Energy harvesting has been “emerging” for several years, but the technology is now poised to break out commercially, driven by developments in areas that are, themselves, emerging applications. The market got its initial acceptance in wireless building automation and control, with deployments in Europe. These opportunities spread to North America, where home automation and control technologies were added to the mix. Wireless sensor mesh networks provided challenges that energy harvesting could meet, particularly where battery use was limited or problematic. Energy efficiency, the Smart Grid, radio frequency ID, and thin-film batteries all helped to advance energy harvesting solutions.