Dennis Siegel is a German student from the University of Arts Bremen, and he is working on a device that can gather energy from various radiation sources, including hi-tech radio signals like WiFi, GSM etc, but this should work with any type of electro-magnetic radiation, including natural sources (if you’re near a magnetar, this could be very handy). The thing is: it’s not so easy to find a natural source that will output as much energy as your router for example.So far, he has created a machine that can harvest the equivalent of one AA battery charge per day. Unfortunately, we don’t know what the electro-magnetic environment is like in his experiment, and that could affect the outcome by a wide margin. Still, the idea and the basic science behind is sound, and that is a concept that would sure make many users dream: what if my phone would always recharge off the surrounding WiFi signal? That would be energy recycling at its best.
The main issue is the actual efficiency of gathering electromagnetic energy like this. Right now, we have not heard of a single case where there is enough energy recuperated that way to make a significant difference in our daily lives. At the moment, this may work to help ultra-low power sensors etc, but those can also be self-powered upon a data request by the incoming wireless transmission (genius). That’s how RFID tags works, and they don’t need to store energy, which means that they are dirt-cheap to make. Hopefully, harvesting energy from environmental radiations will become useful one day, maybe thanks to someone like Dennis.