Dec. 9, 2025 -When the sun sets, the world’s solar panels go dark. But above them, the night sky radiates a different kind of power. Every night, as the world cools, Earth dissipates much of its heat into space. The invisible stream of infrared radiation escaping our planet has been, until now, mostly untapped. That’s until engineers at the University of California, Davis, entered the picture by building a small machine that captures this outward flow of energy and turns it into motion — and, ultimately, electricity.
The invention is a simple, elegant twist on an old-school technology: a Stirling engine. This isn’t a massive, complicated semiconductor electronic rig. Instead, it uses a mechanism that is “mechanically simple and [does] not rely on exotic materials”. The machine essentially runs on the temperature difference between the ground and the open sky.