An issue brief recently released by the Natural Resource Defense Council (NRDC) highlighted the importance of regional studies of biomass energy development. The brief relied on a model developed by the Spatial Informatics Group (SIG) to assess the lifecycle greenhouse gas emissions of energy derived from forest biomass in a nine-state region of the southeast United States. The model built on prior work conducted on behalf of the Southern Environmental Law Center and the National Wildlife Federation in 2012.

The NRDC brief emphasizes what we already know about greenhouse gas emissions from forest biomass energy projects: There is often a carbon debt for a period of time which is gradually erased as new tree growth sequesters the carbon emitted when the energy was produced. This is backed up by a recent review published in the journal Global Change Biology – Bioenergy (Buchholz et al. 2015). Understanding the local ecological, operational, and market contexts are critical elements to determining the potential atmospheric greenhouse gas emissions implications of switching energy sources from fossil fuels to biomass derived from forests. This highlights the need to be cautious in extrapolating findings from one region to other forests and market contexts.

What is also known is that regardless of the region or forest type, the source of the woody feedstock matters in the emissions calculation. For instance, a significant carbon debt can occur if electricity is being produced by burning whole trees that would not have been harvested otherwise. In contrast, carbon benefits can occur immediately if biomass is derived from forest thinnings that were destined to burn in a pile. The NRDC issue brief was focused on a specific context in the southeast United States.

“Our analyses using SIG’s models shows that wood pellets made of whole trees from bottomland hardwoods in the Atlantic plain of the U.S. Southeast will emit carbon pollution comparable to or in excess of fossil fuels for approximately five decades,” said NRDC Senior Scientist Sami Yassa.

Dr. Thomas Buchholz, the SIG Senior Scientist that led the development of the model, added, “Other regions need to do similar analyses because the a priori assumption of carbon neutrality cannot be made. So extrapolating the findings of one regional study to other regions does not capture the complexity of bioenergy greenhouse gas emissions accounting.”

Contact: John Gunn, Executive Director SIG-NAL
Phone: (207) 212-7723
Email: jgunn@sig-nal.org