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Energy

A Fuel Cell in Your Phone

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, NM, 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 five-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, of course, 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 (see “Fill ‘er Up with Hydrogen,” TR November/December 2000). Fuel cells that provide backup power for homes and offices are becoming available, too (see “Power to the People,” TR May 2001). 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, NY. “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, NY-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. As long as there’s a supply of hydrogen or methanol, the fuel cell will produce 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 toughest of all. The design challenges for micro fuel cells start with the choice of fuel. Hydrogen is impractical; it’s a gas and must be compressed at very high pressures, and even then it requires tanks too large for portable electronics. Methanol/water mixtures are more easily stored in a small fuel cell, but using them creates new engineering hurdles. To manage a liquid fuel, tiny pumps and pipes are required. Then there’s the waste water. Not even the most ardent cell-phone users would tolerate power supplies that drip on their shoulders, so fuel cells must evaporate the water. All fuel cells create heat; the small versions operate at anywhere from 15 degrees C to a scalding 60 degrees C. While this provides a means to evaporate waste water, it also requires the right balance of insulation and venting.

Cramming all of this into a nifty package the size of a couple of AA cells presents a real challenge. And given the fierce competition to commercialize a micro fuel cell, most corporate players are cagey about how they’ve begun solving these problems. “There is a lot of posturing among the companies, but that is what you’d expect in the early stages as they try to maintain their positions,” says fuel cell watcher Chris Dyer, editor of the Journal of Power Sources. But, he adds, “This isn’t smoke and mirrors. It’s a real technology and just requires some clever engineering to make it work.”

Most observers predict that the first micro fuel cell on store shelves will be a charging device using methanol. A half-dozen companies are working 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 by side, like components on a microprocessor, making them amenable to semiconductor-manufacturing techniques.

Mechanical Technology has already cofounded a company that sells refrigerator-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 the prospects for commercializing this,” says Mechanical Technology’s Gottesfeld, former director of the Los Alamos lab’s fuel cell research program. “We are not only looking at chargers but a complete system for cell phones. We’re also looking at other possibilities like laptops, the toy market and power tools.”

Motorola and Korea’s Samsung are also actively developing prototypes. Hyuk Chang, a principal researcher at the Samsung Advanced Institute of Technology outside of Seoul, says the company’s goal is to demonstrate working models in a year, again with charging devices leading the way. “I think it will take another two years to get from the lab into customers’ hands,” says Chang. “The hard question is what will be the first application.”

At Motorola, fuel-cell project leader Jerry Hallmark is pursuing a strategy that promises smaller fuel cartridges. He says the company has developed tiny fluid systems that would continually recycle the water in the methanol-water fuel mixture. Replacement cartridges could just carry undiluted 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 any company-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. He says Medis will have a prototype by the end of this year.

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.

Chip Power

Beyond the day when electronics come with built-in fuel cells instead of batteries, another technology frontier looms: building fuel cells directly on chips. Already, Savinell’s group at Case Western has built a prototype only 1.5 centimeters by two centimeters. His group used microfabrication techniques to “print” five to six layers of fuel cell components-the membrane, electrode and catalyst-on ceramic and silicon wafers, and more recently on a flexible polymer material. At this scale, he’s using hydrogen as a fuel, stored as sodium borohydride and released with a platinum catalyst. “The hope is to provide power on a chip with a sensor and a transmitter-a totally self-sufficient device,” Savinell says.

Researchers at the Georgia Institute of Technology, MIT, Stanford University and Sandia National Laboratories in Livermore, CA, are also working on building chip-scale fuel cells. To make these devices run on easily stored methanol, Paul A. Kohl, a professor of chemical engineering at Georgia Tech, is fabricating tiny channels on silicon through which methanol and water can pass. These channels could be created on a conventional silicon-chip assembly line. “You could design the fuel cell to supply exactly the power you want and be the size you want,” says Kohl.

Beyond shrinking fuel cells to the chip scale, another long-term goal is enabling fuel cells to directly tap the power of hydrogen but avoid high-pressure tanks. One ambitious approach would make use of carbon nanotubes: pipelike carbon molecules that have the ability to store and release hydrogen. Researchers envision nano canisters full of hydrogen that could keep fuel cells humming, but this will require breakthroughs in materials and manufacturing methods, says Michael Heben, leader of a nanostructured-materials group at the U.S. Department of Energy’s National Renewable Energy Laboratory in Golden, CO. “It could be that someone puts their finger on this in the next week, or it could take 20 years,” he says.

The most credible, reproducible results to date, says David Tomanek, professor of physics at Michigan State University, were achieved by Mildred Dresselhaus, a physicist at MIT, and colleagues at the Chinese Academy of Sciences who reported finding a way for carbon nanotubes to store 4.2 percent of their weight in hydrogen. That may be enough for micro fuel cells, Tomanek says. “It will be lighter, smaller and safer than a tank, even at four percent, and this could be done in a couple of years. But I am an optimist,” he says. Dresselhaus herself is more guarded: “At the moment, we don’t have the magic wand. We have an opening that says, This is something to look for.’ The next step is still missing.” That next step could come within this decade, she adds, but “we need to have a major breakthrough.”

Other electronics giants are also experimenting with carbon molecules to improve micro fuel cells. NEC has reported using horn-shaped molecules known as carbon nanohorns as a substrate for platinum catalysts, providing more surface area for stronger chemical reactions and more power. And Sony says it is using soccer-ball-shaped carbon molecules known as fullerenes-the base components of carbon nanotubes-to construct better electrolytes.

Meanwhile, the first micro fuel cells are rapidly nearing the market. Of course, the prototypes need continual fine-tuning to make sure fuel can’t leak and to increase their efficiency. But these hurdles are relatively minor, industry watchers say. After all, batteries had their share of development troubles, too. The first high-energy lithium batteries tended to catch fire and even explode. As any cell-phone owner knows, those problems were solved.

There are plenty of reasons-about $6 billion worth, in fact-to suggest the same will happen with micro fuel cells, putting these remarkable tiny power packs in millions of consumers’ pockets. Indeed, as micro fuel cells emerge from cluttered labs like the Los Alamos outpost of Manhattan Scientifics, they may put batteries, with their limited power and heavy-metal waste disposal headaches, into technology’s recycle bin.

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