ENERGY AND CARBON FOOTPRINT OF MODERN DESALINATION TECHNOLOGIES

Abstract

Membrane-based desalination technologies demonstrate substantially lower energy consumption than thermal technologies, with seawater reverse osmosis requiring 2–6 kWh/m³ compared to 7.7–24 kWh/m³ for multi-effect distillation and multi-stage flash. RO achieves the highest exergy efficiency at 30.1%, nearly four times that of MSF (7.73%). However, energy source exerts a dominant influence on carbon footprint that often exceeds technology choice effects. Coal-powered RO produces 1.8–11.7 kg CO₂/m³, while renewable-powered RO achieves 0.1–0.3 kg CO₂/m³, representing a 90–95% emission reduction. Grid electricity carbon intensity creates 20–60-fold variation in emissions for the same technology, and thermal technologies utilizing low-carbon heat sources can achieve carbon footprints comparable to membrane systems. Emerging technologies show promise, with adsorption desorption desalination consuming <1.38 kWh/m³ and achieving 70% carbon emission reductions when coupled with renewable energy, though scalability barriers including high capital costs, renewable energy intermittency, and technological immaturity currently limit widespread deployment. For maximum climate impact, transitioning existing desalination capacity to renewable energy sources should be prioritized over incremental technology efficiency improvements.