Last April, when a tin mill closed in Weirton, West Virginia, it was the last remaining part of what was once a sprawling steel works. Over the last five decades, as the American steel industry declined, the town lost thousands of jobs.
But in July, a new factory opened on the same site and started to bring hundreds of jobs back. Instead of turning iron into steel, it uses the metal to make a new type of battery.
"We're reversibly rusting iron," says Mateo Jaramillo, CEO of Form Energy, the company that built the factory. The battery technology, called iron-air, reacts with oxygen to store and release energy. It's designed to store energy for around four days -- something that standard lithium-ion batteries can't do economically.
"When we started the company, we saw that as being the next frontier: how do you cost-effectively attack that opportunity in the market?" says Jaramillo, who previously led work on energy products at Tesla. "It's a growing need. As we have more and more renewables on the grid, of course that means the grid tends to be weather-driven. And increasingly, we have more volatile weather events on our grid that we need to be able to address, and they tend to last multiple days."