Daniel Yergin's new book is "The Quest: Energy, Security, and the Remaking of the Modern World." He received the Pulitzer Prize for his history of oil, "The Prize."

One day in 1948, Caltech chemistry professor Arie Haagen-Smit took a break from trying to decipher the mystery of the flavor of the pineapple. He stepped outside his lab for a breath of fresh air but instead found himself enveloped in what he called "that stinking cloud" of smog. At the time, there was a bitter debate as to what caused smog. So Haagen-Smit decided to put aside his pineapples (he had already worked out the taste chemistry of onions, garlic and wine and had identified the active agent in marijuana) to try to solve the source of smog.

What he discovered explains why plug-in electric cars — the Leafs, Volts, Teslas and all the other models that automakers will bring out in the next few years — are appearing on our roads. Or, to be more precise, reappearing.

In 1900, more battery-powered electric cars ran on the streets of New York City than cars with internal combustion engines, and over the next few years there was a fierce race for supremacy between them. But the arrival in 1908 of Henry Ford's Model T turned the gasoline-powered car into an affordable mass-market product and made the electric car a historical curiosity. The moment when Haagen-Smit exchanged his fascination with food for one for smog marked the beginning of a shift back....