Wood chips, dead trees, branches, and tops left after timber harvest operations are typically burned or left on the ground to rot. But what if you could turn all that material into energy—to fuel your car or even heat your home?

That's the idea behind a multimillion-dollar research project being led by HSU Forestry Professor Han-Sup Han. For the next three years, HSU students, faculty, and a team of researchers from around the country will study the potential of forest residues. Their goal? To find an easy, economical way to convert all that untapped waste into renewable energy.

A team of researchers—including HSU students, academics, forestland managers, and industry partners from around the country—is looking at the best ways to process, transport, and convert that WASTE into energy.

"WATER, THAT'S THE MOST IMPORTANT THING," explains Forestry graduate student Joel Bisson from the driver's seat of the white Ford Explorer.

It's early morning, and Bisson and Forestry Professor Han-Sup Han are driving to a remote expanse of forest east of Korbel, Calif., owned by Green Diamond Resources Company. The narrow, dirt road winds through stands of Douglas fir, redwood, tanoak, and western hemlock.

"When you're in the field by 5 a.m. and not back till 5 p.m., you don't wanna forget the water," he says.

Bisson is one of a handful HSU students studying the energy potential of forest residues, the name given to woody biomass—tree limbs, tops and chunks—left on the forest floor after timber harvesting.

Also known as slash, the material is typically piled and burned. But a team of researchers—including HSU students, academics, forestland managers and industry partners from around the country—is looking at the best ways to process, transport, and convert that debris into energy.

Their research is being funded through a $5.88 million grant from the U.S. Department of Energy—one of the largest ever received by HSU. It's also part of the Biomass Research and Development Initiative (BRDI), a partnership between the Department of Energy and the U.S. Department of Agriculture to support renewable energy research in the rural United States.

In recent years, researchers have identified woody biomass as a highly promising source of clean energy. "When utilized correctly, forest residues have the potential to supply energy and reduce greenhouse gas emissions," says Han, the grant's principal investigator. "The key is proper harvesting and management techniques."

Collecting woody biomass can also mitigate catastrophic wildfires in California, which have grown in number and severity in recent years due to climate change and forest overgrowth. The environmental and economic toll has been staggering. According to the Bioenergy Association of California, wildfires in the state have affected an average of more than 900,000 acres per year and cost taxpayers $1.2 billion annually.

Despite the numerous benefits of utilizing forest residues, researchers are quick to note the barriers to large-scale adoption. They say a major issue is the low quality of existing forest residues. "A lot of what we see has a high moisture content, which makes them heavier and eventually more costly to process," explains Anil Kizha, a postdoctoral researcher studying the physical properties of woody biomass through the grant. A lot of it is contaminated by sand, dirt, and other environmental factors, making it less favorable and more expensive to handle.

Also known as SLASH,
the material is typically piled and burned.

On a recent day, Kizha was testing a variety of techniques—such as log scattering and stock piling—to determine the best method for reducing moisture content in woody biomass. He is one of the six team members working with Han this summer. The group includes undergraduates, two graduate students, a postdoctoral researcher, and a foreign exchange student.

Adenise Ulchak, is an undergraduate student. She's here through Scientists without Borders, a program that brings Brazilian students to the United States.

For Ulchak, the hands-on experience has been invaluable. "This work has exposed me to different operations and machinery we don't have in Brazil," she says. "There, most of my time is spent in a lab."

Another challenge for forestland managers is the cost of processing and transporting forest residues to conversion sites, says Arne Jacobson, the director of HSU's Schatz Energy Research Center (SERC) and a lead investigator on the project. A trip can take hours and cost more in gas than the value of the material. "One of our goals is to reduce the cost associated with the transportation by converting the material at or near field collection sites," he says.

To do that, they're examining mobile conversion technologies that turn woody material into biochar, pellets, and briquettes in the forest. That material provides heat and energy.

In recent years, SERC has been on the forefront of biomass technology development. One example is a project for Blue Lake Rancheria where the Schatz Lab is leading the design and installation of a local distributed biomass energy system. SERC researchers also recently unveiled the RePower Humboldt planning project, which identified biomass as an important renewable energy resource in Humboldt County. According to the report, woody biomass is already being used to "meet 25 to 35 percent of … local electricity demand, and there is potential to expand."

In California as a whole, woody biomass accounts for a much smaller percentage of energy generation. According to U.C. Berkeley's Woody Biomass Utilization Group, forest residues mainly fuel the state's 30-35 biomass power plants, which account for just two percent of the state's electrical generation capacity.

At this point, the U.S. biomass market is also much smaller compared to European countries like Finland and Sweden. In those countries, bioenergy accounts for 20 and 16 percent of consumption respectively, according to the European Biomass Industry Association.

Mike Alcorn, a chief forester with Green Diamond, agrees. His company has been harvesting woody biomass for several years and says the domestic market for selling woody biomass just isn't there. "Our best option at this point is foreign markets," he says.

But things could be changing, especially with recent federal legislation aimed at alternative energy and reducing the risk of wildfires. In 2004, the departments of Agriculture and Interior implemented several initiatives to improve forest health by thinning biomass. And in 2005, the National Energy Policy Act recommended that federal agencies increase the production of biomass, wind, geothermal, and solar power.

Although the potential is there, there's still a public perception issue, says Ted Bilek, an economist with the US Forest Service and a lead investigator on the grant. He says that some people believe biomass collection harms wildlife and the environment.

"It's not enough that the technologies work and produce energy," Bilek says. "We need to make sure they're economically viable, socially acceptable, and environmentally sustainable."

Kizha says that forests in the United States are growing every year. "Collecting biomass allows us to come in to replant along with utilizing the woody residue for energy production," he says. "And at the end of the day, a healthy forest is a managed forest." End Story

"When utilized correctly, forest RESIDUES have the potential to supply energy and reduce greenhouse gas emissions." Forestry Professor Han-Sup Han

CLOCKWISE FROM TOP: Adenise Ulchak, a foreign exchange student from Brazil, helps characterize woody material near Korbel, Calif. • An in-woods grinding operation to process slash for hauling to a power plant. • A close-up of "hog fuel" produced from slash grinding. • Forestry Professor Han-Sup Han (left) and Arne Jacobson (right), director of the Schatz Energy Research Center, are lead investigators on the $5.88 million grant.

TOP: Wood chips derived from forest biomass are a promising source of renewable energy. BOTTOM: SERC engineers (left to right) Kyle Palmer and Greg Chapman work with a torrefier that converts forest waste into energy-dense material which can replace coal in power plants.

Turning Forests into Fuel

WOODY BIOMASS is a general term that includes forest residues—tree limbs, stumps and brush—left on the forest floor after timber harvesting. Woody biomass can also come from urban waste like pallets, furniture, and yard waste.

Mobile conversion technologies turn woody biomass into a more energy dense material.

  • Biomass + Gasification → Biochar
  • Biomass + Pyrolysis → Torrefied Pellets
  • Biomass + Densification → Briquettes

These energy-dense materials (i.e. biochar, pellets, or briquettes) can then be burned to create energy. During the process of gasification and pyrolysis, some gases can be captured and used in the conversion process.

Advantages of Utilizing Woody Biomass

  • Renewable resource
  • Reduces burning woody biomass after a harvest
  • Reduces dependence on foreign oil
  • Reduces the risk of wildfires
  • Restores forest health
  • Reduces the amount of herbicide needed to
  • regenerate managed forests
  • Supports local economy

Barriers of Utilizing Woody Biomass

  • Low-quality material
  • High cost of processing and transporting
  • Lack of markets
  • Lack of knowledge

Converting Biomass
into Energy

View Diagram