Public EV charging in Hawaii has doubled in a year, a positive sign for the islands' shift away from gas cars.

• Electricity used at public charging stations jumped from 3.1 to 6.4 gigawatt-hours, enough to power 12,600 homes for a month.
• The real total is higher, since the count leaves out home charging, which is how most drivers fill up.
• Hawaii now has the third-highest rate of EV ownership per person in the country, behind California and Washington.
• Rising demand points to more pressure on the islands' power grid as drivers plug in.

Outlook: Public charging use looks set to keep climbing as EV ownership in Hawaii grows.