The Iowa Utilities Board has approved an application for advance ratemaking principles for four Alliant Energy solar generating projects in Iowa, including two projects near the former Duane Arnold Energy Center near Palo.
The application was filed by Interstate Power and Light Company, an Alliant subsidiary.
The decision follows an IUB rehearing and a settlement agreement reached by the parties in the proceeding.
The order reverses the IUB’s order Nov. 9, 2022, which found Alliant had not met the statutory minimums required for advance ratemaking.
The IUB granted reconsideration of the November 9, 2022 order for Duane Arnold I and II, but not for the battery storage and extra solar generation projects, in an order issued Dec 29, 2022.
In May, the IUB preapproved the Duane Arnold Solar projects, the first time in state history a utility-scale solar project had received preapproval.
Then in August, Alliant filed an amended non-unanimous stipulation and settlement agreement in the case, seeking reconsideration of the IUB’s decision in the Creston and Wever projects.
The parties to the settlement include 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 the latest order, issued Oct. 19, 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 and projects near Creston and Wever – are reasonable when compared to other feasible alternative sources of supply.
According to Iowa code, the IUB is required to approve advance ratemaking principles for renewable generation facilities once the utility has met the statutory requirements. The Oct. 19 order affirms that Alliant provided the information necessary to meet the Iowa code requirements.
As part of the order, the IUB approved 11 advance ratemaking principles for the four solar generating facilities and approved the settlement agreement subject to modifications.
Alliant now has 20 days to accept the advance ratemaking principles approved in the order.
Requests for advance ratemaking principles enable utilities to establish regulatory treatment for certain aspects of electric generation facilities in advance of construction, but such cases do not immediately impact customers’ electrical base rates. If the utility proceeds with construction, a contested rate case must still be filed with the IUB once the new generation source is placed into service.
Under Iowa code, a rate-regulated public utility such as Alliant 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 in November 2021, in Docket No. RPU-2021-0003.
