SALT LAKE CITY (AP) — A federal plan to cut pollution blamed for global warming by 2030 is winning cheers from environmental advocates, but a key state official says the plan is "bold and aggressive" and questions whether it can be executed.

The rule would curb national carbon dioxide emissions from power plants by almost a third over the next decade in a half. It would require Utah, which relies on coal for 80 percent of its electricity, to cut coal-generated emissions by nearly as much.

Environmental advocates say it could spur alternative energy development, launching Utah as a major player in the solar power industry. They contend it could help to clear Utah's murky wintertime skies.

Current figures from the Environmental Protection Agency don't include power plants on tribal lands; officials are still collecting the data there.

The federal rule tailors specific goals for each state, and it's up to governors to submit a plan to meet the federal standard by 2017. If they choose to forgo making a proposal, the EPA may impose its own regulations. But it's unclear how regulators would police those restrictions.

Cody Stewart, the governor's energy adviser, labeled the plan "bold and aggressive" Monday after skimming the 645-page rule. He praised the plan for giving states flexibility, but said Utah officials need more details.

"Of course we all want cleaner power, but that goal has to be balanced against other goals as well," he said, including consumers' electricity bills and power plant jobs. "Is it doable? I don't know yet. I don't know how much pain it's going to inflict on the state of Utah."

State officials are still waiting on the details of the plan, expected to be finalized next year.

In Utah, about 80 percent of electricity is derived from coal, and about 15 percent comes from gas. That's compared to the national average of about 40 percent coal and 26 percent gas.

Utah spokesman Tim Wagner of the Sierra Club said he anticipates state officials harnessing more solar power and days such an initiative could clear wintertime smog.

"It could have a dramatic impact on our infamous air quality," he said Monday, especially "if more and more people are getting at least a portion of their energy from the sun."

Officials at coal power plant operator Rio Tinto Kennecott are still looking over the plan to determine how it could affect operations there, said spokesman Kyle Bennett in a Monday statement to The Associated Press. The company is willing to work on developing cleaner energy sources, he said.

From 2008 to 2011, the White House said in a statement, Utah carbon emissions dropped by 25 percent. Stewart, the governor's energy adviser, wondered whether the state would receive breaks for converting some plants to natural gas or other cleaner sources.

"If not, then we have a lot of work to do," he said. "It could be painful and a big challenge."