Moss, as a rule, isn't that impressive. In the wetter regions of the world, the stuff grows pretty much wherever you let it. It's green and squishy and pretty enough, we suppose. What moss isn't is a good source of electricity, or at least it wasn't until recently. By wiring together 10 little pots of the stuff, a group of scientists from the University of Cambridge have actually harvested enough moss-grown electricity to power an FM radio.
How the moss actually powers the radio is thanks to something called a Photo Microbial Fuel Cell (Photo-MFC). These are comprised of three basic parts: an anode to collect the electrons the moss strips from water during photosynthesis, a cathode where the electricity is consumed and an external circuit to connect the two. Each of the ten moss pots contained in the Moss FM rig is hooked up to its own Photo-MFC, and these in turn are hooked up to a battery.
The battery stores what energy it can from the process, currently about .01 percent of the moss's output and then powers the radio. So far, that .01 percent output is only enough to run the radio's speaker and tuner for a couple of minutes. That'll change in the coming years, however, since researchers at the University of Georgia have already found a way, using microscopic nanotubules, to produce twice as much electricity from plants as you can get from today's photovoltaic cells. Once the two approaches merge, we could easily see everything from moss to the trees lining our streets turned into, quite literally, the greenest power plants around.