Credit: SciTechDaily.com Engineers at University of California developed a new thermoelectric space =that produces electricity at night by harnessing the frigid vacuum of space, a path toward 24-hour renewable energy without the need for storage, according to Applied Physics Letters.
The system uses a simple, inexpensive aluminum disk painted black and mounted inside a polystyrene enclosure. The disk itself faces the night sky, radiating its own thermal energy as infrared light into space, causing it to become several degrees cooler than its surrounding air.
The study examines how nighttime radioactive cooling enables low-cost tools, such as fans and small pumps. Outdoor testing of the device was conducted in California, where clear skies provided a reliable temperature difference.
An Engine with a Cosmic Twist
Radiative cooling energy could work in real environments, not just in theory, where an off-the-shelf thermoelectric generator then converts the temperature difference between the chilled disk and ambient air into a small – but measurable – electric current.
Researchers compared some of their ideas to a space thermoelectric generator, though their own system is far simpler. According to Professor Jeremy Munday, the Stirling engine can operate even on small temperature gaps.
“These engines are very efficient when only small temperature differences exist,” said Professor Munday.
When the device sits on level ground indoors, it does nothing, since both sides remain at the same temperature. To that, Munday confessed that if you just set it on the table, power is not going to be produced on its own. Part of the innovation is that the design takes advantage of space energy power by letting the top plate release heat directly into the night sky.
The sky-facing panel cools by radiating heat upwards like infrared radiation energy, enabling the engine to continue turning. Munday and his graduate student Tristan Deppe tested the idea outdoors for a full year.
Their approach shows how the system can deliver off-grid night power in areas with strong nighttime cooling.
Experimental Reveals
The temperature difference reached around 10°C, enough for the device to produce small but useful quantities of mechanical power. The generated results support previous concepts on atmospheric power that harness natural temperature fluctuations to circulate energy without fuel.
During the testing, the Stirling engine turned into a small fan and pushed a tiny electric motor. This makes the device a simple example of carbon free power because it uses no fuel.
It may also contribute to the push to generate power from space, even at small scales for the present time. In greenhouse tests, the device moved enough air to help control humidity during the night.
Designs like this support the wider trend toward decentralized energy systems that work in remote or low resource areas.
It utilizes the temperature difference between the ground and the sky, which makes the engine practical for thermal energy harvesting without any electricity. Additionally, researchers said that future versions could give better results than today’s.
Better coatings could help the system evolve into more capable radiative cooling generators that can perform well even in harsh environments.
Therefore, such a type of cooling system generates very gentle airflow, serving like passive cooling electricity for small structures.
The university has filed a provisional patent for the device, and the team sees this early space power generator as a starting point. They predict that further upgrading could result in more efficient variants of the space thermoelectric generator useful for farms and off-grid buildings.
For the moment, the prototype described here demonstrates how the night-sky can drive a simple space power generator without fuel, noise, or sunlight, hinting at a future where nighttime cooling becomes a practical source of renewable energy that helps cities stay efficient, reduces pressure on power grids, and strengthens climate-resilient infrastructure.
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