GreenPeak about Energy Harvesting
Energy Harvesting, Ambient Energy Sourcing, Energy Scavenging... different terms to mean very much the same thing: extract energy from the environment to drive electronics circuits independent from the mains power or from a battery.
The "raison d'être" of energy harvesting in wireless sensor applications is straightforward: ridding the data cable to read the sensor value solves only half of the problem: the installer still needs to run a power wire. And half a problem solved is as good as not solving it at all. Furthermore, replacing the mains power by a battery substitutes the wiring cost by a battery replacement problem, which is not an advance at all.