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Battery technology that will allow electricity to be stored for days is crucial in meeting the challenges of maintaining a stable, reliable power grid as the amount of renewable energy increases and demand continues to rise.
Form Energy, a Massachusetts-based company that recently built its first high-volume battery manufacturing facility in Weirton, W.Va., is using a next-generation iteration of an existing technology to produce long-duration, iron-air battery storage. Diana McMillan, a senior engineering manager with Form Energy, recently discussed different battery technologies, the company’s iron-air battery system, and its role in supporting the electric grid during a webinar as part of CEPM’s Energy Lecture Series.
“Electric grid stability is a critical for the U.S.,” McMillan explained, noting that renewables such as solar produce a lot of energy during the day but not at night. Long-duration battery storage can capture the excess power that is generated during daylight hours, and release it during times renewables are not available or during power demand peaks, acting as a backup source.
The secondary lithium-ion battery, which powers everything from cell phones and laptops to electric vehicles, is the most well-known type of battery storage. These batteries are rechargeable and offer high energy density, but can provide only short-duration storage. They are also expensive and don’t present the best option for providing grid storage.
Form’s secondary air-iron batteries were developed from an existing technology that had not gotten much attention until the need for long-term battery storage came to the forefront. The current generation of Form batteries can provide storage for 100 hours at one-tenth the cost of a lithium-ion battery. They are made with iron, water, and air – all inexpensive, domestically available materials.
Energy is stored and released through a reversible rusting process. When discharging, the battery cell takes in oxygen through an electrode, which reacts with water and electrolytes to form hydroxide ions that react to rust the iron, releasing electrons that form the discharge current. When the battery is charged, an electrical current converts the rust back to iron, storing energy and releasing oxygen.
Form produces the electrodes, cells, and battery modules that can be scaled to provide the needed amount of storage. McMillan noted that the storage is flexible also safe as there is no danger of fire and has high recyclability. The batteries can capture excess power and release it at times of peak electric demand, or during a blackout. She noted that the storage is stationary as each container of battery modules is the size of a truck trailer and is heavy. The iron-air batteries are less efficient than lithium-iron, but McMillan said that their cost effectiveness makes up for the reduced efficiency.
Form Factory 1, a 550,000-square-foot facility, was constructed on the site of the former Weirton Steel mill. Form is ramping up production and has already attracted a number of customers, mainly electrical companies. After a planned expansion, it will have more than 1 million square feet of manufacturing space, employ over 750 people, and have an annual production capacity of 500 megawatts of batteries.