USA - Xcel can capture wind power – now it seeks to store energy

Xcel Energy will soon launch a cutting-edge test project to store wind energy in batteries for future use. The announcement Thursday touted the project as the first storage application of its kind in the United States.

A primary concern with wind power and other forms of alternative energy is consistency. Cities need a steady flow of energy, and wind is variable. Without the ability to store wind-generated energy, utility companies have to constantly adjust the flow of power from other sources to even out the peaks and valleys. Twenty 50-kilowatt batteries, purchased from Japanese firm NGK Insulators Ltd., will test the ability to store wind energy in southwestern Minnesota and move it to the electricity grid when needed. Fully charged, the batteries could power 500 homes for more than seven hours, Xcel officials said.

“Energy storage is key to expanding the use of renewable energy,” said Dick Kelly, president and chief executive officer of Xcel Energy. “This technology has the potential to reduce the impact caused by the variability and limited predictability of wind energy generation.”

Wind tends to blow harder at night, particularly during the summer. But that’s when electricity use is at its lowest point. The test system, designed to ease the burden on Xcel’s other sources of power, will be set up in Luverne, about 30 miles east of Sioux Falls, S.D. The battery installation will begin this spring at the site of an 11.5-megawatt wind farm owned by Minwind Energy, LLC. The battery modules are roughly the size of two semi trailers and weigh approximately 80 tons. Advertisement Testing will begin in October and is expected to last up to two years.

Xcel will work with the National Renewable Energy Lab and the University of Minnesota to collect and interpret data generated by the battery project. Frank Novachek, director of corporate planning at Xcel, said the utility has been asked not to release the cost of the project yet. But he noted that an expected $1 million grant from Minnesota’s Renewable Development Fund will cover less than half of the project cost. The grant must still receive final approval from the Minnesota Public Utilities Commission later this spring.

Xcel has been actively researching various forms of energy storage over the past three years. The testing is part of its overall Smart Grid strategy, which modernizes and upgrades the grid to allow for easier integration of renewable energy sources.

This is the utility’s second storage project. A wind-to-hydrogen test operating south of Boulder, Colo., since December 2006 has produced positive early results, Novachek said. Producing liquid hydrogen could provide fuel for hydrogen-powered vehicles of the future. But large-scale sodium-sulfur batteries, such as the one developed by NGK Insulators, are far more efficient than hydrogen technology, capturing as much as 80 percent of the wind energy generated.

It will be several years at least before drivers begin noticing hulking battery modules littering the landscape near wind farms. But Xcel is laying the groundwork for decades to come, when alternative energy generation is projected to generate as much as one-quarter of the state’s power supply.

“The [variability of] wind is not a problem and we don’t foresee it being a problem for the next several years,” Novachek said. But by 2020, when Xcel plans to have four times as much wind power flowing into the system as it does today, the peaks and valleys of wind power will be far more noticeable – and storing the power will be that much more critical.