An article by Powercast titled “RF Energy Harvesting and Wireless Power” was published by Electronic Products.
“The market growth of low-power wireless devices particularly sensors is driving tremendous interest in using energy sources that can power the devices autonomously. The cost of running wires and the future cost of replacing batteries have discouraged users from widely deploying a verity sensor-based devices.
While solar has been widely used for years to power remote devices, several other types of energy-harvesting approaches have emerged for micro-power applications including vibration, thermal, mechanical, and RF. Of these technologies, RF energy is the only one that can provide either an intentional or ambient power source for wire-free or battery-free applications.”