Columbia Energy Storage Project

Advancing our clean energy future

Alliant Energy and our project partners, including WEC Energy Group, Madison Gas and Electric, UW-Madison, Madison College, Shell Global Solutions US and the Electric Power Research Institute, are teaming up to construct a CO2-based energy storage system – the first of its kind in the United States. The Columbia Energy Storage Project is an innovative new battery system that will advance a more sustainable, reliable and cost-effective energy future.

Fast facts:

  • Location: Town of Pacific, Columbia Co., Wis.
  • Size: Size: 20 MW / 200 MWh
  • Homes powered: about 20,000

Project information

The Columbia Energy Storage Project extends Alliant Energy’s historic presence in Columbia County while also inspiring a coalition of partners committed to a more sustainable energy future. This project will create new construction jobs as well as ongoing positions in operations and maintenance once the system is placed into service.

The town of Pacific is an ideal location for an energy storage system due to the availability of existing electric grid infrastructure. The project, part of a multi-phase site redevelopment effort, will increase energy reliability and resilience while delivering incredible customer value. Pending approval, project construction could begin in 2025 with completion in 2026.

How does a CO2-based energy storage system work?  

Utilizing a system design by Energy Dome, this innovative and efficient approach to long-duration energy storage is both simple and sustainable. The Columbia Energy Storage Project will take energy from the grid and store it by converting CO2 gas into a compressed liquid form. When energy is needed, the system converts the liquid CO2 back to a gas, which powers a turbine to create electricity.

CO2-based energy storage is a proven technology that delivers exceptional efficiency compared to many other long-duration energy storage systems. Using mainly steel, and an initial supply of water and CO2 to construct the system, it is highly sustainable and easily recycled at the end of life.

Energy dome illustration

System illustration for conceptual reference. Diagram not to scale.

Energy storage

As the electric grid continues to evolve, Alliant Energy is leading the way with new and innovative solutions. We are working to integrate emerging technologies and optimize energy resources such as wind and solar power, battery storage and traditional generation systems. These efforts will benefit our customers with improved energy reliability and efficiency.

The expansion of energy storage infrastructure is key to accelerating the transition to cleaner, more sustainable renewable energy. With major transformations underway, we’re working rapidly to balance energy demands, reduce the need for traditional power grid updates and increase security in the event of an outage or severe weather. Additional information about our deployment of energy storage solutions can be found on our Energy Storage page.

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