Fuel cells have a very high buzz factor these days. These seemingly magical devices create electricity from hydrogen and oxygen—producing pure water as their only byproduct. Several major cities already have fleets of buses that use fuel cells. Auto manufacturers promise us that within a few years, we’ll be able to buy fuel cell-powered cars that create no pollution at all—thus enabling us to reduce our dependence on oil and slow global warming while saving money with inexpensive hydrogen fuel. Spacecraft have used fuel cells for decades to produce electricity, since the hydrogen and oxygen they need are both conveniently available in onboard tanks. And in the near future, fuel cells may even be put to more prosaic uses, powering notebook computers, cell phones, and other personal electronic devices.
Ship of Fuels
But although fuel cell technology is by no means new, it has yet to achieve large-scale commercial success. One of the main reasons is that hydrogen, the most common fuel, is surprisingly difficult to obtain. Even though hydrogen is present in water, air, and organic matter of all sorts, pure hydrogen is harder to come by. If you use electrolysis to separate water into hydrogen and oxygen so that you can use the hydrogen as fuel to produce electricity, you get into a sort of vicious cycle of energy consumption—it takes almost as much energy to produce the hydrogen in the first place as the hydrogen will later provide when used as fuel. Once you have the pure hydrogen, it’s a pain to store and deliver it safely. So the net cost is fairly high, and the net efficiency is fairly low. If only there were a handier way to obtain hydrogen—or better yet, a fuel cell design that used a more conveniently obtained fuel. Both of these hopes may be met by microbial fuel cells (MFCs), which use bacteria to process virtually any organic matter and turn it into electricity. [Article Continues…]