Only by using electrical energy captured from the WiFi signal.

Here it is innovation that awaited many people. This little box can take the existing electrical energy in the air around you. Of course, the air must contain a WiFi signal so that the electrical energy can be taken. Wifi power charger is on display in the CES (Consumer Electronic Show) in 2010.
In the demo at CES exhibition stands, this tool is able to recharge the battery BlackBerry containing 30% to full in 90 minutes. Only by using electrical energy captured from the WiFi signal.