Evaluation of environmental impacts of harvest residue-based bioenergy using radiative forcing analysis

The "carbon neutrality" assumption plays an important role in the evaluation of the global warming potential (GWP) of bioenergy relative to fossil fuels. In the case of woody bioenergy, this assumption implies that the carbon dioxide emitted during the combustion of the biomass is equal to the carbon dioxide sequestered from the atmosphere within that biomass. However, the collection and conversion of woody biomass requires energy inputs in various forms that produce emissions to the air or water. To be able to estimate the overall environmental burdens associated with converting woody biomass to bioenergy, and the net reduction in greenhouse gas (GHG) emissions to the atmosphere by avoiding the use of fossil fuel, a life cycle assessment (LCA) is the internationally recognized method of choice. However, the carbon neutrality of woody biomass and the environmental impacts associated with wood-based bioenergy are hotly debated in national and international arenas. This study presents a comprehensive evaluation of the environmental impacts of woody biomass-based bioenergy and proposes a GWP impact assessment methodology using radiative forcing for incorporating the dynamics of carbon sequestration, decomposition of residues and biomass processing in the life cycle assessment of bioenergy.