A semiconductor device called a thermoradiative diode was used to generate power from the infrared light emitted at night. The amount of energy generated this way is tiny, about 100,000 times less than what you get from a solar panel during the day. Nevertheless, the researchers believe the result can be improved in the future once they will find the best materials to convert infrared light into electricity.
“Using thermal imaging cameras you can see how much radiation there is at night, but just in the infrared rather than the visible wavelengths,” says team lead, Associate Professor Ned Ekins-Daukes. “What we have done is make a device that can generate electrical power from the emission of infrared thermal radiation.”
The infrared light at night is there because the sun warmed up the Earth during the day, so technically, the process is still harnessing solar power. According to Dr. Phoebe Pearce, one of the paper’s co-authors, any flow of energy can be converted between different forms.
“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,” says Pearce. “In both cases, the temperature difference is what lets us generate electricity.”
The team at UNSW thinks the efficiency of the process can be significantly enhanced to produce more energy. The first photovoltaic panels only had around 2% efficiency. Still, years of honing the technology have made modern cells convert over 25% of the sun’s light into electricity. It took the PV panels industry half a century to get where it is today, so we might be in for a long journey.
The research also opens a whole new world of possibilities. One of them is powering bionic devices like artificial hearts using only body heat. But to get there, industry giants need to step in and cough up a lot of cash. Universities don’t have the necessary resources to extend the research and bring meaningful results in a timely manner.