Just sharing an interesting article regarding IoT and a concept being developed to harness wifi signals as a means to "recharge" a low power device for many years.
http://www.networkworld.com/article/3149962/internet-of-things/wi-fi-chip-cannibalizes-ambient-wi-fi-signals-for-power.html (http://www.networkworld.com/article/3149962/internet-of-things/wi-fi-chip-cannibalizes-ambient-wi-fi-signals-for-power.html)