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Engineer Hadi Ghasemi, at the University of Houston, is trying to change that. He and a team at the Massachusetts Institute of Technology have developed a cheap material that desalinates water efficiently and fast using solar energy. And the secret to the new technology was sitting right on their desks: the graphite in pencils.
A simple solar still — and even more expensive versions with mirrors and lenses — heats up the entire water surface before it starts to evaporate, Ghasemi says. That takes time and wastes energy.
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The solar still has two layers. The top one contains tiny holes that collect the sun's energy. The bottom layer serves as an insulator that keeps the heat from leaking into the water. The bottom layer also wicks water into the top layer, where it evaporates.
Courtesy of the researchers/MIT
"Why do we need to heat the bulk of the liquid to get steam?" Ghasemi says. "Why not concentrate the solar energy at 'hot spots?' " Then all the energy goes into creating steam.
The trick to creating these "hot spots" is having the right material, he says. And that's where the graphite in pencils comes into play.
http://www.npr.org/sections/goatsan...rom-the-sun-aided-by-a-pop-of-pencil-shavings
A simple solar still — and even more expensive versions with mirrors and lenses — heats up the entire water surface before it starts to evaporate, Ghasemi says. That takes time and wastes energy.

The solar still has two layers. The top one contains tiny holes that collect the sun's energy. The bottom layer serves as an insulator that keeps the heat from leaking into the water. The bottom layer also wicks water into the top layer, where it evaporates.
Courtesy of the researchers/MIT
"Why do we need to heat the bulk of the liquid to get steam?" Ghasemi says. "Why not concentrate the solar energy at 'hot spots?' " Then all the energy goes into creating steam.
The trick to creating these "hot spots" is having the right material, he says. And that's where the graphite in pencils comes into play.
http://www.npr.org/sections/goatsan...rom-the-sun-aided-by-a-pop-of-pencil-shavings