Nearly a year after Missouri regulators unanimously approved Ameren Missouri's terms for very large electricity customers, a consumer group says the rules still leave households exposed to costs created by data centers. State regulators disagree. The dispute was laid out in an Oct. 26 special report by ABC17/KMIZ, and it comes as hyperscale projects in Montgomery County move ahead.

The Missouri Public Service Commission (PSC) approved Ameren Missouri's large-load tariff in November 2025, and it took effect Dec. 4, according to ABC17. St. Louis Public Radio reporting carried by KBIA also described the late-November approval. The Consumers Council of Missouri, which argued then that the terms were too weak, is still making that case.

What the Consumers Council Wants

John Coffman, executive director of the Consumers Council, told ABC17 the group wants stricter terms than the approved tariff contains:

  • Contract length: 15 to 20 years.
  • Demand charge: a monthly demand charge of 95%.
  • Credit and collateral: 10 years' credit and collateral.

Coffman also objects to two parts of the approved structure, ABC17 reported. Under the tariff, Ameren may "at its sole discretion" aggregate loads and grant variances without PSC approval. The council opposes both, citing the need for regulatory oversight.

After the commission's November 2025 decision, the Consumers Council filed a motion for rehearing or reconsideration, according to the KBIA/St. Louis Public Radio report. In that coverage, Ameren's Steve Wills said the PSC had already addressed the issues. An Ameren spokesperson said the order includes minimum terms of service and requirements that large customers pay 100% of upfront interconnection costs and provide collateral.

What the Approved Tariff Says

The PSC's page on large-load tariffs says Senate Bill 4 required the commission to adopt rates for large-load customers that reflect those customers' share of costs. Ameren Missouri and Evergy now have approved large-load tariffs. A case for Liberty Utilities, docket ET-2026-0184, is still in progress, the commission says.

The PSC page and ABC17 describe these main provisions:

  • Term: a minimum 12-year service period plus an optional five-year ramp period. The PSC says that means a potential commitment of 17 years.
  • Minimum bill: a monthly demand charge set at 80%. The PSC describes it as 80% of the "agreed upon rate"; ABC17 describes it as 80% of the customer's contracted maximum electric demand, payable even if the customer uses less electricity than projected.
  • Collateral: creditworthiness requirements and collateral equal to two years of minimum monthly bills.
  • Interconnection: ABC17 reports customers cover full grid hookup and infrastructure costs upfront.
  • Exit terms: exit fees and early-termination fees plus advance written notice.
  • Other features: the PSC lists cost stabilization recovery and optional renewable and carbon-free energy programs.

The two sources do not agree on every detail. The PSC page says exit notice must be given at least 24 months in advance. ABC17 reported 36 months. ABC17 defines a large load as 75 megawatts or more. The PSC summary reviewed for this article does not give a threshold. DataCenterFeed was not able to check either point against the tariff sheets themselves. Readers who need the exact terms should look at the tariff filed in the relevant PSC docket.

Side by side, the gap between the two positions is easy to see. Coffman's proposed contract length of 15 to 20 years is close to the 17 years the PSC says the tariff already allows when the ramp period is included. The larger differences are the demand charge, 95% versus 80%, and the collateral, 10 years versus two years of minimum bills.

The Regulators' Response

Rich Germinder, a senior policy adviser at the PSC, told ABC17 that the White House Ratepayer Protection Pledge and Missouri Senate Bill 4 helped lay the groundwork for consumer protections. Gov. Mike Kehoe signed Senate Bill 4 in April 2025, and a critical component of the bill was the large-load tariff requirement. ABC17 reported that a federal Ratepayer Protection Act is also being discussed, which Germinder said largely follows the same model of making large loads pay their share upfront.

The PSC page lists the current commissioners as Chair Kayla Hahn, Maida Coleman, Glen Kolkmeyer and John Mitchell.

Ameren's Rate Case

The tariff debate is happening while Ameren Missouri asks for a general rate increase. ABC17 reported that the utility filed a request with the PSC for a $343 million annual electric base rate increase that could raise average residential bills by roughly $13 a month, and that Ameren announced it is seeking a rate hike of about 10% in 2027. Ameren's James O'Mara told the station that data centers are not the reason for that request, saying the investment is in general grid upgrades.

The Consumers Council sees it differently. As ABC17 described it, the council says these "improvements" are linked to what is needed for data centers, and that they come as data centers are predicted to drive up energy demand in Missouri. Coffman said he expects energy demand to double over a very short time and that data centers could be as much as 50% of the load someday.

Projects in Montgomery County

The arguments are about real projects. ABC17 reported that Google's data center in New Florence, Montgomery County, known as Project Spade, is a $15 billion development on a campus of more than 900 acres with about 1.5 million square feet of facility space, according to project documents. It is set to target 1.2 gigawatts of utility and power capacity through Ameren. ABC17 also reported that an Amazon Web Services data center is under construction just across Interstate 70 in New Florence, a $10 billion campus spanning roughly 1,000 acres according to project documents.

The 1.2 GW figure reported for Google's project is 16 times the 75 MW threshold ABC17 cites for the tariff.

What Happens Next

On the tariff itself, the PSC lists Liberty Utilities' large-load tariff case, docket ET-2026-0184, as in progress. Ameren Missouri's and Evergy's tariffs are already approved. The sources reviewed do not give a hearing date or decision deadline for the Liberty docket.

Ameren Missouri's request for a $343 million annual electric base rate increase was filed with the commission. ABC17 reported the roughly 10% increase as coming in 2027. The sources reviewed do not list a hearing schedule for that case.

Sources