By Paul Eng
Laptop and portable computers are getting faster
and more powerful processors. Bright, colorful display screens are appearing
on ever-smaller cell phones. And handheld computers are turning into wireless
radios to send and receive Internet data.
But all of these snazzy features have at least one thing in common: They demand lots of electrical power. And experts say current rechargeable-battery technology hasn't progressed at the same pace as these other portable technologies, leaving a so-called power gap.
But bridging that gap may now be possible through fuel cells, a clean-energy technology that produces electricity from the chemical reactions between hydrogen and oxygen.
Developed as part of NASA's 1960s space program, fuel cells are "nonpolluting" since the only byproduct to power production is pure water. For decades, much of the attention for this clean-energy technology has been focused on large applications — alternative power plants and new "engines" for cars.
But at the National Building Museum in Washington, D.C., last week, President Bush and other government officials were shown how fuel cells could be used for other purposes.
Companies such as MTI MicroFuel Cells Inc. in Albany, N.Y., for example, showed off a portable fuel-cell device that could provide power to cell phones and laptops for days and weeks on end.
To spur such thinking "beyond the normal," President Bush called for Congress to budget $1.7 billion over the next five years for the further development of fuel-cell technology.
Such money will undoubtedly be useful in helping to overcome many of the obstacles that still remain in making fuel cells practical for everyday use — especially in portable devices.
In addition to making hydrogen fuel readily available and safe, researchers will need to find ways to shrink the size of fuel cells even further without sacrificing efficiency.
Developing a Denser Power Cell
Neah Power Systems, a fuel-cell technology company in Bothell, Wash., thinks it is on the right path to more portable power.
On Monday, the company unveiled a patent-pending fuel-cell design that could fit within the case of an ordinary laptop computer battery, yet provides two or three times the power. The key to the new fuel cell, the company says, is its unique internal makeup.
Most traditional fuel cells rely on a so-called proton exchange membrane or PEM. Typically made of a flat sheet of precious metal such as platinum, the PEM provides the catalyst that causes hydrogen to give up its electron and produce electricity in the fuel cell.
Instead of a flat PEM, Neah's proposed fuel cell uses a block of material made of "porous silicon." Each microscopic pore of the material contains particles of catalyst that converts the hydrogen into electricity and water.
By "stacking" the reaction through the material's microscopic honeycomb-like maze of pores and tunnels, Neah's CEO David Dorheim says the technology allows for a much higher "energy density."
"The PEM is an old technology where you need very large surface areas to create reactions," says Dorheim. "Our stacked porous silicon allows for the same reactions to occur in a denser and smaller package."
The Power of Porous Silicon
Another advantage of the stacked porous silicon, says the company, is that it's much less prone to "fouling" when used with liquid methanol, an alcohol fuel seen as the safer alternative than using pure hydrogen in portable fuel cells.
When traditional PEMs encounter this fuel, the reaction generates carbon residue that can produce carbon dioxide gas and carbon residue that collects on the PEM plate. Eventually, such carbon byproducts deteriorate the efficiency of the fuel cell.
Neah says since its porous silicon would contain millions of microscopic tunnels, it can maintain its energy-producing capabilities far longer than flat PEM plates. What's more, producing the silicon block would use existing silicon chip-making technologies, which could make Neah overall fuel cell cheaper to build than traditional engines.
Also, Dorheim says that Neah's system would be completely self-contained. A replaceable "fuel tank" would provide both the liquid methanol and an oxidant to produce power within the fuel cell. Separate bladders within the tank would collect the water and carbon-dioxide byproducts.
Dorheim says that such a self-contained fuel cell system would reduce the inconvenience among users. By simply replacing the tank on a dying fuel cell, users would get additional "run time" on their device while getting rid of potentially damaging excess water.
J. Gerry Purdy, a mobile electronics industry analyst with MobileTrax in Cuertino, Calif., agrees the stacked porous silicon technology is fairly impressive.
"They are able to use a silicon-based strategy that can make extremely small 'batteries' with a large [electrical] capacity," says Purdy. "That's a real breakthrough."
However, experts says that portable fuel cells — like their larger stationary counterparts — still have a long way to go before they become ready for widespread use.
Chief among the issues involve the fuel itself.
Much like the automobile industry, mobile electronics makers will have to work with retail outlets and other partners to develop the infrastructure to easily supply the fuel to consumers.
Also, the fuel-cell industry will have to work out safety and regulations issues with the federal government. Current regulations, for example, prohibit passengers from carrying fuels aboard commercial airliners. That means mobile workers wouldn't be able to take advantage of the technology during long overseas flights.
Fuel-cell advocates are confident, however, that all the parts will come together soon — especially with Bush's recent push toward more research.
Neah's Dorheim says researchers are already working with organizations such as Underwriters Laboratories to address safety issues and it will be only a matter of time before federal regulations are adjusted to accommodate fuel cell use.
Still, even advocates acknowledge fuel cells most likely won't be widely available for another two or three years.
Fuel - Cell Technology
By Paul Eng