Environmental impact analysis applied to solar pasteurization systems

In many under-developed regions of the world, most people live in rural villages, where the electrical grid is often not available and traditional potabilization systems would be too expensive and technologically too complex to be implemented. Thus every year, millions of people in the world die due to diseases related to water contamination. Solar Pasteurization Systems represents a promising alternative to address such problems, as they can thermally disinfect water employing solar energy alone, without using fossil fuels or electrical grid connection. Evaluating the cradle-to-grave environmental footprint of Solar Pasteurization Systems, and in general of technologies aimed at producing safe drinking water, represents an issue of major importance. This is relevant because an effective solution has to be, at the same time, environmentally and locally sustainable for a given geographical context. In this work, a complete Life Cycle Assessment and Exergo-environmental analysis are performed in order to calculate and compare the eco-profiles of two Solar Pasteurization technologies: a Natural Circulation and a Thermostatic Valve System. Results show that Natural Circulations Systems are generally more environmentally sustainable (0.30 mPt/l) than the Thermostatic Valve System (0.83 mPt/l) thanks to the higher productivity of treated water. A sensitivity analysis is performed to investigate the dependency of the model systems from different operational and environmental conditions, at different installation sites, i.e. Somalia, Brazil and Italy. The main difference is represented by the productivity of the systems. In all cases the solar collector array is the main item responsible for environmental burdens, impacting for almost 45% of the total score. The analysis also shows that the use of solar energy in Pasteurization is important to avoid direct emissions and to lower the global environmental impact connected with thermal energy production compared to the eco-profiles of other widely diffused pasteurization technologies based on the combustion of fossil fuels or biomass that can be used to provide the same function (in general higher than 1.2 mPt/l). Moreover, with the aim of qualitatively assessing the benefit associated with the potential implementation of solar pasteurization systems, an improvement of the sanitary conditions is envisioned, especially in under-developed countries where, definitively, a large scale diffusion would be recommended.