Study points out inherent flaws in Manomet woody biomass study

By Lisa Gibson | May 19, 2011

A new study contradicting the findings of the well-known 2010 Massachusetts biomass study by the Manomet Center for Conservation Sciences points out inherent flaws and incorrect assumptions in the Manomet authors’ methodology. In short, the inaccuracies lead to flawed findings, which have prompted sweeping policy changes in Massachusetts that threaten to wipe the use of woody biomass off the map in the state.

The Manomet study found and outlined a debt-then-dividend model for using woody biomass to generate electricity, saying it can take decades to pay back the carbon debt. In the new study, however, William Strauss, president of FutureMetrics, says Manomet has it backwards. “The Manomet study implicitly assumes there’s a carbon debt before dividend,” he said of his report, ‘How Manomet got it Backwards.' “The presumption is you’re increasing carbon. My thesis is the dividend has already been accrued.” The Manomet authors are so deeply ingrained into their logic, he adds, that they allow no conclusions other than those that accrue from their debt-then-dividend model, thus limiting the scope of their view of the world and removing information from the system.

Strauss says that there is in fact no debt for several reasons, one being the flawed assumption Manomet uses to suggest that a stand of trees is chosen and then every single tree is harvested from it. “In actual forest systems, assuming sustainable forestry practices, the carbon released by combustion from selective harvesting is offset by carbon accumulation from the rest of the system’s continued growth,” Strauss writes.

For example, if there is a forest system with 1 million tons of biomass on Jan. 1 of a given year and that system has 1.01 million tons on Dec. 31 of that same year, the forest has increased its carbon stock over that given year and it is embodied in the extra 10,000 tons of biomass. If 10,000 tons are harvested on Dec. 31, the system begins the next year with the stock of biomass and carbon at the same level it had at the beginning of the previous year. “What you release into the atmosphere is only what you’ve accrued that year,” Strauss explains. “[Manomet authors are] under the assumption that you go cut down a tree and stand there and wait 30 to 50 years while it regrows.” The Manomet authors lean on the assumption that carbon accounting begins when the tree is harvested.

Strauss continues in his report supposing Manomet’s axiomatic assumption and carbon accounting begins at a point in the past. “In our 1 million ton system, if we start our accounting on Jan. 1, we accrue our dividend first before we harvest the benefits,” he writes. “There is never a debt. Let’s call this a ‘dividend-then-benefit’ logic.” The underlying conclusion, he says is clear: if biomass is harvested from existing forests that will be sustainably managed in the future, there is no debt.

The Manomet study is only an analysis of Massachusetts woody biomass use, but that fact is sometimes lost in the chatter surrounding it. Strauss says he is by no means a Massachusetts expert, so instead uses figures and statistics from Maine forests in his study to prove his points.

“Wood-to-energy from sustainably managed forests, as this paper has shown and as all of Europe has codified in its carbon accounting rules, can provide net zero carbon emission or even positive carbon sequestration if the woody biomass stock is not depleted or grows over time,” he concludes.

Strauss released his study May 18 to about 200 recipients, he said, including some Manomet authors. “I do expect a response,” he said. “I suspect there will be some back and forth.”

Strauss said he does not have a goal of upsetting the course of policy changes in Massachusetts that are based on the Manomet study. Earlier in May, the Massachusetts Department of Energy Resources (DOER) released its final regulations pertaining to woody biomass qualification for the state’s renewable portfolio standard of 20 percent by 2025. The final regulation is no more friendly toward biomass power than the previous proposal and is expected to be implemented swiftly as ordered by the Massachusetts Executive Office of Energy and Environmental Affairs.