Integration of large-scale heat pumps to assist sustainable water desalination and district cooling

Climate change intensifies stress on global potable water supply. Over 2 billion people still lack access to safe potable water, hindering social and economic development in arid regions. As a result, cost-effective desalination is important. The two main desalination technologies are thermal-based and membrane processes. The membrane-based desalination process Reverse Osmosis is gaining more and more popularity. The reason is that thermal-based processes often rely on non-renewable heat sources, while high temperature heat pumps offer a sustainable alternative for heat supply. Thus, this study investigates the integration of a transcritical CO2 heat pump into thermal-based desalination processes. The CO2 process operates at up to 180 degrees C, with an eco-friendly working fluid. The heat pump provides both potable water and potentially cooling energy. Six configurations were considered, showing comparable energy demands to RO. Moreover, considering cooling duty, the inte-grated system outperforms RO. A commercially available 19 MWel transcritical CO2-based heat pump system can produce up to 64.000 m3/d of potable water and 75 MW of cooling energy. This highlights the potential of heat pumps as sustainable solutions for addressing water scarcity and providing cooling.