February 24, 2022

Rusting batteries could help power the electric grid of the future

Bruce Gellerman & David Greene

The same chemical process that ruins your bike chain and eats away at your outdoor grill could help power the electric grid of the future, and perhaps even help save the planet from catastrophic climate change.

Company officials from Somerville startup Form Energy are developing batteries powered by rust, and claim their low-cost, long-duration technology can store energy generated by renewable solar and wind and release it back onto the grid when the sun doesn’t shine and the wind doesn’t blow.

President and COO Ted Wiley remembers the day five years ago he and a group of MIT scientists founded Form Energy with an audacious mission: find a low-cost way to transform the global electric system. They had a eureka moment when they thought about harnessing the rusting process to power batteries.

“My first thought was, ‘Wow, that actually is cheap enough to really have a shot at making renewable energy able to replace coal and gas everywhere in the world,’ ” he said.

Wiley became president and chief operating officer of Form Energy. Until late last year, the company operated in stealth mode. Now, they’re ready to share their work with the world. In the company’s cavernous lab space in Somerville, Wiley removed the lid on one of the nearby 55-gallon drums to reveal the basic raw material to its secret technology.

“They’re about the size of a marble,” he said as he scooped up small, black iron pellets. Each of the drums are crammed with the balls, which are collected from iron mines around the world.

“Right now, we’re starting to establish relationships with the people who supply iron because we’re going to need a lot of it,” Wiley said.

The technology is based on oxidation, the electro-chemical process better known as rusting. When oxygen rusts iron, there’s a transfer of electrons that can be put to work in a circuit just as they can in any battery; positive flowing to negative. Form Energy has perfected “reversible rusting” to store and release that electric energy.

“That’s the magic of what we’re doing,” Wiley said, “rusting is discharging and then, when we’re charging, we’re pushing electricity back in. We’re un-rusting it.”

The company reasoned there’s enough iron in the world, and it’s cheap enough, that it could scale to to the size of the global problem and keep electric grids, the world’s largest and most complex machines, up and running on inexhaustible, but intermittent, solar and wind.

A subscale iron-air battery created for testing. (Robin Lubbock/WBUR)

While the solution is cutting-edge science, it’s not totally new tech. It’s based on the iron-nickel battery Thomas Edison helped to invent in 1901. Form Energy kept the iron electrode but replaced the expensive nickel with low cost, abundant and freely available oxygen from air.

Perfecting the combination in a battery was tough. NASA and GTE scientists tried something similar in the 1960’s but gave up. The research wasn’t worth pursuing; until large scale solar and wind projects came along, there wasn’t a need for grid-scale, energy-storage technology.

The secret sauce

Inside Form Energy’s Somerville facility, researchers test prototypes of iron-air battery cells. They began with beaker-sized cells, honed the technology and are now working with full-size cells wired with sensors that providing a steady stream of data.

When they go into production next year, iron-air battery cells will be sandwiched together to form modules the size of a washing machine, which in turn can be put together to construct huge energy storage systems.

“It’s like a Big Mac,” said company co-founder and chief technology officer Bill Woodford. “You have multiple layers in the Big Mac.”

Researchers are testing different types of iron to see which perform best. Woodford said they think they found the “flavor of iron” they’re looking for, but “we are going to keep that one a secret.”

Mechanical engineer Kalina Yang prepares a section of an iron-air battery for testing. (Robin Lubbock/WBUR)

Form Energy kept its technology under wraps until last year, when it announced it would test its iron-air battery modules with Minnesota-based Great River Energy. The power co-op is the state’s second largest generator of electricity.

Great River vice president and chief power supply officer Jon Brekke said the company has plenty of the right stuff nearby.

“After helping build this country with iron from Minnesota mines, we’re going to help power the country with iron from Minnesota mines and show that this can be done to help power the world,” he said.

“We’re building batteries that let renewables replace coal and gas.”

Great River is rapidly transitioning from fossil fuel to wind power, and Brekke believes Form Energy’s iron-air battery can keep the renewable energy grid of the future up and running when the wind dies down, even for days on end.

“That’s what we’re interested in as a large-scale solution with very low cost and can provide energy for a very long duration,” he said.

Ordinarily an electric utility would have gone with lithium-ion batteries, the same kind used in electric vehicles. They’re the current standard for large-scale energy storage but only last about four hours before they need to be recharged. Form Energy’s iron-air batteries provide 100 hours of power for a tenth of the cost for an hour of power.

“So you’re getting 25 times the amount of energy that will get you through a couple of cold nights,” Brekke said. “And that’s the kind of solution that we think is going to be important to maintain reliability and affordability as we transition the power grid.”

Great River will start with a small pilot project next year using a few hundred Form Energy modules, but has big plans to scale up if they work.

But experts warn building a better battery is just one component of the large scale, energy storage frontier.

“Battery storage is the wild west,” said Dan Shreve, head of global energy storage at Wood Mackenzie Power & Renewables. “There are so many options, so many levers to pull, buttons to push that it’s incredibly complex to understand exactly how these projects are going to make money.”

Still, Shreve says he’s optimistic about Form Energy’s future and bullish on long duration storage technology to help advance the transition to an electric grid powered by renewable resources.

Battery engineer Amelie Kharey looks at data gathered from battery temperature testing. (Robin Lubbock/WBUR)

Form Energy co-founder and senior vice president Marco Ferrara said the company put as much effort developing software as it did hardware development. The result is a unique tool using artificial intelligence to help customers model their future electric grids powered by renewable energy, and determine precisely when a utility should charge and discharge their battery modules to optimize profits.

According to the International Energy Agency, as we electrify everything from heating and cooking to the vehicles we drive, the need to meet 2050 climate goals will require 90% of electricity generation come from renewable resources, with wind and solar together accounting for almost 70% It means the market for grid-scale battery backup is vast.

Form Energy has moved to expand in five times in as many years in Massachusetts, and is already expanding to a new, bigger space for itself in Somerville. It also has facilities in Berkley, California and outside of Pittsburgh.

“We’re building batteries that let renewables replace coal and gas,” said Wiley. “Our goal is to be at the scale of producing gigawatts of energy storage a year by the end of the decade.”

Large-scale batteries could one day replace the nation’s strategic petroleum reserve, Shreve predicts, providing emergency backup energy to power the nation’s electric grids not just for days, but months.

“We are thinking about whether or not there is a path to still even lower costs than iron-air,” which would provide for longer, even seasonal, storage, said Form Energy chief science officer Yet-Ming Chiang.

But getting there will require more research and development, all done back in stealth mode at Form Energy’s facilities.

This segment aired on February 24, 2022.