A battery energy storage unit at Alliant Energy’s microgrid system in Boaz, WI.

Whispering Willow North battery energy storage system

Our Whispering Willow North battery energy storage system (BESS) sits on the same site as our Whispering Willow North Wind Farm. We began construction of the 75-megawatt (MW) site in 2025 with a target completion of late 2026.

We’re in the permitting stage of a second phase to add another 200 MW of battery storage, which we expect to complete in 2027. When finished, the BESS facility will be our largest at 275 MW capacity. 

How does battery storage work?

Battery storage systems charge from the grid when energy demand is low or directly from wind or solar projects when excess renewable energy is abundant. They discharge energy when demand increases, such as on hot summer or cold winter days. The ability to capture and store energy to use when needed improves the overall benefit of renewable resources.

Energy storage FAQ

Project timeline

Late 2025

Prepare site for BESS installation.
Begin to pour concrete pads for Phase 1.

Spring 2026

Finish all concrete pads.
Establish electrical connection between the wind farm, substation and BESS.
The first batteries arrive.

Summer 2026

Phase 1 online target date.

 Concrete pads complete for Phase 1 BESS.

How does battery storage get us ready for the future?

The Whispering Willow North battery storage project is one way we deliver safe, reliable energy and keep bills as low as possible for all customers. We can store excess energy for use as needed, which helps ensure we have enough to meet growing needs today and tomorrow.

As the electric grid evolves, we are leading the way with new and innovative solutions for our customers. We integrate new technologies with existing resources such as wind, solar and traditional generation systems.

Learn more about energy storage
employee near battery storage equipment

Recent stories from our blog