Life-Cycle Assessment of Urban Water Provision: Tool and Case Study in California

The exploration of life-cycle energy use and environmental effects from U. S. water infrastructure has been limited in spite of the strong connection between energy and water use. This research presents a methodology for quantifying the life-cycle energy consumption and associated air emissions from water supply, treatment, and distribution. A decision-support tool, the Water-Energy Sustainability Tool (WEST), has been developed to aid such analysis. WEST calculates the environmental effects of material production, including the supply chain, material delivery and transportation, construction and maintenance equipment use, energy production, and sludge disposal. Deterministic and probabilistic results for a California case study utility are provided to show the tool's capabilities. Results indicate that producing a million liters of water consumes 5.4 GJ and produces 390 kg of CO(2)-equivalent greenhouse gases. Energy production is the most significant activity (50%), but material production, especially for treatment chemicals, is also important (37%). This case study is contrasted with two previously published case study utilities, and the reasons for the range of results are analyzed. The results demonstrate that estimating water supply's energy needs and emissions without a life-cycle lens can underestimate the total effects significantly. DOI: 10.1061/(ASCE)IS.1943-555X.0000036. (C) 2011 American Society of Civil Engineers.