German student creates electromagnetic harvester that gathers free electricity from thin air | ExtremeTech

By Sebastian Anthony on February 12, 2013 at 1:30 pm12 Comments Share This Article 16 inShare 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. Dennis Siegel, of the University of Arts Bremen, does away with the charging pad, but the underlying tech is fundamentally the same. We don’t have the exact details — either because he doesn’t know (he may have worked with an electrical engineer), or because he wants to patent the idea first — but his basic description of “coils and high frequency diodes” tallies with how wireless power transfer works. In essence, every electrical device gives off electromagnetic radiation