Water–Energy Nexus: The Case of a Desalination Plant in the Semi-Arid Region of Brazil

Abstract

Water and energy are interdependent resources essential for economic development and societal well-being. Consequently, increasing water demand has intensified water scarcity in many regions, a problem exacerbated by climate change. In such contexts, seawater desalination can provide a reliable and climate-independent source of freshwater, reducing pressure on conventional water resources through reverse osmosis. This paper provides an assessment of the integrated water–energy benefits of producing 1.0 m3/s drinking water through seawater desalination within a large-scale water-transfer system. It introduces a framework that accounts for the energy recovered from avoided inter-basin transfers, including pumping savings, increased downstream hydroelectric generation in the São Francisco River (SFR) basin (Brazil), and energy consumption for water treatment. To that end, an extensive database was compiled from Brazilian public documents and information, aiming for an integrated analysis of the water matrix of an important part of the Brazilian semi-arid region in relation to its electricity demands. Results reveal that desalination requires less electricity from the grid than transporting and treating water from the SFR, with a favorable balance of 0.29 kWh/m3 and a potential to reach 3.29 kWh/m3 when powered by renewable energy. This study shows that desalination in the Northeast of Brazil can be an asset with an energy-positive balance for the country.