EMISSIONS

When is a tree a tree, when is it 'waste' and why does it matter for the Clean Power Plan?

When presenting the case for wood energy use under the Obama administration's proposed Clean Power Plan, the Biomass Power Association created a simple diagram to answer a complicated question: When is a tree a tree and when is it "waste biomass"?

This question is a contentious issue in the debate over whether burning wood at power plants is a renewable, carbon-neutral energy source or harmful to the global climate. The issue may also have a bit to do with combating wildfires in the drought-parched West.

The diagram, which the BPA said it has presented to a number of Washington, D.C., policymakers, depicts two plants, one a shorter sapling and the second a taller, more tree-like tree. The small limbs and the top of the taller tree are blue, which the diagram categorizes as "waste biomass," while its trunk and larger branches are green, which the diagram categorizes as "sawlogs," more valuable wood used for purposes like home construction.

The slim sapling is entirely blue, meaning that the BPA considers it to represent 100 percent "waste biomass."

At the smokestack, burning wood for energy produces emissions just like burning fossil fuels. But many environmental groups like the Natural Resources Defense Council agree with the biomass industry that burning "waste" wood material like sawdust is probably good for the climate compared to burning fossil fuels because this material would otherwise decompose and produce emissions. Additionally, trees absorb CO2 when they grow, so burning this form of wood "waste" is considered carbon-neutral.

But there is disagreement surrounding the category of biomass represented by the smaller, blue-colored sapling in the industry group's diagram, a plant that represents what some may call a "whole tree" and others may call "residue," "waste" or "thinnings."

Many environmental groups are less happy with the idea of burning what they call "whole trees" for energy. Sasha Stashwick of the NRDC wrote in a recent blog post that burning "whole trees and other large-diameter wood ... actually increases carbon emissions compared to coal and other fossil fuels."

"Those increases can persist for anywhere from 35 to 100 years or more, depending on regional variations in climate and forest type, and would therefore make climate change worse," Stashwick wrote.

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Jessie Stolark, policy associate with the nonprofit Environmental and Energy Study Institute, said the U.S. EPA is actively grappling with the question of what trees are beneficial to burn for energy and what trees are not.

"When we're talking about whole trees, what constitutes a 'whole tree'? Are we talking about particular diameters? Does it have to do with the health of the tree?" Stolark asked. "It is hard to say at any given time what the mixture is, because it so depends on the rest of the marketplace for wood products."

Biomass boosters say thinning aids forests

The BPA and other wood industry groups want EPA to conclude that when it comes to helping the climate and the nation's forests, not all trees are created equal.

"Biomass is part of a larger forest products industry; the fuels that our members use come from residues from forestry operations," explained Carrie Annand, vice president of external affairs for BPA. "It's really not realistic to think that our members are using anything other than the lowest-value fuel they can find."

Finding markets for low-value trees through the biomass industry is beneficial, Annand said, because it can help pay for thinning in Western forests to help protect them against wildfires. In some Western forests, brush and small trees that have grown in after years of fire suppression can serve as kindling to make the fires hotter and more threatening to the whole forest, especially during a drought. Forest owners' groups also argue that biomass creates markets for small trees that allow private landowners to keep their land as forest rather than converting it to agriculture or housing developments.

Matt Willey, corporate communications manager for Drax, agrees with Annand on these points. Drax is a power station in the United Kingdom that imports large volumes of wood from the southeastern United States to burn in two of its formerly coal-fired, 660-megawatt generation units. According to a recent report by industry publication ENDS Waste & Bioenergy, Drax recently imported a record 60,000 metric tons of biomass in a single shipment, a new record.

"Forest thinning is an integral part of good forest management and actually helps produce healthier, larger and more valuable trees for other industries," Willey said in a May email.

In a separate email in February, Willey argued that the wood fiber used in Drax's generators comes from "sustainably managed" forests, meaning that the trees they use are what his company considers to be "low grade" trees, including trees that are diseased and damaged.

Willey vehemently denied that his company is causing deforestation in the United States, pointing to recent research by the U.S. Forest Service that found the Southeast's forests are growing, not shrinking, in response to increased European demand for biomass (ClimateWire, Feb. 3).

'Hiding behind semantics'?

But some environmentalists contend that if EPA allowed states to burn material sourced from "whole trees" for energy as a way to comply with the Clean Power Plan, this could result in more, not fewer, emissions and speed climate change.

"What we need is a science-based, consistent system for evaluating the actual carbon impacts of different sources of biomass," Stashwick of NRDC said in an email. "The science tells us that when power plants burn trees and other large-diameter wood, it increases emissions compared to coal for many decades, whether that biomass is called a 'waste' or not."

Scot Quaranda, communications director with the activist group Dogwood Alliance, calls the biomass industry's stance on forest "residues" and thinnings "hiding behind semantics, essentially."

"It starts to become disingenuous when you start to call them just 'residuals' or 'thinnings' or other things besides 'whole trees,'" Quaranda said.

The Dogwood Alliance, which aggressively lobbies against the growth of the biomass industry in the U.S. Southeast, has repeatedly published reports alleging the industry is already using large-diameter "whole trees" to manufacture wood pellets, while the industry has repeatedly responded that it only uses "low-grade" wood, "thinnings" and "residues."

The group argues biomass' growth in the Southeast will lead to large-scale clearcutting and widespread conversion of natural forests to plantations, activity it says will do more to harm the climate than to help it. It and other environmental groups are worried EPA will take the side of the industry when it comes to biomass use under the Clean Power Plan.

"The EPA, they don't regulate sustainability in forests, that's not what they do, that's not their area of expertise," Quaranda said. "To assume that that's going to be an easy thing to do is nonsense."

EPA mulls over how wood energy can be sustainable

So how will EPA draw the line between a "whole tree" and "waste"?

EPA officials have repeatedly stressed that the agency is in the process of working through the science of what biomass use is "sustainable" and exactly how this energy source can reduce America's greenhouse gas emissions. The agency has appointed a panel of scientific experts, called the Science Advisory Board, to deliberate on this issue, and this group is not expected to come to a conclusion until later this year.

However, agency leaders have hinted that they will accept at least some forms of biomass burning for energy as a way for states to comply with the Clean Power Plan.

"We very much are in favor of recognizing sustainable forestry and the efforts that it provides to essentially lower greenhouse gases," EPA Administrator Gina McCarthy said in a recent call with reporters.

But for now, it remains unclear how and when EPA will conclude how big, small, healthy or unhealthy a tree must be for its use as energy to count as "sustainable."

The BPA recently met with the White House Office of Management and Budget to discuss how wood energy emissions will be counted under the Clean Power Plan.

During a recent webinar hosted by Biomass Magazine, Annand said of the meeting, "we don't really have a lot of clues about what the final Clean Power Plan is going to look like, but we are hopeful that it will be positive toward our industry."

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