Stephentown Flywheel Failure Still A Mystery

by David Flint
Beacon Power CEO Bill Capp, speaking to investors on Tuesday at a presentation of the company’s second quarter financial results, made mention of the flywheel failure that occurred in their Stephentown plant on July 27. Capp said that with all the flywheels operating in a 20 megawatt frequency regulation plant, it is assumed that there will be a limited number of failures and funds have been set aside to deal with that. At Stephentown, he added, everything worked the way it was supposed to. The other 199 flywheels continued to operate normally so that the grid operator was not even aware that there was a problem. The flywheel that failed has now been replaced and the plant is back operating at its full 20 megawatt capacity.
The company, he said, is still in the process of gathering data to figure out exactly what happened to cause the failure. Their initial conclusion is that there was a defect in the flywheel hub that somehow had made it through the post-manufacture inspection process.