New Desalination System Produces Freshwater That Is “Cheaper Than Tap Water”

Credits: Jintong Gao and Zhenyuan Xu

MIT, in partnership with Chinese engineers, has introduced a groundbreaking solar-operated apparatus to transform seawater into drinkable water. What sets this design apart is its adeptness at circumventing the issue of salt accumulation, which other systems grapple with.

Highlighted in the Joule journal on September 27, this avant-garde solar desalination blueprint leverages the power of natural sunlight to warm saltwater. The system’s architecture ensures water moves in spiraling patterns, mirroring the grandeur of the “thermohaline” dynamics seen in our oceans.

Under the sun’s influence, the water undergoes evaporation, detaching from the salt. Subsequently, the resultant vapor is condensed back into pure, consumable water. Meanwhile, instead of causing obstructions, the residual salt is kept in a loop, continually moving and eventually getting ejected from the mechanism.

This innovative methodology boasts an edge over existing passive solar desalination prototypes in its efficacy of water generation and salt elimination.

Projecting its potential, if this innovative design were magnified to match the dimensions of a portable suitcase, it could consistently churn out 4 to 6 liters of fresh water every hour.

Remarkably, this apparatus promises durability, anticipating several years before any replacement components become a necessity. From an economic standpoint, this sustainable method of producing water might very well outperform the standard costs associated with procuring tap water.

Peering into the future, the research team envisions this system, once enlarged, serving the daily hydration needs of a modest family unit. Furthermore, they anticipate it could be a game-changer for remote coastal regions where there’s an abundance of seawater but a dearth of potable water.

The research roster is adorned with eminent personalities: Yang Zhong, an MIT prodigy; Evelyn Wang, the esteemed Ford Professor of Engineering; alongside illustrious scholars from Shanghai Jiao Tong University in China.

This novel endeavor refines the foundational logic of the team’s antecedent multi-tiered model. While the preceding design commendably harnessed solar energy for evaporation, it faltered due to salt crystallization, which would impede operations within mere days. Endeavoring to rectify this, the subsequent rendition, though adept at preventing salt from forming crusty obstructions, was critiqued for its languid desalination pace.

This contemporary version appears to harmoniously blend the strengths of its predecessors. It espouses a tiered framework that concurrently amplifies water’s circulation, ensuring salts are consistently in flux, and reducing the chances of sedimentation.

This strategy is evocative of the sea’s “thermohaline” currents—majestic flows determined by variances in marine temperature and salt concentration.

Central to this model is a compartment that can be likened to a slender, elongated box, adorned with a sun-absorptive dark veneer. Within, the box is bifurcated: its upper segment facilitates the passage and evaporation of water, while the lower half is tasked with the condensation of the vapor into an uncontaminated liquid.

Ingeniously positioning this box at a slight gradient within an overarching receptacle and fortifying it with a tube, the apparatus promotes uninhibited flow and the generation of eddying currents. This vital configuration ensures salts are mobilized, negating their chances of sedimentation.

The research brigade meticulously crafted and subjected various iterations of this model to rigorous testing. Their findings were invigorating. By extrapolation, a scaled avatar, extending a square meter for every stage, could yield up to 5 liters of potable water per 60 minutes.

Given its robust longevity and the fact that it thrives without external energy inputs, the team is optimistic about its cost-efficacy, possibly underselling even the prevalent expenses of tap water in the United States.