Importance of Energy Harvesting: Energy is typically the scarcest resource of a sensor network; however, by applying EH techniques to any system network, the overall available energy to a system can be increased. The integration of EH techniques also expands the potential of sensor network application into environments where they may not have been viable without EH. For example, when sensor networks need to be deployed in remote, hard to reach or hazardous locations, replacing batteries or using a hard-wired energy source may be nearly impossible. But, by creatively applying EH techniques like solar, wind RF, piezoelectric, or wind currents, the potential areas for operation are expanded and the lifetime of the network is no longer limited by energy needs.

Applications:

Although many EH applications are still only viable in the lab, it is an ever expanding focus area for embedded systems and sensor network designers. For example, a functional, solar powered, EH smart microsensor node has been created, for measuring intraocular eye pressure, that is only one cubic mm in dimension.

SHM (Structural Health Monitoring): Sensor nodes within an SHM system can make use of EH by capturing the kinetic energy from ambient vibrations inherent in the infrastructure of a bridge.

Remote Locations: Mobile sensor nodes that are deployed in remote locations (for example, from airplanes to the land and sea) can harvest solar energy, or kinetic energy, associated with wind and ocean currents.

Wearable Electronics: Ambient energy from the biomechanical motions of walking and running can be captured while a person, or animal, is using a wearable, mobile sensor node.

MEMS (micro-electromechanical): MEMS microsensors, ranging in size from 0.02 to 1.0 mm, have minute power needs and, therefore, readily lend themselves to harvesting the microwatt amounts of ambient energy present in a variety of backgrounds (solar, temperature, vibrations, etc)

HVAC and Building Automation: Within this industry, remote RF transmitters have been successfully used to broadcast RF energy that perpetually powers wireless sensor nodes, without the need for batteries or wires.