Warren Buffet’s MidAmerican Energy puts in Iowa’s latest big battery project

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Grand Ridge, an existing Invenergy project that combines wind power and energy storage, in Illinois. Image: Invenergy.

The US state of Iowa got its first grid-scale solar-plus-storage system at the beginning of this year, and this has already been followed by the completion of another, larger battery project in the US state this week.

Energy-Storage.news reported last week on the completion of a solar PV system at Maharishi University of Management equipped not only with solar trackers but also with a 1.05MWh flow battery.

This week, project developer Invenergy said a four month “construction sprint” had been successfully undertaken and the company has begun commercial operations of a 1MW / 4MWh lithium iron phosphate battery energy storage system.

Located at a substation in Knoxville, Iowa, the project has been executed for utility MidAmerican Energy, one of billionaire investor Warren Buffet’s companies as a subsidiary of Berkshire Hathaway Energy. MidAmerican serves just under 800,000 electricity customers.

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In a November press release, MidAmerican’s VP of resource development said the utility-scale storage system would teach lessons about “how best to use an energy storage system, and how it can serve our customers in the future,” adding that the primary purpose of the system will be to help manage peak loads on the utility’s network.

“Energy storage has the potential to allow us to retain energy when customer demand is low and release it during peak usage times. That would give us new options to manage peak loads, enhance overall reliability and help keep electric costs low and affordable for our customers,” Mike Fehr of MidAmerican Energy said.

The utility highlighted four of the main benefits of energy storage that it will explore through the application of the lithium system: flattening and managing peaks in electricity demand through storing off-peak energy for later use, reducing the required run times and capacities of natural gas peaker plants with energy storage, enhancing the value and usefulness of renewable energy through smoothing the output of solar farms before it enters the grid and improving power quality and extending the life of transformers and other grid infrastructure.

“Energy storage is still in the development stages and the economic feasibility on a larger scale is being assessed as well; however, prices are trending downward,” Mike Fehr said.

“MidAmerican Energy wants first-hand experience with the technology so we’re positioned to quickly and efficiently add it to our system in ways that benefit our customers when the price is right.”

For Invenergy, which already owns and operates four other large-scale battery systems it developed, this has been its first project as an EPC (engineering, procurement and construction) partner.

“We are excited by the new opportunities for battery storage that we are seeing around the country. We are grateful for partners like MidAmerican Energy who are seeking innovative ways to deliver value to their customers and are proud to have provided them with this solution in such a short time,” Invenergy senior VP Kris Zadlo said.

15 September 2026
San Diego, USA
You can expect to meet and network with all the key industry players again in 2025 from major US asset owners, operators, RTOs and ISOs, optimizers, software and analytics providers, technical consultancies, O&M technology providers and more.

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