Aaswath Raman

This new device generates light with help from the darkness of space

Solar panels are great for powering devices during the day. But they don’t work after the sun goes down. Now, a new technology that takes advantage of the cold darkness of space may do the trick.

Researchers used a thermoelectric device that relies on a temperature difference in two faces of an electrically conducting material to push electrons through from one side to the other and create a small electrical current. Thermoelectrics have been around for decades. Most are placed next to high heat sources such as car engines to generate the needed temperature difference.

But in this case, researchers designed their ceramic material to be heated, on its bottom side, by warm air just above the surface of a rooftop, and to be passively cooled, on its top side, by the sky. The chill is caused as the top surface radiates heat energy at a wavelength that passes through the atmosphere and is dumped into the vastness of space. That creates a 2°C temperature difference across the device—enough to make 25 milliwatts of power per square meter and to power a light-emitting diode, the researchers report today in Joule. The researchers suggest the technology could one day power carbon-free lights and sensors in remote areas.