A research team from McGill University has pioneered a sustainable method for desalinating seawater, potentially transforming water purification processes. Their study introduces a technique known as thermally driven reverse osmosis (TDRO), which employs low-grade heat sourced from renewable energy, including solar thermal and geothermal energy, to generate fresh water.
This innovative approach is detailed in the paper titled “Thermally driven reverse osmosis: thermodynamics of a novel process that uses heat for desalination and water purification,” authored by Saber Khanmohammadi, Sanjana Yagnambhatt, Dan DelVescovo, and Jonathan Maisonneuve, published in the journal Desalination on October 15, 2025. The research marks a significant advance in understanding the thermodynamic limits of TDRO, building on previous studies that indicated its potential.
Desalination processes that rely on electricity are often impractical for remote regions, requiring between one and four kilowatt hours (kWh) to produce one cubic meter of fresh water. In contrast, the new TDRO method, which optimizes design elements proposed by MIT researcher Peter Godart, estimates a requirement of approximately 20 kWh per cubic meter. Maisonneuve, an Associate Professor of Bioresource Engineering and co-author of the study, noted that while this figure is higher than traditional methods, the use of heat can be more cost-effective due to its abundance.
TDRO operates by manipulating a working fluid in a sealed chamber through cycles of heating and cooling. This process causes the working fluid to expand and compress, driving a piston that forces seawater through a reverse osmosis membrane. The combination of thermodynamic cycling and water purification presents a unique solution for addressing global water scarcity.
Maisonneuve explained the advantages of harnessing existing heat from renewable sources, stating, “If we can find a way to harness existing heat from renewable sources, that could be very advantageous, because it’s so abundant.” This perspective highlights the broader implications of TDRO not only for desalination but also for enhancing the sustainability of water infrastructure.
While the initial findings are promising, the researchers acknowledge that further investigation is necessary. Maisonneuve emphasized the need for detailed modeling to assess the operational speed of the system and to factor in potential non-ideal effects, such as heat loss to the environment. The team aims to refine the technology to enhance its efficiency and practicality for widespread adoption.
As water scarcity continues to pose challenges globally, advancements in desalination technologies like TDRO represent a crucial step toward ensuring sustainable access to fresh water. The research from McGill University underscores the potential of integrating renewable energy sources into vital infrastructure, offering hope for a future where clean water is accessible to all.
