Manomet: Biomass Isn't Green

A much-anticipated study of biomass by the Manomet Center for Conservation Sciences has found that burning wood to make electricity is potentially worse for the environment than burning coal.

The Manomet study, commissioned by the state Executive Office of Energy and Environmental Affairs in November, 2009, delivered a severe blow to an industry that has long been touted by proponents as providing a “green” alternative to fossil fuels, with possible implications beyond Massachusetts. Ian Bowles, Massachusetts’ secretary of energy and environmental affairs and a longtime proponent of biomass technology, said the state would “re-evaluate” financial incentives it currently provides to developers of biomass plants. Should Massachusetts remove biomass, specifically wood, from its list of renewable energy sources, the move could trigger a reconsideration of biomass nationally.

In a statement, Bowles summarized the study’s central conclusions: “Electricity from biomass harvested from New England forests is not ‘carbon neutral’ in a time frame that makes sense given our legal mandate to cut greenhouse gas emissions….” In effect, the scientists working for Manomet found that the carbon released from burning wood, in combination with accelerated harvesting of wood to fuel the plants, resulted in a high net “carbon debt.” In fact, the study concluded that biomass plants release more CO2 into the air for every kilowatt of energy produced than oil, coal, or natural gas.

The Manomet study reaffirmed a view offered by many biomass opponents, who had argued that treating wood as a renewable resource in the context of any effort to lower carbon emissions relied on a form of creative accounting. Because trees that die and decompose in the forest release CO2 as they rot, proponents of biomass reasoned that burning wood was “carbon neutral.” But, the Manomet study says, harvesting trees, which remove carbon from the atmosphere as they grow, for biomass plants would result in an imbalance—more carbon going into the air with fewer trees in the forest to absorb greenhouse gases—that would take several decades to overcome.

When the state ordered the study last fall, it suspended its consideration of a number of proposed biomass plants in Western Mass. that, until late last year, appeared to be on a fast track, enjoying political and financial support from the Patrick administration. Reaction to the Manomet study by proponents of biomass has largely focused on what Matt Wolfe of Madera Energy, Inc., a company proposing to build a biomass plant in Greenfield, terms an “incorrect” assumption: most of the wood the Greenfield plant plans to burn, Wolfe said in published reports, would not be specifically harvested for use in a biomass plant, but would comprise the byproduct of logging operations, debris from storms and trees taken from land being cleared for development.

David P. Tenny, president and CEO of the National Alliance of Forest Owners, said in a written statement that “the conclusions drawn from this study by Massachusetts confuse rather than inform public policy by suggesting that fossil fuel energy that increases atmospheric carbon over the long term is preferable to renewable forest biomass energy that recycles and reduces atmospheric carbon… Massachusetts’ determination that fossil fuels are preferable over renewable biomass for energy is a policy decision unique to the state, not a broad scientific conclusion. The prevailing science is clear on the carbon benefits of producing energy from sustainable forest biomass as compared to fossil fuels.”

The operative word for Manomet, however, was “sustainable.” The study concluded that there is not a significant enough supply of “wastewood” to provide large-scale plants with a sustainable source of fuel. To provide enough wood to significantly offset electricity generated from coal, oil or natural gas, the study found, there would have to be a significant increase in the number of trees being harvested from forests in New England.

Author: Tom Vannah

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