A German student has built 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.

This might sound a bit like hocus-pocus pseudoscience, but the underlying science is actually surprisingly sound. We are, after all, just talking about wireless power transfer — just like the smartphones that are starting to ship with wireless charging tech, and the accompanying charging pads.

via German Student Creates Electromagnetic Harvester That Gathers Free Electricity From Thin Air.