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 are ineffective for hypersaline streams, while conventional thermal methods waste water through evaporation. We recently proposed multichannel thermodiffusion (MTD) as a thermal method for desalination and brine concentration without phase change or functional materials. Here, we assess its economic viability through a techno-economic analysis under realistic operating scenarios. We model grid electricity and low-grade waste heat (LGWH) as heat sources under atmospheric and high-pressure conditions, and evaluate performance across a feed concentration C₀ range of 10 ppt to 200 ppt (parts per thousand) for seawater. Our results show that thermodiffusive brine concentration outperforms evaporation ponds for hypersaline feed, even without accounting for the added value of water recovery, reduced environmental impacts, and faster processing. Specifically for seawater brine, pressurised thermodiffusion with LGWH can become more cost-effective than evaporation ponds for concentrations exceeding approximately 95 ppt; with grid heating, this threshold is likely to increase to about 200 ppt. In contrast, current thermodiffusive desalination remains costly, even as a pre-treatment step in a hybrid system that achieves partial desalination, albeit further technological developments are expected to make it more competitive. A sensitivity analysis identifies heat cost and construction materials as key economic drivers. We also briefly explore the economics of using MTD to treat other concentrates such as sodium hydroxide, potash, and lithium brines. In general, this work demonstrates the potential of MTD as a faster, more sustainable, and cost-effective alternative to evaporation ponds for the management of hypersaline brine.