Duke Energy intends to match a $22 million grant from the U.S. Department of Energy (DOE) to design, build and install large-scale batteries to store wind energy at one of its wind farms in Texas.

The batteries at Duke Energy’s Notrees Windpower Project in Ector and Winkler counties, Texas, will store excess wind energy and discharge it whenever demand for electricity is highest, not just when wind-turbine blades are turning.

The prevailing technology used at wind and solar farms throughout the world allows electricity to be produced only when the wind is blowing or the sun is shining. The intent of the Notrees grant is to demonstrate how energy storage can help overcome this issue, often referred to as “intermittency.” Meeting energy demand with stored renewable power instead of electricity from conventional generation sites that burn coal or natural gas may also help reduce greenhouse gas emissions.

“Energy storage truly has the potential to serve as a ‘game-changer’ when it comes to renewable power,” said Wouter van Kempen, president of Duke Energy Generation Services, a Duke Energy unit that owns and develops renewable energy assets. “Through this project, Duke Energy intends to show that renewables can play an even bigger role in our country’s energy future.”

According to Duke, this project represents one of the nation’s first demonstrations of energy storage at a utility-scale wind farm. The 95 wind turbines in operation at Duke Energy’s Notrees site can generate 151 megawatts (MW).

In April 2009, Walmart began purchasing energy from the Notrees project to power up to 15 percent of its stores and facilities in Texas.

The total value of the 20-MW energy-storage project at Duke Energy’s Notrees site is $43.6 million.

The American Recovery and Reinvestment Act of 2009 made the DOE grant possible. Duke Energy and the DOE must negotiate the terms and conditions of the grant before any funds are released.