Google is helping bring cutting-edge battery tech to an old West Virginia strip mine
For decades, a sprawling site in West Virginia was mined for coal, and part of the operation is still active. But on a 500-acre section abandoned 20 years ago, something new is taking shape: a clean-energy project pairing solar power with cutting-edge battery technology that could help renewables deliver electricity around the clock.
The $350 million project, called Mammoth Solar, will sell energy to Google, which has a goal to get to 24/7 carbon-free energy on every grid where it operates. It’s the first development where the tech giant will rely on zinc batteries, an emerging long-duration technology that can store electricity for 10 hours.
It’s the next step in the evolution of renewable energy. A decade ago, most solar and wind projects didn’t include batteries at all, says Jon Yoder, president and CEO of MN8 Energy, which partnered with Google to build and operate the new plant. “There was no economically viable way to store that power when the sun wasn’t shining or the wind wasn’t blowing,” he says.
A few years later, lithium-ion batteries became viable for short-term storage. They work well for storing electricity for about four hours, helping cover the evening spike in demand after the sun goes down. But using them to bridge longer gaps remains too expensive.
MN8 and Google researched new options for long-term storage that could be used along with lithium-ion batteries, and “ran literally dozens of different combinations of technologies to compare the functionality against the cost,” Yoder says.
Zinc stood out, he says, because the batteries have a relatively high round-trip efficiency, meaning the amount of electricity you get out for the amount that you put in. The zinc batteries, made by a company called Eos, also use sustainable materials and don’t pose a fire risk.
“We chose to support Eos’s batteries because the chemistry relies on Earth-abundant materials—zinc and bromine—and a more resilient supply chain than traditional lithium-based systems,” says Campbell Howe, advanced energy program manager at Google.
“Additionally,” Howe says, “Eos’s manufacturing facility in Pennsylvania is already stood up, which will continue to support job growth and economic development in the Appalachian region.”
The project will break ground in 2027, with 86 megawatts of solar panels in place by 2028; 70 megawatts of lithium-ion storage will be added by 2029, followed by 10 megawatts of the zinc batteries in 2030.
The zinc technology is still a relatively small amount of the project. “Because this is relatively new technology and because we want to see how it performs in real-world situations over an extended period of time, we sized it in a way where the economic investment still is prudent even with the remaining risks that could be latent in the business model for the zinc,” Yoder says.
But it’s a meaningful amount, and it will let both MN8 and Google see how the zinc batteries perform, including their real-world efficiency, to help plan future projects.
As the lithium-ion batteries cover the evening, the new batteries can help cover more of the night. “We can serve those hours from, let’s say, 10 at night until 8 the next morning, when the sun is coming up again,” Yoder says.
Because the zinc batteries are a smaller piece of the development, the project isn’t yet designed to provide energy all the time, “but that’s the theory of where we’re headed,” he says. “These three technologies, in combination between solar, short duration, and long duration, move the needle much closer to the ability to serve power on a 24/7 basis.”