The designers, Hierve, say this concept uses the same technique as a conventional hydroelectric generator, but on a much smaller scale. A box containing a micro-turbine is installed in the pre-existing plumbing after it enters the house and before any other outflows. Each time someone turns on the water to shower, wash dishes, or flush the toilet, the flow of water through the plumbing is used to turn the turbine, which then converts the motion into electrical current. The resulting current is stored in a battery in the wall, which powers the light bulb, according to DesignBuzz.
Markham Derek (2012 March 30) Home Lighting Concept Powered by Plumbing. Retrieved on November 19, 2014 from Treehugger.com