Aside from having a very cool name, parasitic power is an innovate way to recapture already spent power. This power can come in the form of wasted heating or cooling of a building for example. Last week the Southern Methodist University activated the first commercial Green Machine from ElectraTherm. The unit recycles residual heat from the building into electricity. So far, the 50kW Green Machine has exceeded expectations. The company also says owners can recoup the units cost after about three years.
Pictured above is a Parasitic Wind Turbine built as an experiment to see if any useable energy could be captured from a standard home air conditioning unit. Although not listed on the website, the 6 phase 90 V 4.0 the motor used here is available from Skycraft or auction websites like eBay. Using the rotor of a standard box fan and placing it at a 45 degree angle yielded the best RPM.
Lastly, these applications of parasitic power remind us of an art project by Michael Rakowitz from 1998. Rakowitz created temporary homeless shelters that were inflated by a building exhaust vents. The air flow from these vents provided both structure and heating for the shelters. They also served to draw attention to the homeless housing situation and encourage cities to think of new ways to address the problem.
http://www.hackaday.com/2008/06/01/parasitic-power-devices/