Duke Energy will be able to use whole trees harvested for power plant fuel, the N.C. Utilities Commission says.

A commission order Monday clarified the type of wood that may be used under the state's 2007 renewable-energy law. Wood is part of a broad category of organic fuels called biomass that will play a large role in helping utilities meet the state green-energy mandate.

Utilities, environmental advocates and the wood-products industry had awaited the decision. All have an interest in whether the state's forests, long used for lumber and wood products, could also be used to make electricity.

Duke had argued that the state green-energy law allowed any type of wood to be burned, including whole trees chipped into fuel. Limiting it to the "wood waste" referred to in the law would not provide enough fuel for power plants, the utility said.

The commission agreed, ruling that whole trees could be used to help fuel Duke's coal-fired Buck power plant in Rowan County and its Lee plant in Williamston, S.C. Wood would be mixed with coal.

Duke expects biomass to play "a significant role" in complying with the green-energy law, spokesman Jason Walls said. Buck and Lee together will use less than 100,000 tons a year, Walls said. By 2021, when the law is in full effect, the annual volume could rise to about 1 million tons.

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