Quantifying the environmental trade-offs of large-scale seawater desalination: a nexus of water-energy-ecology

Diagram of a fossil fuel power plant producing electrical energy and CO₂ emissions. The electrical energy powers a reverse osmosis desalination unit, which takes in seawater and produces freshwater and brine. This study examines the environmental implications of seawater desalination using Seawater Reverse Osmosis (SWRO) technology, with a focus on the Isfahan industries in Iran. Although desalination offers a solution to freshwater shortages, it has adverse environmental impacts. This research evaluates key sustainability indicators, including energy consumption, brine discharge, and carbon emissions, through a four-stage analytical framework to assess the environmental footprint of the Phase IV desalination project. Based on the calculated specific energy consumption for producing desalinated water and the production target, the annual consumption of natural gas and fuel oil was determined to be in the ranges of 3.5 × 108–3.6 × 105 m3/year and (2.4–3.4) × 108 kg CO2/year in emissions, respectively. Additionally, the annual brine discharge volume was calculated as 600 million m3. Subsequently, the indirect sustainable environmental indicators per industrial production unit were determined. The findings highlight the sustainability challenges in on-site (water intake and brine discharge) and off-site (energy supply chains and carbon emissions) contexts. Finally, the study proposes key recommendations for sustainable desalination management, focusing on water demand, policy, technology, and ecosystem protection.