(WEB HOST INDUSTRY REVIEW) — In addition to offering lower lifecycle costs, quick recharging capabilities, and high reliability, the main reason IT infrastructure services provider Terremark (www.terremark.com) chose flywheels for backup power at its new Santa Clara data center is because of their small size.
A flywheel power system works like a mechanical battery, storing energy kinetically in the form of a rotating mass, which is immediately convertible to DC power. Like a lead-acid battery bank, it connects to the DC bus of a UPS, charging from the bus and returning power whenever the bus voltage droops below a threshold level. Unlike large metal flywheels of the past that weigh hundreds of pounds, new materials let flywheels take up about half the footprint of valve-regulated lead-acid batteries, and about a fifth that of wet cells.
In an interview with SearchDataCenter.com, Terremark facilities engineering senior vice president Ben Stewart said, “The biggest reason we go with flywheels is that [they take] up so much less room. You don’t have to set aside so much space for the battery room. Plus flywheels can sit in pretty much any weather, they weigh less and, with battery strings, you have to swap them out every five years at $100,000 a string.”
Contrary to the more traditional battery-based UPS that uses hazardous chemicals in storing energy, the flywheel system stores energy in a silent, spinning, composite flywheel cylinder to provide a reliable and predictable source of power. They offer a cost-effective, reliable, safe and environmentally responsible solution. Unlike lead-acid batteries, flywheels require minimal maintenance, are temperature-tolerant and withstand hundreds of thousands of cycling events without degradation.
Terremark, however, is not the only company to choose a flywheel system over a battery-based UPS. In 2006, web hosting and other online services provider NetAlliant (www.netalliant.com) installed a Pentadyne (www.pentadyne.com) carbon-fiber flywheel, which has been able to successfully respond to an average of 25 to 50 power disturbances per quarter, all the while taking up less space than previous UPS solutions.
NetAlliant president John Smith said in a statement, “We were very impressed with the smaller footprint and nearly maintenance-free aspect of this flywheel.”
The battery-free flywheel UPS kicks in to provide seamless power protection for all short duration disturbances and outages. Ninety-nine percent of all power disturbances are 10 seconds or less, according to a study from utility trade organization, the Electric Power Research Institute (www.epri.com). Disturbances lasting significantly longer are gradually handed off to NetAlliant’s 250-kVA backup generator.
“We’re also impressed with the look of the units. We located the UPS and flywheel out in the open so we can bring customers to our offices to see the system,” Smith said.”Having this level of protection assures our customers and prospects that we take power protection seriously and that their servers are protected 24/7/365 against whatever the utility throws at us.”
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