When Stanford engineer Aaswath Raman drove by a village in Sierra Leone that didn’t have a single light on in its streets, he was inspired to build a device that generates electricity using the temperature differences that arise after sunset.
The thermoelectric generator creates energy from the dark similar to how solar panels create energy from the sun’s heat and light, though in a much smaller scale.
“I figured the amount of electricity we could get would be pretty small, and it was,” says Dr. Raman. “But walking around in Sierra Leone, I realized lighting remains a big problem, so it’s an opportunity as well.”
After the sun sets, solar cells don’t work and winds often die down, underlining the value of having a device that could produce electricity at night, no matter the amount.
“This is a neat combination of radiative cooling — a technique where Raman has pioneered real working devices — with thermoelectric materials that generate electricity if one side is hotter than the other side,” said Ellen D. Williams, a physics professor at the University of Maryland and a former director of the Department of Energy’s Advanced Research Projects Agency-Energy. “Both technologies are proven and practical, but I haven’t seen them combined like this. They did this with inexpensive materials, suggesting it could be made into useful products for the developing world.”
