develops mandatory reliability standards for utilities, is focused on examining the challenge faced by an electric system dominated by natural gas and more renewables.

The group said in its 2016 reliability report that there are advantages to having tons of coal on site at a power plant to maintain the power supply, whereas natural gas is a just-in-time resource that must be transported via pipeline. Pipelines cannot always keep up with demand if there is a spike in electricity consumption during a bout of extreme hot or cold weather.

NERC works with the nation's lead grid regulator, the Federal Energy Regulatory Commission, in evaluating those issues and approving standards to prevent blackouts and brownouts.

"I mean, it's a smart strategy for this country to invest in technology and innovation, burn coal, burn natural gas, use renewables, make sure we advance nuclear," Pruitt said. "But it truly needs to be a part of the fuel diversity with utilities across the country."

Pruitt's statements show a willingness to wade into matters regarding the electric grid, which is an area the EPA does not directly oversee but has influenced immensely by its regulations on coal plants.

Pruitt's remarks come as Energy Secretary Rick Perry is conducting a grid study that would address some of the concerns the EPA chief raised.

FERC has principal oversight over the wholesale electric and natural gas markets and routinely examines those matters with NERC.

Republicans had blasted the Obama administration's EPA for not adequately consulting with FERC in developing its climate change regulations, because of the impact the rules would have on the grid.

The platform from the 2016 Republican National Convention even proposed the idea of transforming the EPA into a bipartisan commission akin to FERC or the Nuclear Regulatory Commission. Both commissions are formed by equal numbers of Republicans and Democrats with the chairman being of the same party as the president.