When the 20-passenger transit bus pulled up to the curb with its engine purring, one of the passengers exited the bus, walked to the rear, and collected in a cup some of the clear liquid trickling out from the bus' tail pipe. As onlookers gasped, he drank from the cup, then passed it around to the doubting Thomases, who hesitantly followed suit.
"It's just water!" declared one of the amazed sippers.
Fact or science fiction?
While the scenario may sound like a scene from a science fiction movie, last August's demonstration has been repeated several times over by Ballard Power Systems, a Vancouver, British Columbia, firm that is showing off the first bus powered by a fuel cell.
Fuel cells are power sources somewhat akin to batteries. Both produce electrical current through an electrochemical reaction.
But batteries carry all their electrical energy around in their cells and must be recharged when that energy is depleted. Fuel cells, by contrast, can produce electrical energy continuously, without recharging, as long as they are supplied with oxygen and hydrogen, which is the fuel.
Fuel cells are also akin to internal combustion engines in that they continue to produce energy so long as they are supplied with fuel. However, because fuel cells generate electricity directly in an electrochemical reaction, instead of through combustion, the only emissions they produce are water and heat, which can be captured and reused. (Fuel cell systems that derive their hydrogen fuel from a precursor hydrocarbon fuel emit a third product--carbon dioxide.) In general, the process by which fuel cells generate electrical power is up to 20 times cleaner than that of traditional electric power plants. And its efficiency is two to four times that of an internal combustion engine.
A fuel cell contains no moving parts, but its auxiliary water pump and air circulation system make a quiet hum similar to that of a window air conditioner.
The advantages of fuel cells, combined with recent breakthroughs in their technological development, have set off an international race to bring them to the marketplace. Governmental and private industry research during the past decade, primarily in the United States, Canada, Japan, and Germany, has resulted in fuel cells that are on the brink of commercialization.
In fact, some few commercial fuel cells are already available. Thirty-eight 200-kilowatt fuel cells made by ONSI Corporation, a subsidiary of International Fuel Cells of South
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