On the Fly

Flywheel energy stortage eliminates the need for uninterruptible power supplies’ (UPS) lead-acid battery banks, which heightens reliability, longevity, uptime availability and safety.

Lower operating costs and reduced space requirements and maintenance are other benefits, and unlike lead-acid batteries, compact flywheel energy storage systems don’t require air conditioned space. You can roll one into a hot electrical room and wire it into the UPS just like a battery cabinet, in minutes.

Battery technology has proven costly, hazardous and of limited reliability in safeguarding equipment from power disturbances. Batteries require plenty of care and feeding, need frequent replacement, and too often simply don’t do the job when needed. That’s why healthcare facilities are having batteries hauled away in favor of a more reliable, compact and economical alternative: flywheel energy storage systems.

Flywheels store energy kinetically instead of chemically. So time, temperature and usage—each of which degrades batteries—don’t impact flywheels. Instead of replacing batteries every two or three years, flywheels spin for decades.

The latest models, using magnetically levitated carbon fiber cylinders, use less energy and half the space of a comparable 5-minute valve-regulated lead-acid (VRLA) battery set. Minor hardware maintenance intervals occur only once every six years.

How does this technology translate into the real world? Flywheel technology was set up at the Scripps Green Hospital’s Cardiac Catheterization Labs, La Jolla, Calif. California is sometimes plagued by rolling blackouts, and power is vital to hospitals. Lives actually depend on it.

For accreditation, hospitals are required to have emergency generators online and able to accept full load within 10 seconds of an outage. For example, the power needs of a catheterization lab are particularly stringent.

“If the power is interrupted during a procedure, the doctors have to start the procedure all over again,” said Alan Beyea, engineering services and operations manager.

Scripps Green Hospital’s cath lab was operating with a 250-kVA UPS combined with gel batteries, not enough power for an expansion. The hospital was under tight spacing requirements-, with only 300 square feet to accommodate the electrical equipment and batteries, which was simply not enough room to shoehorn in all the needed batteries.

“Dealing with batteries is especially problematic and expensive. Even in the first year, several cells in our battery bank went bad, so we’d replace the batteries at very short intervals—way before their stated end of life. In our circumstances, we just can’t take any risks,” Beyea said.

Beyea opted to use two Pentadyne flywheel systems to serve as energy storage instead of the battery bank for a new 500-kVA UPS. For this method of providing ride-through time until the backup generator could be brought online, the flywheel system is a safe, low-maintenance, environmentally responsible al  power—but for only for a short duration—to ensure transfer to the backup generator, the flywheel systems were ideal. Once the generator takes the load, the flywheel recharges rapidly, ready to immediately respond to any further disturbances.

The simple, modular system design enables easy paralleling for higher power, longer runtime or redundancy, all without troublesome communication links. This provides quick and easy expansion capabilities, which occurred in this case.

“That’s another of the great advantages of flywheel technology,” said Keith Field, Pentadyne’s vice president of marketing. “You can size the energy storage to load needs, not to the nameplate rating of the UPS, as is commonly done with batteries. As load grows, you can add a flywheel or two. You would never want to do that with batteries. Mixing old and new would be a disaster.”

“I was very impressed with the flywheel technology ... The previous gel-cell batteries were twice the size of the old UPS system,” Beyea said. “We now have 500 kVA of capacity taking up less room than our previous 250-kVA UPS with batteries.”

Pentadyne’s flywheel devices fully levitate a 50-pound spinning carbon fiber mass in thin air. And to keep that “air” exceedingly thin (to minimize aerodynamic drag), a maintenance-free integrated sleeve with tiny helical grooves keeps the inner containment at a near-space vacuum in between the 20-year factory recommended maintenance intervals.

Since the Scripps Green Hospital installation a few years ago, Pentadyne flywheels are backing up more patient care and IT equipment in hospitals.

Jon Harris, who heads electrical services at the 500-bed Sparrow Hospital in Michigan, became a quick fan of flywheels. After starting out with a small purchase of Liebert FS flywheels by Pentadyne, the hospital now has a total of 18 flywheels on UPS.

“Patients first. That’s what we are all about here,” Harris said. “With cardiac and neurological catheterization, there’s no room for a power glitch. That’s certainly [the attitude] everyone would want if they were on that table”

STONG-MICHAS, a freelance writer, lives in central Pennsylvania. She can be reached at JenLeahS@msn.com.

About the Author

Jennifer Leah Stong-Michas

Freelance Writer
Jennifer Leah Stong-Michas is a freelance writer who lives in central Pennsylvania.

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