Techno-economic analysis of multichannel thermodiffusion for desalination and brine concentration

Freshwater scarcity and industrial brine pollution—stemming from desalination and hydrocarbon extraction—are interconnected challenges, yet technological solutions remain largely decoupled. Membrane technologies struggle with hypersaline streams, while disposal methods sacrifice water through evaporation or deep-well injection. We recently proposed multichannel thermodiffusion as a thermal method for desalination and brine concentration without phase change or functional materials. However, its economic viability remains uncertain. Here, we perform a techno-economic analysis under realistic operating scenarios. We show that thermodiffusive brine concentration outperforms conventional evaporation ponds for hypersaline brine, even without accounting for the added value of water recovery, reduced environmental impact, and faster processing. We modelled grid electricity and low-grade waste heat (LGWH) as heat sources under atmospheric and high-pressure conditions, and evaluated performance in a salinity range of 35 ppt to 250 ppt (parts per thousand) for seawater and other concentrates such as sodium hydroxide, potash, and lithium brines. Our results show that pressurised thermodiffusion at 15.5 bar with LGWH becomes more cost-effective than evaporation ponds above 115 ppt to 135 ppt; with grid heating, this threshold increases to 200 ppt. Thermodiffusive desalination remains energy-intensive for a cost-effective pre-treatment for RO. A sensitivity analysis identifies heat cost and construction materials as key economic drivers. This work demonstrates thermodiffusion as a cost-effective, faster, and more sustainable alternative for managing hypersaline brines.