Models versus Common Sense

By Jeffrey Frost, Executive Director of AgRefresh

When the models we use generate answers which violate common sense, it is time to check the prevailing assumptions within. The Manomet study for Massachusetts, “Biomass Sustainability and Carbon Policy Study”, essentially concludes that global warming will be exacerbated by substituting forest biomass energy for fossil fuels for the production of electricity. I do not have to think very hard or long to conclude that digging up ancient carbon from coal, oil, and natural gas is unlikely to reduce greenhouse gas emissions as compared to growing renewable biomass in our forests and harvesting it for energy use. Yet, this is exactly what the Manomet study tells us, wrapped in massive amounts of very sophisticated analysis.

I have no wish to invalidate the strong work product produced by a stellar team regarding an analysis of prime importance: Will renewable forest biomass or fossil fuels best serve our needs for a low-carbon energy future (1)? I do suggest a need to examine the logic behind some of the prevailing assumptions – explicit and inherent – in this extensive analysis. Here then are questions which need to be answered:

  1. How do you choose the point in the growth and harvest cycle for forest biomass at which to begin the analysis? Manomet chose to begin the life cycle analysis with the day of harvest. If they had taken the other extreme and started the analysis the day after harvest (the first day of sequestration), the results would have flipped entirely and showed the huge benefits of biomass over fossil fuels instead of the reverse finding. Intuitively, the biomass must be grown and the carbon sequestered before it can be combusted anyway. The most defensible answer is probably to begin the analysis midway between harvests which will improve the relative status of biomass substantially.
  2. How does Manomet justify basing this study on the assumption that whole forest harvests will be used for biomass energy? The expert groups I have worked with refused to consider this extreme case because they considered it outside the bounds of reasonable likelihood. These other experts describe actual practices where forest thinnings and forest residuals and harvested biomass byproducts – along with agro forestry, and other purpose-grown biomass – are the current and expected future sources of bioenergy feedstocks.
  3. When the analysis assumes the use of biomass energy sources, how does Manomet justify excluding the avoided emissions benefits from not mining fossil fuels? The analysis does not assess the avoided greenhouse gas emissions – not to mention the huge other environmental, social, and economic consequences – from reductions in mountain-top coal mining, Gulf of Mexico deep water drilling, and natural gas hydrofracking. Similarly, the greenhouse gas emissions associated with the entire infrastructure of activities supporting our fossil fuel economy need to be considered. For example, we would be less likely to have the Middle East wars and the U.S. military effort to protect shipping lanes if we grew our own fuel supplies instead of importing oil?
  4. Which form of life cycle analysis is appropriate for this type of policy-informing analysis, attributional or consequential? Manomet does not specify which form of life cycle analysis they have used or the reasons they choose one over the other. Yet the differences in outcomes for this type of analysis can be material. It appears that consequential is the appropriate analysis framework for this study and that instead, attributional, the less appropriate form was implicitly chosen.
  5. Does the Manomet study give proper acknowledgement to the manner in which harvesting energy biomass and generating carbon credits produces supplemental income streams which will keep land in forests which may have otherwise been converted to urban development? Manomet anecdotally dismisses this issue by noting that current green biomass payments to forest owners are minimal. Yet this study, which is intended to inform policy development for coming decades, should consider the more robust biomass pricing which will emerge under future national renewable energy standards and cellulosic biofuel production. Similarly, the inevitable price of carbon from future policy will enhance carbon credits as a source of income. Avoided loss of forestland is an issue which needs a robust treatment beyond that received here.

This note is authored by a reader who confesses to having found time for only a brief scan of the Executive Summary and Chapters 5 and 6, the chapters most relevant to the carbon accounting issues. In the event the above five questions were answered in a satisfactory manner elsewhere in the study, apologies to the authors.

Jeffrey Frost
AgRefresh Executive Director

1 Manomet and the author of this note would both assume that energy efficiency and other forms of renewable energy or low-carbon energy are important too. The purpose of Manomet analysis was keyed to a comparison between forest biomass and fossil fuels for electricity and thermal generation in Massachusetts.

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