When the Grid Goes Down, Can a Fleet of Batteries Replace It?

Last week, as millions of his fellow Texans were plunged into unrelenting darkness and cold, Nicholas Littlejohn considered himself lucky. In the area outside Austin where he lives, the power first went out early Monday morning, and then flickered on and off, all week long, for 20 minutes at a time. Littlejohn decided to make the most of those minutes. When the power was on, he charged up his 2011 Nissan Leaf, parked outside under a layer of snow. Then, when the lights went out again, he connected his car to an inverter, pushing electrons out of its 24-kilowatt-hour battery and into other things that were, at the time, more essential: lights, a space heater, an electric blanket, and his Wi-Fi router. He skipped plugging in the fridge.

How many cars like Littlejohn’s would it take to replace the energy that was missing last week from the Texas power grid? Emily Grubert, an energy infrastructure expert at Georgia Tech, posed the question last weekend on Twitter. Her thought was sparked by a dispiriting reality: “The idea was that a lot of people during these outages have been climbing into their cars for heat,” she later told WIRED. In a way, car engines were doing at least some of the work that should have been done by the power grid. What if, she wondered, all the cars were electric? And what if that energy could be redistributed not just into homes, but onto the grid itself, powering up everyone’s lights and heaters? Assuming the grid lost 1 terawatt-hour of energy overall, and also assuming a bigger car battery, such as the one in a Tesla Model S, it would take perhaps 10 million electric vehicles to make up the total energy lost, she figured. Which sounds like a lot of cars. But as she points out, there are 22 million vehicles registered in Texas alone. And soon, many more of them will be electric.

A grid backed by a 10 million Teslas is unlikely to be the top priority of most energy experts thinking about how to prevent future Texas-style crises. Yes, people need to drive. And yes, it would be impractical, if not impossible to coordinate. Experts have identified plenty of sensible ways to make the Texan grid better: weatherization of existing power plants and lines, improved connections to other grids, and regulations that encourage various forms of resilience as well as low prices. Better planning, basically. But as Grubert puts it, the crisis pointed to many possible futures for a more reliable electric grid. Batteries, both large and small, are becoming more ubiquitous, whether we consciously tie them into the power grid or not. So how could we harness them to make the grid more nimble and keep the power on? “What I was getting at was there are many ways we could think about planning for the future,” she says.

In states like California, finding ways to store energy has long been on the minds of regulators and utility operators. The primary reason is the state’s goal of relying on 100 percent clean energy by the year 2045. The problem with that is that the sun doesn’t always shine and the wind doesn’t always blow—at least not everywhere across the state and not all at once. And so, since 2013, utilities have been required to procure energy storage systems that suck up otherwise wasted power when renewables produce more than is needed, and disburse it when there’s a gap in supply. It’s a matter of balancing a load that’s uneven, but often predictably so, such as when solar panels go offline at night.

www.wired.com

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