Dutch designer Teresa van Dongen has developed an LED pendant lamp called 'Spark of Life' that gets fed power from an unexpected source. Rather than drawing from an AC or DC power source, the pendant lamp needs to be literally fed to emit light -- thanks to its implementation of electrochemically active bacteria.
The bacteria in Spark of Life are found in nature. When these special bacteria clean waste water, their metabolic process naturally emits a small electrical current. With enough of them together, this current can power low-energy appliances like LEDs.
Spark of Life requires no external power source in order to emit light. Rather, consumers just need to fill its four bacterial compartments with a teaspoon of acetate every two weeks and fresh water every month.