How daylight might flip seawater into freshwater for coastal communities – Egypt Independent
A summer season of maximum warmth and drought world wide has been a reminder that water shortage is a urgent subject and one that can solely worsen with local weather change. Already, greater than two billion individuals worldwide lack quick access to wash water, in accordance with the World Health Organization (WHO).
For some international locations, desalination crops provide an answer – eradicating salt from seawater to fulfill their freshwater wants. The Middle East has the highest concentration of those on the earth. But such crops, nonetheless principally powered by fossil fuels, are energy-intensive and the method creates an especially salty wastewater referred to as brine, which may injury marine ecosystems and animals when it’s pumped again into the ocean.
That’s why some startups and researchers are updating centuries-old photo voltaic nonetheless know-how, which makes use of solely daylight to purify water. While the know-how remains to be a great distance off from producing the amount of freshwater generated by desalination crops, it might show invaluable for off-grid or coastal communities.
Abu Dhabi-based startup Manhat, based in 2019, is growing a floating system that distills water with out requiring electrical energy or creating brine. It consists of a greenhouse construction that floats on the floor of the ocean: daylight heats and evaporates water beneath the construction – separating it from the salt crystals which, are left behind within the sea – and as temperatures cool, the water condenses into freshwater and is collected inside.
“It’s really similar to the natural water cycle,” says Dr. Saeed Alhassan Alkhazraji, the corporate’s founder and affiliate professor at Abu Dhabi’s Khalifa University. He says photo voltaic evaporation has lengthy been used for this objective, however sometimes it entails placing water in a basin the place, as soon as the water has evaporated, salt is left behind.
Unlike conventional photo voltaic stills, Manhat’s system floats within the ocean, drawing water straight from the ocean. Salt doesn’t accumulate within the system and the angle of the gathering cylinder prevents water droplets evaporating again to the ocean, says Alhassan.
Earlier this 12 months, Manhat’s patented know-how gained the Water Europe Innovation award for small and medium enterprises with breakthrough options within the water sector, recommended for its potential to supply freshwater with “zero carbon footprint and zero brine rejection.”
The startup plans to harness its know-how in floating farms, which might use its desalination units to offer freshwater irrigation for crops with out the necessity for water transportation and its related emissions.
This would profit arid coastal areas the place land is intensively farmed, says Alhassan. “If you produce (fresh) water on the sea’s surface and use it for farming, you can effectively allow arable land to be rejuvenated,” he says, including that the know-how might work nicely for international locations just like the Maldives which have little land out there for desalination crops.
Others have additionally been innovating with photo voltaic stills. In 2020, researchers on the Massachusetts Institute of Technology (MIT) developed a free-floating desalination unit consisting of a multilayer evaporator that recycles the warmth generated when the water vapor condenses, boosting its general effectivity.
While area exams are ongoing, it was touted as a know-how that would “potentially serve off-grid arid coastal areas to provide an efficient, low-cost water source.” Researchers urged it may very well be configured as a floating panel on the ocean, delivering freshwater via pipes to the shore, or it may very well be designed to serve a single family, utilizing it atop a tank of seawater.
Geoff Townsend, who works on improvements in water shortage for water remedy and hygiene firm Ecolab, believes that whereas photo voltaic nonetheless improvements are unlikely to interchange typical desalination, they may “supplement existing technology, reducing the overall carbon footprint of desalination.”
But he cautions that “desalination typically needs to provide a very predictable supply of water,” and that “there will be potential concerns on the extent to which diurnal (daily) and seasonal changes in performance could impact the ability to achieve the minimal production requirement.”
An even greater problem for this type of know-how is scale. “A drawback is their intrinsic low efficiency,” says Townsend, including that they have a tendency to take up lots of house for the small quantity of water they produce.
MIT’s system was discovered to supply round 5 liters of freshwater per hour for each sq. meter of photo voltaic gathering space. Manhat’s present floating prototype, which covers 2.25 sq. meters however solely has one sq. meter open to water, produces 1.5 liters of freshwater per day – a drop within the ocean, contemplating the World Health Organization estimates that a median individual wants not less than 50 to 100 liters a day to be wholesome
Alhassan says Manhat is working to extend this quantity to 5 liters by optimizing supplies and design, with the long-term aim of reaching not less than 20 liters. The startup has raised $130,000 in funding up to now, predominantly through a collaboration with Abu Dhabi Ports, however with elevated funding he’s assured these targets might be met.
A pilot of the floating farm idea will start subsequent 12 months. By linking up a number of modular units in a grid formation, Manhat believes that its present know-how might present sufficient desalination to develop much less water-intensive crops, comparable to mushrooms, and because the units enhance they may begin concentrating on different crops comparable to lettuce or tomatoes.
Despite the challenges, Alhassan believes photo voltaic stills will someday turn into an necessary supply of freshwater. “We have to accept the fact that seawater should be a key player in providing freshwater,” he says. “But we need to have a solution that will minimize CO2 emissions and eliminate brine altogether.”