Quantifying the life cycle water consumption of a passenger vehicle
Tejada, Francisco Javier
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Various studies have pointed out the growing need to assess the availability of water sources in regions around the world as future forecasts suggest that water demands will increase significantly for agricultural, industrial and human consumption while freshwater resources are being depleted. One such emerging issue is the effect of industrial operations on said resources, specifically from automobiles. With numerous localities experiencing stresses on water availability, key stakeholders - suppliers, automakers, and vehicle end-users - need to better realize the effect vehicle manufacturing, usage, and disposal have on water resources. While efforts to improve the overall environmental performance of vehicles have mainly concentrated on improving technologies, there has also been considerable effort devoted to characterizing the life-cycle performance of the vehicle product system. However, much of this work has focused on energy consumption and carbon emissions while few studies have examined water. The difference between water use versus water consumption were highlighted and the life-cycle water consumption of a gasoline-powered midsize vehicle were analyzed from material extraction through production, use, and final disposition/end of life. This analysis examines each of the phases to determine a carâ s water footprint using data from the EcoInvent Life Cycle Analysis database as well as data collected from literature sources. Although water use is typically metered at the factory level, water consumption (i.e., water lost through evaporation and/or incorporation into a material, part, and/or product) is much harder to quantify. As shown in this thesis, the difference can be an order of magnitude or more because much of the water that goes into the different processes is either reused, recycled, or discharged back to its original source. The use phase of a vehicle has the biggest impact on the overall vehicle water consumption, followed by material production, whereas water consumption for the end of life processing seems to be relatively insignificant. It is also shown that the impact of energy consumption as part of the total water footprint is very large when compared to the other processes given the dependence on water for energy production. The assessment in this thesis represents a life-cycle inventory and serves as an initial benchmark as no previous study has been completed to determine the water consumption for the life of a vehicle, let alone for most other products. The impact of water consumption varies by region and locality, and a differentiation of impact would still be needed to determine whether the water consumption actually happens in water scarce regions or not.