Revolutionary Engine Harnesses Space's Cold for Nighttime Power
Scientists at the University of California, Davis have developed a groundbreaking engine that generates mechanical energy by tapping into the extreme cold of outer space. The innovative system uses a modified Stirling engine that operates passively throughout the night without any external power source, creating a sustainable way to produce energy when solar panels are inactive.
How the Space-Powered Motor Works
The engine's upper surface is coated with a special paint that emits infrared radiation directly toward space, which maintains a temperature of approximately -270 degrees Celsius. 'Our system essentially uses the universe as its heat sink,' explains Professor Jeremy Munday, lead researcher on the project. 'By radiating heat into space through the atmospheric window between 8 and 13 micrometers, we create a temperature differential that drives the engine.'
Meanwhile, the engine's lower section remains warm through an aluminum plate buried five centimeters underground, absorbing heat from the Earth. This temperature difference of about ten degrees Celsius is sufficient to power the Stirling engine cycle, where gas in a sealed cylinder expands when heated, pushes a piston upward, then cools and contracts at the top, repeating the process continuously.
Performance and Testing Results
During year-long testing in California, the prototype consistently generated over 400 milliwatts of mechanical energy per square meter, with the flywheel rotating at approximately one revolution per second. 'The system performs most reliably during clear, dry nights when atmospheric interference is minimal,' notes graduate student Tristan Deppe, co-author of the study published in Science Advances.
While current output is modest, researchers believe optimization could increase efficiency to more than six watts per square meter. The engine can also generate electricity when coupled with a small dynamo, though this conversion results in some mechanical energy loss.
Practical Applications and Future Potential
The technology demonstrates immediate practical value for agricultural applications. When researchers replaced the flywheel with a fan blade, the system generated airflow exceeding 0.3 meters per second—sufficient for circulating carbon dioxide in greenhouses to enhance plant growth. 'This could revolutionize nighttime ventilation in agricultural settings without requiring grid power,' Munday emphasizes.
With larger temperature differences, the system could provide adequate ventilation for public buildings like libraries. The research team has identified several improvement areas, including better cold-plate insulation, more efficient ground heat transfer, and larger engine cylinders to boost performance.
As radiative cooling technology advances toward commercial applications, this space-powered motor represents a significant step in sustainable energy innovation. UC Davis has filed a provisional patent for the technology, which could eventually provide clean, continuous power for various nighttime applications worldwide.