MIT team devises method for recovering drinking water from power station cooling plants

All around the world, the cooling needs of power stations – whether they are fossil fuelled or nuclear – accounts for a large percentage of water usage. Some of that water is fresh (in the US, 39 per cent of water withdrawn from rivers lakes and reservoirs is used for power station cooling) and some of it is seawater, but in either case much of that water floats away from cooling towers as vapour. The MIT team, inspired by systems used to recover water from sea-fogs, has devised a method to recover a large percentage of that lost water in a drinkable form.

Fog catchers use a plastic or metal mesh hung in the path of the fog to condense it and recover the water. They are often used in water-scarce coastal areas, but are very inefficient, capturing only 1-3 per cent of the water droplets that pass through them. In laboratory studies, PhD student Maher Damak and mechanical engineer Kripa Varanasi found that the aerodynamics of the system led to the inefficiency. As a vapour-laden air stream passes through the mesh, the individual strands force the airflow to deviate, carrying water droplets away from the strand.