Biomass Sustainability and Carbon Policy Study
This study addresses a wide array of scientific, economic and technological issues related to the use of forest biomass for generating energy in Massachusetts. Appendix 1 of the report also contains and detailed and very useful summary of federal and state- or regional-level subsidies to biomass energy. See also Chapter 1 of the report for a discussion of subsidy-related policies, including some outside of the United States.
The initial level of the carbon debt is an important determinant of the desirability of producing energy from forest biomass. One of the metrics the study examines are the cumulative carbon emissions of biomass (net of forest recapture of carbon) relative to continued burning of fossil fuels at some future point in time.
The Massachusetts Global Warming Solutions Act establishes 2050 as an important reference year for demonstrating progress in reducing greenhouse gas emissions. The study compares 40 years of biomass emissions with 40 years of continued fossil fuel burning, and shows that replacement of oil-fired thermal/CHP capacity with biomass thermal/CHP fully offsets the carbon debt and lowers greenhouse gas levelscompared to what would have been the case if fossil fuels had been used over the same period—approximately 25% lower over the period under a rapid recovery scenario. In contrast, for biomass replacement of coal-fired power plants, the net cumulative emissions in 2050 are approximately equal to what they would have been burning coal; and for replacement of natural gas cumulative total emissions are substantially higher with biomass electricity generation
Sustainability of productive land is also an important factor. At the stand level, the most significant sustainability concerns associated with increased biomass harvests are maintenance of soil productivity and biodiversity. Current Chapter 132 Massachusetts forest cutting practices regulations provide generally strong protection for Massachusetts forests, especially water quality; however, they are not currently adequate to ensure that biomass harvesting is protective of ecological values across the full range of site conditions in Massachusetts. Other states and countries have recently adopted biomass harvesting guidelines to address these types of concerns, typically through new standards that ensure (1) enough coarse woody debris is left on the ground, particularly at nutrient poor sites, to ensure continued soil productivity and (2) enough standing dead wildlife trees remain to promote biodiversity.