Why you should care

Because clean energy isn’t enough — you need clean storage too.

Solar panels and wind turbines are everywhere these days, but the sun doesn’t always shine and the wind doesn’t always blow. Meaning, the more panels and turbines you build, the more you need a backup for rainy days (literally). Storing excess solar and wind energy would be ideal, but conventional batteries wear out quickly, sometimes catch fire, often leak toxic crud and leave behind heavy metal waste when they go. That leaves unconventional batteries — say, power cells built out of something cheap, plentiful and nonflammable that’s also utterly nontoxic. Maybe, since we’re dreaming here, even safe enough to eat.

Make that, safe enough to eat and drink, and somewhere Jay Whitacre’s ears perk up. For the past five years, the Carnegie Mellon professor and a team of engineers at his startup, Aquion Energy, have been developing a long-lived, eco-friendly and inexpensive battery out of nothing more than salt water and other simple components. This isn’t a battery that will juice your phone or your car, at least not directly; instead, it’s intended for big power farms that could soak up excess electricity during the day — for instance, from home solar systems — and then shoot it back out at night when the sun’s down. The French consulting firm Yole Développement figures this “stationary storage” market could be a $13.5 billion opportunity by 2023, compared with less than $1 billion this year.

Whitacre and his saltwater battery have made some serious waves. Aquion, headquartered in a former railroad engine foundry in an industrial neighborhood of Pittsburgh, has raised $135 million to date from several investors, among them Bill Gates and the venture arm of Shell Oil. It’s won accolades from MIT Technology Review, Fortune, Popular Science and others as a global energy innovator. And Whitacre is rumored to be on the short list for the prestigious Lemelson-MIT Prize, a $500,000 award for inventors whose work can improve the world.

Cheap, long-lived batteries could make the antiquated electric grid more efficient, more resilient to usage spikes or natural disaster, and better suited for renewable energy that helps fight climate change. (These storage options just need to get “cheap enough and big enough,” Whitacre says.) In some ways, the development resembles the locavore trend in food, only with billions of dollars at stake — not to mention the electricity that powers your air conditioner, TV and Internet connection. The prospect has drawn high-profile competitors like Tesla Motors, which a few months ago announced its own big push into home-battery systems that could help some homeowners disconnect from the grid entirely.

Whitacre himself lives a renewable and frequently recharged life. Even in the depths of winter, he rides his bike 2.5 miles from the Carnegie Mellon campus to Aquion; his staff estimates he spends 90 percent of his commuting time generating pedal power. (When he gets behind the wheel, he drives a Prius, naturally.) Tall, curly-haired and passionate about fitness, the 43-year-old researcher rarely stops moving, as if some internal generator is storing his excess energy for later use. He’s quick with a boyish grin and exudes professorial charm.

Raised in a family of doctors, Whitacre had little interest in medicine. He was the kid dismantling and reassembling the household appliances and dreaming about outer space. By the tender age of 12, he was bringing home trophies and ribbons from Ohio state science fairs. He studied physics and engineering in college, used X-rays to study “thin film” materials for his doctorate at the University of Michigan, and then bounced from Caltech to his “dream job” at NASA’s Jet Propulsion Laboratory in 2001. There, among other things, Whitacre designed a thermal battery system that eventually made its way into the Mars rover Curiosity.

But he had bigger dreams. In 2007, Whitacre moved to Carnegie Mellon, and spent the next eight months hunkered down in his fourth-floor office experimenting with different battery materials. He considered lithium. Flammable and expensive. He tried an acid electrolyte. Too caustic. At last, with an assist from a wad of cotton hole-punched from his T-shirt, he created an early version of an aqueous hybrid ion battery, using a saltwater chemical solution borrowed from the first battery invented 200 years ago by Alessandro Volta. “There was this big hole in the market for storage,” says Ray Lane, a partner with the venture firm Kleiner Perkins Caufield & Byers, now Aquion’s lead investor. The saltwater battery not only fit the bill but also was cleaner than any other technology around. To prove the point, Whitacre has taken a piece of the battery’s electrode and, Lane says, “eaten it as a joke.”

With so many companies jockeying for position, of course, Aquion could still flame out. Tesla Motors is betting big with a sprawling $5 billion battery “gigafactory” under construction in Nevada; its Powerwall battery also aims to store renewable energy for homes, businesses and utilities. Boston-based Ambri, founded by an MIT professor, is working on a promising low-cost liquid metal battery technology. Aquion has also had its ups and downs; there have been layoffs at the factory as the company tweaks its manufacturing line. And some experts remain skeptical that batteries have a big role to play in renewable-energy systems — they’re compact and fast for storing and discharging energy, says Mark Jacobson, director of the Atmosphere/Energy Program at Stanford University, but they still have a “relative high cost” compared with alternatives.

Aquion is currently churning out batteries as fast as its plant east of Pittsburgh can produce them, in sizes suitable for residential use all the way up to commercial and utility installations. More than 75 international partners currently install Aquion batteries in solar arrays around the world, with a focus on solar-friendly locations like Germany, California and Australia. Tropical islands with sky-high electricity costs are another attractive market; a few months ago, a private residential estate along Hawaii’s environmentally sensitive Kona coast installed one of the largest Aquion systems to date.

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