LED Lamp Runs on Mud
Dutch designer Marieke Staps has built a lamp with the LEDs powered by soil. She writes:
"Free and environmentally friendly energy forever and ever. The lamp runs on mud. The metabolism of biological life produces enough electricity to keep an LED lamp burning. The mud is enclosed in various cells. These cells contain copper and zinc that conduct the electricity. The more cells there are , the more electricity they generate. This technique offers a wealth of possibilities. The only thing the lamp needs is a splash of water every now and then."
Now, an LED lamp powered by copper/zinc cells with a mud electrolyte is kind of cool, but there are no magical biological organisms involved, and the lamp will inevitably stop functioning once the chemical reaction has run its course. In any case, they've been making little digital clocks powered like this for a long time, so it's not exactly a huge leap forward.
The anode and cathodes (copper and zinc) are depleted over time and will need to be replaced. These materials are manufactured using "non-free" energy. In a round about way you could argue that the energy released via the process that erodes the metals is "stored" in them when the metal is processed from ore.
Whatever, it is very pretty. Mstaps via PSFK photo by Rene van der Hulst.
Other Lovely Lamps on TreeHugger:
Sun Jar: Storing Sunshine
Knock Off Your Own Homage to the Sun Jar
IKEA Lighting The Way To Warmer LED Lamps