Joseph Weller, the manager of computer operations at Delta Dental has just purchased a hydrogen fuel cell car kit for his 10-year-old grandson's birthday. "I thought it was kind of cool," he said with a wide grin between sessions at the Afcom data centre conference in Florida, USA. But Weller said he has a professional interest in the toy car's energy system, too.

"We have to find alternative means of power -- we can't rely on current technology," said Weller, noting that if the fuel cell can move a 12-inch toy car, the technology may have the "capability of providing energy to a facility." The insurer has some 5.5 million members.

There's a growing interest in "green" technologies, even if data managers at this conference will readily admit that they don't see things like fuel cells arriving in their data centres anytime soon because of the technology's immaturity and cost. But efforts are under way to figure out how best to power data centres with alternative fuels.

The US Department of Energy and the National Institute of Health (NIH) have begun exploring whether fuel cell technology can be used to power the NIH's data centre facilities, said Paul Powell, data centre manager for the federal agency. Powell is interested in fuel cells, but finds it difficult to believe that the technology can power his data centres.

"As a data centre manager, I have concerns: It's going to take up an awful lot of space," he said.

Fuel cells rely on hydrogen and chemical reactions to produce energy, leaving water as a by-product. One company that introduced fuel cells last year for data centre use is American Power Conversion (APC), but the technology is intended for niche uses at this point. A fuel cell costs about 10 times that of a generator, and those firms that have either adopted fuel cells in data centres are typically located in high-rise buildings where generators aren't an option, or in situations requiring portable energy supplies.

"It's really in an experimental stage," said Steven Carlini, director of product management at APC.

APC's fuel cell technology, which can support up to 30kW of electricity -- about the amount some large blade servers use -- gets about 10 minutes from each tank of hydrogen, which are typically the size of a welder's tank. The fuel cell will continue to supply power as long as it doesn't run out of hydrogen fuel.

That's where Powell's concern about size comes in. He houses a 25,000-square-foot mainframe data centre and a separate 5,500-square-foot facility for Unix and Windows machines, which together use about one megawatt of energy a month. He envisions the need for a separate building just to house a fuel cell's power supply.

Brian Cihak, a network and data centre engineer at Bridgestone Firestone Retail and Commercial Operations, said he doesn't know if fuel cell technology has "quite reached the maturity that's needed yet, but it's certainly well on its way," he said.

With fuel cell use still somewhere down the road, other technologies are getting attention. Less exotic are flywheel technologies from companies such as Pentadyne Power, and Emerson Network Power's Liebert -- who are working together on that technology -- and Active Power. In the event of a power interruption, the spinning flywheels can provide power in lieu of batteries until the data centre generators kick in. A flywheel may provide power up to 30 seconds, but that is typically enough time for a switch to generator power to occur.

James Montanio, a system administrator at the Lower Colorado River Authority, is using flywheel technology and has a 20-second window to kick over to the generator. The system works, but he still has concerns about the amount of time needed for the generator to kick in.

But a benefit of the flywheel is that there is no need for batteries. "It's a little more green," said Montanio. "It's pretty efficient and there's not a lot of waste to it. There's no batteries to throw away."