Research engineers at US's Massachusetts Institute of Technology (MIT) have developed a simple, low-cost technology to extract water from water vapor and fog which could become a significant source of clean, safe drinking water for coastal cities where seawater is used to cool local power plants.
The plan, the researchers say, is simple: Zap air that’s rich in fog with a beam of electrically charged particles, known as ions. This creates water droplets that are electrically charged and can be drawn toward a mesh of wires, similar to a window screen, placed in their path. The droplets collect on the mesh, drain into a collecting pan, and can be reused in the power plant or can be sent to a city’s water supply system.
Fog collection systems can be inefficient as air flow mechanics deflect droplets from the wire mesh. Researcher Kripa Varanasi proposes to zap the fog with an ion beam before the fog hits the mesh. The result is that not only do all of the droplets that are in the path of the wires land on the mesh, even droplets that were aiming for the holes in the mesh get pulled toward the wires. The system captures a larger fraction of droplets passing through, improving efficiency .
The team also focused on capturing water from plumes of power plant cooling towers, where the stream of water vapor is more concentrated than any naturally occurring fog, which can make the new system even more efficient.
Since capturing evaporated water is in itself a distillation process, the water captured is pure, even if the cooling water is salty or contaminated. This water could potentially abe piped to a city’s drinking water system, or be used in processes that require pure water, according to the researchers.