Harvesting Biomass (10/29/2007)

Removing woody biomass material decreases the wild fire risk to encroaching housing developments. Photo courtesy of Joe Roise

Eastern North Carolina forests contain a hazardous yet valuable resource that could hold the answer for decreasing dependence on petroleum products.

"We are in an energy crisis right now and we have a gigantic energy resource just sitting around on the ground," says Dr. Joe Roise, professor of forestry at North Carolina State University. "This is a resource people haven't thought of, and it's also a critical fire risk that needs to be removed."

Through a grant with the U.S. Forest Service, researchers at NC State are testing a machine that harvests small- diameter woody biomass for use as feedstock for electrical power generation. At the same time, the biomass harvester – think of a mulching machine on steroids – makes the forest less prone to wild fires and provides the opportunity to restore endangered habitats and associated species.

Roise says they will be testing the harvester in two areas – totaling about 393 acres – in the Croatan National Forest. "In that area alone, there are more than 20 tons per acre of biomass that we can use, not including trees larger than 6 inches in diameter."

"Energy is certainly one thing that is not going away in terms of demand," says Dr. Glenn Catts, a senior research associate in the College of Natural Resources, who is also working on the project. "The idea that we can generate energy in an alternative form while at the same time decrease the risk of wild fires is the most compelling thing about this project."

Roise says that, rather than "growing" biomass by extracting ethanol from corn, for example, the NC State forest researches are taking a different approach.

"What we have is not a product you grow, it's an existing resource that could support the energy needs of the South if you could convert it," says Roise. "So the real question is not how to grow biomass, but how to use the biomass that we already have."

In order to harvest the material, though, you need a machine that can grab the small diameter woody material from the forest understory, reduce it to chips and place it in a collection bin, Roise says.

That machine never really existed, until now.

NC State researchers worked with FECON, a company that manufactures mulching machines, to devise a machine that can navigate through the forest and take out trees up to six inches in diameter.

The fallen trees and thick underbrush are both a blessing and a curse, the NC State researchers say. While it provides a source of woody biomass for fuel, this forest material also presents both a major fire hazard and unsuitable surroundings for endangered species like the red cockaded woodpecker.

Removal of this material decreases forest-fire risks – saving encroaching housing developments – and helps restore ecosystems, the researchers say. The dense ground cover of these ecosystems is filled with extremely diverse species that are competing for nutrients and water.

"Woodpeckers, for example, need pine savanna-like ecosystems to be restored to promote their survival," Roise says.

The researchers say the challenge now is figuring out if they can efficiently operate the harvester and utilize it in a cost-effective way.

"People already pay to have their land mulched (to reduce fire hazards) and they are paying $500 to $1,200 an acre," Roise says. "There is a market right now just to leave it on the ground. So if we could actually remove it from the ground for less than what they are paying people to leave it there, then we could reduce the fire hazard on more land."

Roise says that if they can economically harvest this hazardous fuel load, it will revolutionize the management techniques of this material.

"Ultimately, the goal for this project is reducing the risk to society of gigantic fires, while restoring ecosystems and providing energy," Roise says. "What more could you want?"

Note: This story has been adapted from a news release issued by North Carolina State University

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