Abstract
The purpose of the present study was to evaluate the environmental performance of domestic seawater desalination in terms of CO2 and water consumption as well as life cycle cost. In addition, we determined differences between expected values based on facility plans and actual observations. Results of assessments per 1 m3, both environmental burdens and costs were higher under real operating conditions than had been expected during planning. Most life cycle CO2 emissions were related to electricity usage, and indirect water consumption for the production of chemicals also had a big influence on the total environmental burden(CO2: 95 - 99%, water consumption: 50 - 95%). The impact of electricity in Okinawa was calculated based on coal-fired power generation, while in Fukuoka it was based on thermal power generation using natural gas. The production of chemicals for cleaning reverse osmosis membranes was a dominant contributor to water consumption. As a result of LCC comparison between calculations and actual measured values in Okinawa, actual measured values was about 5.5 bigger than calculations because of low operation rate (8%). Based on the results of a sensitivity analysis and comparison of this study with the existing literature, we found that it is possible to reduce CO2 emissions by changing electric power sources, and this finding is consistent with previous results.
