Experts say forest woody biomass could become a critical component of the conversion to clean energy in the U.S. and can be a sustainable resource, but its extraction concerns conservationists.
Interest in extracting woody biomass-usually the limbs, tops, needles, logging slash and other low-value wood-has increased because of rising fossil fuel costs, concerns about carbon emissions from fossil fuels and the risk of wildfires. Environmentalists are concerned about tapping into available forest biomass, but officials say it can be done in ways that meet the country's energy needs while maintaining crucial forestlands.
How Much is Available and Where is It?
Forestlands make up about one-third of the nation's total land area and could supply about 368 million dry tons of biomass annually, according to "Biomass as a feedstock for a bio-energy and bioproducts industry: the technical feasibility of a billion-ton annual supply," a joint study sponsored by the U.S. DOE and USDA. Several factors including environmentally sensitive areas were taken into consideration when calculating the figure, which included forest and agricultural biomass potential. To displace 30 percent or more of the nation's petroleum consumption would require 1 billion tons of dry biomass annually, the report says.
In 2008, 2.9 million green tons of biomass was removed from national forests, according to Ed Gee, chair of the USDA Woody Biomass Utilization Group. It is possible that more will be used in the future, he said, and more biomass is available on private lands than federal because of timber residue. The USDA alone manages 193 million acres of forestland, including grasslands, and the Bureau of Land Management manages another 263 million acres.
Nearly 70 percent of the existing biomass feedstock comes from forest products industries, the billion-ton report says. Although 368 million tons are available, estimates of what the workforce is capable of harvesting have not been nailed down, Gee says.
Gee says he believes forest woody biomass could meet America's renewable energy needs, but the forests need to be sustained for future generations. "It's very difficult to balance that," Gee says. "Folks need to work together and find common ground."
The most biomass-dense forests are in the southeast portion of the country. The "Southern Bioenergy Roadmap," a report by the Southeast Agriculture and Forestry Energy Resources Alliance and the University of Florida, found that 12 southern states-Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee and Virginia-contain 30 percent of the nation's bioenergy potential in their agricultural and forestry resources.
In California, about 20 percent of the total 4.5 million bone-dry tons of biomass used annually to fuel the state's 27 biomass power plants comes from forests, according to John Shelly, woody biomass utilization specialist at the University of California-Berkeley, and Forest Products Society president-elect. Biomass plants produce about 2 percent of California's power, or 640 megawatts, he said, and forest-based biomass makes up 7 percent of the estimated 50 million tons of biomass available in the state per year. "It's estimated we could probably double that without negative effects on the forests," he says.
Pennsylvania's 17 million acres of forestland also have generated interest from the biomass industry, but the current estimate of available low-grade wood for biomass harvest in the state-6 million tons-is overly optimistic and doesn't adequately consider several ecological, social and practical concerns, according to the Pennsylvania Department of Conservation and Natural Resources.
Differences also exist among forests east and west of the Mississippi River because of fire susceptibility relating to weather, density and insect infestations, Shelly says. Wildfires are common in the west, where forests are dense and fuel availability for fires is high. "If you're going to remove it, a good place to put it is into the biomass sector," he says.
The primary short-term benefit of biomass harvest for wildlife in a forest is to create clearings that provide the habitat needed by a variety of species, according to the DCNR report.
The long-term benefit lies in the potential for biomass markets to provide economic incentives to cut low-value wood and promote the regeneration of a new, healthier and more diverse forest, it adds.
"From my point of view, it's positive because we're using residue," Shelly says. It would end up in landfills if it wasn't used, he adds.
The Flip Side
Harvesting biomass from forests, if not done properly, can expose soil to drying and erosion, reduce biodiversity, negatively impact the food supply for beneficial insects and wood-boring species, reduce organic matter, eliminate habitats and denning sites, and limit flowers that support declining species of pollinators like bees, bats, butterflies and hummingbirds, among other adverse effects.
"It's detrimental when you overharvest without a careful review of scale and sustainability," Gee says. It's imperative that the health of the forest isn't compromised, he adds.
"To address the supply side and not the conservation side is a weak approach," says Wayne Jenkins, executive director of Georgia Forest Watch. The conservation group focuses mainly on the 865,000 acres of the Chattahoochee-Oconee forests in Georgia. It is public land and Jenkins says Forest Watch believes public lands in the state should not be harvested. "We believe that material should come off the private lands in Georgia."
WildEarth Guardians, a conservation group based in the southwestern U.S. also focuses on public forests. "When you go in and remove woody biomass, there are impacts on the forest," says Bryan Bird, Wild Places program director. "Standing forests are very important in combating climate change," he says. "It's important to be diligent in understanding the role forests play in sequestering carbon." Besides cleaning the air, forests provide clean water and habitats for wildlife.
Concerns particularly associated with the extraction of forest woody biomass include the mechanical equipment used, the amount left to help regenerate the forests and the greenhouse gas emissions associated with removing and transporting the woody biomass, Bird says.
"From the forest to the gate is the issue," Gee says, recognizing the problems that arise during transportation, especially if the forest is a long distance from the plant. But to address other environmental concerns he says, "We are going to operate by the laws," citing the National Environmental Policy Act and the Endangered Species Act. "It makes sense that scale and sustainability is in everyone's best interest."
Bird says he believes biomass extraction is not necessary for a forest to thrive, even in the case of insect infestations and wildfires because they are naturally occurring processes and forests have survived for millenniums without human intervention. "Naturally functioning forests do not waste material," he says.
Shelly says it's not waste, but a resource. "Wood is just an amazing storehouse for resources."
Biomass harvesting is a complex issue and Jenkins says Georgia Forest Watch does not oppose it altogether, but looks at it on a case-by-case basis. "We would have to look at it forest by forest," he says. "What might be appropriate in one place might not be appropriate in another place."
"The only place where I would see a potential benefit is in community interface," Bird says. For example, it can be good if it helps protect a community from a spreading fire. He added that logging slash in private forests harvested for timber does increase the fire hazard and removing it reduces fuel thinning, but he questions the need to log on public forestlands in the first place.
Current laws make it much easier to acquire woody biomass from private forests than federal, presenting another problem, Gee says. With legislation pushing toward the utilization of private forest biomass, those forests will be depleted much faster. Private forestlands come under the review of state foresters' offices, whereas federal forestlands are under review of federal laws and NEPA. "As such, any harvesting of woody biomass products can be reviewed by the public and therefore repealed by the public," he says.
In addition, the definition of biomass in the Energy Independence & Security Act of 2007 excludes forest woody biomass from federal and native forests from counting toward the 36 billion-gallon renewable fuels standard if it's used to produce biofuels. The White House recently announced that $786.5 million from the economic stimulus bill will be used to fund pilot biofuel refineries and research into creating more efficient fuels, but President Barack Obama's strategy still doesn't include biomass from federal forests or from natural private forests.
Bird is adamant that biomass should not come from public forestlands. "The public forestlands in this nation are not the place to look for biomass energy," he says. "They have much higher values than that."
Developing a Forest Management Plan
A 100-megawatt biomass power plant scheduled to go on line in 2013 in Gainesville, Fla., will run on 1 million tons of woody biomass annually. The majority of the wood will be residue from timber operations within about a 75-mile radius, but some will be other woody waste such as storm debris.
Gainesville Regional Utilities will purchase and own all the output of the facility, operated by Gainesville Renewable Energy Center LLC, an American Renewables project company. GRU also is in discussions with some water management districts working to restore long leaf pine trees by removing low-value wood in populated areas. In-depth studies have shown there is an adequate supply of forest biomass for the plant to operate, while sustaining the forests, according to GRU. Using biomass from nearby forests will help with transportation costs and emissions, according to Josh Levine, director of project development for American Renewables. Money spent on fuel will stay in the region, another benefit,
To promote good forest management, the companies assembled a technical committee to study the issues related to forest biomass and developed an incentive program for biomass suppliers, says Joe Wolf, GRU forester.
"It's the first of its kind in the nation," Wolf says. The program provides a financial incentive-50 cents to $1 more per ton-for suppliers who go above and beyond to practice good forest management by joining a third party sustainable forestry program, such as the Forest Stewardship Council, and abiding by the group's standards. The stricter the program standards, the more the supplier will earn.
The company will continue research into how biomass harvesting impacts the forests, Wolf says, but believes it will help foresters in the state achieve their objectives, such as removing fuel thinning from the state's clogged forests. "We have wildfires burning out of control because of poor management," he says.
For the most part, the plant has the support of conservation groups that have weighed in, Levine says, adding that some have concerns and conditions. "I can't think of a single group that flat-out opposes it," he says.
The biomass energy potential in Florida is great and will play a significant role in the state's conversion to clean energy, Levine says. "And in the long run, we do believe that biomass power will lower the region's electricity rates."
States Step Up
Several states and the Forest Stewardship Council have developed guidelines regarding the harvest of woody biomass from forests.
Guidelines established through a variety of state agencies in Minnesota, Pennsylvania, Wisconsin, Maine and Missouri all address issues with dead wood, wildlife and biodiversity, water quality and riparian zones, soil productivity and silviculture, according to the Forest Guild's January 2009 report, "An Assessment of Biomass Harvesting Guidelines."
Minnesota, Missouri, Pennsylvania and Wisconsin also address disturbances like insects, fire or disease. Guidelines can differ depending on what type of forestland is being considered for biomass harvest.
Definitions of biomass usually are similar, but can differ between states and as the timber market fluctuates. For example, Maine guidelines define biomass as all organic material, but go on to identify "energy wood," woody material used in a bioenergy facility, and "energy fiber," a subcategory of energy wood that excludes wood suitable for saw timber.
Some harvests remove only woody biomass, while others combine the harvest of saw timber or other products.
The main sections of the FSC guidelines that address biomass harvesting include habitat, dead wood and retention. They allow a variety of practices to be used, as long as the management objectives and FSC standards are not compromised.
Other states also have developed and implemented guidelines as the nation moves toward conversion to clean energy and independence from foreign oil. Woody biomass is a component of that conversion, Shelly says. "Theoretically, wood has about 20 million British thermal units per bone-dry ton locked up in it," he emphasizes, adding that efficiency rates with current woody biomass technologies range from 30 percent to 70 percent. "More research needs to be done, but we'll get there," he says. "It's about meeting the demands of the world and woody biomass is a big part of that picture. The tree is really one of our few naturally renewable resources. It's an amazing resource for now and the future."
Lisa Gibson is a Biomass Magazine associate editor. Reach her at firstname.lastname@example.org or (701) 738-4952.