PSC Approves Agreement in Ameren Missouri Request for Battery Storage and Solar Projects with Conditions - PR-27-28

The projects included in the Agreement are as follows:

• Castle Bluff BESS Project: A 95-megawatt (MW) battery energy storage facility in St. Louis County at the retired Meramec coal-fired facility.

• Huck Finn BESS Project: A 200 MW battery energy storage facility at Ameren Missouri’s Audrain Energy Center in Audrain County.

• Millcreek BESS Project: A 250 MW battery energy storage facility in Lincoln County.

• Quinn Switching Station: A new 161-kilovolt switching station in Lincoln County to connect the Millcreek BESS Project to the existing transmission system.

• Tom Sawyer Solar Project: A 175 MW solar generation facility in Audrain County.

• Ringer Solar Project: A 225 MW solar generation facility in Stoddard County.

The Commission’s decision to approve the Agreement takes into consideration safety and cost considerations that protect the customers of Ameren Missouri, as well as balance the interests of the landowners near the projects.

Highlights of Ameren’s obligations under the Agreement:

• Ameren Missouri will work to expand information addressing community concerns about the Millcreek BESS Project, including fire safety, battery testing, and nearby infrastructure.  

• Ameren Missouri will submit a copy of the site-specific Hazard Mitigation Analysis or Hazard Mitigation Plan developed for each BESS facility after each BESS facility goes into service.

• Ameren Missouri will submit plans for restoring safe and adequate service following significant outages, provide site-specific hazard mitigation information and environmental response procedures for the battery storage facilities, and address safety testing of the BESS batteries prior to installation and compliance with the National Fire Protection Association (NFPA) 855 standard for stationary energy storage systems.

• Ameren Missouri will submit a copy of procedures and best practices that the Ameren Environmental team develop regarding environmental mitigation or containment methods developed and implemented as part of a fire response strategy to be followed at the BESS facilities after any corresponding BESS facility goes into service.

• Ameren Missouri is required to notify the Commission if the project's total costs change by more than 15% of the applicable base or risk-adjusted project costs, is required to explain the reasons for the increase, and  must describe efforts to mitigate the cost.

• Ameren Missouri must submit quarterly progress reports addressing construction milestones, permitting, costs, delays, and any potential impacts from legislative or executive actions.

• Ameren Missouri will provide a copy of each State, Federal, and Local permit obtained for each BESS project.

• Ameren Missouri will agree to meet with OPC and Staff to discuss the results of the Tesla Megapack 3 safety testing after it is complete and the steps the supplier has taken to ensure the BESS complies with the NFPA 855 standard. Ameren will also file a public pleading stating that the safety testing has been completed, identifying the results of it, and attaching the supplier's confidential safety testing report for the Staff and OPC’s review, at least 90 days prior to the installation of the batteries at the Millcreek site.