After initial denial, Iowa Utilities Board reconsiders preapproval of Duane Arnold solar projects

The Iowa Utilities Board has decided to partially reconsider an application from Interstate Power and Light Company — Alliant Energy’s Iowa subsidiary — that included the Duane Arnold Solar projects in Linn County, according to an order filed Thursday.

Interstate Power and Light’s application originally asked for IUB preapproval of 400 megawatts of solar and 75 megawatts of battery storage in Iowa, including the Duane Arnold solar projects, along with their associated costs and rates. If approved, those rates would last the lifetime of the constructed facilities — which is why they are carefully considered so projects are cheaper for both utilities and customers.

The IUB denied that application last month, saying that Interstate Power and Light (IPL) didn’t adequately consider alternative and potentially more cost-effective generation options in its application, as required by Iowa Code.

The denial made it less likely that Alliant ends up owning the Duane Arnold Solar facilities, an Iowa Environmental Council representative previously told The Gazette. While Florida-based NextEra will develop the 200-megawatt solar projects near Palo, Alliant 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.

IPL filed a motion to the IUB on Nov. 29 for reconsideration of its application and a potential rehearing.

According to the Thursday order, IPL had said the IUB disregarded the “plain language of the statutory requirement in Iowa Code,” which established advance rate-making principles to “encourage utility investment in new generation.”

IPL also asserted that its decisions were grounded in its Iowa Clean Energy Blueprint and supplemental analyses, which “overwhelmingly selected solar as the best alternative” for addressing capacity needs. The IUB previously said that blueprint didn’t adequately consider other more reasonable energy sources.

Additionally, IPL said it conducted further analyses of 200 megawatts of the proposed solar generation — which don’t include the proposed megawatts at the Duane Arnold facilities in Palo. The new evidence could lead to lower overall costs, which would help its proposal meet the IUB’s requirements, IPL said.

“IPL argues that the Board’s order puts the construction of the projects at risk …,” read the Thursday order. “The Board’s incorrect standard, according to IPL, would require IPL to undertake a number of actions not mandated by statute.”

In its Thursday order, the IUB said it found no basis for fully reversing its decision.

It again pointed to a lack of consideration from IPL regarding other sources of energy supply, like power purchase agreements — in which generators sell electricity to buyers. The board also said it was complying to state standards in its judgment.

Even with additional evidence for the 200 megawatts of solar generation, the IUB said economic analyses showed that projected costs for customers are greater than the benefits of the projects, and battery storage systems are unproven for large-scale and long-term use.

“As shown by IPL’s economic analysis, the cost of the facilities will result in a significant burden on ratepayers,” the IUB said in the order. “For the Board to find that the proposed facilities are reasonable … there must be evidence in the record showing IPL’s analysis of the feasible alternatives.”

“The Board did not create new criteria,” it continued later, “the Board applied the evidence in the record to the statutory requirement and found that IPL did not perform the necessary complete analysis to meet the statutory requirement.”

However, the IUB granted reconsideration or a rehearing for additional information about the Duane Arnold Solar facilities on a stand-alone basis, which could allow IPL to meet state requirements and show the projects are reasonable when compared to alternative sources.

“There is no question that IPL needs additional capacity and these two solar facilities, which have been approved for generation certificates by the Board, will provide some of the needed capacity,” the order said.

The order is contingent upon IPL supplying additional evidence within 30 days that demonstrates the proposed solar generation at Duane Arnold is reasonable compared to alternative sources of energy.

Alliant representative Morgan Hawk said the company is pleased with the IUB’s reconsideration of the solar energy generation at the Duane Arnold Solar location but disappointed in its determination about the rest of the proposed projects.

“We will be evaluating our next steps as we continue our steadfast focus on serving our customers and building stronger communities,” he said in an email.

Brittney J. Miller is the Energy & Environment 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