The Iowa Utilities Board (IUB) issued an order today approving an application for advance ratemaking principles for four solar generating projects in Iowa filed by Interstate Power and Light Company, a subsidiary of Alliant Energy (Alliant). The decision follows an IUB rehearing and a settlement agreement reached by the parties in the proceeding. 

On August 25, 2023, Alliant filed an amended non-unanimous stipulation and settlement agreement in Docket No. RPU-2021-0003. The parties to the settlement are Alliant; the Office of Consumer Advocate, a division of the Iowa Department of Justice; and the Environmental Law & Policy Center and Iowa Environmental Council, referred to as the Environmental Intervenors.

In today’s order, the IUB found that Alliant had considered other sources for long-term electric supply and that the proposed generating facilities – Duane Arnold Solar I, Duane Arnold Solar II, Creston, and Wever – are reasonable when compared to other feasible alternative sources of supply. Iowa Code section 476.53 requires the IUB to approve advance ratemaking principles for renewable generation facilities once the utility has met the statutory requirements. The order affirms that Alliant provided the information necessary to meet the statutory requirements under Iowa law. 

In the order the IUB approved 11 advance ratemaking principles for the four solar generating facilities and approved the settlement agreement subject to modifications. Alliant has 20 days to accept the advance ratemaking principles approved in the order. 

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 with a nameplate capacity of at least 300 megawatts, or a combined-cycle electric power generating facility, or an alternate energy production facility, to help serve its customer base.

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