Energy harvesting, otherwise known as energy scavenging is needed to boost and eventually replace the batteries in printed and other low cost and miniature electronics, particularly in order to extend their life in use. For example, it is starting to be used for the three generations of active RFID – Conventional, Real Time Locating Systems (RTLS) and Wireless Sensor Networks (WSN).
The market for energy harvesters is estimated to be $611 million in 2009, with 67% of it being applications for consumer goods. By 2019 the market is predicted to have grown to over $4 billion, with 75% of it being consumer goods harvesters. The rest of the market will be industrial, military or healthcare applications.
Surrounding sources of useful energy are: light, linear motion / pressure, heat difference (eg using Peltier effect), temperature change, rotation/vibration and ambient RF energy. In fact Nokia is close to releasing a cell phone using ambient RF energy to charge the battery.
Then there is the nanoscale approach. Options include nanobatteries and nanogenerators that harvest energy from their environment. By converting mechanical energy from body movement, engine vibrations, or water or air flow into electricity, these nanoscale power sources could enable a new class of self-powered medical devices and sensors including WSN nodes.
Once you combine energy harvesting with extraordinarily small RFID chips like Hitachi’s RFID ‘Powder’ (which has yet to be commercialized) or even their ‘mu’ chip (which is no longer sold in the U.S., sad to say) you start to get the idea of what scale I’m talking about.