A team of researchers from the University of New South Wales (Unsw) managed to produce electricity from solar energy even at night.
The night intermittence of photovoltaics represents one of the main challenges for the energy transition, but the accumulation solutions and new technologies during development, such as the “Moon photovoltaic”, are progressively reducing the problem.
Like the land at night
The group of the photovoltaic engineering school and renewable energy of the Unsw managed to generate electricity by exploiting the heat radiated in the form of infrared lightthrough the same process with which the Earth dissipates the heat accumulated during the day. Infrared light is a form of electromagnetic radiation with a greater wavelength than visible light. This type of radiation plays a fundamental role in the thermal balance of our planet, as it represents the main mechanism through which, after sunset, the earth releases the accumulated heat.
To achieve this, the researchers used a semiconductor device called thermorarative diodemade with materials similar to those used in night viewers, to generate energy starting from the emission of infrared light.
“The amount of energy produced is still reduced – about 100,000 times less than a traditional sun panel – but represents an unequivocal demonstration of the possibility of generating electricity in this way”,
Professor explained Ned Ekins-Daukesat the head of the project.
The results have experimentally confirmed a process so far only theoretical and, since then, the team has started working with new materials more easily produced on a large scale.
How technology works
During the night, the heat accumulated by sunlight dissipates in space in the form of infrared radiation, visible as red, white and yellow regions in the images of the thermolets.
“In the same way that a solar cell generates electricity by absorbing the sunlight emitted by a very hot sun, the thermorarative diode generates electricity by emitting infrared light in a colder environment. In both cases, it is the difference in temperature that allows energy production”,
explained the doctor Phoebe Pearceone of the researchers involved in the project.
Future applications: from the wrist to space
The research team is convinced that this technology can have multiple applications in the future, allowing you to generate energy in impossible ways so far.
“In theory, we can generate energy with the method that we have also shown by body heat”,
the Professor said Ekins-Daukes.
In the future, this technology could collect that energy and eliminate the need for batteries in some devices, or contribute to their charging. This could lead, for example, to the creation of wrist watches fueled directly by the heat of the human body.
At the opposite extreme, in terms of applications, the team is currently adapting this technology for use in space vehicles, such as satellites. In the terrestrial orbit, where the International Space Station (ISS)every day lasts about 90 minutes, divided equally between sunlight and darkness. Currently, space vehicles rely on solar cells for energy and use batteries during eclipses. The team is studying the application of the thermorarative diode to generate electricity even during the night of the orbit.
