Assessing the Energy Footprint of Desalination Technologies and Minimal/Zero Liquid Discharge (MLD/ZLD) Systems for Sustainable Water Protection via Renewable Energy Integration

Abstract

Water scarcity necessitates desalination technologies, yet their high energy demands and brine disposal challenges hinder sustainability. This research study evaluates the energy footprint and carbon emissions of thermal- and membrane-based desalination technologies, alongside Minimal/Zero Liquid Discharge (MLD/ZLD) frameworks, with a focus on renewable energy source (RES) integration. Data revealed stark contrasts: thermal-based technologies like osmotic evaporation (OE) and brine crystallizers (BCr) exhibit energy intensities of 80–100 kWh/m3 and 52–70 kWh/m3, respectively, with coal-powered carbon footprints reaching 72–100 kg CO2/m3. Membrane-based technologies, such as reverse osmosis (RO) (2–6 kWh/m3) and forward osmosis (FO) (0.8–13 kWh/m3), demonstrate lower emissions (1.8–11.7 kg CO2/m3 under coal). Transitioning to RES reduces emissions by 90–95%, exemplified by renewable energy-powered RO (0.1–0.3 kg CO2/m3). However, scalability barriers persist, including high capital costs, RES intermittency, and technological immaturity in emerging systems like osmotically assisted RO (OARO) and membrane distillation (MD). This research highlights RES-driven MLD/ZLD systems as pivotal for aligning desalination with global climate targets, urging innovations in energy storage, material robustness, and circular economy models to secure water resource resilience.

Keywords

• desalination
• zero liquid discharge (ZLD)
• minimal liquid discharge (MLD)
• energy
• renewable energy
• brine