Life Cycle Inventory Analysis of CO_2 Emission from the Manufacturing of Polyvinyl Chloride Resins

摘要

Plastics are indispensable materials for life cycle assessment (LCA), because they are as important basic raw materials as steel with its variety of applications including automobile and electric/electronic equipment. The LCA is also useful for evaluating the validity of recycling of plastics. In this paper, the amount of CO_2 emission from the production of Polyvinyl chloride resins (PVC) was calculated by using the LCA methodology. The energy structure such as in-house electric power generation in the industries associated with the production of PVC was analyzed. The analysis of life cycle inventory (LCI) has been conducted under various scenarios based on the trading extent of the processes related to PVC production, and as a result, the followings have been observed. (1) The groos CO_2 emission from the production of PVC varied in the range of 1.5-2.0 kg/CO_2/kg-PVC, reflecting the difference in the unit value of CO_2 emission attributable to in-house electric power generation in each of the industries related to PVC production. (2) The gross electricity consumption of PVC production was as high as 1.3 kWh/ kg-PVC, and the CO_2 emission attributable to the power geenration was 63-72% of the total CO_2 emission, while chlorine production consumed 0.73 kWh/kg-PVC. (3) It was encessary to evaluate the average amount of CO_2 emission from the production of PVC in Japan based on the energy structure of the indstries related to PVC production. Moreover, the amount of CO_2 emission is greatly influenced by the allocation methodology for electrolysis of NaCl. Also, the effect of reduction on the CO_2 emission of the projected gas diffusion electrode for energy saving was discussed by means of quantitative LCI analysis.