A German student, Dennis Siegel, creates electromagnetic harvester that gathers free electricity from thin air by building an electromagnetic harvester that recharges an AA battery by soaking up ambient, environmental radiation. These harvesters can gather free electricity from just about anything, including overhead power lines, coffee machines, refrigerators, or even the emissions from your WiFi router or smartphone.
The underlying science is sound. We are just talking about wireless power transfer. Every electrical device gives off electromagnetic radiation. If that radiation passes across a coil of wire, an electrical current is produced. The efficiency of wireless charging depends on the range and orientation of the transmitter and how well the coil is tuned to the transmitter’s frequency.