Battery Power - May/June 2012 - (Page 9)

Flywheel Energy Storage – A UPS Battery’s Best Friend Dann McKeraghan, Vice President VYCON In today’s mission-critical facilities, the role of the uninterruptible power system (UPS) has changed from providing enough back-up time to shut down IT systems safely to one of providing a “bridge” to a facility’s diesel generator-set for continuous power availability. Traditionally, facilities have depended upon UPSs with valve-regulated lead-acid (VRLA) batteries to provide energy during short-term power disturbances, diesel generators (gensets) for longer-term outages, and control electronics to bridge the two. However, flywheels paired with UPSs are common purchases among facility and data center managers looking to enact sustainability initiatives and reduce total cost of ownership (TCO), while still maintaining high 9s of availability. The leading cause of a UPS failing to support the load is battery failure. Battery life is impacted by number of cycles, temperature and maintenance. Flywheel technology when combined with lead-acid batteries will extend the run time and reduce battery cycling, which reduces battery life. Flywheel Basics The flywheel works like a dynamic mechanical battery that stores energy kinetically by spinning a mass around an axis. Electrical input spins the flywheel rotor up to speed, and a standby charge keeps it spinning 24/7 until called upon to release the stored energy. The amount of energy available and its duration is proportional to its mass and the square of its revolution speed. In the flywheel world, doubling mass doubles energy capacity, but doubling rotational speed quadruples energy capacity: E = kMv2 k – Depends on the shape of the rotating mass M – Mass of the flywheel v – Angular velocity During a power event, the flywheel will provide backup power seamlessly and instantaneously. In research conducted by the Electric Power Research Institute (EPRI), they concluded that 80 percent of all utility power anomalies/disturbances last less than two seconds and 98 percent last less than 10 seconds. In the real world, the flywheel energy storage system has plenty of time for the Automatic Transfer Switch (ATS) to determine if the outage is more than a transient and to start the generator and safely manage the hand-off. From 40 kVA to multi megawatts, flywheel systems are increasingly being used to assure the highest level of power quality and reliability in a diverse range of applications. The flexibility of these systems allows a variety of configurations that can be custom-tailored to achieve the exact level of power protection required by the end user based on budget, space available and environmental conditions. In any of these configurations, the user will ultimately benefit from the many unique benefits of flywheel-based power protection systems, including: • No down time for regular maintenance (no bearings to replace) • High-power density, small footprint • Scalable / Parallel capability that allows for future expansion • Fast recharge (under 150 seconds) • No special facility requirements • No special / additional cooling required • Low maintenance • 20-year useful life • Simple installation • N+1 redundancy options • Quiet operation • Wide temperature tolerance VYCON Article Continued on Page 10 Figure 1. During a power event, the flywheel is the primary (first) source of backup power. During a power disturbance or complete power failure from the grid, the flywheel will discharge first and immediately support the load. For applications where longer runtime is required, such as syncing multiple generators or when input power failure is frequent, the combination of a battery and flywheel (battery hardening) can help improve battery life and UPS system reliability. Additionally, a “walk-in” of the battery is managed by the flywheel, eliminating a harsh step-load demand (Coup de Fouet or whiplash) on the battery, thereby removing one more factor of battery life reduction. www.BatteryPowerOnline.com May/June 2012 • Battery Power 9 http://www.BatteryPowerOnline.com

Table of Contents for the Digital Edition of Battery Power - May/June 2012

Battery Power - May/June 2012
New Battery Interface Specification to Address Key Consumer and Manufacturers’ Issues
Demand Spike for Backup Power Systems Stokes Growth in the Global Stationary Lead Acid Battery Market
Battery Management Considerations for Large Cell Count Systems
Flywheel Energy Storage – A UPS Battery’s Best Friend
Zero-Volt: Medical and Satellite Battery Technology Can Help Improve Safety of Electric Vehicles
Second Edition of IEC 62133: The Standard for Secondary Cells and Batteries Containing Alkaline or Other Non-Acid Electrolytes is in its Final Review Cycle
Batteries
ICs and Semiconductors
Charging & Testing
Components
Power Supplies
Industry News
Marketplace
Calendar of Events
Research and Development

Battery Power - May/June 2012