Depending on whom you’re asking, renewable energy and electric vehicles will either destroy the grid or save it. The sun doesn’t always shine and the wind doesn’t always blow, true enough, while a gas-fired power plant can generate electricity any time. That supposed precarity of renewables will get even shakier, critics argue, as Americans ditch conventional vehicles for electric ones, which will draw ever more power from an already strained grid.

Luckily, that’s not a realistic scenario because of what renewables and EVs have in common: giant batteries. Solar and wind farms are plugging into huge banks of them to store energy to use as needed, fixing their intermittency challenge. (Engineers are turning Earth itself into an even bigger battery .) And a growing number of cars with cord

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