IUB denies advance ratemaking principles for Alliant Energy’s proposed solar and battery energy storage system projects
(Des Moines) – The Iowa Utilities Board (IUB) issued an order today denying the application for advance ratemaking principles filed on November 2, 2021, by Interstate Power and Light Company (IPL), a subsidiary of Alliant Energy, in Docket No. RPU-2021-0003. The IUB found that IPL relied on a 2020 analysis in support of its decision to construct 400 MW of solar generation and 75 MW of battery storage, but it should have considered other sources of electric supply as required by Iowa Code § 476.53 and therefore could not proceed.
Today’s order finds that IPL did not demonstrate that the solar and battery storage projects are reasonable when compared to other feasible alternative sources of electric supply as required by Iowa Code. The IUB's decision explains that IPL did not fully consider other sources of electric generation and did not update its analysis for changes in costs. In addition, the IUB found that the federal Inflation Reduction Act (IRA) presents IPL with other potential sources of electric supply.
In the order, the IUB stated that its decision does not indicate that IPL should not go forward with the projects, or that the projects are not reasonable, but that IPL needs to do additional analysis as required by Iowa Code § 476.53 before requesting advance ratemaking principles, or IPL can request cost recovery in a general rate case proceeding.
Documents regarding the proposed IPL solar and battery storage projects are available for review in the IUB’s electronic filing system under Docket No. RPU-2021-0003.