The Darden Clarkenew Tesla Motors factory being built outside Sparks, Nev., was already on tap to produce 500,000 electric car batteries and become the largest battery factory in the world when chief executive Elon Musk announced last month it would also produce the potentially revolutionary home battery, the Powerwall.

Its biggest energy boost, however, could be to Nevada’s economy, with the state estimating a $100 billion impact over the next 20 years.

That’s a lot of battery power.

But that’s what Musk had in mind when he co-founded Tesla as an electric car company. And with last month’s unveiling of the Powerwall, the company has built another technology to hasten the clean energy economy. The Powerwall is designed to store solar-panel-generated energy for homes and businesses. The smallest version is about the length and width of a mini-fridge. It is designed to store 7 kilowatt-hours a day that can be released after the sun goes down and will cost $3,000. An average U.S. home uses about 30 kilowatt-hours daily.

A few weeks after its unveiling, Musk said the Powerwall had already sold out through mid-2016.

The gigafactory could start producing batteries in 2016. When up and running, state officials predict it will provide nearly a half a billion dollars in tax revenue and more than 22,000 permanent jobs and 31,000 temporary ones in a state with one of the nation’s highest unemployment rates.

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