The theme of this year’s UN World Water Day is “Water and Energy.” Water is required in nearly all forms of energy production, and likewise, energy is needed at all stages of water extraction, treatment, and distribution. Not surprisingly, places that lack clean water are often without consistent electricity as well.
For a simple system that at least partially addresses both needs, students at the Technological University of Mexico (UNITEC) have designed a microturbine that purifies rainwater, IEEE Spectrum reports.
Their device -- which they call Pluvia -- is similar to that of hydroelectric dams, which use water to rotate a microturbine and generate electricity. Here, rainwater can be collected by funneling it into a gutter on the rooftop (pictured) or by adding sheeting to simulate a slope, routing the water in one direction.
The water passes through the first filter, which is specifically designed to clean rain that falls during the first two weeks of the wet season (since it’s higher in acidity, soil, and contaminants). Then it’s stored in a tank.
The water is flowed past the small turbine, and with the help of a pump, enough water pressure is exerted to drive the microturbine, generating some electricity.
When the microturbine turns, the rechargeable battery is loaded. The cylindrical power generator is only about 10 inches high and two inches wide.
After passing through the turbine, the water proceeds through a charcoal filter to remove smells, flavors, colors, and other contaminants.
"With this latest filter the liquid is equal to or cleaner than the water in the network supply system of Mexico City," says Omar Enrique Leyva Coca, who developed the project with Romel Brown and Gustavo Rivero Velázquez. They’ve already tested it in a community in Iztapalapa, Mexico City.
While the device does gain back some of the power needed to purify water, the pump requires more energy than the turbine can output. Right now it’s only possible to recharge 12-volt batteries, which is sufficient to power lights, but not an entire home. They’re trying to increase both generation and storage capacity, IEEE explains, which would allow the system to power the pump and maybe even small homes in the area.
These microturbines are typically used as smaller versions of hydroelectric dams to generate bits of electricity from streams with relatively low flow rates. IEEE explains:
That application, of course, only works in more rural areas. Those areas are often energy-poor, meaning such small off-grid systems are a great idea, but urban areas often are saddled by both energy and water poverty. Harnessing any bit of water and power that comes through a place like Mexico City, or any number of other large cities around the world, could eventually be a revolutionary idea if the devices are cheap to build and distribute.
Janet Fang has written for Nature, Discover and the Point Reyes Light. She is currently a lab technician at Lamont-Doherty Earth Observatory. She holds degrees from the University of California, Berkeley and Columbia University. She is based in New York.
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