抄録
Objective. Water consumption is one of the environmental performance indicators and should be managed as a significant environmental aspect of business. Recently, huge water consumption outside Japan corresponding to the productions of imported goods, known as ‘virtual water’, is considered to be a serious environmental issue. The objective of this study is to estimate total water consumption of Japan, including the indirect water consumption in upstream processes of the supply chain.
Results and Discussion. Annual water consumption in Japan was estimated based on various statistics and allocated to the input-output table of Japan. Applying the input-output analysis method, embodied intensities of water consumption in Japan have been estimated. In order to clarify the data quality, they have been compared with results estimated by the process analysis method, focusing on grains, livestock and meat. In the case of differences in embodied intensities of water consumption, parameters of their estimation processes are discussed. In addition, total water consumption of Toshiba Group, which includes direct and indirect consumption, was calculated by using the embodied intensities estimated in this study. As a result, it was found that total water consumption was about 0.167 billion tons and indirect consumption was about 2.6 times larger than direct consumption.
Conclusion. In this study, embodied intensities of water consumption in Japan were estimated based on the latest input-output table of Japan. They were compared with results based on process analysis. A case study was also presented in which total water consumption of Toshiba Group was calculated. In future work, we intend to apply life cycle impact assessment method and, in order to make the embodied intensities of water consumption more useful for the environmental management, improve the data quality.
