In yesterday's article, we saw how Moore's law has created a demand for power that today's rechargeable batteries are having trouble keeping up with. For the long term, most vendors have pinned their future hopes on fuel cells. What are their prospects?

Potential - and challenge
Government and private investments in fuel-cell research have been substantial, and more than 60 companies are working on designs to power electronics, says Jim Balcom, president and CEO of PolyFuel in Mountain View, California.

Fuel cells combine a fuel such as hydrogen or methanol with oxygen in an electrochemical reaction. The most popular design, the direct methanol cell, uses methanol or a methanol/water mix. Fuel cells show promise in delivering dramatically higher energy densities, and the ability to swap out fuel cartridges could guarantee a virtually endless power supply. As little as 1cc of fuel can generate 1Wh of electricity - enough to power a cell phone for about two hours, says Alan Soucy, chief operating officer at MTI MicroFuel Cells in Albany, N.Y.

But the technology faces several challenges. Fuel-cell systems are complex, requiring

  • an engine, or "stack"
  • tiny pumps, sensors and other electronics
  • a venting system and
  • a fuel tank (see diagram below)
. Squeezing them into something the size of a notebook battery that can be sold at a reasonable price and that works reliably is a major engineering hurdle.

Fuel cells are also relatively inefficient - turning 70 percent of the energy they produce into waste heat vs. 10 percent for batteries - which is a problem for notebook designers, who are already facing thermal challenges. And the systems vent small amounts of carbon dioxide and water vapour.

Fuel cells also don't respond well to sudden spikes in power demand, so early designs, such as Intermec Technologies' fuel-cell-powered IP3 radio frequency identification (RFID) reader prototype, are coupled with a lithium ion battery. The IP3 fuel cell, an MTI design, trickle-charges the battery in addition to directly powering the RFID reader. The unit runs for 30 hours on a 55cc fuel cartridge compared with about 10 hours for a traditional battery. Other vendors are experimenting with ultra-capacitors, solid-state devices that can deliver short bursts of supplemental power to handle peak loads.

Prototypes are on view
"Toshiba's big investment is in fuel cells," says Pinto. Toshiba, Hitachi and NEC have shown prototype "swap bay" designs that attach to a notebook or handheld, with internal units to follow. But real products won't come until standards are ironed out. A standard fuel mix and cartridge design is needed for broad acceptance, and regulators still need to approve its safety and use, particularly on airplanes. Getting Federal Aviation Administration approval to carry the flammable methane tanks onboard commercial flights may not be easy, given the agency's recent ban on butane lighters.

Approval of fuel-cells for use on planes is likely to come slowly, but already a UN expert committee has approved their carriage in planes' cargo holds.

ABI Research's Ozbek says fuel-cell makers have made significant strides in the past six months, reducing the package size by 50 percent while surpassing the energy density of lithium ion in test units. Early fuel-cell power packs will ship this year and next, ramping up to a few thousand units in 2007. "Then it's going to be millions by 2010," he says.

NEC agrees that fuel cells won't come into use till 2007. In the meantime, new fuel cell designs are likely to better performance and lower prices. To avoid the confusion that multiple designs will cause, the IEC standards body has set up a group to define power and packaging standards for fuel cells.

Till then, eke out your power
In the interim, users will have to make do by dimming screens and using the power-saving features available to them. Those features can help, says GM's Scott. Strategies to prolong battery life are more subtle than you might think - read our primer on saving power.

But power-saving alone isn't going to close the power gap, he adds. "Batteries have been the boat anchor in terms of real progress."

Next: Buying spare batteries seems like a good idea. But don't get burned with knock-offs

Batteries and fuel cells