It might be a while before this new engine hits the roads, but it’s surprisingly inexpensive to make and just might lead to a seismic shift in the way we think about transportation. According to the Washington Post, a prototype presented by researchers at Columbia University can run on nothing but water and bacterial spores.

The team of scientists announced several prototypes in a study published in the journal Nature Communications this Tuesday. Though they are simple in design, the mechanism used to generate energy definitely is not. The engines use the shrinking and expanding of certain bacterial spores as a result of changes in humidity to move themselves forward.

Researchers say that they’ve only just started to unlock the technology’s energy potential. Lead author and associate professor Ozgur Sahin has been studying bacterial spores for quite some time now. After nearly a decade of work studying bacterial spores, he is just beginning to exploit the spores’ responses to changes in humidity for the purpose of generating energy.

“People before us had shown that the spores change shape in response to humidity. They shrink when they’re dry and expand when exposed to moisture,” Sahin explained. He noticed how rigid the spores were under dry conditions, which meant that the shift in shape must be the result of a significant energy change. Sahin sketched out an idea where a device rested on the surface of a body of water.

Shutters would control the flow of moisture throughout the system, exposing spores to a controlled level of humidity. When the spores became too dry, they would close the shutters and increase the moisture present. When they became too moist, the spores would expand and open the shutters. This would create a type of perpetual motion that is almost entirely self-regulated.

So far, Sahin and his team have developed devices that can turn light bulbs on and off using the spores, as well as an engine that can power a miniature car. Though the devices seem like toys, they can be significantly scaled up for a wide range of industrial applications.

You can watch the amazing little car in action here: