8500 megawatt hours: Why the world's largest battery relies on rust
Iron-air batteries could revolutionize the energy transition: They are significantly cheaper than lithium-ion batteries and use abundant raw materials.
The world's largest battery is to be built in a factory in West Virginia.
(Image: Form Energy)
The largest battery storage facility in the world is currently being built in the USA. It is set to have a capacity of 8.5 gigawatt hours. In one fell swoop, that would be almost half of the total battery storage installed in Germany – including all home storage systems. And more than 30 times as much as Germany's largest planned Battery Park in Alfeld.
However, the real highlight of the new storage system is not its sheer size, but its technology: it does not work with the critical raw material lithium, but with air and iron or rust. Due to the abundance of available raw materials, it should only cost a tenth as much as conventional batteries. The system is also non-flammable and contains no toxic substances.
The company behind it is the Massachusetts-based start-up Form Energy. It was founded in 2017 by the energetic MIT professor Yet-Ming Chiang and Mateo Jaramillo, former Vice President for stationary energy storage at Tesla, among others. It now has more than 300 employees.
How the technology works
In its uncharged state, the metal electrode consists of rust, or more precisely iron hydroxide (Fe(OH)2). When charging, electricity breaks down the rust. This produces hydroxide ions (OH–), which enter the water and migrate through a membrane to the air electrode. Oxygen is formed there, which bubbles out of the electrolyte.
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During discharge, a fan blows air into the electrolyte. The oxygen from the air contributes to the formation of hydroxide ions. These migrate back through the membrane to the iron. There they combine to form iron hydroxide and release electrons in the process.
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Technical challenges and solutions
The idea for rust batteries of this kind first emerged in the 1960s. However, building a functioning battery from this simple principle is not easy. One problem is dealing with solid, liquid and gaseous substances that have to react with each other. To increase the contact surface of the metal electrodes, Form Energy uses pressed, but still porous, iron powder. In addition, pumps and fans keep the gases and liquids in constant motion.
Current developments
According to the company, pilot production in the first factory has been running since September 2024. Commercial production is due to start this year. The expansion of production is already underway.
This article first appeared on t3n.de .
(mki)
