Power harvesting
From Wikipedia, the free encyclopedia
Power harvesting (sometimes termed energy scavenging) is the process of acquiring energy from the surrounding environment ("ambient energy") and converting it into usable electrical energy.
Traditionally electrical power has been generated from fossil fuels in large, centralized plants. Large-scale ambient energy, such as sun, wind and tides, is widely available but trickier to harvest. In urban areas, there is a surprising amount of electromagnetic energy in the environment as a result of radio and television broadcasting. But small amounts of ambient energy, in the form of heat, vibration, sound, light, etc. are available all around us, even in very remote locations.
These mini-sources of power — which can be tapped using Energy harvesting devices — become more attractive as many popular devices require less and less power. For example, iPod-like devices, which are popular with joggers, could be powered with energy harvested from jogger's shoes or swinging arms.
The "self-winding watch" is a historical example of a power harvesting device. The watches were wound by cleverly extracting mechanical energy from the wearer's arm movements.
The use of piezoelectric materials to harvest power has already become popular. Piezoelectric materials have the ability to transform mechanical strain energy into electrical charge. Piezo elements are being imbedded in walkways [1] [2] to recover the "people energy" of footsteps. They can also be embedded in shoes [3] to recover "walking energy".
[edit] Some applications
- Wearable computing. The iPod, for example.
- Smart clothing. [4]
- Embedded sources. Power sources are embedded in common surfaces such as tabletops. Laptops sitting on a tabletop with embedded power coils could "harvest" power from the table.
- Remote sensing. The U.S. government is exploring ways to harvest "ambient power from temperature differences, flows, electromagnetic fields, and light to power wireless sensors." [5]
- Medical devices. For example, a "patient's normal daily activities" could power "an implantable pump that delivers insulin to a diabetic." [6]
- Ubiquitous computing. For example, at Intel Research, ambient energy has replaced batteries in a sensor using a microcontroller attached to an RFID tag. [7]
