Alliant Energy tries batteries over grid upgrades to boost solar energy in Iowa


The next frontier for solar energy is solutions that do not affect the performance and efficiency of the electric grid. An innovative battery-storage solution in Decorah, Iowa, jointly supported by Alliant Energy, US Department of Energy (DOE), and the Iowa Economic Development Authority (IEDA), looks to seamlessly connect customer-owned solar while maintaining reliable electrical service across the community.

Battery storage is needed in Decorah because one electric circuit that serves the community will start to reach capacity as more customer-owned renewables are added. Until now, energy companies have had to either upgrade the grid in a community, which was expensive, or restrict the number of solar arrays that could be added in one area. Using battery storage to meet this challenge is just one of many applications which may lower customer costs.

The 2.5-megawatt, 2.922-megawatt-hour battery will serve as an “electron bank” to store excess solar power. It will store energy generated when the sun is most powerful and then release it in the evening, when demand for electricity peaks. It will also provide valuable insight into the challenges of providing reliable and affordable electricity in areas with a concentration of customer-owned solar. Lessons learned from the Decorah pilot will inform similar, future battery projects.

“By working hand-in-hand with renewables, energy storage can contribute toward creating a cost effective, resilient, and greener grid,” said Dr. Imre Gyuk, Energy Storage Program Manager, DOE Office of Electricity. “We are pleased to be joining Alliant Energy in this project, which will serve as a model for the entire country.”

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The Decorah energy storage project is expected to be complete and in service by the end of 2020. It will be the company’s third battery storage project in Iowa. Alliant Energy has a smaller battery in a similar application near Wellman. It is also adding a battery to store energy from the company’s solar garden in Marshalltown.

“This battery project is a game-changer in Decorah,“ said Terry Kouba, President of Alliant Energy Iowa. “We’re installing it on a circuit that’s near capacity for solar. Using batteries can add critical capacity and may save our customers money, because a battery costs a fraction of the total to upgrade our system.”

The project is jointly supported by a $250,000 cost-share from the U.S. Department of Energy, Office of Electricity (DOE-OE) and a $200,000 grant from the Iowa Economic Development Authority (IEDA). The battery will sit on land Alliant Energy leases from the City of Decorah. Sandia National Laboratories is providing technical support for the project and will collect operational data.

This data is critical to inform DOE’s national energy storage research as part of the DOE-OE Stationary Energy Storage Program under the direction of Dr. Imre Gyuk. Sandia’s assistance will help to ensure that the Decorah battery is sized, integrated and operated optimally to provide the most economic benefits. Iowa State University will also study the project.

DOE-OE conducts jointly supported federal-state energy storage deployment projects across the US, with deployment projects in numerous states including Massachusetts, Oregon, Hawaii, Vermont, New Mexico and Alaska, and also supports state energy storage policy development. Technical support for state storage projects and policy is provided through Sandia National Laboratories, which administers the Energy Storage Technology Advancement Partnership (ESTAP) with the assistance of the Clean Energy States Alliance (CESA).

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