PARK FALLS, Wis. (AP) -- The quest for alternative energy is raising fears that too much logging debris such as limbs and bark will be removed from the nation's forests.
Such material is increasingly in demand for bio-energy projects.
A number of ventures in the Upper Midwest would use forest biomass. They include a paper mill in Forest Park, Wis., that will get steam heat from a new diesel fuel refinery.
Marvin Roberson of the Sierra Club says there isn't enough waste wood for all the biomass projects on the drawing board.
A recent study found about 4.1 million tons of woody biomass is available yearly in Michigan, Minnesota and Wisconsin, while annual demand soon could reach 5.7 million tons.
Federal and state officials say there's enough to go around.