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Capturing Electricity in the Cold

Credit: PBS

Engineers have found a way to generate renewable power when the sun goes down at night.

A University of California Los Angeles materials scientist, Aaswath Raman, along with Standford University engineers Wei Li and Shanhui Fan, created a device that is able to generate voltage by grabbing all the warmth from the day into cooling air. This is a great way for science to take advantage of the cold air produced from outer space and use it as a renewable energy resource.

They are hoping this can be used as a complementary technology to solar used throughout the day. It will not be able to generate the same amount of power that solar is able to during the day but it will still be able to produce some forms of electricity when solar cells are not.

When you think about it, it is usually the nighttime when we need solar power the most. In order to take advantage of the nighttime hours, the engineers used a material called thermocouple, which allowed them to convert a change in temperature into a change in voltage. In order for this to work, one side would need to be extremely warm with a place for that heat to escape to on the other side.

They created a cheap thermoelectric generator and connected it to a black aluminum disk to hide the heat in the night air. The generator was positioned inside a polystyrene enclosure that was sealed with a window that was very transparent to infrared light. It was then linked to a single small LED.

They left it out for six hours one night and noticed that enough heat flowed from the ground into the sky to produce just enough of a current to make the light flicker. This is about enough energy to keep a hearing aid working.

Even though the power generated was minuscule, it is promising; something bigger could be built to harness more electricity in the future.