MA biomass study finds complex carbon impact

By Lisa Gibson
Woody biomass power production is commonly thought to be carbon neutral, but a Manomet Center for Conservation Sciences study shows a more complex picture of biomass energy's carbon footprint. The study, however, may have a fundamental flaw, as it bases its analyses on new forest biomass instead of the waste wood and residues most plants would use.

"Biomass Sustainability and Carbon Policy Study" examines three main aspects of biomass energy in Massachusetts: feedstock availability; impacts of increased harvest on forest ecosystems; and carbon accounting implications. The study was commissioned and funded by the state Department of Energy Resources, which suspended all new applications for renewable portfolio standard (RPS) qualification, awaiting the results.

The six-month study, commissioned largely in response to citizen opposition of proposed biomass facilities in the state, shows that using forest biomass for energy results in "carbon debt" because burning wood releases more carbon dioxide into the atmosphere than coal, oil or natural gas. Unlike fossil fuels, however, forests can grow back and recapture carbon dioxide from the atmosphere, paying off the carbon debt. After the debt is paid off, if the forest continues to grow, a "carbon dividend" is realized and the use of wood then becomes increasingly beneficial for greenhouse gas (GHG) mitigation, according to the Manomet Center. As a result, using forest wood for energy can lead to lower atmosphere GHG levels than fossil fuels, but only after the time when the carbon debt has been paid off. Whether or not full carbon neutrality can be achieved will depend on if, when and how the forest is harvested in the future, the study found.

In addition, combined-heat-and-power (CHP) facilities and biomass heating operations reach carbon dividends much sooner than forest biomass power plants because of greater efficiency, the study said. Replacing oil-fired CHP and thermal capacity yields benefits within a decade and when replacing natural gas thermal it takes between 20 and 30 years. Dividends from the replacement of coal-fired electricity with forest biomass begin approximately 20 years later, and when biomass replaces natural gas electricity capacity, carbon debts are still not paid off 90 years later, according to the study.

The work also determined that forest biomass availability depends heavily on prices that bioenergy facilities are able to pay for wood. At present, landowners in the region typically receive between $1 and $2 per green ton of biomass. Under that scenario, the estimate for new biomass that can be harvested annually from forests in the state is only between 150,000 and 250,000 green tons, only enough to generate 20 megawatts of power. Those estimates could potentially increase 50 to 100 percent when out-of-state forest biomass resources are taken into account. If prices were to increase to $20 per green ton, availability from combined in-state and out-of-state forest biomass could total between 1.2 million and 1.5 million green tons per year, but the study says that scenario is unlikely.

"There are wood supplies from forest biomass and nonforest biomass," said Peter Bos, developer with Russell Biomass, which plans to build a 50 megawatt (MW) power plant in Russell, Mass., that would use residues, stumps and other debris not considered new forest biomass. "Manomet estimated forest biomass conservatively, but that's probably OK because that will be taken into account when DOER establishes its new wood sustainability policies for each biomass plant." Nonforest biomass has substantially lower global warming impacts than forest biomass because it does not require cutting new wood, he said. At least 1 million tons per year of nonforest wood is available in the state and surrounding areas, he said, adding that estimate is conservative, as well.

A 2002 report found that 2.5 million tons of nonforest biomass are available in the state, the Manomet Center report cites, adding that the potential and value of these sources may be substantial and worthy of further investigation. This point is crucial to feedstock availability for Massachusetts biomass plants, as none of the proposed facilities have included cutting new forest biomass in their plans. "They're making a fundamental assumption that is not correct," said Bob Cleaves, president and CEO of the Biomass Power Association, in reference to the Manomet Center study. "I think they missed the point that the overwhelming feedstock for biomass projects in the country is tops and limbs from the forest products industry, rice hulls, orchard prunings, all byproducts of another process." When taking that point into consideration, biomass power is absolutely carbon neutral, he added. "The report's authors appear to focus primarily on growing and harvesting trees for use in the generation of energy." Biomass was recently deemed exempt from California's cap-and-trade program, Cleaves emphasized, and respected scientific and environmental groups such as the Union of Concerned Scientists and the Forest Guild have expressed strong support for biomass power.

Bos is not concerned that the DOER might rule out biomass altogether for RPS qualification, saying the only way that would happen is if there was no waste wood available at all. "I think DOER in Massachusetts now has a framework they can use for allowable sources of wood supply," he said.

As for forest sustainability and biomass harvests, the study shows that harvesting rates would not increase from current levels in the low-price scenario. The combined volume of timber and biomass harvests in the scenario represents less than half of the annual net forest growth across the state's operable forest land base. In the high-price scenario, however, the total harvested approaches the total amount of wood grown each year on the operable private forest land base, the report states. The study can be viewed in its entirety at

A public comment period of one month followed the June 10 release of the findings and the DOER is now carrying out a redrafting process. RPS qualification applications will remain suspended until new standards are finalized.

A Swift Change

But two days before the public comment deadline of July 9, the Massachusetts Executive Office of Energy and Environmental Affairs ordered the DOER to take swift action in revising the state's RPS regulations in light of the study findings. "We're perplexed by it to say the least," Cleaves said of the timing. He added he is baffled by the process being undertaken for adopting regulations, as well as the language in a letter from the EEA to DOER. "Two days before the comments are due, they essentially adopt a final rule and direct their agency to promulgate the rule," he said.

In the letter, Massachusetts EEA Secretary Ian Bowles wrote, "In light of the Manomet study, we have a deeper understanding that the greenhouse gas impacts of biomass energy are far more complicated than the conventional view that electricity from power plants using biomass harvested from New England biomass forests is carbon neutral. The findings of the Manomet study have changed the policy landscape for biomass energy production derived from wood fuels." He wrote that the state's policy should reflect the "current science" by supporting facilities with the GHG profile needed to fulfill the state's emission reduction mandates of reaching 80 percent below 1990 levels by 2050 and 10 to 25 percent by 2020. "Given the general findings of the Manomet study, our obligations under the Global Warming Solutions Act of 2008, and the authority of the DOER to regulate state incentives for renewable biomass sources of energy, � I direct you and your staff at the DOER to move expeditiously to align our regulations with our better understanding of the greenhouse gas implications of biomass energy."

The letter outlines six important changes to policy: in order to qualify for renewable energy certificates, facilities must be designed, constructed and operated to achieve maximum practicable efficiency as determined by the DOER, providing significant near-term GHG dividends in a combined-heat-and-power (CHP) facility or comparable technology; renewable energy generating sources must yield at least a 50 percent life-cycle GHG reduction per unit of energy over 20 years; the fuel source must be grown, harvested and used sustainably; construction and demolition debris will not be eligible for renewable energy certificates; regulations will not apply to energy from anaerobic digestion of agricultural crops, animals wastes, food or sewage sludge; and regulations must address the use of forest residues.

Disregarding Public Opinion?

Issuing such an order before the comment period is over shows a lack of transparency and implies a disregard for public input, according to Cleaves. Robert Keogh, spokesman for the EEA, doesn't see it that way. "The point of Secretary Bowles' letter at this point was to set out his expectations and essentially his first comment on the direction that he sees for policy coming out of the Manomet study," he said, adding that the rulemaking process will include public comment periods, hearings and comment periods on draft regulations. "This is an ongoing process of back and forth between the public and state officials, so that comment process is ongoing." Keogh said there's no doubt the policy will change and the letter represents the start of that process.

Despite the language and timing of the letter, which does add that questions remain to be answered, Keogh assured that public comments play a large role in drafting policies, although the intent to make policy changes will stand. "Certainly the final terms of the policy change will be very much informed by the public comment," he said. "The fact that there will be policy changes, I think, is not likely to change. We're not going to wind back the tape and say we don't need sustainability and carbon criteria for biomass after all. We do need that."

Following release of the letter, grassroots group Stop Spewing Carbon announced it will no longer push for its ballot initiative limiting biomass power emissions to 250 pounds per megawatt hour, as it considers the letter a sign of its victory. "Ending renewable energy credits for dirty incinerators was the central goal of our ballot question and we have won," said Meg Sheehan, chair of the campaign, in a statement published on its Web site. "This is a groundbreaking development that means an end to commercial biomass electric power plants in Massachusetts," she also is quoted saying. Sheehan did not answer inquiries about whether the group gathered enough signatures for ballot inclusion. Keogh agrees the policy change does achieve the group's goal of restricting renewable energy incentives to only those technologies that contribute to the state's GHG goals. He added that it's hard to say at this point whether Sheehan is correct in her statement that biomass power will be eliminated in the state.

Bowles requests in his letter that the DOER draft regulations on or before Sept. 1 of this year, draft final rules on or before Oct. 31 of this year, and have final regulations in place by Dec. 31 of this year.
When asked if forest residues will be as thoroughly assessed as new forest wood was in the Manomet Center study, Keogh said, "It will be fully and thoroughly vetted through the rulemaking process, yes."