Only about 3% of the world’s fresh water supply is available for drinking and agriculture, and nearly 70% of it is trapped in glaciers and ice sheets. So far, that’s been enough to keep us going, but severe drafts have limited access to potable water in areas such as Jordan, Egypt, sub-Saharan Africa, Spain and California.
One possible solution is to harness the remaining 97 percent of the water on Earth. The problem is that this water contains salt, which must be removed to make it drinkable. Desalination is also an energy-intensive process. But MIT researchers led by Jonathan Bessette may have found the answer. They built an efficient, self-regulating desalination system that runs solely on solar power, without the need for batteries or a connection to the grid.
investigate groundwater
The ocean is the most obvious source of water for desalination. However, they are only a good option for some people living in coastal areas. The majority of the world’s population (more or less 60 percent) lives more than 100 kilometers from the coast, which makes it impossible to use desalinated seawater. So Bessette and his team turned to groundwater instead.
“From a global demand perspective, about 50% of low- to middle-income countries rely on groundwater,” Bessette said. This groundwater is trapped in large quantities in underground reservoirs, which in most locations exist at depths of less than 300 meters. It is primarily caused by rain that seeps into the ground and fills the empty spaces left by broken rock layers. Sadly, as rainwater percolates, it also picks up salt from the soil along the way. As a result, in New Mexico, for example, about 75 percent of groundwater is brackish, meaning it’s less salty than seawater, but still too salty to drink.
