For more than 20 years Geoffrey Ballard, chairman of Vancouver's General Hydrogen, has led the charge for hydrogen-based fuel cells, which produce electricity to power vehicles, with essentially only water vapor for emissions. For his efforts in the past year, he received the Scientific American 50's award for business leader of the year.

A geophysicist by training, the 70-year-old Ballard turned to fuel cell research in the late 1970s to address the growing levels of smog in large cities. Fuel cells, he says, are cleaner than the internal combustion engines in gasoline-burning cars and can reduce the health impacts of automobile air pollution if in wide use.

The trick, he adds, is to introduce hydrogen-based fuel cells in a way that doesn't disrupt the current automobile market economy and to find a common ground between car manufacturers and environmental legislators. Toward that end, he cofounded General Hydrogen in 1999 to determine the best way to make hydrogen into a popular, accessible fuel. We asked Ballard to reflect on the potential of fuel cells. --Tariq Malik

SA: Why choose hydrogen-based fuel cells as an energy source for vehicles?

GB: Hydrogen is a very clean-burning fuel. It reduces down to water when you run it through a fuel cell, meaning no emissions. It can also be manufactured in a central place then doled out for use. This would allow us to keep any pollution caused by actually generating hydrogen, whatever that method may be, in one location, away from cities and out of the people's lungs.

I find the most important thing that we have to be concerned about is air pollution in our inner cities. There's a growing need to curb car emissions in cities such as Los Angeles, San Francisco, New York and internationally, places like Mexico City and Kuala Lumpur.

The other thing is that fuel cells, like internal-combustion engines, are scaleable to the amount of power you want. In cars today, if you want more power, you get a bigger engine. And if you want to go farther, all you need is a bigger gas tank. Unlike electric cars, whose batteries are good for things like golf carts and small Post Office vehicles, fuel cells can be scaled like internal combustion engines, and they're cleaner.

SA: How has your work has affected the general push toward developing alternative fuels?

GB: Nobody was really too enthusiastic about the fuel cell at first, not until we put one in a bus and drove it around at energy conventions. I think people just couldn't grasp that it could really happen. But when you put a hydrogen fuel cell in something and then drive it around--well, it's pretty hard to argue with that.

Now almost every major manufacturer--General Motors, Toyota, you name it--is looking into the idea of a commercial fuel cell vehicle. There is definitely an interest there, and the larger companies wouldn't commit to the research unless they thought there might be a payoff too.

SA: What are the challenges that you and others face in developing fuel cell technology?

It comes down to reliability and cost. We've already demonstrated that it's possible to make hydrogen-based fuel cells, The chief engineering problem of affordably integrating a dependable hydrogen-based fuel cell into a car will have to be solved by automobile makers. But the other problem is: Once you've got a fuel cell in your car, where do you get the hydrogen?

That's a big problem, because there are no hydrogen stations around ever corner. We're working on ways to address that infrastructure need without disrupting the existing car economy. This is important, especially since the automotive and fuel industry make up an entire third of the North American economy. You can't just play games with that.

SA: What are you hoping to avoid as you continue your work?

The idea of the social disruption or established markets by the rapid introduction of fuel cells is something I take very seriously. When the first cars were first introduced, around the time of horse and buggies, towns in Massachusetts required drivers to have people running along in front them with red lanterns in hand to warn horse owners of possible backfires.

There were dire predictions of that every horse and buggy driver would be out of a job. It was a complete social disruption. That's what I'm working to avoid, and we have a number of strategies that we're working on to incorporate this technology as a major tool for transportation.

SA: When do you expect to see commercial hydrogen fuel cell vehicles on city streets?

I don't like predicting these things, because you can always turn out to be wrong. Current automobile makers seem to think they can have a fuel cell vehicle in showrooms by the end of the decade, so it may be possible. But it has to come about; there's just no denying that.

I do think, however, that the personally owned, privately housed family car will be the last thing to receive a hydrogen fuel cell to drive it, simply because a better place to start is with government vehicles. City vehicles are generally housed in central yards or garages where they can be serviced and fueled as needed. It's just more practical at the beginning that way.

Tariq Malik is based in New York City.