The mound of woodchips piled up behind the Animal and Poultry Waste Management Center Processing Facility at the Lake Wheeler Road Field Laboratory could fuel a pretty spectacular bonfire. But as Chris Hopkins surveys the mound, he has a better idea. Hopkins, a doctoral student in forestry at NC State University, is part of a team of researchers working to turn woodchips into a substitute for coal.
Nearby the team members have set up a tall metal machine called a torrefier that performs modern-day alchemy. Woodchips go into a large funnel at the top of the machine and come out as hard, dry, black pellets at the bottom. In the process, they’ve changed more than just their appearance. They’ve been physically and chemically altered – through heat and pressure – to make them denser, drier and easier to crush.
The pellets – called bio-coal – are lighter than woodchips but retain 90 percent of their original energy content. That makes them an ideal feedstock for electric power plants that traditionally use coal to generate energy for businesses and residential neighborhoods.
“This process could help us build a bridge to more energy independence,” Hopkins says.
Woodchips are more abundant in North Carolina than coal and easier to collect. And, more importantly, they’re a carbon neutral source of energy. For a state that spends more than $4 billion a year importing coal, torrefied wood could be an economic windfall as well.
Hopkins explains that nearly half of the state’s forests are not adequately thinned because landowners lack a market for small diameter trees, rotten or unusable trees and logging residue. That land could be producing more valuable wood products if it was managed more effectively, he says.
If woodchips were collected and sold to help fire North Carolina’s energy generating plants, the state’s tax base could be increased by nearly $400 million a year, he estimates. Since the torrefier machine is small enough to transport on the back of a flatbed truck, it could be set up close to forest-clearing operations, making the process even more efficient.
Hopkins and his NC State colleagues are working with Progress Energy to test bio-coal wood in some of the company’s coal-powered generating stations this year.
NC State’s Office of Technology Transfer (OTT) recently announced an exclusive license agreement with AgriTech Producers, LLC of Columbia, S.C., to commercialize this technology, called “Carolina Coal.”