Diverting residual biomass to energy use: Quantifying the global warming potential of biogenic CO2 (GWPbCO2)

• Published in: Global change biology. Bioenergy 2023-05, Vol.15 (5), p.697-709
• Main Authors: Adetona, Adekunbi B., Layzell, David B.
• Format: Article
• Language: English
• Subjects: Agribusiness; Alternative energy sources; Biofuels; biogenic CO2; Biomass; Biomass burning; Biomass energy production; Biosphere; Carbon dioxide; Carbon dioxide emissions; Climate change; Crop residues; Decomposition; Emissions; energy; Energy consumption; Environmental assessment; Farm buildings; Food; Forest residues; Forestry; fossil fuel; Fossil fuels; Global warming; global warming potential; Greenhouse effect; Greenhouse gases; Landfill; Landfills; Lignocellulose; Raw materials; Renewable energy; residual biomass; Residues; Waste disposal sites
• ISSN: 1757-1693; 1757-1707
• DOI: 10.1111/gcbb.13048

To calculate the global warming potential of biogenic carbon dioxide emissions (GWPbCO2) associated with diverting residual biomass to bioenergy use, the decay of annual biogenic carbon pulses into the atmosphere over 100 years was compared between biomass use for energy and its business‐as‐usual decomposition in agricultural, forestry, or landfill sites. Bioenergy use increased atmospheric CO2 load in all cases, resulting in a 100GWPbCO2 (units of g CO2e/g biomass CO2 released) of 0.003 for the fast‐decomposing agricultural residues to 0.029 for the slow, 0.084–0.625 for forest residues, and 0.368–0.975 for landfill lignocellulosic biomass. In comparison, carbon emissions from fossil fuels have a 100GWP of 1.0 g (CO2e/g fossil CO2). The fast decomposition rate and the corresponding low 100GWPbCO2 values of agricultural residues make them a more climate‐friendly feedstock for bioenergy production relative to forest residues and landfill lignocellulosic biomass. This study shows that CO2 released from the combustion of bioenergy or biofuels made from residual biomass has a greenhouse gas footprint that should be considered in assessing climate impacts. The low value of residual wood & straw biomass has increased interest in diversion to energy feedstocks, especially because the resulting CO2 emissions are typically not considered to contribute to global climate change. This study develops a method to calculate the 100‐year, global warming potential associated with diverting residual biomass to energy use by taking into consideration the timing of CO2 releases and removals from the atmosphere compared to a business‐as‐usual reference case. The results show significant climate impacts when slowly decomposing biomass is diverted to energy use. This impact must be considered when quantifying and crediting bioenergy initiatives.