UPS designed to help you go green

Flywheel technology, found in everything from potter's wheels to airplane altitude-control systems, has also found a home in UPS systems for data centers.

Active Power this week plans to introduce its latest UPS that relies on a flywheel-based energy-storage system. The company eschews the use of lead batteries in its CoolAir DC, which provides 85 kilowatts of power for as long as 15 minutes and is intended for power-backup applications in the 10 to 100kVA (kilovolt ampere) range found in small data centers.

What's more, the flywheel-based device cools the data center as it powers it.

A flywheel consists of a heavy rotating disk that, as its momentum increases, energy is stored as electricity. When power is disrupted, the inertia of the flywheel continues to generate electricity, which can be used to power the data center until a backup generator kicks in.

Starting at $29,000 ($8,000 leased for one year), a CoolAir DC costs roughly the same as a lead-acid battery model, Active Power says. While a conventional battery must be changed or recharged every three to four years, flywheels have a lifetime of about 20 years. During that time, the bearings that hold the flywheel in place need to be replaced.

CoolAir DC is designed to work with a traditional UPS or with a backup generator.

"Lead-acid UPSs consume a lot of space in data centers and are sensitive to conditions prevailing in data centers, such as dust and temperature," says Farah Saeed, an industry analyst for Frost & Sullivan. She says flywheel-based systems make up just a fraction of the multibillion-dollar UPS market. "They also generate a lot of heat, which causes degeneration of the UPS itself. On the other hand, flywheels can better handle voltage sags and surges and situations that could slowly drain the batteries of a traditional UPS."

Freescale Semiconductor in Austin is among the companies that has installed Active Power flywheel-based UPS systems. A spokesman says the systems have proved effective and environmentally friendly.

"Active Power has played a successful role in helping us manage through power disturbances this past year which were caused by bad weather or power surges," the spokesman says. "It has helped us avoid lost production time and lost product, thereby resulting in cost avoidance."

Active Power, which started in 1992, competes with such companies as American Power Conversion and Emerson Network Power. The latter recently introduced a flywheel-based UPS that can support as much as 150kVA.