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Estimating GHG Emissions from the Manufacturing of Field-Applied Biochar Pellets

Informally Refereed

Abstract

Biochar application to forest soils can provide direct and indirect benefits, including carbon sequestration. Biochar, the result of thermochemical conversion of biomass, can have positive environmental climate benefits and can be more stable when field-applied to forest soils than wood itself. Categorizing greenhouse gas (GHG) emissions and carbon sequestration profile are critical to the long-term sustainability of this practice. Using life-cycle assessment as a sustainable metric tool, this study evaluated the fuel consumed to pelletize, transport, and field-apply biochar produced from a novel thermochemical process from gate-to-gate on a per functional basis of one oven dry (OD) tonne. In the present study, pellet transport and field application were considered part of the manufacturing process. The fossil GHG emissions released from gate-to-gate manufacturing, 76.6 kg CO2eq/OD t, was far exceeded by the amount of biogenic carbon sequestered long term at 2,430 kg CO2eq/OD t, even considering the decay of biochar carbon over 100 years into biogenic CO2. Biogenic CO2 as part of the global carbon cycle does not contribute to climate change when the feedstock came from sustainably managed forests, as in this study. Quantifying global warming impact showed that consuming primary energy for field-applied biochar pellets had relatively small contributions to climate change relative to the carbon sequestration potential of the biochar pellets.

Keywords

Life-cycle assessment, climate change, forest, biochar, spreading, sequestration, sequestrations

Citation

Bergman, Richard D.; Zhang, Hanwen; Englund, Karl; Windell, Keith; Gu, Hongmei. 2016. Estimating GHG emissions from the manufacturing of field-applied biochar pellets. In: Proceedings of the 59th International Convention of Society of Wood Science and Technology. 6-10 March 2016; Curitiba, Brazil. p. 139-149.
https://www.fs.usda.gov/research/treesearch/51056