Spearmint Energy (“Spearmint” or the “Company”), a next-generation energy company bringing stable, secure and cost-effective energy solutions to the power grid with large-scale battery storage, today announced that Tierra Seca and Seven Flags, two 100 MW / 200 MWh Battery Energy Storage Systems (“BESS”) located in Del Rio and Laredo, respectively, within the ERCOT power market, began operation in late December 2025 and have completed nearly six months successful operation. Construction of the projects was led by Mortenson, a leading Engineering, Procurement, and Construction (“EPC”) contractor with deep experience in battery energy storage. Tierra Seca and Seven Flags both utilize Sungrow Power Supply Co., Ltd.’s state-of-the-art PowerTitan 2.0 energy storage platform.
Andrew Waranch, Founder, President, and Chief Executive Officer of Spearmint, commented, “We are pleased to achieve commercial operation for Tierra Seca and Seven Flags. This milestone is an important step toward expanding access to reliable, safe, and cost-effective energy in ERCOT as power demand continues to rapidly grow. We appreciate the collaboration with our construction partner, Mortenson, whose team worked closely with us throughout development and construction to help bring energy storage capacity online across the region.”
Kevin Boyce, Mortenson’s Vice President and General Manager for Energy Storage said, “Mortenson is proud to partner with Spearmint Energy as Tierra Seca and Seven Flags reach commercial operation. These projects add flexible capacity that supports ERCOT reliability and demonstrate how strong collaboration can bring complex energy infrastructure online safely and on schedule.”
This milestone follows over $250 million of construction financing Spearmint secured in Q2 2025 from Manulife, East West Bank, Investec, and Sugar Creek Capital, and the subsequent close of an investment from Kyuden International Corporation in January 2026 that supported the addition of 400 MWh of energy storage capacity to ERCOT.
About Spearmint Energy
Spearmint Energy (“Spearmint” or the “Company”) is a leading energy company focused on developing, owning, operating, and optimizing battery energy storage systems (“BESS”) to reduce grid volatility and increase system resiliency. Spearmint currently operates 350 MW / 700 MWh in ERCOT, and has over 20 projects, totaling over 15 GWh of capacity, under development in 13 states across 5 U.S. regions. Headquartered in Miami, with an additional office in Minneapolis, the Company employs over 60 professionals and is guided by strong values rooted in people, partnerships, and the planet.
For more information, please visit: https://www.spearmintenergy.com/
About Mortenson
Mortenson is a U.S.-based, top-25 builder, developer, and engineering services provider serving the commercial, institutional, and energy sectors. Mortenson’s expanding portfolio of integrated services helps its customers move their strategies forward, ensuring their investments result in high-performing assets. The result is a turnkey partner, fully invested in the business success of its customers.
Mortenson has operations across the U.S. with offices in Chicago, Denver, Fargo, Iowa City, Milwaukee, Minneapolis, Nashville, Phoenix, Portland, Salt Lake City, San Antonio, and Seattle. For additional information, visit www.mortenson.com.
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