Iowa Utilities Board denies Alliant solar, battery plan

The Iowa Utilities Board has denied an Alliant Energy application regarding the utility’s proposed construction of 400 megawatts of solar and 75 megawatts of battery storage in Iowa, including the Duane Arnold Solar projects in Linn County.

A Wednesday IUB order stated that Interstate Power and Light Company, an Alliant subsidiary, didn’t adequately consider alternative energy generation options in its application for IUB pre-approval of the projects and their costs. The application, known as an application for advance ratemaking principles, was filed last November.

The application included new rates that would help accommodate the costs of the proposed projects. If approved, those rates would last the lifetime of the constructed facilities. That’s why the rates must be carefully considered, along with any alternative options that may make projects cheaper for both the utility and its customers.

“Advance rate-making decisions have a more long-term impact than perhaps any other decision made by the Board,” the IUB said in the order.

Interstate Power and Light primarily relied on analyses within its 2020 Clean Energy Blueprint, which outlined the proposed 400 megawatts of solar energy generation and 75 megawatts of battery storage, to justify the projects. The board said the utility didn’t adequately consider other electric supply sources that could be more reasonable, as required by Iowa Code.

Michael Schmidt, an Iowa Environmental Council staff attorney, said Interstate Power and Light went through a yearlong planning process to consider other generation alternatives, which the Council participated in.

“The order makes it clear that the (IUB) has a higher standard for looking at alternatives,” Schmidt said.

The IUB also noted that the generation capacity of the proposed projects did not satisfy energy gaps left by the decommissioned Duane Arnold Energy Center nuclear power plant and Alliant’s retiring coal-fired power plant in Lansing.

Additionally, the board found that changing conditions of the energy generation market made some of the utility’s analyses outdated. The recently passed Inflation Reduction Act could give Interstate Power and Light other potential sources of electric supply.

Because of these reasons, Interstate Power and Light’s proposal did not meet every Iowa Code requirement and was denied. This may be the first time the board has denied such an application, Schmidt said.

“We are disappointed with this decision and will be evaluating our next steps,” said Alliant spokesperson Morgan Hawk. “We will continue our steadfast focus on serving our customers and building stronger communities.”

The decision does not prevent Interstate Power and Light from moving forward with its plans, Hawk said. However, it does require the utility to do additional analysis on alternate sources of electric supply in order to gain IUB pre-approval.

Implications for Duane Arnold Solar projects

The proposed projects in the application included the Duane Arnold Solar projects in Linn County, which were recently approved and are now involved in a lawsuit.

While Florida-based NextEra will develop the rural Linn County project near Palo, Alliant Energy filed a proposal with the IUB to buy the large-scale solar farm from NextEra and further develop it into the state’s largest solar and battery storage facility.

Duane Arnold Solar I project proposes to use 316 acres of an 857-acre area to place photovoltaic solar arrays capable of generating up to 50 megawatts of energy.

The Duane Arnold Solar II project would use 815 acres of a 1,780-acre plot to place solar arrays capable of generating up to 150 megawatts. It also would include a 75-megawatt, four-hour battery energy storage facility with around 96 20-by-8-foot containers that will house 7,040 lithium-ion battery modules.

Schmidt said he suspects IUB’s denial may throw a wrench in some of those plans.

“To me, the high-level take-away is that it makes it much less likely that Alliant will end up owning the Duane Arnold Solar facilities,” he said. “But Alliant could still potentially get the energy from them.”

Alliant is evaluating its next steps following the IUB decision, Hawk said.

The decision could also spell future impacts for MidAmerican Energy’s Wind PRIME proposal, for which the IUB is currently considering a similar application.

Brittney J. Miller is an environmental reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com