Learn to monitor and control your home & environment with self contained, inter-communicating microprocessors. Arduino / Raspberry Pi DAQ and IOT Applications include ham radio, robotics, weather stations, model railroading, toys and more. - KK4HFJ
Several of my projects use Ethernet to communicate data back to a server or internet connection. Our Web Enabled Weather Server for one. I've decided to power the remote arduino and sensor board over the ethernet connection. Common Power Over Ethernet solutions send 48vdc over the spare Ethernet pairs (others send the power over the data pairs as well). The solution I have chosen takes the Ethernet signal from my router, injects the power, and on the other end, strips the power back out before supplying the Ethernet connection to the Arduino. It contains a 48v to 12v/9v/5v DC-DC converter.
TP-LINK TL-POE200 Power over Ethernet Adapter Kit, 1 Injector, 1 Splitter, up to 100 meters (325 Feet), 12/9/5V power output