On a Wednesday afternoon last month, an Uber Technologies Inc driver in San Francisco was about to run out of charge on his Nissan Leaf. Normally this would mean finding a place to plug in and wait for a half-hour, at least, but this Leaf was different.
Instead of plugging in, the driver pulled into a swapping station near Mission Bay, where a set of robot arms lifted the car off of the ground, unloaded the depleted batteries and replaced them with a fully charged set. Twelve minutes later the Leaf pulled away with 32 kilowatt-hours of energy, enough to drive