Life cycle assessment of a biomass based chemical looping combustion

Abstract

Chemical looping combustion (CLC) is a promising technology that generates energy while inherently separating carbon dioxide from air using oxygen carriers. This allows for an efficient and cost-effective means of carbon capture and storage. Current CLC systems use coal with metal oxides for combustion in the fuel reactor, thus, resulting in some environmental impacts. Recent life cycle assessment (LCA) of CLC studies have indicated the environmental impacts of conventional coal-based CLC, especially on the global warming potential. To mitigate these environmental impacts, this study proposes the use of a biomass-based CLC and evaluates its impacts using LCA. A case study in the Philippines is adopted where rice husks are used as biomass feedstock. A kilowatt-hour of electricity generated from the CLC plant is utilized as the functional unit. A relative comparison of environmental impacts was considered between the coal-based power plant, the coal-based CLC plant, and the biomass-based CLC plant. The single score results have shown that the biomass-based CLC has the least environmental impacts relative to the coal-based power plant and the coal-based CLC plant. However, it is noted that water consumption is the main drawback of utilizing rice husks as CLC biomass feedstock. The majority of the environmental impacts of the coal-based CLC and the coal-based power plant were derived from upstream processes such as coal mining and processing. With the use of rice husks as CLC biomass feedstock, net negative emissions were achieved.

Keywords: Biomass; Chemical looping combustion; Life cycle assessment; Net negative emissions; Philippines.