On 2025-08-14, the Minnesota Public Utilities Commission (PUC) approved a site permit for the Snowshoe Energy Storage Project, a 150 MW/600 MWh grid-scale battery storage system in Olmsted County, aiming to enhance renewable integration and grid reliability by storing excess electricity for discharge during peak demand periods.
Project Overview and Specifications
The Snowshoe BESS, developed by Snowshoe BESS, LLC (a subsidiary of Spearmint Energy), will be the state’s first standalone battery energy storage system (BESS), with a rated power capacity of 150 MW AC and energy storage capacity of approximately 600 MWh. The facility is planned to occupy around 23–27 acres in Kalmar Township, situated between Byron and Rochester.
Timeline and Cost
Spearmint Energy filed the permit application in October 2024, and the PUC approved it in mid-August 2025. Construction is scheduled to begin in early 2027, with operations starting by late 2027. The project’s total estimated cost ranges from US $214 million to US $255 million, with lifetime costs, including decommissioning, approaching US $457 million. Annual operating expenses are projected at US $8.2 million, and expected property tax revenue is estimated at around US $18 700 per year.
Grid Connection and Function
The facility will interconnect to the MISO grid via the Southern Minnesota Municipal Power Agency (SMMPA)’s Maple Leaf substation. It is designed to store surplus electricity for up to four hours, releasing it during periods of high demand to help stabilize voltage and frequency, and improve grid flexibility. The project is currently in MISO’s definitive planning phase, with a Generation Interconnection Agreement expected in early 2026.
Safety, Local Coordination, and Regulatory Conditions
In response to stakeholder input, the PUC included safety and preparedness conditions. The developer must, at its own expense:
- Collaborate on a water main extension report with local authorities.
- Develop a plan to acquire specialized emergency equipment.
- Provide training for first responders.
Commissioner John Tuma stated this project “represents a crucial evolution in our state’s energy infrastructure,” highlighting its role in advancing Minnesota’s clean energy capabilities.
Broader Significance
As Minnesota’s first standalone grid-scale battery storage project, Snowshoe BESS establishes a precedent for independent energy storage development. It supports the integration of renewables and demonstrates a structured permitting framework inclusive of safety and local coordination. As policymakers increasingly mandate energy storage in utility planning, this project may inform future infrastructure decisions in the state and beyond.