Spearmint Energy Brings 200 MW / 400 MWh

Spearmint Energy announced on May 12, 2026, that two of its standalone battery energy storage system (BESS) projects in Texas, the 100 MW / 200 MWh Tierra Seca in Del Rio and the 100 MW / 200 MWh Seven Flags in Laredo, have completed nearly six months of commercial operation in the ERCOT market, adding a combined 200 MW / 400 MWh of fast-response capacity. Both projects began commercial operation in late December 2025.

What Is Being Built

The Tierra Seca and Seven Flags projects each provide 100 MW of power and 200 MWh of energy storage. Mortenson served as the engineering, procurement, and construction (EPC) contractor for both sites. Each project employs Sungrow’s PowerTitan 2.0 energy storage platform.

Why It Matters

With these projects operational, Spearmint Energy now operates 350 MW / 700 MWh in ERCOT. The company reports over 20 additional projects totaling more than 15 GWh are under development across the United States. This announcement arrives during a period of significant battery storage commissioning. In the same week, Clearway Energy Group brought its 320 MW / 1,280 MWh Honeycomb Energy Centre online in Utah, and Polaris Renewable Energy commissioned a solar-plus-storage project in Puerto Rico.

Critical Perspective

Spearmint Energy founder, president, and CEO Andrew Waranch stated the milestone supports ERCOT reliability as Texas power demand grows. Mortenson vice president and general manager for energy storage Kevin Boyce echoed this, saying the projects add flexible capacity supporting ERCOT grid reliability. However, with 200 MW / 400 MWh added to a grid that experienced significant strain in recent years, the question remains whether this incremental capacity meaningfully alters the fundamental reliability challenges faced by ERCOT, or if it represents a continuation of existing trends.

Sources

• https://pv-magazine-usa.com/2026/05/13/spearmint-energy-brings-400-mwh-of-new-battery-storage-online-in-texas/
• https://www.energy-storage.news/us-roundup-bess-project-updates-from-spearmint-polaris-and-clearway-in-texas-puerto-rico-and-utah/

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