Water footprint calculationfor truck production

Sammanfattning: Water is an irreplaceable resource, covering around two thirds of Earth´s surface, although only one percent is available for use. Except from households, other human activities such as agriculture and industries use water. Water use and pollution can make water unavailable to some users and places already exposed for water scarcity are especially vulnerable for such changes. Increased water use and factors such as climate change make water scarcity to a global concern and to protect the environment and humans it will be necessary to manage this problem. The concept of water footprint was introduced in 2002 as a tool to assess impact from freshwater use. Since then, many methods concerning water use and degradation have been developed and today there are several studies made on water footprint. Still, the majority of these studies only include water use. The aim of this study was to evaluate three different methods due to their ability to calculate water footprint for the production of trucks, with the qualification that the methods should consider both water use and emissions. Three methods were applied on two Volvo factories in Sweden, located in Umeå and Gothenburg. Investigations of water flows in background processes were made as a life cycle assessment in Gabi software. The water flows were thereafter assessed with the H2Oe, the Water Footprint Network and the Ecological scarcity method. The results showed that for the factory in Umeå the water footprint values were 2.62 Mm3 H2Oe, 43.08 Mm3 and 354.7 MEP per 30,000 cabins. The variation in units and values indicates that it is complicated to compare water footprints for products calculated with different methods. The study also showed that the H2Oe and the Ecological scarcity method account for the water scarcity situation. A review of the concordance with the new ISO standard for water footprint was made but none of the methods satisfies all criteria for elementary flows. Comparison between processes at the factories showed that a flocculation chemical gives a larger water footprint for the H2Oe and the Ecological scarcity method, while the water footprint for the WFN method and carbon footprint is larger for electricity. This indicates that environmental impact is considered different depending on method and that a process favorable regarding to climate change not necessarily is beneficial for environmental impact in the perspective of water use.