According to the Associated Press, Pacific Gas and Electric, Southern California Edison and San Diego Gas and Electric were targeted by the Public Utilities Commission and prohibited from inking long-term deals with energy sources that exceed the carbon dioxide emissions of a modern gas plant.

The utilities argue that coal accounts for little of their power source. Coal makes up 1%, 7% and 3% of the companies’ electricity, respectively, the news service said.

Local utilities in the state are not required to abide by the ruling, as they are not regulated by the PUC; however, their overseeing body, the California Energy Commission, is developing similar rules that could be enforceable by July.

The National Mining Association’s Luke Popovich told the AP that, unless the move is widespread, the global warming effect will be minimal and energy costs could rise.

“We don’t think it makes sense for the United States to unilaterally deny itself use of its most abundant energy source, which is coal,” he said.

Wyoming officials spoke up on the issue shortly after the announcement, concurring with Popovich and saying that the move won’t have an immediate affect on the state’s coal industry and could actually create new power generation opportunities for it.

“What these regulations say is their utilities can’t go out and sign contracts for coal-fired electricity unless these plants have carbon sequestration equal to a level at or better than natural gas-fired combined cycle plants,” Wyoming Governor Dave Freudenthal’s energy adviser, Rob Hurless, told the Billings Gazette.

He and the state’s Infrastructure Authority director, Steve Waddington, are confident in the opportunity for clean energy from their state to be transported to California, potentially including natural gas, wind and coal facilities with “aggressive” carbon dioxide controls.

“The coal issue isn't resolved,” he told the paper. “Their economy is growing; they need power.”