The Airnergy Harvesting Battery Charger from RCA is a revolutionary gadget that takes a WiFi signal and converts it into a DC power which can then used to power up your gadgets. The recharge time depends on the proximity to a WiFi signal. The Airnergy comes equipped with a battery inside it, so you can carry it around and as long as you’re near WiFi hotspot, it charges itself. RCA’s spokesman claims the charged battery of the Airnergy is able to charge a BlackBerry for about 70% capacity in a few hours. RCA will launch the Airnergy for $40 to $50 in the near future.