12:22 PM EDT, 10/10/2025 (MT Newswires) -- (Updates with the latest stock movement in the first paragraph and headline.)

ESS Tech ( GWH/WS ) shares were up nearly 129% in recent Friday trading after the company said it signed a new iron flow battery pilot to deliver power under a 10-year agreement with Salt River Project.

The agreement involves adding a 5-megawatt, 50 megawatt-hour battery system to the grid, the parties said late Thursday.

The Iron Flow Battery project aims to evaluate the performance of non-lithium, long-duration energy storage in the Arizona climate. The pilot seeks to validate the company's technology as a safer and sustainable alternative to lithium-ion batteries, it said.

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