You’re in a strange airport, your laptop’s running low on power, there’s no wall socket, and your half-done report must get done today or you’re toast. You gape in horror as your screen fades to gray. The last thing you see before it winks out is the depleted-battery icon.
That’s the nightmare scenario sketched by the proponents of fuel-cell rechargers, and here’s the happy ending they offer in its place: you smile as you pull a fuel cartridge the size of a disposable lighter from a flap in your briefcase and swap it for the laptop’s depleted cartridge. The screen brightens, you hammer out that report, and nobody gets hurt.
So why haven’t fuel cells already shouldered batteries aside? Because fuel cells suck. Suck fuel, that is.
And consumers have shown little interest in carrying fuel around with them. People are set in their ways, which helps explain why QWERTY keyboards, pocket watches, and the Windows operating system are still with us. A product can break through such habits only if it offers obvious and overwhelming advantages, and so far fuel cells have done so only in tiny niches of the market.
What do we mean by overwhelming? Well, instead of the 5 or 6 hours you get on a good day out of your laptop battery, you could get several days of continuous use, at least in theory, with an advanced fuel cell.
News cameramen are big fans of rechargers, because they have to be absolutely sure they’ll have power out in the field, says Jeff Shepard, publisher at the Darnell Group, an industry consultancy in Corona, Calif., that has studied the fuel-cell market. ”But you and I wouldn’t care,” he adds. ”No way I’d pay for an extra fuel cell.”
Other gotta-have-’em users include the military, which wants soldiers to be able to lug all the power they will need for days on end. But the military needs something bigger than a mere laptop recharger, says Thomas Reitz, a chemical engineer at Wright-Patterson Air Force Base, in Ohio. ”With a radio you’re normally just listening, at 25 watts, but if you suddenly need to transmit, you’d need 150 or more,” he says. ”Because a fuel cell designed to that spec would be too large for its purpose, we design it for 30 W and use the extra 5 W to charge a battery.”
Thirty watts is far more than you can wring from a portable proton exchange membrane (PEM) fuel cell, the kind that has been around for decades. The military is therefore looking into a more powerful design that uses a solid-oxide ceramic as the electrode. Such cells derive their high performance from an operating temperature that ranges from 600 to 1000 C. It’s not a big problem for the military, because the cell comes in a relatively large and well-insulated pack. And let’s face it, if you’re going into combat, you’ve got other things to worry about besides stray heat from your power pack.
But shrinking the design down and applying it to consumer applications is a decidedly courageous move. Few companies are working on such products, and just one has decided to make a commercial go of it: Lilliputian Systems, a Wilmington, Mass., start-up.
”Consumer electronics need to use high-energy fuel, to process it efficiently, and to keep it small, and that really leads you to solid oxide,” says Ken Lazarus, the company’s chief executive. ”Also, it’s much less vulnerable [than the PEM design] to impurities that might ’poison’ a catalyst, and to moisture. At high temperatures, contaminants in the fuel tend to just burn up.”
Butane, the fuel in question, packs about 70 percent more energy per gram than the methanol that is commonly used in PEM cells. Butane is already packaged in disposable plastic cigarette lighters, and several international aviation agencies, including the U.S. Federal Aviation Administration, have recently allowed fuel-based rechargers aboard planes. It may, however, be hard to impress that point of law on the nervous, submachine-gun-toting guards at some of the world’s more remote airports—precisely the kind of places where you might want a reliable, long-duration power source, in other words.
The heat, though, is what critics always mention first. ”I don’t want 600 degrees sitting on my lap,” says Shepard.
”It sounds like a bad problem, especially in a product like a laptop, which already has a problem dissipating heat,” says Daniel Rosen, executive chairman of Neah Power Systems, in Bothell, Wash., which makes a PEM fuel cell.
Lazarus dismisses their concerns, saying that his product grew out of an MIT project that was expressly aimed at building high-temperature reactors on silicon substrates. The solid-oxide electrode is laid down on the silicon and enveloped in a bubble that thermally insulates the active region in a vacuum. ”Think of the filament of a lightbulb, burning at 2500 C, but in a vacuum package,” he says. ”The outside of our cell is basically at room temperature.”
Other experts who specialize in solid-oxide fuel cells agreed that such vacuum packing seemed doable. What they wanted to know was how the electrodes could last through many heating and cooling cycles, which would cause the ceramic and silicon layers to expand and contract at different rates. What keeps the package from coming apart at the seams?
Lazarus says the company has several ways of keeping things together. First, the cell’s active area is small, so that the varying expansion rates produce only small absolute differences in size. Second, the ceramic electrode is precracked, as it were, so that it harbors the kind of expansion joints that keep a concrete sidewalk from crumbling. The trick is to make the tiles the right size.
”Think of a dry lake bed,” he says. ”It’s cracked, but only to a certain size—it doesn’t turn to dust. If a device is smaller than this critical size, it won’t crack.”
Lazarus didn’t spell out how his company keeps the seal intact. Alex Ignatiev, the director of the Center for Advanced Materials at the University of Houston, suggests that the company has built a kind of sandwich. ”You can have silicon expanding at one rate, put a layer on top that doesn’t expand quite so much, then another that expands a little less, then finally the ceramic layer,” he says. Yet even a sandwich can go through only so many expansion cycles before it falls apart, Ignatiev points out.
”They don’t say what the lifetime is,” he notes. ”Lifetime is defined by temperature, materials, and the time of heating and cooling, and eventually you will get cracks, like in highway bridges, where the concrete doesn’t expand as much as the steel. The cracks become defect points, propagating bigger cracks.”
But for the moment, let’s assume that Lilliputian Systems’ cell can do everything the company says and last as long as the laptops (and, later, cellphones) it is meant to power. Even then, the company must somehow solve the marketing problems that have dogged methanol-fueled rechargers.
Can everyday users be trained to carry fuel around? To stock up on cartridges of it and keep them in their desk drawers, briefcases, and glove compartments? Will retail outlets in out-of-the-way places stock them? Will that machine-gun-toting airport guard learn to wave little vessels of butane onto passenger aircraft while turning away 3.1 ounces of shampoo? Most important: will battery makers sit idly by, watching this upstart eat their lunch?
We think not. Miniature solid-oxide fuel cells may find niche applications, but few people will use them anytime soon.
Miniature Solid-Oxide Fuel Cell
Goal: To supplant batteries in portable devices.
Why It’s a Loser: Nobody wants to lug fuel cartridges.
Player: Lilliputian Systems
Where: Wilmington, Mass.
Staff: Not available
Budget: US $40 million in venture capital
More: No Web site