Science

New Device to generate electricity in the dark

By Holly Giles

In recent years solar panels have become a house-hold name that most are aware of and many even have experience using. An Anti-solar panel, however, does not have the same mass publicity. This is a solar panel that harvests energy from the cold night sky, meaning it works at directly contrasting times to the light-dependent solar panel. 

The principle manipulated by the scientists behind the device is the temperature difference between Earth and outer space which can be converted into usable energy through a process called radioactive cooling. The system is made from an aluminum disk which is a radiation emitter and several degrees cooler than the ambient air. The disk is painted black to absorb the Earth’s heat and is hooked up to thermoelectricity generators. When heat flows from Earth and into the air it passes through the generators and into the disk which then radiates heat upwards. This radiation can be converted to electricity. 

A massive advantage of this project is that is made with $30 worth of materials, all of which can be found in local stores. This is in stark contrast with solar panels which can cost hundreds to make. The low cost of the device means researchers hope this could help the 1.3 billion people that currently lack reliable access to electricity. 

And it’s not just a far-fetched idea; the new device has already passed its first test using a 20-centimeter prototype of the device in Stanford, Calif. The generator produced 25 milliwatts of power per square meter; equivalent to the energy needed to light a small LED bulb. Despite the small amount of power produced, researchers think they can improve on this figure with larger disks and more insulation. They see this result merely as a proof of concept that the device is possible and one day (or night) could light a home continuously. Obviously this device is never going to replace solar panels but it still fills a definite need: “This may be useful in polar regions that don’t see sunlight for months at a time” explained Aaswath Rama, a material scientist at the University of California, “If you have some low-power load and you need to power it through three months of darkness, this might be a way. It provides a way to generate electricity at a time that solar panels can’t.” 

Jeffrey Grossman, a materials scientist at a university not involved in the project, describe the work as “quite exciting” and said: “They have suggested reasonable paths for increasing the performance of their device. However, there is definitely a long way to go if they want to use it as an alternative to adding battery storage for solar cells”. Work on the project continues.

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