Wood energy C study misinterpreted

June 17, 2010, Plymouth, MA – The results of a study on using forest wood for energy in
Massachusetts have been misinterpreted and broadcast throughout the
mainstream
media as evidence that biomass is worse than coal. This is incorrect. A
summary
by the study authors shows why:

The Massachusetts Department of Energy Resources (DOER)
and Manomet Center for Conservation Sciences (Manomet) have released the
results of a six-month study that began last December to answer some critical
questions about using forest wood for energy in Massachusetts. An eight-member
team of policy and science experts from several organizations conducted the
Manomet-led study, commissioned by DOER in fall 2009.

Some of the major
questions addressed by the study include: (1) How much wood is available from
forestland for biomass energy in Massachusetts? (2) What might be the impacts
of increased biomass harvests on forest ecosystems? (3) What are the carbon
accounting implications of using forest biomass for energy?

Many U.S. states and
countries around the world are promoting and investing in forest biomass energy
because using wood for energy is commonly assumed to be carbon neutral and
therefore good for mitigating climate change. The Manomet study, which is based
on a comprehensive life-cycle carbon accounting framework, reveals a more
complex picture. The study shows that using wood for energy can result in an
initial carbon debt because burning wood releases more CO₂ into the
atmosphere per unit of energy than fossil fuels (oil, coal, or natural gas).
But unlike fossil fuels, forests can grow back and recapture CO₂
from the atmosphere. Over time, through accelerated forest growth, the carbon
debt can be paid off. After the carbon debt is paid off, if the forest
continues to grow, a carbon dividend is realized, and the use of wood for
energy then becomes increasingly beneficial for greenhouse gas mitigation. As a
result, using wood for energy can lead to lower atmospheric greenhouse gas
levels than fossil fuels, but only after the point in time when the carbon debt
is paid off. Whether or not full carbon neutrality will be achieved in these
circumstances depends on if, when, and how the forest is harvested in the
future.

The most innovative
and policy-relevant finding in the report is the “debt-then-dividend” model,
which shows that using forest biomass for energy can increase greenhouse gases
for a period of time before it reduces them. The length of time it takes to pay
off the carbon debt and begin accruing carbon dividends (i.e., greenhouse gas
benefits) can vary widely, from five years to decades. The length of time
depends on a complex interaction of the type of biomass energy used
(electricity, heat, or combined heat and electricity), the fossil fuel that
biomass energy replaces (coal, oil, or natural gas), and the degree the growth
potential of the forest is realized by the landowners' forest management
methods.

As an example, with
an electric power plant that relies on biomass using whole trees from natural
forests in the Massachusetts region—and not waste wood from tree work and
landscaping that has different carbon cycle effects—the carbon debt period is
likely to last for at least 20 or 30 years before carbon benefits begin to be
realized. In contrast, using forest biomass in thermal applications such as
heating municipal buildings or schools has lower carbon debts and can provide
carbon dividends for the atmosphere sooner, generally within 10 to 20 years.

The study also
examined woody biomass energy policies from other states, federal agencies, and
international agencies, which might help inform Massachusetts’ policy. The team
modeled forest growth rates and examined the economics of supplying forest
biomass for energy. At current electricity prices, biomass for electricity
generation will remain a low-value product, with prices ($1 to $2 per green
ton) that will not motivate forest landowners to increase harvest levels very
much. However, the value of wood as a heating fuel is much higher. Increased
development of small-scale thermal applications could provide landowners with
greater financial incentives to harvest biomass.

Thomas Walker, the
study team leader, says, “Understanding the greenhouse gas impacts of woody
biomass energy is extremely complex. We’ve come up with a comprehensive but
relatively straightforward framework and methodology that can help policy
makers in Massachusetts, or anywhere, better understand if and when any
particular wood biomass energy scenario might be climate friendly. Forests in
other geographic areas can be evaluated similarly, but will yield
context-specific results with respect to greenhouse gas costs and benefits.”

Manomet president Dr.
John Hagan adds, “Our interest is in getting the best, unbiased information in
the hands of policy makers and the public so they can draw their own
well-informed conclusions about whether woody biomass energy makes sense. The
team has cleared away a lot of the former confusion about wood energy.” Hagan
says that although the study was conducted for Massachusetts, the team’s carbon
accounting approach has worldwide relevance for informing biomass energy
policies. “Massachusetts deserves a lot of credit for getting answers to some
critical questions about biomass energy that people have been asking all around
the world.”

The executive summary
and full report can be downloaded from the Manomet web site: www.manomet.org/node/322.

The Manomet study
team members are:
Thomas Walker, Team
Leader – Independent Resource Economist
Dr. Peter
Cardellichio – Independent Forest Economist
Andrea Colnes –
Biomass Energy Resource Center
Dr. John Gunn –
Manomet Center for Conservation Sciences
Brian Kittler –
Pinchot Institute for Conservation
Bob Perschel – Forest
Guild
Christopher Recchia –
Biomass Energy Resource Center
Dr. David Saah –
Spatial Informatics Group