EO-2025-0235

This docket concerns Ameren Missouri's Notice of Change in its Preferred Resource Plan (2025 PRP), filed in February 2025. Ameren concluded that its previously filed 2023 Integrated Resource Plan (IRP) was no longer appropriate and should be revised due to two key changes in the planning environment:

- Significant new interest from potential data center customers, representing up to 3 GW of possible new load, with 1.8 GW already having signed interconnection contracts.
- A reassessment of expected savings from company-sponsored energy efficiency programs under MEEIA, resulting in a reduction of expected winter peak demand savings by 300 MW by 2032 and 700 MW by 2043 relative to the 2023 IRP, in response to concerns raised by the Missouri Public Service Commission (MPSC) and stakeholders about the reliability of such savings for resource planning.

The MPSC staff memorandum raises concerns about Ameren's continued reliance on questionable demand savings assumptions and the risk that over-building generation for uncertain load growth could harm affordability for ratepayers. Staff did not make formal recommendations but emphasized the need for caution to avoid both resource adequacy and affordability issues. Stakeholders such as Grain Belt Express also noted persistent deficiencies in Ameren’s planning, particularly regarding the evaluation of supply-side resource options 1, 1.

Key events and submissions in the Ameren Missouri preferred resource plan (PRP) proceeding (File No. EO-2025-0235) include:

- February 13, 2025: Ameren filed a "notice of intention to submit notice and supporting materials under 20 CSR 4240-22.080(12)" in its 2023 triennial IRP proceeding (File No. EO-2024-0020). This notice did not contain substantive information about changes to the acquisition strategy or their impacts 1.
- February 28, 2025: Ameren Missouri filed its "notice of change in preferred resource plan" (the 2025 PRP report) in File No. EO-2025-0235. On the same day, Ameren filed a motion for protective order 2, 2, 2, 2, 2.
- March 14, 2025: The Missouri Public Service Commission granted Ameren's motion for protective order 2, 2, 2, 2.
- May 14, 2025: Staff of the Missouri Public Service Commission filed its memorandum, providing comments and concerns on Ameren's notice of change in the preferred resource plan 2, 2, 2.
- May 27, 2025: Grain Belt Express filed a reply to staff’s memorandum 1.

No further scheduled events are specified in the provided excerpts.

The financial and timeline risks and concerns discussed in this docket primarily center on two key issues: the uncertainty of large new data center loads and the reliability of projected winter peak demand savings from energy efficiency programs.

Financial Risks:
- If Ameren Missouri invests in new generation to support anticipated data center load growth, but that load does not materialize, the increased revenue requirement will be spread over a smaller load, resulting in higher levelized rates for ratepayers. This risk is significant because the 2025 Preferred Resource Plan (PRP) has the second highest present value of revenue requirements (PVRR) among the alternatives analyzed, mainly due to higher load growth assumptions. Overestimating future load could thus lead to rate increases, impacting affordability for all customers 1, 1.
- There is further risk if the company relies on winter peak demand savings from energy efficiency programs that may not be as reliable as projected. If these savings are overestimated, Ameren Missouri could under-build generation, leading to resource adequacy concerns, or over-build, leading to affordability issues 1, 1.

Timeline Risks:
- There is uncertainty in the timing and magnitude of new large loads (such as from data centers), as interest exists but not all potential customers have committed or may ultimately interconnect. This uncertainty complicates planning and could result in either under- or over-investment in generation assets if actual load growth diverges from projections 1.
- The company is initiating a new demand-side resource market potential study to inform its next triennial Integrated Resource Plan (IRP) filing in 2026. Until updated study results are available, planning relies on potentially outdated or questioned levels of achievable demand savings, adding to planning uncertainty 1.

In summary, the docket highlights significant financial exposure if Ameren Missouri misjudges either load growth or the effectiveness of energy efficiency savings, with potential consequences for both ratepayers and system adequacy. Planning caution and contingency analysis are recommended to mitigate these risks 1, 1, 1.

The docket identifies two primary areas of growth:

1. Data center and large load potential
2. Changes in company-sponsored energy efficiency programs

Key considerations for each are as follows:

Data center and large load potential:
- Ameren Missouri has seen significant growth in interest from potential data center customers, with aggregate potential peak demand of about 3 GW and signed construction contracts totaling 1.8 GW. The 2025 PRP supports 1.5 GW of new demand by 2032 and 2.5 GW by 2040, with contingency plans for higher or lower demand scenarios.
- The main concern is that if Ameren invests in new generation facilities to meet this anticipated load, but the actual data center load does not materialize, levelized rates for all ratepayers could increase because the revenue requirement would be spread over fewer kilowatt-hours. Thus, there is a risk of over-building (affecting affordability) or under-building (affecting resource adequacy) if projections are not accurate 1, 1.

Changes in company-sponsored energy efficiency programs:
- Ameren Missouri revised its long-term expectations for demand savings from energy efficiency programs due to concerns from the Missouri Public Service Commission (MPSC) and stakeholders about the reliability of such savings for resource planning. The company expects a reduction in winter peak demand savings of approximately 300 MW by 2032 and 700 MW by 2043 compared to previous plans.
- The key consideration is that relying too heavily on projected demand savings that may not be fully reliable can lead to resource adequacy or affordability issues. The company is initiating new studies to better inform future planning and address these concerns 1, 1.

In summary, the two areas of growth are (1) large potential new loads from data centers, and (2) changes to expected energy efficiency program outcomes, each bringing significant planning and risk management considerations.

The provided excerpts do not list all specific stakeholders by name, but they do reference some key parties:

- Ameren Missouri (Union Electric Company d/b/a Ameren Missouri) is the utility that filed the notice of change in its preferred resource plan (PRP) and is the subject of the docket.
- The Missouri Public Service Commission (MPSC) and its staff are reviewing Ameren Missouri’s filing and have issued a memorandum expressing concerns about aspects of the PRP, particularly regarding projected winter demand savings and data center load growth.
- Grain Belt Express is mentioned as a stakeholder with a direct and immediate interest in Ameren's IRP process and methodology. Grain Belt Express has requested intervention in this proceeding and seeks to have its reply to staff’s memorandum accepted by the Commission 1.

Positions on proposals:
- Ameren Missouri is proposing a revised PRP due to increased data center load potential and changes in its energy efficiency programs, resulting in reduced expected winter peak demand savings 2, 2.
- MPSC Staff does not make formal recommendations in its memorandum but expresses concerns about the reliability of projected winter demand savings and the risks of both over-building and under-building generation 2, 2.
- Grain Belt Express, while not explicitly stating support or opposition to specific proposals in the excerpts, is seeking participation to provide input and ensure a comprehensive record in the proceeding 1.

The excerpts do not provide explicit positions (support or opposition) for all stakeholders regarding each specific proposal, nor do they identify all possible intervenors or parties. They focus mainly on Ameren Missouri, the MPSC staff, and mention Grain Belt Express as an intervenor.