Can nuclear power plants like California Diablo Canyon be replaced without greatly raising emissions? It's an open question.
Closure of the state's last coal power station will leave a potential gap in the electricity supply.
We already have them in many sizes – but we're still looking for a battery to store truly large amounts of energy.
As it's done with its electric cars, Tesla will need to rely on well-heeled early technology adopters and friendly regulations to sell lots of home batteries.