Energy harvesting is the process by which ambient energy is captured and converted directly into electricity for small and mid-sized devices, such as autonomous wireless sensor nodes, consumer electronics and vehicles. Energy harvesting can make some devices self-sufficient and in other cases can improve the energy efficiency of the device. Energy harvesting, otherwise known as power harvesting or energy scavenging, includes photovoltaics (energy from light), thermovoltaics (energy from heat), piezoelectrics (energy from movement), electrodynamics (energy from movement) and biological (energy from biological reactions), among others. It is enabling battery-free, maintenance-free devices.
In addition, new forms of energy storage are being developed which overcome previous technology limitations by being able to be recharged tens of thousands of times, accept lower input voltages and deliver charge more quickly. Electronics companies are also designing compatible ultra low power electronics.
Where energy harvesting competes with a battery, the higher up-front cost of an energy harvesting system over a conventional battery is offset by the reduction in maintenance when batteries in conventional devices fail. It enables wired switches to become wireless, saving installation and wiring cost. It is improving the efficiency of vehicles by capturing energy otherwise lost as heat or vibration.