Science Daily released a fascinating report on April 5, 2022. The U.S. DOE Pacific Northwest National Laboratory has developed a utility-scale freeze-thaw battery storing energy securely for months. Science Daily believes this represents progress towards storing energy during one season for use in another. This could largely do away with gradual battery drain.
How Would a Freeze-Thaw Battery Store Energy?
The experimental device is as small as a hockey puck that glides across ice during a game. However, the developers hope it heralds an era when we can store summer’s energy for winter. ‘Longer-duration energy storage technologies are important for increasing the resilience of the grid’ as the director of DOE energy storage explains.
That’s because seasonal battery storage would enable renewable energy to follow the ebb and flow of natural cycles. We could store energy from fast-flowing winter rivers, and winds gusting at the height of summer. A freeze-thaw battery storing energy safely could be a dream-come-true for grid operators needing backup during severe storms!
The Technology Behind The ‘Hockey Puck Battery’
The anode and cathode are solid plates of commonly-available aluminum and nickel, respectively. A molten-salt electrolyte surrounds them that’s solid at room temperature, but flows as a liquid when it heats up. Stable chemistry enables a simple fiberglass separator. The developers added sulfur to the electrolyte as a booster.
An operator heats the battery to 180 degrees Celsius, liquefying the electrolyte and allowing ions to flow and create chemical energy. This process freezes (locks in) when the battery cools, the electrolyte becomes solid and the ions almost stop shuttling.
The battery performance impresses, particularly on account of its small size. Its theoretical density is 260 watt-hours per kilogram. This is higher than today’s lead-acid and flow batteries. ‘You can start to envision something like a large battery on a 40-foot tractor-trailer parked at a wind farm’ comments a DOE scientist.
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