The sun is a powerful energy source, and solar panels are a great way to harness this energy.
However, solar panels have their disadvantages, as their installation is expensive, just like the energy storage, they are weather dependent and associated with pollution, but probably the biggest issue is that they are useless when the sun goes down.
Yet, this new invention could solve this, by generating renewable energy even in the dark.
Solar panels can be of two types, the first one generating electricity from the sun via physical process called the photovoltaic (PV) effect, and the second one generating electricity from heat through thermal processes, (hen the Earth is cooler and the sun is hotter, the temperature difference can be turned into usable energy).
Researchers at Stanford University in Palo Alto, California, developed a system founded on the same concept of using heat, but it is an inverse version, generating energy in darkness.
It uses the variance in temperature between Earth and outer space, by using “a passive cooling mechanism known as radiative sky cooling to maintain the cold side of a thermoelectric generator several degrees below ambient.”
The study has been published in the scientific journal Joule, and the researchers indicated that 1.3 billion people lack reliable access to electricity.
Those communities require lighting at night, and their costs increase as they need battery storage from solar panels to use the energy later. Therefore, the device aims at creating electricity at night on the spot.
The study author Shanhui Fan, Stanford electrical engineering professor, explained:
“The amount of power coming in from the Sun has to be approximately equal to the amount going out from the Earth as thermal radiation, to keep the Earth at a roughly constant temperature. The amount of power available for harvesting is very large.”
Some call the device an “anti-solar panel”, and it can be a successful solution to the gap left by solar energy, by collecting energy from the night sky.
According to the researchers:
“We use a passive cooling mechanism known as radiative sky cooling to maintain the cold side of a thermoelectric generator several degrees below ambient.
The surrounding air heats the warm side of the thermoelectric generator, with the ensuing temperature difference converted into usable electricity.
We highlight pathways to improving performance from a demonstrated 25 mW/m2 to 0.5 W/m2. Finally, we demonstrate that even with the low-cost implementation demonstration here, enough power is produced to light a LED: generating light from darkness.”
Yet, the system was only tested with a 20-centimeter prototype. It had an aluminum disk painted black, attached to commercial thermoelectricity generators.
The generator produced up to about 25 milliwatts of power per square meter of device, which is enough to light a small light-emitting diode, or LED bulb, and it might act in reverse during the day, absorbing sunlight and producing electricity from a heat traveling from the sun to the disk and into the outside environment.
Researchers believe that a larger version of the device “could someday light rooms, charge phones or power other electronics in remote or low-resource areas that lack electricity at night when solar panels don’t work.”
The technology is still in the research and development stage, and researchers intend to make some design improvements, like adding enhanced insulation around the top plate to boost production up to at least 0.5 watts per square meter.
This device could eventually revolutionize the renewable energy sector, being less expensive and can generate electricity at a time that solar panels can’t.
Dr. Aaswath Raman, an assistant professor of materials science and engineering at the University of California, Los Angeles, who has come up with the device, explains that it isn’t really comparable to solar energy, which can generate maybe 100 times more power than this device operating at its limit.
Yet, he believes that the generator could help power remote weather stations or other environmental sensors, especially in polar regions that don’t see sunlight for months at a time.
“If you have some low-power load and you need to power it through three months of darkness, this might be a way.”