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Conclusions of biomass report contested by both sides

Date: 8/4/2010

Aug. 4, 2010

By G. Michael Dobbs

Managing Editor


HOLYOKE -- Has the debate on biomass in the state been settled by a report that concludes burning wood to generate electricity creates more carbon than burning coal?

If the reactions from the audience at a state-sponsored meeting last week are any indication, the answer is "no" and the study's conclusions didn't seem to satisfy many.

A study commissioned by the Department of Energy Resources (DOER) conducted by the Manomet Center for Conservation Sciences concluded the use of biomass for heating and combined heat and power (CHP) facilities would result in a 25 percent reduction in greenhouse gas emissions in 2050 relative to oil, but biomass-fired electricity would result in a 3 percent increase in emissions over coal-fired electricity in 2050.

So if anything, the report seemingly shifts the emphasis from developing biomass electrical generation to encouraging facilities that produce both electricity and heat.

The DOER convened two hearings recently -- one last week at Holyoke Community College -- to present the findings of the report and to solicit comments from the public to help shape polices governing the state's Renewable Portfolio Standard.

Under law, the state must reduce its carbon emissions 80 percent by 2050.

The auditorium was filled with more than 100 people. They were divided over the subject of biomass into two groups: the people who own forests and see biomass as an additional market for their product and the people who are deeply opposed to the concept of burning wood.

At the heart of the study was several factors: whether the carbon produced by burning wood is less or greater than burning coal or oil and how long does it take for the carbon released in burning to be re-absorbed by a new generation of trees.

For some members of the audience the debate extended to whether or not Western Massachusetts, with its poor air quality thanks in part to the Connecticut River valley, can afford another source of pollution.

The Manomet study did not address any other pollutant from the burning of wood, other than carbon. It also did not address the implications of burning of construction and demolition waste, which is the fuel for a biomass facility slated for Springfield.

The researchers wrote in the executive summary, "The atmospheric greenhouse gas implications of burning forest biomass for energy vary depending on the characteristics of the bioenergy combustion technology, the fossil fuel technology it replaces, and the biophysical and forest management characteristics of the forests from which the biomass is harvested. Forest biomass generally emits more greenhouse gases than fossil fuels per unit of energy produced. We define these excess emissions as the biomass carbon debt.

"Over time, however, re-growth of the harvested forest removes this carbon from the atmosphere, reducing the carbon debt. After the point at which the debt is paid off, biomass begins yielding carbon dividends in the form of atmospheric greenhouse gas levels that are lower than would have occurred from the use of fossil fuels to produce the same amount of energy. The full recovery of the biomass carbon debt and the magnitude of the carbon dividend benefits also depend on future forest management actions and natural disturbance events allowing that recovery to occur."

John Gunn from the Manomet Center said, "The time element [to achieve carbon neutrality] is complicated."

The study indicates it might take up to 40 years for the carbon generated in the burning to be captured by a new generation of trees.

"There is not one magic number to look at," he added.

At the meeting, DOER Commissioner Philip Giudice called the study, "great science and really useful."

The report also addressed the impact biomass would have on forests in Massachusetts.

The DOER reported, "In terms of sustainable biomass supply, the report determines that, at current market prices and renewable energy incentives, biomass energy could increase forest harvesting in Massachusetts by 150,000 to 250,000 green tons per year -- not enough to support one 50 mega watts biomass electric plant, but sufficient to fuel 16 CHP units. Harvested acreage is not expected to increase from current levels, but rather biomass fuel would come from removal of logging residues and poor quality trees at sites harvested for timber.

"At this level of harvest, the combined volume of timber and biomass harvests represents less than half of the annual net forest growth across the state's private forestlands. Only significantly higher prices for forest biomass, due to sharp increases in fossil fuel prices or renewable energy incentives, could result in additional harvesting approaching the net annual growth of existing forest stock."

Others did not agree with the report's methodology or its conclusions.

One of the tree farmers who spoke also questioned the financial statistics in the report concerning the cost of the wood used.

Several speakers addressed the high asthma rates in Western Massachusetts and questioned how biomass would affect those with that illness.

A speaker identifying himself as a soil scientist asked if the study took into consideration the problems of removing so many trees from the forest that would naturally die and rot, contributing to the health of the soil.

Giudice said the complete report is online at and written public comments on the study are still being accepted through Aug. 12 at The state will make its policy changes in September.