Achieving carbon emission reduction through industrial & urban symbiosis: A case of Kawasaki

Industry and fossil fuel combustion are the main sources for urban carbon emissions. Most studies focus on energy consumption emission reduction and energy efficiency improvement. Material saving is also important for carbon emission reduction from a lifecycle perspective. IS (Industrial symbiosis) and U_rS (urban symbiosis) have been effective since both of them encourage byproduct exchange. However, quantitative carbon emission reduction evaluation on applying them is still lacking. Consequently, the purpose of this paper is to fill such a gap through a case study in Kawasaki Eco-town, Japan. A hybrid LCA model was employed to evaluate to the lifecycle carbon footprint. The results show that lifecycle carbon footprints with and without IS and U_rS were 26.66 Mt CO₂e and 30.92 Mt CO₂e, respectively. The carbon emission efficiency was improved by 13.77% with the implementation of IS and U_rS. The carbon emission reduction was mainly from “iron & steel” industry, cement industry and “paper making” industry, with figures of 2.76 Mt CO₂e, 1.16 Mt CO₂e and 0.34 Mt CO₂e, respectively. Reuse of scrape steel, blast furnace slag and waste paper are all effective measures for promoting carbon emission reductions. Finally, policy implications on how to further promote IS and U_rS are presented.