Renewable energy in Minnesota is about to take a potentially big step forward.
Connexus Energy is building two electricity "storage" systems — solar-panel arrays connected to big batteries. Each battery can store up to two hours of power, allowing Connexus to inject renewable energy into the grid on command.
"It's a big endeavor, especially since it is new and first of its kind," said Greg Ridderbusch, CEO of Ramsey-based Connexus, the state's largest cooperatively owned electricity provider. "It's not research and development. This is a commercial project."
The $31 million undertaking marks the first commercial-battery deployment in Minnesota, and the largest by an electric co-op in the country. Falling battery prices have made "solar-plus-storage" a viable alternative for Connexus.
The improving economics of storage, combined with regulatory mandates in some states, have prompted a surge in battery projects nationwide. Minneapolis-based Xcel Energy has plans for one of the country's largest energy-storage initiatives in Colorado.
Xcel's battery efforts in Minnesota have been limited, though it may unveil bigger plans next year.
Batteries address gaps in power
Batteries can smooth out the variability of renewable energy. The sun shines only during the day, and clouds can obscure it when it does. Prime time for wind gusts is often at night, when power demand is low. With a battery, renewable energy can be captured and pushed onto the grid when it's most needed.
"The holy grail for renewable energy is to have storage you can dispatch at any time," said Ellen Anderson, executive director of the University of Minnesota's Energy Transmission Lab.