Life cycle inventory analysis of CO2 emissions -: Manufacturing commodity plastics in Japan

The goal of this study was to calculate the average CO2 emissions for manufacturing three commodity plastics, polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) in Japan. The CO2 emissions were calculated from cradle to gate, excluding the calcination processes after use. As the results, the followings were observed: 1) The gross CO2 emissions for the manufacture of plastics in Japan were 1.3, 1.4, and 1.7 kg-CO2/kg-PE, PP, and PVC, respectively. These mainly reflected the difference of CO2 emissions for the in-house electricity generation. 2) The CO2 emissions for the electricity used for manufacturing PVC were higher than that used for PE and PP, because additional electricity was required for the electrolysis to produce chlorine. The gross electricity consumption for manufacturing PVC was 1.3 kWh/kg-PVC, and the other plastics consumed 0.5 kWh/kg-Products. In addition, the effects of energy saving were studied using a projected gas-diffusion electrode for the electrolysis of salt on the reduction of CO2 emissions. It was estimated that the reduction in CO2 emissions was 7% compared with the present PVC manufacturing processes.