Missouri rate case could add $13 to power bills as data center demand keeps climbing

Another jump in electricity costs may be on the way for Ameren Missouri customers.

The company has asked Missouri regulators for a change that would raise the typical monthly bill by about $13 starting in mid-2027, while also proposing a discount aimed at some lower-income customers.

What's happening?

In a June 26 filing with the Missouri Public Service Commission, Ameren Missouri requested roughly $343 million in additional annual electric base-rate revenue, as the Fulton Sun reported, citing a Public Service Commission press release. The review is expected to take 11 months, and if the request is approved, the new rates would begin in mid-2027.

Missouri's rate case process is just getting underway. People or groups that want to participate have until July 15 to join, and the Consumers Council of Missouri has already sought to intervene. Other consumer-focused organizations, including the Missouri Office of Public Counsel, are also expected to take part.

Ameren says the extra revenue would support several priorities, including spending under its Smart Energy Plan, upgrades to older grid infrastructure, and storm resilience work in St. Louis and southeast Missouri after the destructive 2025 tornadoes. 

The utility also expects to have three energy centers online by the end of 2026, which would add about 400 megawatts of generation.

The filing also includes a proposed low-income discount through Ameren's tariff. If approved, customers at 0%-150% of the federal poverty level would receive 20% off their monthly bills, while those at 151%-200% would get 10%, provided they meet enrollment requirements tied to assistance and budget billing programs.

Why does it matter?

Utility bills already consume a growing share of family budgets during hot summers and cold winters.

One source of that strain is surging demand from so-called large-load customers, including data centers. Steven Willis, director of regulatory affairs for Ameren Missouri, said, "By the end of 2029, these new end users are expected to consume more than half as much electricity as the rest of the customers in the company's service territory that covers most of Eastern Missouri."

Serving that kind of growth often requires new power plants and other infrastructure on a compressed schedule. Ameren says large-load users will pay for certain grid connections and face higher rates, but some costs are still shared. 

The expense of adding new generation is not fully isolated and instead is spread among customers, fueling concern that ordinary residents could end up helping fund a boom driven by corporate electricity demand.

In a March memo, Geoff Marke, chief economist for the Missouri Office of Public Counsel, put it this way: "Data centers have already raised the cost of service for electric utilities through socialized transmission costs, volatile wholesale markets, and increased costs for generation, transmission and distribution investments driven by unprecedented demand."

What's being done?

Before any increase can take effect, the Public Service Commission will scrutinize Ameren's request through its review process. Over the next 11 months, staff will examine the company's books and facilities, and consumer advocates will be able to challenge whether the proposed spending should be passed along to customers.

Ameren says it has already built protections for other customers into its Large Load Tariff. According to the company, those users must sign agreements, pay imported power costs while new generation plants are under construction, and accept a base rate higher than the one charged to other large industrial customers. 

Ameren also told the Fulton Sun that this setup would save average customers a combined $21.2 million.

Willis said large-load customers are "reverberating throughout the industry and even society," while Marke warned that failing to charge data centers for the power they "alone need and want will raise electric bills in St. Louis and for the rest of Ameren Missouri's service territory."

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