The sun can now help generate electricity even in the dark. Researchers at UNSW have made a major breakthrough in renewable energy technology by producing electricity from the so-called ‘night-time’ solar power.
The team from UNSW’s School of Photovoltaic and Renewable Energy Engineering have used the Earth’s radiant infrared heat to generate electricity, even after sunset. The researchers used a semiconductor device called a thermoradiative diode, composed of materials found in night-vision goggles, to generate power from the emission of infrared light.
The results of the research have now been published in ACS Photonics.
According to the researchers, this process generates miniscule amounts of power – around 100,000 times less than that supplied by a solar panel; however, it’s a work in progress with scope for improvement in terms of outcomes.
Associate professor Ned Ekins-Daukes, who is leading the research team, said, “We have made an unambiguous demonstration of electrical power from a thermoradiative diode. Using thermal imaging cameras you can see how much radiation there is at night, but just in the infrared rather than the visible wavelengths. What we have done is make a device that can generate electrical power from the emission of infrared thermal radiation.”
He explained that the process is ultimately still harnessing solar power, which hits the Earth during the day in the form of sunlight and warms up the planet. At night, this same energy radiates back into the vast, cold void of outer space in the form of infrared light with the thermoradiative diode now proven to be able to generate electricity by taking advantage of this process.
A thermal imaging camera highlights the amount of heat radiating from Sydney Harbour and its surroundings back into the atmosphere at night. Image supplied.
“Photovoltaics, the direct conversion of sunlight into electricity, is an artificial process that humans have developed in order to convert the solar energy into power. In that sense the thermoradiative process is similar; we are diverting energy flowing in the infrared from a warm Earth into the cold universe,” Dr Phoebe Pearce, one of the paper’s co-authors, said.
“In the same way that a solar cell can generate electricity by absorbing sunlight emitted from a very hot sun, the thermoradiative diode generates electricity by emitting infrared light into a colder environment. In both cases the temperature difference is what lets us generate electricity.”
Observing that the commercialisation of these technologies is still a long way down the road, Dr Michael Nielsen, co-author of the paper, said: “By leveraging our knowledge of how to design and optimise solar cells and borrowing materials from the existing mid-infrared photodetector community, we hope for rapid progress towards delivering the dream of solar power at night.”
The new technology has scope for application in several areas in the future by helping to produce electricity in ways not currently possible. For instance, it could be used to power bionic devices such as artificial hearts, which currently run off batteries that need to be regularly replaced.
The research team now hopes that industry leaders will recognise the potential for the new technology and support its further development.
Image: The UNSW ‘night-time solar’ team captured via infrared camera. They used the same kind of semiconductor technology to produce power for the first ever time from the emission of light.
Source: UNSW
