(Des Moines) – The Iowa Utilities Board (IUB) today issued an order that sets the procedural schedule and public hearing date of August 2, 2023, to reconsider Interstate Power and Light Company’s application for advance ratemaking principles for a proposed 475-megawatt (MW) solar and battery energy storage system (BESS) project. Interstate Power and Light Company is a subsidiary of Alliant Energy (Alliant).

The 475 megawatts includes Alliant’s Duane Arnold I and Duane Arnold II solar projects, plus an additional 200 MW of solar and a 75-MW BESS project.

The order requires the parties to discuss in testimony the tax implications, alternatives analysis, individualized cost breakdown, and return on equity.

The evidentiary hearing will begin at 9 a.m. August 2, 2023, in the IUB’s Hearing Room, located at 1375 E. Court Ave., Des Moines, Iowa. Individuals with disabilities who will require assistive service or devices to observe or participate in the hearing may contact the IUB’s Customer Service staff at (515) 725-7300 at least five business days in advance of the hearing to request arrangements.

Under Iowa Code 476.53, a rate-regulated public utility can seek advance ratemaking principles when it intends to construct (or acquire) an electric power generating facility to help serve its customer base with a nameplate capacity of at least 300 megawatts, or a combined-cycle electric power generating facility, or an alternate energy production facility.

Alliant filed its application for advance ratemaking principles on November 2, 2021, in Docket No. RPU-2021-0003.