Ern Worthman, Technology and Editorial Director
Every now and then I have to take a bit of editorial license and find the humor in, what most of the time is, serious business. In this particular case, I'm referring to the emerging fuel cell industry.
Now don't get me wrong. I'm a big proponent of fuel cells technology. To me, it represents the best of ALL worlds. Theoretically, hydrogen is free and plentiful, and the only by-product is good 'ol pure H2O. At first glance, this seems like the panacea for all of our energy woes, but it turns out that it's a bit more complicated than that. And to meet other criterion (specifically miniature size, light weigh, and high efficiency), the equation starts to elongate.
Eventually I think fuel cell-based energy will play large to satiate our seemingly logarithmically insatiable appetite for energy. It likely won't have an exclusive on future energy sources, but the upside sure looks promising. And, before I do my George Carlin take on miniature fuel cells, let me take a few paragraphs to throw out a bit of the technology.
Most of the visibility stemming from fuel cell technology is in the transportation sector. But recently, there has been a number of developments in directions other than automotive, specifically miniaturization for wireless, portable, and wearable electronics.
And, while the polymer electrolyte membrane (PEM) fuel cells (also called proton exchange membrane fuel cells) have been getting the lion's share of the press, a derivative of the technology more suited to miniature fuel cells has emerged the direct methanol fuel cell (DMFC).
One of the players, Toshiba, has developed a prototype cell that measures about 22 mm by 45 mm and weighs 8.5 grams. At present it seems to be the smallest working DMFC prototype. While this seems to be one of the leading products, there are other companies (quite a few, actually, including Motorola) on the same footprint track. They aren't all using the same process, but they are all driving to produce miniature fuel cell for the same market.
DMFC fuel cells use methanol as the source fuel. The basic overall chemical reaction is: CH3OH + 3/2O2 - CO2 + 2H2/O. Since the fuel cell operates isothermally, all the free energy associated with this reaction should in principle be converted to electrical energy. However, kinetic constraints within both electrode reactions together with the net resistive components of the cell mean that this isn't possible. So, the working voltage of the cell falls with increasing current drain md> much like traditional battery technology. And, current efficiencies are still ... well, pretty inefficient. One other issue with miniaturizing the DMFC and extending its life, is that it requires a highly concentrated form of methanol, which can cause problems with the membrane and some wastage of methanol.
Well, all of this kinda shoots in the foot, the free source fuel theory (I can see it now, to recharge our mobile communicators, we all have a tank of methanol in our garages with a miniature fuel pump where we stick the miniature nozzle into the miniature fill tube of the device). Or, we can be drive up to a gas station with the slogan — "One-stop fill up shop for all your vehicles, computers, phones, PDAs, MP3s and other wearable electronics — deep discounts for five or more devices".
Also, methanol is extremely flammable and toxic md> guess I'd better not be puffing on my favorite cigar while I'm recharging my 99-G devices.
In spite of the good, bad and the ugly, the present reality is that the fuel cell's future is inherently murky. Fuel cells still face significant technological, political and economic hurdles before they can realize their truly awesome potential.
IMHO, some of that murkiness is deserved. One of my concerns is the containment of hydrogen. If hydrogen is used instead of methanol, it has a small problem of needing to be stored at mere — 253° C ( ± 423° F) to remain in liquid form. While hydrogen disperses quickly in the atmosphere, I'm going to need a lot assurance that its containment is fail-safe, either as a fuel source or from a chemically derived process, if it is going to be a few mm from my ear. Furthermore, hydrogen-air mixtures can ignite or explode at both lower and higher concentrations of the gas. I'd hate to read a headline like "Static discharge ignites concentrated hydrogen pocket while the user is talking on their cell phone md> hat size reduced by 20%." And let's not forget that methanol isn't exactly inflammable either. Methanol vapors can travel a considerable distance to an ignition source and quot>flash back.quot> I wonder just how much damage a 20 cc charge can cause if it goes up while I'm jammin' to my tunes from a fuel-cell-powered wireless iPod.
Ok, so maybe I'm a bit paranoid. I just happen to remember a car called the Pinto. For those of you too young to know it, that was a car with a gas tank design so poor that if it was hit from the rear (and not even that hard), poof — instant incendiary. My main concern is that if were are going to make the switch from battery source to fuel cell source for portable and wearable electronics, we better make sure we don't take our lead from the automobile industry
As I said at the beginning and just for the record, even though I'm being a bit sarcastic, I'm all for fuel cells as the premier 21st century power sources — from space shuttles to watches, and especially for automobiles. But like any technology on the fast track, corners get cut, especially with such ubiquitous opportunities on the horizon. I want to be sure that when I sit down at the local Tarbucks with my all-inclusive, fuel cell powered, holographic real-time mobile workstation/intergalactic communicator I won't have to worry that the hazmat guys will be showing up to pick up my parts.
Oh yea, and as a closing note, I can't wait to see how fuel cells are going to get through airport insecurity.