Concerns over exploding computer batteries may be heating up, but alternative power sources for portable devices like laptops, music players and cellphones could still be up to 10 years away.

Sony Corp., Matsushita Electric Industrial Co. Ltd., Hitachi Ltd., Toshiba Corp. and MTI Micro Fuel Cells are among those racing to develop fuel cells, which produce electricity from an external supply of fuel as opposed to a battery's internal storage capacity.

They are leading the charge for more efficient power systems to keep up with revolutionary changes in consumer gadgets. Laptops, once used primarily for creating documents and spreadsheets, are now hubs for power-eating tasks like video conferencing, hosting websites and interactive games.

At the same time, consumers are starting to watch full-length movies on pocket-sized digital players, or view live television on mobile phones.

There is nothing in the near term that can satisfy all the requirements that have to come from a battery, It has to be light, small, last a long time and relatively safe, said NPD Group analyst Stephen Baker. They haven't come up with a chemical combination yet that can satisfy all those requirements.

The prevailing technology to power gadgets is lithium-ion batteries, which experts view as relatively safe despite last month's recall of a total of some 6 million notebook PC batteries by Dell Inc. and Apple Computer Corp..

In both cases, the batteries were made by Sony and were recalled on fears they could overheat and catch fire.

This month, Matsushita, best known for its Panasonic brand, recalled 6,000 PC batteries for similar reasons. This follows other recent red flags over lithium-ion, including Kyocera Corp.'s recall of 1 million cell phone batteries due to overheating.

SOME IMPROVEMENT

Engineers have struggled to efficiently fuel 21st century devices with battery technology developed decades ago.

Improvements have come from companies like Valence Technology Inc., whose systems are used by motorized scooter maker Segway. Under its Saphion technology, Valence's lithium-ion batteries use chemicals that are less likely to ignite, the company says.

Altair Nanotechnologies Inc. says its batteries can be charged more often than conventional rechargeable batteries because of the absence of particle fatigue that occurs in lithium-ion batteries.

UltraLife Batteries Inc., privately-held Zinc Matrix Power and Optodot Corp. are among those boasting systems that keep batteries safe.

Still, analysts are unconvinced these evolutionary systems can keep up with the changes in gadgets.

In time, fuel cells will be able to supply 10 times more power, and will be instantly recharged. But mass deployment is years away, after a long period of testing and tweaking, analysts said.

The next step is fuel cells, but (they) are a little way away, said Jim Tully, chief of research at Gartner. In five to 10 years, fuels cells will become an integrated replacement for conventional batteries.

Unlike other technologies, where engineers, for example, put more chips on a circuit or build larger plants for display screens, battery science involves raw elements. Chemicals like nickel and lithium are not as easily manipulated.

Battery technology is energy technology (and) it is not growing as fast as compared to microprocessors or hard drives, said Peng Lim chief executive of MTI Micro Fuel Cells, a unit of Mechanical Technology Inc. It is created by chemical reaction (and) we extract energy. Every time you get a breakthrough next generation technology, it takes some time.

Brian Kimberlin, director of marketing for Panasonic Battery Corp of America, a unit of Matsushita, said they have developed a fuel cell technology for laptops, but it would take three to five years to get it to the marketplace.

We are very cautious and we don't rush anything to the market. We want to make sure things are working properly and safe, he said.