Against the backdrop of an increasingly acute global water shortage, a new desalination technology from Australian National University researchers may ensure large boosts in water security for military operations in the hottest and most remote regions. The process, called thermodiffusion desalination TDD- might prove to be a game-changer in military logistical processes in search of sustainability.
Current desalination technologies such as reverse osmosis and thermal desalination are energy-intensive and expensive processes. Therefore, using them on a large scale in many of the most water-scarce parts of the world is out of the question. This is because they either require high pressure or high temperature or involve complicated material systems such as membranes, which can easily foul and are thus costly to keep functioning. In contrast, TDD operates at a fraction of the energy of conventional systems and does not depend on phase changes related to evaporation or freezing.
Juan F. Torres of ANU says that TDD exploits a process called thermodiffusion, in which salt migrates to the cold side of a temperature gradient. “TDD is the first thermal desalination method that does not need phase change, such as evaporation or freezing,” Torres says. That equates to significant energy savings since the process does not have to undergo energetic phase-change steps.
The system is simple in setup: Seawater is forced through a narrow channel between a heated top plate and a cooled bottom plate. As the salt heads towards the cooler side, less salty water emerges from the top. Repeated cycles of this can reduce seawater salinity from 30,000 ppm to between 1,000-5,000 ppm, suitable for agricultural use-which consumes about 70% of global freshwater resources.
This technology is most relevant to military operations in highly water-scarce regions, such as the Middle East. Conventional desalination systems in these regions require a very large amount of energy, but TDD utilizes low-grade thermal sources, such as sunlight or industrial processes’ waste heat, and hence is more deployable by being sustainable.
Ms. Shuqi Xu is a PhD candidate at ANU and was a key contributor to developing TDD. According to her, water desalination needs urgent optimization so that there will not be a crisis that would be worse with climate change. “Severe drought is happening more often due to climate change,” she notes. “Optimizing water desalination is our best hope to prevent famine caused by lack of water for agriculture.”
TDD has various military uses. Its application in remote, desert regions introduces the possibility of sustained military operations without the associated logistical burdens due to shipping large volumes of water. Furthermore, the simplicity and scalability of TDD make it an appropriate solution for implementation in developing nations and rural areas where the application of traditional methods of desalination is out of the question.
The ANU research team is currently developing a multichannel TDD device for deployment in the Tonga region severely affected by drought-powered a solar panel, to demonstrate how the technology can be used in areas not covered by an electrical grid. “There are thousands of remote regions and dozens of small countries with acute water shortage around the world,” Torres underlines. “There are thousands of remote regions, and dozens of small countries around the world facing water scarcity,” Torres emphasizes. “We need thermodiffusive desalination to decentralize the process and sustainably bring water security to these regions.”
As freshwater resources across the globe become increasingly strained, it will be key for the military to continue to adapt and innovate in its methods of water management. The development of TDD constitutes one real step forward in ensuring that military operations can function effectively in developing environmental challenges.