AUSTIN, Texas -- Technology that significantly improves the ability of high-speed flywheels to store energy has been developed by research engineers at The University of Texas at Austin.
A flywheel made with the new technology set a speed record, spinning at 3,000 miles per hour, demonstrating the capability of storing 70 percent more energy than the same-sized flywheel made with current technology.
“This is an important step toward the routine use of energy storage flywheels in space,” said Kevin Konno, the NASA program manager for the project.
An example of the need for energy storage in space is the solar-powered space station, which spends 30 minutes of every 90-minute orbit in the dark. That’s when the space station turns to battery power. High-speed flywheels are being developed to provide more reliable, efficient and longer lasting energy storage.
Research engineers in the Center for Electromechanics at The University of Texas at Austin designed, fabricated and tested the record-setting flywheel in a project funded by NASA. The work is being done in collaboration with a space flywheel program at NASA’s Glenn Research Center in Cleveland and Test Devices Inc., a private test company, based in Hudson, Mass.
Composite flywheels store energy by rapidly spinning a small wheel to ultra high speeds. The technical challenge is obvious to anyone who has spent time on a child’s merry-go-round—when you are in the center, it is easy to hold on. As you get farther from the center, it gets harder to hold on. At these high speeds, the material of the flywheel itself has trouble “holding on” and the flywheel grows as it spins. The researchers solved the problem of controlling how the structure grew to achieve very high speed without breaking.
“This achievement is the result of our ability to design state-of-the-art complex objects using carbon fiber composites that have unprecedented, but predictable, mechanical properties,” Richard Thompson, the research mechanical engineer who led the development team.
The record-setting flywheel his team developed included a novel, bell-shaped composite structure rotating on a metallic shaft in vacuum that well suits the design needs of NASA’s future space missions.
High-speed flywheels offer several advantages over low-speed flywheels and the chemical batteries now considered for space applications. High-speed flywheels store and release energy in a package that’s smaller and weighs less than other technologies, thus allowing more space on board for scientific payloads.
High-speed flywheels also last longer. Last year, researchers at The University of Texas at Austin charged and discharged a flywheel 110,000 times with no change in performance. In addition, a flywheel system can be operated so that it wastes less than 5-10 percent of the energy stored as it is charged and discharged. By comparison, chemical batteries can typically be charged and discharged a few tens of thousands of times at best and typically waste more than 20 percent of the energy on charging and discharging.
NASA’s flywheel achievements, while directed toward space applications, are also expected to benefit companies using flywheels to improve power delivery for factories, businesses and hybrid vehicles.
“Records like this should provide confidence to potential customers of the new companies, like Active Power Inc. of Austin, that are marketing high technology flywheels,” said Dr. Bob Hebner, director of the Center for Electromechanics, “The university sets records to show how far the technology can be advanced. Companies can use the results both to improve their products and to help show that commercial levels of performance are readily achievable with today’s technology.”
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