By Jan TenBruggencate
Advertiser Columnist

One of the major issues with energy technologies is storage.

There is considerable discussion of new types of batteries, of fuel cells and other forms of storage.

And then there are some old ones.

Some folks have suggested, for instance, that solar and wind power — which provide power intermittently — could be used to pump water uphill to reservoirs. Later, at night or when the wind isn't blowing, it could be run back down through a hydroelectric generator to produce power when it's needed.

What about very short-term storage?

The standard uninterruptible power supply uses batteries, which require replacement and recharge costs.

One option, studied by NASA and power storage firms, is the flywheel, set to spin at extremely high speed and from which power can be drawn at will for short periods.

There's a flywheel energy storage system at The Honolulu Advertiser overseen by Bill Bogert, the paper's vice president of production.

The newspaper found that standard, battery-based uninterruptible power supplies weren't doing the job during power failures and fluctuations.

"Once we had a big rain storm and wind storm and this switching back and forth happened maybe seven or eight times during a 24-hour period. Well, the batteries couldn't recharge fast enough. They got depleted and the power went out," Bogert said.

The newspaper worked with Hawaiian Electric and the Texas firm Active Power to install a flywheel system with a rotor that turns at 7,700 revolutions per minute. Because the energy in a flywheel increases with the square of the velocity, that's a lot of power. In The Advertiser's installation, it provides enough energy to power critical systems for about 40 seconds, but it spins back up to full potential quickly.

"I don't believe we've had a single instance of sag or interruption or power surge affect our computers. Some lights and other things not hooked up to the system will go out, but everything hooked into the new UPS works fine," Bogert said.

It's the only system of its kind in the state, although flywheel uninterruptible power systems are a growing feature on the Mainland. A firm called SatCon Technologies is marketing a power backup system that uses a flywheel to flatten out power drops of less than 12 seconds, and then a big diesel generator to carry longer-term power drops.

Other technologies for short-term power production include compressed air storage, which works fine but can require a lot of space, and higher-tech solutions such as superconducting magnetic energy storage and super-capacitors.

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. You can call him at (808) 245-3074 or e-mail jant@honoluluadvertiser.com.