Quantifying the global warming potential of carbon dioxide emissions from bioenergy with carbon capture and storage

Abstract

This study provides estimates of the global warming potential (GWP) of carbon dioxide emissions from bioenergy produced from forests (termed GWPbio). The specific contribution of the study is twofold. First, we consider how GWPbio will be impacted by the inclusion of bioenergy with carbon capture and storage (BECCS) technology. Second, we determine how the assumed baseline or reference scenario impacts GWPbio, considering both bioenergy harvests from currently unmanaged land and harvest residues from currently managed forest lands. BECCS is a major component in the Intergovernmental Panel on Climate Change (IPCC) scenarios that highlight pathways to reduced climate change impacts, and results of this study will inform the viability of using BECCS in forestry to meet IPCC emissions goals. By considering multiple scenarios and using a full carbon-accounting through the inclusion of all carbon pools impacted by harvesting for bioenergy, we demonstrate the conditions under which the value of GWPbio is negative, and thus BECCS acts as a negative emissions technology. Results indicate that assuming a 100-year horizon, GWPbio can vary from between -0.92 and 1.57, depending on a variety of assumptions and whether BECCS is employed. Estimated GWPbio values indicate that bioenergy exceeds the climate impact of fossil fuels if one focuses on unmanaged lands and does not employ BECCS. If one harvests residues from currently managed lands, bioenergy is preferable to fossil fuels without BECCS, but GWPbio is positive. When considering BECCS, bioenergy will have a lower GWP than fossil fuels in all scenarios but will only produce negative emissions if residues are used from currently managed forest lands. The results of this work indicate that bioenergy from forests can only be used to meet IPCC policy goals (produce negative emissions) if BECCS is used on currently managed forest land.