Electric meters are likely a Zigbee (peer to peer) network and eventually communicate via a cell phone data stream. The meters are TWO-WAY. The power company can disconnect power remotely.

Water meters have batteries. Supposedly they are "truck" activated and only talk back when prompted. Yes, they have a battery.

The gas meters, I don;t know, but they may operate the same way as the water meters. They contain batteries.

Battery life is estimated to be about 7 to 10 years as I understand it.