A study by scientists at the University of Georgia's Warnell School of Forestry and Natural Resources has confirmed that new methods can successfully harvest significant amounts of forest biomass for energy production from southern pine forests without adversely impacting roundwood (pulpwood and sawtimber) production. Slash, tree tops and limbs that are removed from harvested trees, and forest understory growth are prime examples of forest biomass that have traditionally held zero value. Today, however, members of the forest products industry are beginning to power entire manufacturing plants with this raw material. They can even generate excess electricity that they sell to local utilities.

The biomass chipper at work. (Photo courtesy of University of Georgia's Warnell School of Forestry and Natural Resources.)

Simply by adding a 250-horsepower chipper to the usual allotment of harvesting equipment, a logging contractor can produce 10 or more tons of biomass chips per acre of trees harvested from a coastal plain, slash pine plantation. According to Dr. Dale Greene, the principal investigator for the study and Professor of Forest Operations in the Center for Forest Business at the Warnell School, "the chips produced from these biomass sources worked well in the electricity co-generation plant where they were burned and our lab analyses suggest that the chips also have very competitive heating values."

A review of the study's data also revealed that the energy gain to energy required ratio for these biomass chips is close to 50 to 1 for a forty mile haul. That means for every Btu (British thermal unit) expended to acquire forest biomass fuel chips and transport them to the manufacturer's generator; 50 Btu's of energy can be generated to operate a manufacturing plant, as long as the plant is within forty miles of the harvest site. "This is a remarkably efficient process," Dr. Greene argues. "These kinds of efficiency ratios make use of biomass very competitive with use of fossil fuels."

And while creation of bio-energy chips from timber harvesting has exciting potential for forestland owners and the forest product manufacturing industry, some industry leaders have been concerned that a developing bio-energy industry might interfere with their traditional supply source for roundwood. Dr. Greene now believes this concern is unwarranted. "While this approach required some additional work from the felling and skidding operation, roundwood production did not suffer significantly and costs appear favorable for this treatment," Dr. Greene concluded.

By Eugene MacIntyre; Public Relations Coordinator, Warnell School, University of Georgia, Athens.