technical report

A Fuel Cell in Your Phone

• by David Voss
• Former Editor,Science Magazine

Tired of short-lived batteries? Methanol-powered micro fuel cells are racing toward market, promising up to 20 hours of cell-phone talk time. In a Los Alamos, New Mexico, industrial park not far from the laboratory birthplace of the atomic bomb, Robert Hockaday sits in the cluttered lab of his startup company, Manhattan Scientifics, holding a business-card-sized patch of clear plastic. Closer inspection shows a circuit-board-like pattern of black platinum and ruthenium printed on either side. The contraption is the innards of a 5-centimeter-by-13-centimeter power plant that generates its own electricity using methanol as fuel. It may not look like much at first glance, but it's one member of a new class of tiny power packs that is ready to explode onto the market – and that just might annihilate one of the world's most ubiquitous technologies, the battery.

These miniature power plants, called micro fuel cells, promise a huge power boost for portable electronics ranging from cell phones to laptop computers to future generations of power-hungry, Web-enabled handheld devices. Today's best lithium-ion cell-phone batteries provide an average of only four hours of talk time; micro fuel cells could provide up to 20 hours of talk time. And after that, instead of plugging in the cell phone overnight, or swapping batteries, you'd just snap in a new methanol cartridge.

Fuel cells are already bursting onto the market in other forms and in far bigger sizes. Buses powered by fuel cells are making their first appearances, and cars are next. Fuel cells that provide backup power for homes and offices are becoming available, too. Electrolux has even prototyped a cordless fuel-cell vacuum cleaner. Among other advantages, fuel cells use readily available sources of energy – namely, hydrogen or methanol – and produce only water, carbon dioxide and heat as waste products.

Now, industry is gearing up to make fuel cells small enough for consumer electronics. Building practical fuel cells this small – devices that produce one-tenth of a watt to 50 watts – presents huge engineering and materials challenges, but the market opportunity is enormous. "Portable fuel cells have the real potential of being profitable in a shorter time span than either stationary or automotive fuel-cell applications," says Atakan Ozbek, vice president for energy research at Allied Business Intelligence, a technology research firm in Oyster Bay, New York. "In five years this could be potentially a billion-dollar-a-year market. This industry is going to kick." Not surprisingly, a race to commercialize the technology is in full swing and includes everyone from Motorola and Korean electronics giant Samsung to startup companies like Hockaday's. The competitors are betting on different designs and even slightly different chemistries, but they share a common goal: taking a bite out of the $6 billion world market for rechargeable batteries.

The first successful application is likely to be methanol fuel cells that produce approximately one-tenth of a watt and can recharge conventional batteries, liberating consumers from the dashboard lighter or the wall socket. Next will be fuel cells small enough to actually fit in the battery compartments of existing phones and yet powerful enough – one watt for cell phones, 50 watts for laptop computers – to be used for direct power.

Even farther on the horizon, microchips will be directly powered by built-in fuel cells. These fuel cells will provide a boon to miniaturization by removing the need for separate power sources. They'll be custom designed to provide precise power needs. And production costs should drop when both chip and power source are fabricated as one unit. Self-powered chips, in turn, could enable a future generation of self-sufficient gadgets, like tiny networked sensors that can operate in remote areas, detecting pollutants, biowarfare toxins or anything else that needs detecting, and sending out the data for months.

Getting Small

The problem with conventional batteries is that they rely on electrochemistry that dates to the late 18th century, and they have some severe limitations. Most notably, once the supply of chemicals inside the battery has finished reacting, the battery goes dead. You must either connect it to a charger plugged into the wall socket or throw it away — preferably in the recycle bin because of toxic ingredients like cadmium and mercury. And batteries aren't likely to get much better; virtually every chemical combination has been tried, says Shimshon Gottesfeld, chief technology officer at Albany, New York-based Mechanical Technology, a company developing micro fuel cells. "Even the best batteries have little chance to go very much higher" in the power they can produce by weight, he says.

Fuel cells are more complex, but they carry fundamental advantages. Aslong as there's a supply of hydrogen or methanol, the fuel cell willproduce electricity. Moreover, thanks to the high-energy fuels they use,fuel cells produce more energy for their weight than batteries ever will.

But fuel cells are tough to engineer, and the smaller ones are toughestof all. The design challenges for micro fuel cells start with the choiceof fuel. Hydrogen is impractical; it's a gas and must be compressed atvery high pressures, and even then it requires tanks too large forportable electronics. Methanol/water mixtures are more easily stored ina small fuel cell, but using them creates new engineering hurdles. Tomanage a liquid fuel, tiny pumps and pipes are required. Then there'sthe waste water. Not even the most ardent cell-phone users wouldtolerate power supplies that drip on their shoulders, so fuel cells mustevaporate the water. All fuel cells create heat; the small versionsoperate at anywhere from 15’C to a scalding 60’C. While this provides ameans to evaporate waste water, it also requires the right balance ofinsulation and venting.

Cramming all of this into a nifty package the size of a couple of AAcells presents a real challenge. And given the fierce competition tocommercialize a micro fuel cell, most corporate players are cagey abouthow they've begun solving these problems.

"There is a lot of posturing among the companies, but that is whatyou'd expect in the early stages as they try to maintain theirpositions," says fuel cell watcher Chris Dyer, editor of the Journal ofPower Sources. But, he adds, "This isn't smoke and mirrors. It's a realtechnology and just requires some clever engineering to make it work." Most observers predict that the first micro fuel cell on store shelveswill be a charging device using methanol. A half-dozen companies areworking on variations on this theme, including Manhattan Scientifics. In Hockaday's design, the fuel cell components aren't arranged in a stack,like traditional automotive fuel cells. Rather, they're laid out side byside, like components on a microprocessor, making them amenable tosemiconductor-manufacturing techniques.

Mechanical Technology has already cofounded a company that sellsrefrigerator-sized commercial and residential fuel-cell power plants.Now, Mechanical Technology is setting its sights on smaller things,starting with charging devices. "We are very optimistic about theprospects for commercializing this," says Mechanical Technology'sGottesfeld, former director of the Los Alamos lab's fuel cell researchprogram. "We are not only looking at chargers but a complete system forcell phones. We're also looking at other possibilities like laptops, thetoy market, and power tools."

Motorola and Korea's Samsung are also actively developing prototypes. Hyuk Chang, a principal researcher at the Samsung Advanced Institute ofTechnology outside of Seoul, says the company's goal is to demonstrateworking models in a year, again with charging devices leading the way."I think it will take another two years to get from the lab intocustomers' hands," says Chang. "The hard question is what will be thefirst application?"

At Motorola, fuel-cell project leader Jerry Hallmark is pursuing astrategy that promises smaller fuel cartridges. He says the company hasdeveloped tiny fluid systems that would continually recycle the water inthe methanol-water fuel mixture. Replacement cartridges could just carryundiluted methanol. "The fuel cell can't run on concentrated methanol;it needs a dilute solution. But you don't want to carry a dilute fuel,"he says. Hallmark adds it will likely take three to five years for anycompany, including Motorola, to begin selling a product.

Packing a Punch

What Motorola and the other companies want most of all, though, are battery-like fuel cells that snap right onto phones and other electronics to power them directly. "The cell phone is one of the hardest, because people would like to replace their battery with a fuel cell the same size. I'd love to be able to give it to them, but we're a long way from having something like that," Hallmark says. To realize this vision, the companies are pursuing varied strategies. New York City-based Medis Technologies believes it can make a fuel cell that could replace the cell-phone battery, providing 20 hours of cell-phone talk time and hundreds of hours of standby on a single fuel cartridge. Robert K. Lifton, Medis's chief executive officer, says the company is using a proprietary liquid electrolyte that can operate with higher concentrations of fuel and provide correspondingly more power than conventional alternatives. But Medis is not saying exactly how it works. "We have around 17 patents filed, and we're waiting to get them before we discuss the details," says Lifton. The business strategy, though, couldn't be plainer: it's the razor blade approach. "The payoff for us would be the refills," at about $1 per refill, explains Lifton. Another strategy involves carrying methanol as the fuel and then converting it when needed into hydrogen. Because hydrogen packs more power by weight than methanol, the scheme could produce more powerful and efficient fuel cells. Robert Savinell, a chemical engineering professor at Case Western Reserve University, is trying to build just such a small fuel cell; so far his group has built a 25-square-centimeter prototype.

The chemical conversion of methanol to hydrogen – often called "reforming" by engineers – is simple enough technologically, except when you try to do it on a thumbnail-sized device. "People have built reformers on a large scale for kilowatt applications, so the question is not whether it works. The question is whether you can make it small enough to fit in a cell phone or laptop," says Motorola's Hallmark.