Could a Maglev Flywheel Save Your Datacenter? - Page 2

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Competing with batteries

Olsen said that flywheels compete with batteries. Batteries must be carefully monitored.

He admitted that flywheels also have to be carefully monitored, and that Active Power's system track 150 telemetry points, but he said that when the flywheel's spinning, you know it can deliver the power, whereas it can be difficult to be certain that batteries can provide the power they're rated for.

Olsen said that Active Power flywheels use less space than a battery-powered UPS and waste less energy. Batteries are 92 percent efficient, but flywheels are 98 percent efficient, he said. Flip the numbers around, and batteries waste eight percent of the power they store, while flywheels only waste two percent, making them four times better by this metric, Olsen said.

Wasting less is more green, he added. The overall solution has one-fourth the carbon footprint of a comparable battery-based solution, Olsen said.

He said that flywheels are more reliable than batteries -- seven times less likely to fail, he claimed -- but admitted that datacenter owners have expressed some skepticism about them.

"In the beginning, the biggest concern was that we deliver 15 seconds of power and batteries provide 15 minutes. Some customers are still concerned about getting their generator started within 15 seconds, but that has never been a problem and never will be a problem because generators are federally mandated to start in five to eight seconds for critical environments, such as life support for a hospital, and generator manufacturers don't make different kinds of generator," Olsen said.

"Some people want the extra time in case they need to attempt to start the generator manually," Olsen added. "But if the generator doesn't start the first time ... the issue is likely that there's no fuel or bad batteries or water in the lines from condensation."

"Sometimes the emergency stop button is still set to manual," Olsen said. "People press the emergency stop button because they don't want the generator to start while they're doing maintenance and sometimes they forget to press it again."