Perpetual motion machines are a thing of fantasy/delusion, but there's a lot of energy floating around that doesn't cost anything to harvest. The calculator and weather station shown here run off of microwaves from that TV tower in the distance.
Broadcasters pump out tons of of RF from their big microwave towers, operating on the mere hope that some of the RF will hit a TV antenna and deliver unto someone the evening news. Since power demands for electronic devices continues to reduce (see Moore's Law), those radio waves can now act as currents in a stream, turning the digital wheels inside small electronic devices. The catch is that the antenna harvesting the electricity has to be in line-of-sight with the microwave tower. On the bright side, the TV station (or cell tower or home Wi-Fi network) will never feel the burden of these added devices. It's just RF that didn't make it to its intended location.
The same team at Intel Labs Seattle also figured out a way to develop motion-sensing RFID tags that require the same off-the-shelf RFID transceiver used to simply count boxes and other simple tag apps—in other words, gear that's already in place in many buildings. By sticking the little tags on a bunch of household products in a room, the researchers could track what people were doing with 90% accuracy. Some people are already testing these Wireless Identification and Sensing Platform (WISP) RFID chips for use inside the human body (pacemaker location) and deep under the sea (testing seawater 1km below the surface).
The thing is, none of these technologies are going to charge your phone or power your laptop. For that, you'll need Intel's other wireless power initiative, Wireless Resonant Energy Link, first shown off in 2007. Currently, a demo model features a 45W lightbulb operating at full brightness at 1 meter with around 80% efficiency. And best of all, it doesn't electrocute people when they walk by. [Intel Labs Seattle]