Archive for January 21st, 2008

21
Jan

Power from Poop?

Prior to my present position in climate change research I worked on ocean sediment biofuel cell research and herein lies the premise of this post. In a world where the populace is (thankfully) becoming increasingly concerned with reducing their carbon footprint, biofuel cells could play an important role in this reduction, especially where outdoor activities are concerned. Imagine you are on a trip on the Grand Canyon and you are charged with being the human waste carrier. Some might think this a crappy job (if you pardon the pun) but in the future, poop maybe the biggest source of energy for such an expedition, through use of microbial fuel cells (MFC’s). Alternatively imagine a world with heated pogies, paddles and seats. MFCs have a lot of potential applications in the future.

grandcanyon.jpg

Courtesy Photo: Colorado River, Grand Canyon by James Bagley Jr.

A fuel cell is an electrochemical energy conversion device. It produces electricity by extracting electrons from fuel (on the anode side) and producing oxidized product (on the cathode side). Microbial fuel cells acquire their electrons from organic material or waste (e.g. poop). Under oxygen free conditions, Geobacter, (the most common microbe used in such cells) can be injected into the organic material and it feeds on this waste. During digestion, Geobacter pulls electrons from waste material, subsequently shuttling those electrons to the anode, forming part of a circuit. As electrons flow through the circuit (toward the cathode), they generate electricity. This electricity could be used be used to power small portable units such as lights, stoves, etc.

fuel-cell.JPG 

Schematic: Adapted from here The process is currently under development by numerous academic, governmental and industrial research groups worldwide, all aiming to optimize power output per unit of organic material. While current developments have not progressed enough to release commercially available units, the motions have been set in place to make power from poop.