MIT Researchers Envision Charging Your Mobile Phone Using Water Droplets

Well here’s one: MIT researchers are developing a way to harvest energy from, off all things, water droplets. They discovered that when water droplets spontaneously “jump” away from a superhydrophobic surface, they generate a tiny electric charge.

Condensation is the real mechanism for the movement of the water, and the team figured out that by using interleaved metal plates--particularly when adjacent plates have opposite charges--they could gather that energy and send it through an external circuit, thus powering small electronic devices.

This machine harvests energy from water droplets

What’s really cool about the whole thing is that it’s a passive process, meaning a device rigged up with these plates would generate power with zero external power or intervention. Of course, it’s also not a very efficient means of harvesting energy just yet. The team hopes to tune their system to generate a microwatt (that’s a millionth of a watt) per square centimeter of plate.

That said, using the above as a metric, the team figured that a system in a cube form factor measuring 50cm and each side could produce enough juice to charge up a mobile phone in half a day. Thought of another day, that would be a fairly effective generator if you’re trying to power a few lightbulbs out in the middle of nowhere.

Artificially green-colored water droplet jumping between fins

In any case, kudos to the two lead researchers on the project, MIT postdoc Nenad Miljkovic and associate professor of mechanical engineering Evelyn Wang, on some strong innovation, and here’s hoping they continue to make it more efficient.