In a groundbreaking achievement, engineers from MIT and China have designed a passive solar desalination system that converts seawater into drinkable water. Better yet, it's cheaper than tap water.
“For the first time, it is possible for water, produced by sunlight, to be even cheaper than tap water,” said Lenan Zhang, a research scientist in MIT’s Device Research Laboratory. “This opens up the possibility for solar desalination to address real-world problems.”
The concept, articulated in a study published in the journal Joule, harnesses the dual powers of the sun and the inherent properties of seawater, emulating the ocean’s “thermohaline” circulation on a smaller scale, to evaporate water and leave salt behind. This new system surpasses all existing passive solar desalination prototypes in terms of water-production rate and salt-rejection rate.
The device, if enlarged to roughly the size of a briefcase, could produce approximately 4 to 6 liters of drinking water per hour and have a lifespan of about a decade. The team envisions that a scaled-up device could provide the daily water needs of an average household and greatly benefit off-grid coastal communities with ready access to seawater - and sunshine. And, since only 3 percent of the world's water is drinkable, easy access to desalinated water is likely to become increasingly important.