By Jeffrey Frost
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 the questions which need to be answered:
- 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. Read the rest of this entry »
