Scientists from Saudi Arabia devised a system where they grow crops in the desert. In doing so, they use solar panels and the water vapor hanging in the air. Does this offer a solution to water shortage?
Change.inc ROMY DE WEERT 4 maart 2022
The hydrogel under the solar panels absorbs water droplets at night and drops them in a box under the panels during daylight
Researchers at King Abdullah University of Science and Technology (KAUST) have found a way to still grow crops without water. And what’s the best place to try that out? The desert.
The scientists developed a system with solar panels that convert water vapor from the air into water. That offers a solution for small, remote farms that can grow their crops in dry areas without a water supply.
It works like this: with a typical solar panel, 10 to 20 percent of the solar energy is converted into electricity. The other 80 to 90 percent is converted into heat. On the back of the panel is a layer of hydrogel material, a kind of jelly. This jelly allows the solar panel to cool and not overheat. But it has another function: it can absorb water vapor from the air through the calcium chloride (road salt) contained in the panel. This causes the hydrogel to swell and retain moisture.
80 percent humidity in desert
And in a desert, that can be enormously helpful. Deserts can be dry, but that doesn’t mean there aren’t drops of moisture in the air. Relative humidity in deserts is around 30 percent. At night, that can be as high as 80 percent. The hydrogel absorbs all those water droplets at night and drops it into a box under the panels during daylight.
The scientists tested the system in a desert north of Jedda, on the western side of Saudi Arabia. They grew water spinach, a crop that requires little water and grows quickly. In two weeks, the spinach grew to a height of seven inches. The system can be used for non-water intensive crops. Rice or sugarcane, for example, require a great deal of water, and the system cannot provide that.
Easy scaling up
The system can be easily scaled up, according to the researchers, because none of the steps require electricity from the solar panels. The electricity generated by the panels can be used itself or supplied directly to the grid.