鉄鋼産業における廃プラスチック利用のライフサイクルインベントリとコスト評価

抄録

Environmental impact and cost of waste plastics utilization in the steel industry as feedstock materials for blast and electric furnaces were evaluated using scenario-based life cycle assessment technique. These processes were compared with conventional processes including liquefaction and incineration with electric power generation. Since existent process inventory data do not include an input flow of plastic materials and cannot be used for the analysis of scenarios varying plastics flow rate, new process inventory models, which have an input flow of plastics and have other input/output flows depending on the flow rate of plastics, were developed.
A case study of the utilization of the industrial waste plastics from Aichi district was performed using our life cycle model. Total emission of carbon dioxide and total energy consumption were used as environmental indices and costs of transportation, investments and utilities were estimated as well. We found that every process is effective from the view point of the reduction of carbon dioxide emission and energy consumption. Especially, the blast furnace has large potential to reduce carbon dioxide emission. The transportation does not have significant contribution to environmental impacts and total cost. As a result, waste plastics utilization in the steel industry is an effective technology to reduce environmental impacts.