Using Life-Cycle Assessment to Evaluate the Environmental Impacts of Water Network Design and Optimization

The paper presents a multi-objective optimization approach that accounts for supply-chain environmental outputs linked to the production and manufacturing of water network components and to the generation of electricity for pumping water. The optimization approach combines the non-dominated sorting genetic algorithm (NSGA-II) with economic input-output life-cycle analysis (EIO-LCA) to minimize capital cost, energy use, and environmental impact objectives. A previously developed environmental impact (EI) index is used to evaluate environmental impacts in the multi-objective optimization framework. The EIO-LCA-based NSGA-II is applied to the expansion of the `Anytown' water distribution network (Walski et al. 1987). The results indicated that capital cost and the EI index were inversely related and that annual pumping energy use and the EI index were linearly related (or nearly so). Additional research is needed to explore how the EI index can be used as an objective function in multi-objective optimization to make water network retrofit and expansion decisions.