Greenpeace, the environmental group known for facing off against whalers on the high seas, has targeted its own behemoth in Duke Energy.

The group said Tuesday it has launched a campaign to make Duke “the clean energy company that North Carolina and the United States deserve.” Greenpeace faults Duke for its use of coal and for what the group considers inaction on renewable energy.

Duke says the campaign ignores its work to reduce pollutants and invest in renewables, especially wind.

Charlotte-based Duke is an imposing target. It will be the largest U.S. utility if a merger with Progress Energy is approved. It is one of the largest U.S. emitters of heat-trapping carbon dioxide.

It is also led by a chief executive, Jim Rogers, who has been outspoken on the industry’s need to reduce emissions and address climate change, an effort that has stalled in Congress.

Greenpeace says it’s calling on Duke to back up its rhetoric.

“It’s a question of action at this point,” said Greenpeace coal campaign director, Gabe Wisniewski.

Greenpeace wants Duke to stop buying coal mined by destructive mountain-removal mining, make one-third of its energy from renewable sources by 2020 and “quit coal altogether” by 2030.

The group has already hinted at its tactics. On Monday, 16 activists were arrested in Asheville after some of them unfurled a banner on a smokestack at a Progress Energy power plant. On Feb. 1, Greenpeace flew a blimp over Cincinnati, Duke’s Midwest hub, with banners reading “Dump Duke Energy” and “Cleaner is Cheaper.”

Duke says it is making cleaner energy even as it increases the amount it generates.

Duke’s projected emissions per megawatt-hour from its plants show sulfur dioxide, which forms acid rain and haze, will fall 75 percent between 2011 and 2017. Ozone-forming nitrogen oxides will drop 47 percent and carbon dioxide 7 percent. By 2015, all its Carolinas plants will be equipped with updated pollution controls.

“We have been providing affordable, reliable, clean energy effectively and will continue to do that with the plans we have in place,” said spokesman Tom Williams. “Our system is getting dramatically cleaner each year, and has been over the previous three years.”

Duke has installed 1,100 megawatts of wind power, though none of it in the Carolinas, and will start up 800 megawatts this year. It also adopted a policy of buying coal that doesn’t come from mountain-removal mining when it can do so without paying a premium.