Jonette Øyen with her Nissan Leaf outside the National Archives in Norway, where she works. Next month Norway is expected to become the first country where one in every 100 cars is purely electric. Sidsel Overgaard /NPR hide caption

itoggle caption Sidsel Overgaard /NPR

A prototype of a flexible battery from Imprint Energy, one of 40 companies working on battery technology in the San Francisco Bay Area. Imprint Energy hide caption

itoggle caption Imprint Energy

BMW's electric i3 Concept is presented before the Paris Motor Show last September. The car was officially unveiled Monday; purchasers can reportedly opt for using a gas-powered SUV several weeks each year. AFP/AFP/Getty Images hide caption

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A Ford Focus electric concept car with a home charging unit on display at the 2013 North American International Auto Show in Detroit, Mich., in January. Stan Honda/AFP/Getty Images hide caption

itoggle caption Stan Honda/AFP/Getty Images