Under growing pressure to improve energy efficiency, automakers around the world have already spent approximately $2 billion to develop electric cars powered by fuel cells. The technology involved, which uses hydrogen to generate electricity, has been heralded as the key to tomorrow's cleaner-running car. But is it really environmentally friendlier?

In the short term, the answer is no, according to a recent MIT study. Over the next two decades, fuel cells will deliver an environmental performance only slightly better than advanced versions of the familiar internal-combustion gasoline engine, the study says. During that time, another technology-internal combustion/electric hybrid cars like the Honda Insight and Toyota Prius, which premiered last year-promises the lowest energy consumption and emissions.

If every corner gas station sold hydrogen, fuel cells would be more efficient and competitive. But as a practical matter, hydrogen must first be extracted from today's widely available fuels, like gasoline and methanol. "Fuel cells offer no important advantages over other technologies," says Malcolm Weiss, who headed the MIT study, with funding from four oil companies, Ford, and a foundation. "You can more quickly and easily produce and introduce improvements in traditional technologies than new technologies."

The study used computer simulations of various combinations of fuels and engines and included the "life cycle" energy costs of building the engines and producing the fuel. The study concluded that in 2020, internal combustion/electric hybrids will consume about 55 to 65 percent of the energy of an advanced gasoline car, while fuel cell/electric hybrids will consume more: 72 to 104 percent.