The proposed Bonanza Power Plant expansion in Uintah County has thrust Utah into the "ground zero" of a national debate over controlling carbon-dioxide emissions and global warming, according to Sierra Club national president Robert Cox.

Cox said the plant was the first to receive an Environmental Protection Agency permit following a Supreme Court ruling this past April that said the EPA can regulate greenhouse gases. The ruling specifically applied to mobile sources of pollution, such as cars and trucks, but Cox believes the same logic applies to power plants.

However, the EPA has declined to impose any carbon-dioxide controls on the 110-megawatt plant in Utah, saying the agency only has authority to regulate greenhouse gases from mobile sources.

Cox, who is a communications professor at the University of North Carolina at Chapel Hill, was in Salt Lake City Thursday for an environmental communications seminar. The Sierra Club is based in San Francisco and has 1.3 million members and supporters.

In an interview, he also criticized the planned Mountain View Corridor in Utah, saying it would encourage urban sprawl. But the issues surrounding the power plant have more far-reaching consequences nationally, he said.

"Bonanza will emerge as one of the leading cases to test the willingness of the EPA to be serious in the aftermath of the Supreme Court ruling," he said in an interview.

In the court case, Massachusetts vs. EPA, states sued the federal government over regulation of carbon dioxide and other greenhouse gases emitted by cars and trucks. In a stinging rebuke to the EPA, the court agreed with the states.

The justices held that respected scientific opinion links the well-known rise in global temperatures — and the attendant damage to the climate and environment — to greenhouse gases. These gases include carbon dioxide.

According to a summary of the court's findings, the Clean Air Act requires the EPA to regulate motor-vehicle emissions when the pollution can endanger public health and welfare. Harm associated with climate change is serious, it adds, and the EPA did not dispute a connection between man-made greenhouse emissions and global warming.

Asked why the petitioners in the Massachusetts case, including the Sierra Club, focused on vehicles and not power plants, Cox said a dozen states had launched actions to control vehicle emissions beyond the EPA's regulations. "EPA's been dragging its feet" in the matter, he said.

But he contended that the same legal arguments apply to other pollution sources like power plants.

Asked whether the group would sue over the Bonanza decision, he said the Sierra Club has not decided but is looking closely at the matter.