Summer is upon us, so it’s cool to know that humidity could weirdly be a force for good: Scientists have powered a tiny vehicle by using humidity as their fuel. That means evaporation could be an energy source for gadgets in the future.


According to a study published yesterday in Nature Communications, a team at Columbia University used microscopic, moisture-sucking spores as an energy source for a teeny, 0.1-kilogram car. The concept is still pretty, well, conceptual, but down the road, we could feasibly use the free power of humidity changes to run transistors, Science suggests.

The spores used in the study came from a bacteria species called Bacillus subtilis, which is found in delightful places like dirt or human intestines. Those spores swell or shrink depending on how much moisture is in the air, you see, with swings of up to six percent changes in size as they suck up moisture and release it.


In the video below, those yellow polymer strips are covered in the spores, and expanded and contracted as this wheel-shaped vehicle cycled the strips through closed air and open air. This caused the wheel to turn and make the toy car move (very slowly). The study also suggested that using humidity changes, these spores could lift up to 50 times their own weight (again, very slowly).

Humid weather still sucks, but leveraging it for energy could be a pretty incredible upshot.

[Nature Communications via Science]