No Carbon Debt is Accrued When Using Woody Biomass for Energy

As the U.S. EPA decides how it should treat woody biomass in its Greenhouse Gas Tailoring Rule, I hope they take into account William Strauss’s study titled “How Manomet got it Backwards: Challenging the ‘debt-then-dividend’ axiom.”
By Rona Johnson | May 20, 2011

As the U.S. EPA decides how it should treat woody biomass in its Greenhouse Gas Tailoring Rule, I hope they take into account William Strauss’s study titled “How Manomet got it Backwards: Challenging the ‘debt-then-dividend’ axiom.” 

In his report, Strauss, president of FutureMetrics, challenged the Manomet Center for Conservation Sciences study’s debt-then-dividend model of forest carbon stocks that says switching from fossil fuels to woody biomass for energy production in Massachusetts would increase greenhouse gases for anywhere from 10 to 100 years before it can be reduced by forest regrowth. The study prompted many in the mainstream media to incorrectly state in articles that burning biomass is worse than coal.

Strauss is not the only one who has criticized Manomet’s carbon accounting methods. Alan A. Lucier, senior vice president of the National Council for Air and Stream Improvement Inc., wrote an article titled “A Fatal Flaw in Manomet’s Biomass Study” that was published in The Forestry Source.

Strauss and Lucier both make the point that looking at one stand of trees that is cut down, doesn’t take into account the whole landscape of trees that are still sequestering carbon.

“In real forests, changes in carbon stocks depend on rates of harvesting, growth, and mortality at larger spatial scales (e.g., landscape or regions),” according to Lucier. “In any given year, carbon stock depletion on harvested stands is offset to some degree by carbon accumulation on stands that are not disturbed. That is why carbon stocks are increasing in Massachusetts and across the United State despite ongoing harvesting of trees to produce renewable energy and materials.”

 In his study, Strauss provides an example that makes it easy to understand.

“Describing this in simple terms, 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 of biomass on Dec. 31 of that same year then the forest has increased its carbon stock over the year and it is embodied in the extra 10,000 tons of biomass. If 10,000 tons are harvested from the system on Dec. 31, then the system begins the next year with the stock of biomass and carbon at the same level that it was at the beginning of the previous year.”

In Strauss’s example there is no debt. Forests have a carbon dividend that’s been accumulating as the trees grow and we derive a benefit from that forest when we use the trees for energy. “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 explained. “There is never a debt. Let’s call this a ‘dividend-then-benefit’ logic.”

The only problem with Lucier and Strauss’s points of view is that they haven’t been picked up by the mainstream media. I was especially annoyed when on the same day that we posted and tweeted a story about Strauss’s study, there were news articles about woody biomass opponents that were still quoting the Manomet study as if it was the last word on woody biomass.

For some reason, the media just doesn’t want to report that there might be some sort of benefit derived from burning woody biomass, possibly because they are afraid of the backlash they would get from environmentalists. Take it from someone who knows, it’s just like ripping off a Band-Aid, it stings for a second and then it’s forgotten.

And, although I shouldn't have to mention it, but both Lucier and Strauss are talking about sustainably managed forests.









3 Responses

  1. Patrick McGovern



    Sustainably managed forests should also include coppice and sucker regeneration models. While conventional poplar and willow can regenerate from a cut stump, aspens are also capable of re-sprouting from their parent root systems continuing biomass growth above and below ground without human intervention via re-planting.

  2. Doug Heiken



    Strauss got it wronger. He failed to account for the opportunity cost of biomass removal. If forests are not logged they can store more carbon. Strauss used an improper baseline represented by carbon depleted forests, and he assigns no cost to the forgone opportunity to store more carbon in the forests if they are left unharvested. See this slide show clarifying many misconceptions about forests, logging, and carbon:

  3. kparcell



    Thank you for explaining the flaw in the Manomet study. Good people with good intent can still make mistakes, and looking at biomass used for fuel in isolation rather than as part of a managed system explains it all.

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