Utilities eye energy storage solutions

A 20 MW flywheel-battery system proposed for upstate New York is the latest effort to introduce large-scale energy storage into utility operations. Developers see the systems as peak-shaving resources and as a means for helping manage intermittent renewable resources.

The proposed $50 million Stephentown, N.Y., project would incorporate an array of 200 flywheel batteries over several acres. The batteries’ manufacturer, Beacon Power Corp., Tyngsboro, Mass., claims its equipment offers faster response than traditional peak-shaving generating plants, enabling rapid power-balancing capabilities for grid operators.

The project is awaiting final environmental approval from local authorities, and its application is pending with the New York Independent System Operator, which controls the state’s electrical grid.

Utility giant AEP, Columbus, Ohio, is planning to install at least two 2 MW sodium-sulfur batteries in its transmission system by the end of this year, the first step in a plan to boost its energy-storage capabilities to 25 MW by the end of 2010, and 1,000 MW by 2020. The company sees the technology as a necessary addition to successful integration of wind-energy resources, which are most plentiful during low-demand nighttime periods.

Compressed-air energy storage (CAES) is seen as a possible resource for demand balancing and for evening out wind-farm generating capacity. The technology involves pumping air under pressure into underground storage facilities—including suitable natural geologic formations and retired salt mines—and releasing and heating it to drive a turbine generator. An Alabama CAES plant has operated since 1991, but interest has waned since that facility was commissioned. However, Iowa’s municipal utilities banded together to propose the Iowa Stored Energy Project, scheduled to go online in 2013 as a load-balancing strategy. A prototype CAES design for use in wind-farm development is scheduled for completion in 2012, with manufacturer General Compression, Newton, Mass., now seeking potential sites in wind-rich Texas, California, or the Rocky Mountain states.

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