Researchers at the University of New South Wales in Australia have created a device capable of generating electricity from thermal radiation using a mechanism similar to night vision goggles. Following major advances in heat capture technology, it may soon be possible to capture the sun's enormous energy even in the dead of night. During the day, solar radiation warms the Earth's crust tremendously, but when the sun sets, that heat is lost to the icy depths of space.

Researchers from UNSW's School of Photovoltaic and Renewable Energy Engineering have now successfully tested a device that can convert infrared heat into electricity. The team, including individuals from the ARC Center of Excellence for Exciton Science, used a power-generating tool called a "thermal radiant diode," which is comparable to the technology found in night vision goggles. The study was published May 9 in ACS Photonics.

"In the late 18th and early 19th centuries, it was discovered that the efficiency of a steam engine depends on the temperature difference across the engine, and the field of thermodynamics was born," said Nicholas Ekins-Daukes, associate research fellow at the ARC Centre of Excellence in Exciton Science, who led the research team. "

"The same principle applies to solar power generation -- the sun provides the heat source, and the relatively cool solar panels on the Earth's surface provide the cold absorber. This allows electricity to be produced. However, when we consider the infrared rays emitted from Earth into outer space, now Earth are relatively warm celestial bodies, while the vast expanses of space are extremely cold."

"Power can also be generated from this temperature difference according to the same thermodynamic principle: sending infrared light into space."

The theoretical possibilities of such a device were first explored by Norwegian researcher Rune Strandberg, and researchers at Stanford University are investigating other ways to capture thermal energy at night.

The energy produced by this new test is small (about 0.001% of a solar cell), but the proof of concept is important.

"We usually think of the emission of light as something that consumes electricity, but in the mid-infrared, where we're all emitting light with radiant energy, we've shown that it's possible to extract electricity," Nicholas said.

"We don't yet have the wonder material that makes thermal radiating diodes an everyday reality, but we have done a proof-of-principle and are eager to see how much we can improve on this result in the coming years."

The team is now excited to move on to the next phase of research, creating and perfecting their own device to harness the power of the night, and welcomes potential industry partners.