Energy harvesting is the process of capturing energy from physical processes such as light, vibrations, or electromagnetic fields. While there are large scale applications like solar or wind farms, I am interested in harvesting tiny amounts of energy in places that would usually not be considered power sources and doing something interesting with the harvested energy.
There are multiple appeals to energy harvesting devices. First, energy harvesting gives freedom from the cable, or the battery which has to be recharged. Energy harvesting devices are by their nature stand-alone and can operate over their life time without any intervention as long as they stay within range of their source of power.
Second, there is something magical about a device that draws energy from the environments and converts it into something useful or interesting. This is especially true if the source of energy is not easily apparent to the observer. Energy seems to come from “thin air”.
Third, computation and light generation are very efficient and cheap in terms of energy. Considering that we used to create light by heating up a piece of metal not long ago while high power LEDs can do the same at about one order of magnitude less power. Similarly, computers used to be factory-sized, while now you can buy micro-controllers, that can operate with less than 1mA and power down at less than 1uA.
Fourth, from the creator perspective, building an energy harvesting system needs skill and creativity. Its easy to slap together a microcontroller with an LED as long as it is powered from a outlet. It is significantly harder to do so without that cable.
Some cool energy harvesting projects