Spearmint Energy Secures Site Permit for 150MW/600MWh Midwater Battery Storage Project in MISO Grid

July 19, 2026

Business Wire USA

Overview

Spearmint Energy has obtained a site permit from the Minnesota Public Utilities Commission for its 150 MW / 600 MWh Midwater Energy Storage Project in Freeborn County, Minnesota. This approval marks a critical step for the utility-scale battery energy storage system (BESS), designed to provide essential grid stability and renewable energy integration services to the Midcontinent Independent System Operator (MISO) network. The project underscores the increasing importance of large-scale storage in modernizing U.S. power infrastructure and achieving decarbonization goals.

In Depth

Key Findings

Spearmint Energy has officially received the site permit from the Minnesota Public Utilities Commission for its Midwater Energy Storage Project in Freeborn County, Minnesota. This significant regulatory approval paves the way for the construction of a substantial 150 MW / 600 MWh standalone Battery Energy Storage System (BESS), slated for interconnection with the vast Midcontinent Independent System Operator (MISO) transmission network.

Technical & Project Details

The Midwater Energy Storage Project is designed to dramatically enhance the grid’s capacity for integrating renewable energy within the rapidly expanding MISO operational area. This BESS will facilitate the supply of power during peak demand periods and store surplus energy from intermittent renewable sources, thereby increasing the flexibility and reliability of grid operations. As a standalone project, its dispatch will respond directly to market needs, contributing to the wholesale energy market.

Background & Industry Context

The United States is witnessing a growing demand for large-scale energy storage solutions to maintain grid stability and reliability amidst the accelerating deployment of renewable energy. Regional transmission organizations like MISO are actively supporting such projects to achieve clean energy targets and stabilize power supply. BESS technology, known for its rapid response times and scalability, is particularly favored for grid-scale applications.

Strategic Significance & Outlook

The acquisition of this site permit signifies the project’s transition to the construction phase. Once operational, the Midwater Energy Storage Project is expected to bolster energy security across Minnesota and the broader MISO grid, contributing significantly to carbon emission reduction goals. Looking ahead, such large-scale BESS installations are anticipated to play a pivotal role in powering high-demand consumers, including the burgeoning AI data center sector.

Source: #

Get our weekly technology intelligence — free

Receive an infographic that lets you judge at a glance whether each field’s analysis report is worth reading.

Subscribe Free — Weekly Tech Intelligence

By subscribing, you’ll receive Troy-Technical’s weekly technology intelligence newsletter.