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A better battery? MIT researchers say discovery could improve storage of energy from wind, sun

Gordon Welters/The New York Times

What if the energy from a sunny, windy day could be stored in a massive battery and used at night when the wind dies down?

By Laney Ruckstuhl Globe Correspondent 

Massachusetts Institute of Technology researchers say they’ve improved a large-scale battery, opening the possibility of storing massive amounts of renewable energy for a rainy day — or a day without wind.

The researchers say their changes to liquid-sodium batteries will make them more durable and useful.

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“I consider this a breakthrough,” MIT professor Donald Sadoway said in a prepared statement. He said the batteries, invented five decades ago, could finally become practical because of the new research.

A team led by Sadoway, which included postdoctoral researchers Huayi Yin and Brice Chung and four others, published its study this week in the journal Nature Energy.

Sadoway said the battery’s innards previously contained a fragile ceramic, but the team found a way to replace it with durable metal.

Currently, buildings powered by solar and wind energy have a problem: “The wind doesn’t blow all the time; the sun isn’t there after dark,” Sadoway said. And if there’s surplus energy, large amounts can’t be stored.

Because of that, the buildings still have to be connected to an electrical grid. But the improved liquid-sodium batteries could eliminate that need, Sadoway said.

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“You’d effectively be in a position to go off-grid,” Sadoway said. “The idea is that the storage would be close to the demand center — whether it’s in a single-family home or a hospital,” he said.

He said the batteries could also be used by utilities, and that could eliminate their use of fossil fuels.

“The big thing that is holding back grid-scale storage is cost,” he said. “With the cost of natural gas being what it is, it’s a lot cheaper to hook up a gas-fired unit than it is to install batteries.”

The batteries can be made of cheap, abundant raw materials and are safe to operate, he said.

Unlike lithium-ion batteries used in cellphones and laptops, the liquid-sodium batteries won’t lose their capacity quickly, Sadoway says. There isn’t yet definitive research on how long they’d last, but preliminary findings point to much longer than a couple of years.

He said four years of tests indicate the batteries can be recharged thousands of times.

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Sam Jaffe, an energy expert with Cairn Energy Research Advisors, said in an e-mail that it could take years of development before a more durable metal-interior battery can be proved to work. Because of their high heat requirement, Jaffe said, liquid-sodium batteries still aren’t as efficient as lithium-ion, the common type of batteries used today.

“This type of battery deserves more research resources, but the chances of it replacing the incumbent technology anytime in the next 10 years are extremely low,” Jaffe said.

Sadoway says his motto is “science and service to society, not science and service to career advancement.” He hopes his team’s findings can be useful to the public.

“There’s this connection between basic research at the university and meeting larger needs,” Sadoway said. “This thing just might be able to solve an important societal problem.”


Laney Ruckstuhl can be reached at laney.ruckstuhl
@globe.com

Follow her on Twitter @laneyruckstuhl.