Solar-powered desalination for groundwater

Could this tech bring clean water to remote, water-scarce communities?

Spotted: Over 700 million people around the world don’t have easy access to clean water. One way to boost access to safe water is through ocean desalination technologies, but this method isn’t feasible for inland communities far from the coast. Now, researchers from MIT may have a solution: a solar-powered desalination system that cleans groundwater instead of seawater.

The innovative technology targets the relatively abundant brackish groundwater found in salty underground reservoirs, which could serve as a significant source of drinking water. While solar-powered water treatment isn’t new, MIT’s process stands apart in its ability to respond to changes in available sunlight.

For instance, the system boosts its desalination process as sunlight increases throughout the morning before adjusting automatically to any sudden variation, such as passing clouds. This way, the efficient technology makes maximum use of available solar energy, requiring no additional power input or external energy storage system.

Three to five times every second, the system assesses how much solar power is available. If there is more power available than the technology is using at that moment, the electrodialysis system will automatically start pumping more water through ion-exchange membrane stacks to draw out salt ions, enabling more water to be cleaned in sunnier periods.

During testing, which was conducted over six months at various wells in Alamogordo, New Mexico, a prototype of the technology was able to produce up to 5,000 litres of water per day, even though the amount of sunlight could vary dramatically. According to the researchers, the highly efficient system was able to use over 94 per cent of the available electrical energy to generate clean water.

Now, the engineers plan to test the technology further to ensure its reliability. In order to scale and commercialise the system, the team will also be establishing a spin-out company, with hopes that the innovation could help to provide communities around the world with affordable access to safe water.

Written By: Duncan Whitmore and Matilda Cox