Today I was reading a lot about wireless for some reason. Not on purpose, there just seemed to be a lot of wireless articles in my feed. One of the most interesting articles I read was about what's now being called Passive WiFi.The way regular wireless service works now (on our computers, phones, light bulbs, etc.) is that there must be a power source to generate the radio waves. The way I understand Passive WiFi (read: not an expert) is that it uses the power at one of the transmission points and reflects it off the device where you're trying to access internet wirelessly.
I'm not sure we'll ever have a phone without a battery because obviously the power is necessary for other things, but it sure could mean a lot of the Internet of Things. We could have sensors on things that would work for years without changing the battery or plugging it in. If you think about this in regards to third world countries, an example might be having a sensor on a water source and knowing when it breaks or something like that. The possibilities are really endless.