A state-commissioned study indicated biomass produces more carbon emissions than other renewable sources.
This conveyor belt, front right, conveys wood chips into the McNeil Generating Station biomass plant in Burlington, Vt.BOSTON — The Patrick Administration has proposed tough new rules aimed at discouraging large-scale wood-burning power plants in Massachusetts.
Under the proposals announced Tuesday, plants must burn at 40 percent overall efficiency to earn half a renewable energy credit from the state and 60 percent efficiency for a full credit. The credits are vital to making the plants economically feasible.
Officials say none of several biomass plants proposed for Western Massachusetts would qualify for the credits.
Wood-burning plants have been proposed in Greenfield, Pittsfield, Russell and Springfield.
A state-commissioned study indicated biomass produces more carbon emissions than other renewable sources. The state said it's trying to direct the industry toward building combined heat and power units — unusually smaller facilities used at places such as industrial parks.
Wood power advocates said the efficiency standards were arbitrary and unscientific when they were released last year in draft regulations.