Assessing the carbon footprint of desalination plants: A narrative review

Greenhouse gas emissions (GHG), resulting from anthropogenic activities, have exacerbated the negative impacts of climate change, like water shortages. As an alternative to produce freshwater, desalination presents the inconvenience of emitting GHG when employing fossil fuels. To decarbonize this water-energy nexus, choosing the right mitigation measures using adequate indicators is crucial. Carbon footprint (CF) is an example of such, and Life Cycle Assessment (LCA) is a method used for its accounting. This paper explores the factors and estimation methods for CF applied to desalination plants. The reviewed literature shows that energy demand and carbon emission factor are key ingredients to calculate the CF of a desalination facility, which can be evaluated using international standards and LCA norms. The results indicate that harnessing renewables in reverse osmosis desalination, for example, takes its CF from 1-10 kgCO2eq/m3 to 1.75-2.79 kgCO2eq/m3, which translates into reducing GHG emissions of approximately 90%. Despite the importance of assessing CF for desalination plants, further research is needed for more precise GHG emissions calculation methods, especially when water resource management gets less attention in this area compared to other fields like agriculture.