Abstract
As a case study of life cycle assessment (LCA) of urban infrastructures, the life-cycle energy (LCE) and the lifecycle CO2 (LC-CO2) of an urban sewage system in Fukuoka City were analyzed. The estimation covers the construction and the operation of the sewerage pipeline network, waste water treatment plants, and pumping stations. The data derived by input-output analysis are used to determine energy and CO2 intensities for the construction of the plants and the manufacturing of machinery, while those for plant operation are obtained from actual data. The energy recovered by the use of digestion gas is counted as negative. It is estimated that the construction and the operation account for 55.5% and 44.5% of the total LCE, and 56.4% and 43.6% of the total LC-CO2, respectively.
