Xcel Energy on wind-to-battery technology: ‘it works’

August 6, 2010

The nation’s top utility for wind power capacity has reported promising results for a wind-to-battery storage technology it is trying out at a Minnesota wind farm.

Xcel Energy has been testing out a one megawatt battery storage system at Luverne, about 30 miles east of Sioux Falls, SD, since October 2008.

And, the utility said this week that “the bottom line is – the technology works.”

Reporting preliminary test results from the project, which is connected up to an 11MW wind farm owned by Minwind Energy, Xcel said the technology can effectively shift wind energy from off-peak to on-peak availability.

It said wind-to-battery systems can reduce the need to compensate for the variability of wind generators, and allows support for grid voltage and transmission system balancing.

“Proved”

Frank Novachek, Xcel Energy director of corporate planning, said: “We have proved that this technology can perform the functions of storage that we were looking for to help us manage the variability of wind energy on our operating system.”

Xcel Energy, confirmed as the top utility for wind power capacity in its portfolio by the DOE (see this BrighterEnergy.org story), is using sodium-sulfur battery technology from Japanese firm NGK Insulators Ltd.

Chicago firm S&C Electric provided power conversion systems for the Wind-to-Battery project, while smart grid specialists Gridpoint provided communication technology.

Although other wind operators are looking into the use of battery systems to improve the power supply from wind turbines (see this BrighterEnergy.org story), Xcel said its project has been the first to use of the sodium-sulfur battery technology in the United States for direct wind energy storage.

It also suggested that the system could be used with solar power plants.

Testing

The Xcel project uses 20 battery modules, each 80-ton unit rated at a 50 kilowatt level and roughly the size of two semi trailers. Xcel said they are able to store about 7.2 megawatt-hours of electricity, with an instant discharge capacity of one megawatt.

Fully charged, the system could power 500 homes for more than seven hours.

Testing is due to continue, including a look at how battery systems could allow a larger percentage of wind power on the grid and how cost effective the technology is, with a final report expected in summer 2011.

Mr Novachek said: “The success of this technology is important to both Xcel Energy – the nation’s leader in wind power distribution – and our customers, and we are greatly encouraged by these results.”

Other partners in the project include the University of Minnesota, the National Renewable Energy Laboratory and the Great Plains Institute.