Flywheel Energy Storage Summary A flywheel, a component of all automobiles, consists of a wheel whose heavy weight resists sudden changes of speed, thereby securing uniform motion in the working parts of a car engine. Less commonly known is that they have energy densities hundreds of times that of lead-acid and other chemical batteries and can store and discharge energy often and rapidly. Flywheel storage systems operate at speeds exceeding 60,000 revolutions per minute (rpm). Performing functions similar to that of batteries, they can fill in the peaks and valleys of electrical loads by charging during off-peak hours and discharging in peak hours. Functioning in this manner, flywheels can save energy costs for the home owner. A sufficient number of homes with flywheels can also help defer the use of expensive utility peak shaving plants or the construction of new power plants to meet increasing energy loads. Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the U.S. Department of Housing and Urban Development (HUD/FHA), The Partnership for Advancing Technology in Housing (PATH), or any PATH-affiliated Federal agency or private company. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.
Details By rotating a flywheel in an minimum-friction environment, it can store energy. To store sufficient energy to make it useful, the rotors must spin very fast. A flip of a switch turns on electric current, powering a permanent magnet motor/generator that sets the wheel into motion. A typical unit has a carbon fiber rotor causing the flywheel to spin on nearly frictionless bearings in a vacuum casing that reduces losses from wind. Although flywheel units need not be small and light to fit in a residential environment, a 50 kWh unit discharging at 10 kW, a rate exceeding the needs of a typical residence, would be about the size of a coffee pot. Recent technology developments have facilitated the possibility of economical residential designs: lower cost, compact electronic controls for power reduce the expense and size of components; stronger fibers from the sporting goods industry contribute to stronger, low-cost rotors; and, miniature motors developed for computers provide magnetic materials for flywheel brushless motors.
Installation In the few large, commercial, utility, and industrial applications, the two most common methods of installation are mounting the entire system in the ground or above ground on a floor. The whole unit is welded shut.
Benefits/Costs Flywheels last ten times longer than batteries, use no hazardous chemicals, tolerate nearly any temperature, and require less maintenance than batteries. Consequently, depending upon the application, they have a long potential life of 20 to 40 years. Researchers have proven flywheel components and feasibility of systems and need no fundamental technological breakthroughs to propel flywheels into the market. Claims are that flywheels are especially feasible for smaller, niche stationary applications within 10-250 kw, a range suitable for residential use. The cost of flywheel materials, about $400 -$500 per kWh, is declining and materials account for about 65 - 75 percent of cost. The installed cost of the most common configuration, a 50kW/5kWh product for non-residential use, is $30,000, but the projected cost for a 600W/0.5kWh unit for the residential market is $3,000.
Limitations The principal limiting factor for entering the residential market is high cost. The challenge is to move the technology significantly lower on the cost/performance curve. The main technical barrier is to develop containment systems for handling instances of malfunction. Because of the possibility of dangerous projectiles falling off during failure, designers prefer composite materials, or more commonly graphite, for flywheels. These materials are easier to contain in case of failure than metal.
Code/Regulatory The chief obstacle in the near-term is the development of safety protocols and standards for cases of functional failure.
Availability Despite the absence of major technical barriers, no commercialization of small stationary flywheel systems suitable for residential use has occurred yet. Limited commercialization of larger scale non-residential uses has taken place . A number of companies, however, claim to be developing smaller stationary applications appropriate for residential use. One company reported that a residential flywheel technology had reached the fundable stage and that an agreement on investment was pending.
Contact(s) Do you have a specific question about this technology and/or its 'real life' applications? Try the contacts listed below: Oak Ridge National Laboratory
P.O. Box 2008
Oak Ridge, TN 37831
www.ornl.gov Nth Power Technologies
50 California Street
Suite 840
San Francisco, CA 94111
415- 983-9983
Fax: 415-983-9984
www.nthpower.com Salt River Project
1521 N. Project Dr.
Tempe, AZ 85281-1298
Phone: 602-236-4741
www.srpnet.com Arizona State University
University Drive & Mill Ave.
Tempe, AZ 85287
480-965-9011
www.asu.edu Flywheel Energy Systems, Inc.
25C Northside Rd.
Nepean, Ontario
CANADA K2H 8S1
613-596-0856
Fax: 613-596-6052
www.magma.ca/~fesi |
