Many attempts have been made to create an engine that does not need fossil fuels to work. Luckily, one of the most successful projects uses water instead. Learn more about the recently discovered evaporation engine.

The First Humidity Engine

All started when a team from Columbia University realized that the evaporation is a force of the nature that can produce high quantities of energy when it is scaled up. If mixed with the new material called HYDRA, they provide amazing results. First of all, what is HYDRA? HYDRAs are essentially thin, muscle-like plastic bands that contract and expand with tiny changes in humidity. A pinky finger-length HYDRA band can cycle through contraction and expansion more than a million times with only a slight, and almost negligible, degradation of the material. The idea of this material came when the director of the project was studying the physical properties of micro-organisms with advanced imaging techniques, he discovered that the spore of the very common grass bacillus bacteria responds in a strange way to tiny amounts of moisture. To make HYDRAs, he paints the spores onto plastic strips using a laboratory glue. By painting dormant spores in altering patches on both sides of a single strip, the pulsating spores cause the plastic to flex and release in a single direction in response to moisture. Once they had the material, they used it to create a rotating movement by sticking strips into a wheel and using the evaporation energy mentioned before. Half of the wheel is in contact with dry air while the other half is in a humid environment. They only need to fulfil a line on the top of the device with water and the wheel starts to move. When the strips get in contact with the dry air, they shrink and they expand when they pass through the line of water. The output is a continuous rotating movement. Furthermore, they have mount the wheel on a platform with wheels so that the device can move autonomously. How does it work?
The team has also developed other devices working with this material such as a piston and they state that now the device is able to power a led with this movement. Finally, the best part is that it can be built with less than 5$, according to the team director. https://www.youtube.com/watch?v=Vj2kuZm-aCA Could you come up with another use for this revolutionary discovery? Join our engineering community here