WHY THIS MATTERS IN BRIEF
Earth has an energy shortage, apparently, and now we have yet another way to produce infinite clean energy forever.
The obvious drawback of solar panels, despite the continuous sound of efficiency records being smashed all the time as we develop new 3D printed Perscovite solar panels that will one day be 32 percent efficient, and cyborg bacterial solar panels which one day could smash through the 50 percent barrier, is that in the main they still need sunlight in order to generate electricity. Unless that is you build a huge solar plant in space like the Chinese are planning to do in 2025… but that’s another story. And while this is all well and good, frankly, there are some researchers that just can’t wait five or so years for that too happen, so they came up with a new energy solution, and it involves Space. With a capital “S.”
Over the past couple of years the international team of researchers noticed that for a device on Earth facing space, which has a frigid temperature, “the chilling outflow of energy from the device can be harvested” using the same kind of optoelectronic physics we use today to harness solar energy. In short they could use nothing more than the coldness of space to generate electricity on Earth.
The team published their findings in Applied Physics Letters and then created a prototype product that, in a world first, demonstrated that it’s possible to generate a measurable amount of electricity in a diode directly from the vast coldness of the universe. It’s chilling and awesome at the same time, ah yes, puns…
But is this the end of solar I hear you ask? Afterall, while the Sun bathes the Earth in Terawatts worth of energy every second the amount of “cold” in space is infinite.
“The vastness of the universe is a thermodynamic resource,” said Shanhui Fan, an author on the paper. “In terms of optoelectronic physics, there is really this very beautiful symmetry between harvesting incoming radiation and harvesting outgoing radiation.”
In contrast to leveraging incoming energy like a normal solar cell would the “negative illumination effect allows electrical energy to be harvested as heat leaves a [materials] surface” they added.
Today though the teams technology isn’t very efficient, so it’s not going to challenge solar anytime soon, but it’s a start. But by pointing their demonstration device towards space, whose temperature approaches mere degrees from absolute zero, the group was able to find a great enough temperature difference to generate electricity.
“The amount of power that we can generate with this experiment, at the moment, is far below what the theoretical limit is,” said Masashi Ono, another author on the paper.
The team found that their negative illumination diode generated about 64 nanowatts per square meter, a tiny amount of electricity, but an important proof of concept nonetheless, and they say they can improve on that figure by enhancing the quantum optoelectronic properties of the materials they use.
Calculations made after the diode generated electricity showed that when atmospheric effects are taken into consideration the current device can theoretically generate almost 4 watts per square meter, roughly one million times what the group’s device generated and enough to power a wide variety of machines. By comparison, today’s solar panels generate 100 to 200 watts per square meter.
While the results show promise for ground based devices directed to the sky, Fan said the same principle could be used to recover waste heat from machines. For now though he and his group are focusing on improving their device’s performance.