Water footprint of energy system is a topic of main concern in the framework of sustainable development. Recently a new framework has been introduced by ISO 14046:2014, integrating water footprint assessment in the Life Cycle Assessment (LCA) methodology (ISO 14040:2006). The goal of the present work is to assess the water footprint of Italian electricity mix, using (LCA) methodology. The case study was aimed also to point out the needs for data improvements. For the Italian electricity mix, more than one hundred types of power plants were considered. In accordance with ISO 14046, first, water consumptions along the entire electricity life cycle were evaluated. Then the impact of the water consumptions on local water scarcity (water scarcity footprint) was assessed. To this end, among impact assessment methods available in literature, we selected AWARE which is the result of a recent process of harmonization carried out by the Water Use Life Cycle Assessment (WULCA) working group. Results were also compared with the results of another impact assessment method. Although the hydropower contributes 18.5% of the national electricity mix, it dominates the overall water consumption (over 66%) and water scarcity footprint (78%). On the other hand, natural gas plants with a contribution to the mix of 28% are responsible for only 3.51% of water consumption and for around 3.6% of water footprint. With a share of 7% in the mix, photovoltaic contribution is 3.5% of the consumption and 2.7% of the water footprint. Imported electricity covers 14% of the mix and accounts for 17% of consumption, but only 8% of the water footprint. The application of the WAVE method leads to similar conclusions. The allocation of impact of hydropower to the various uses in multi-purpose reservoirs remains a topic to be further investigated. Moreover for hydropower a monthly assessment should be implemented in consideration of temporal variability of water consumption and availability. The study provided first results of water footprint assessment of Italian electricity mix according to ISO 14046 and can support water footprint assessment in a wide field of LCA applications, since electricity is often the most water intensive process in the life cycle of industrial products. The use of primary data for cooling systems led to more accurate evaluation and is recommendable for similar studies. The analysis of water consumption by geographic location put in evidence the need for data improvements especially for studies aimed at comparisons between different technologies or alternative fuel supply chains.

Key words: Water footprint, LCA, electricity mix, AWARE.
 

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