New Battery Holds the Wind

Groundbreaking project offers new technology to store energy generated by breezes.

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Testing begins soon on Xcel Energy’s cutting-edge technology to store wind energy in batteries. The company says it will be the first use of the technology in the United States for direct wind energy storage.

Integrating variable wind and solar power production with the needs of the power grid is an ongoing issue for the utility industry. Xcel Energy will begin testing a one-megawatt battery-storage technology to demonstrate its ability to store wind energy and move it to the electricity grid when needed. Fully charged, the battery could power 500 homes for more than seven hours. Xcel Energy has signed to purchase a battery from NGK Insulators Ltd., an integral part of the project. The sodium-sulfur battery is commercially available, and versions of the technology are already being used in Japan and in a few U.S. applications, though the Excel project is the first U.S. application of the battery as a direct wind energy storage device.

The 20 50-kilowatt battery modules are roughly the size of two semitrailers and weigh approximately 80 tons. They store about 7.2 megawatt-hours of electricity, with a charge/discharge capacity of one megawatt. When the wind blows, the batteries are charged. When the wind calms down, the batteries supplement the power flow. The project will be located in Luverne, Minnesota, about 30 miles east of Sioux Falls, South Dakota. Battery installation begins this spring, adjacent and connected to a nearby 11-megawatt wind farm owned by Minwind Energy, LLC. The battery is expected to go on-line in October.