PHOENIX - Arizona utilities can't use electricity generated by burning trash to meet their renewable energy requirements, a judge ruled Wednesday.

Maricopa County Superior Court Judge Crane McClennen rejected the Arizona Corporation Commission's arguments that it is entitled to consider power from incinerators burning waste to be the same as solar, wind and geothermal energy. The judge said that's not what the commission's own rules state.

Wednesday's ruling most immediately affects plans by the Mohave Electric Cooperative to meet part of its renewable energy mandate through power generated from a proposed plant near Surprise. But unless overturned it also slams the door on any other utility trying the same thing.

McClennen's action, however, does appear to leave the door open for the utility regulators to amend their own rules to specifically include trash burning as a renewable resource.

But Sandy Bahr, director of the Grand Canyon Chapter of the Sierra Club, which filed the lawsuit, said that would require the commissioners to make a conscious - and public - declaration that they consider trash burning environmentally advantageous.

"There is strong public support for solar and wind and the truly clean renewable energy resources. And there is not strong support for trash incineration, especially in areas that already have significant air quality problems," Bahr said, noting Maricopa County's ongoing problems complying with federal pollution rules.

Commission regulations require all utilities to obtain at least 15 percent of their power from renewable resources by 2025.

Recognizing the higher cost of alternatives, commissioners also agreed to let utilities impose a surcharge on customers.

The Surprise trash-burning plant was pushed by a company called Reclamation Power Group. The company needed it to quality as "renewable" power in order to charge the rates to justify the cost of the power plant.

Commissioners approved the request two years ago on a 3-2 party-line vote, with Republicans in support.

Bob Stump, chairman of the panel, defended the decision. He pointed out that even the federal Environmental Protection Administration classifies waste energy as renewable.

"And, of course, if the choice is between landfilling the waste and converting it to energy, it made sense to us to convert it to energy," he said.

Stump said no decision has been made whether to appeal the ruling.