Fuel cells have been around for more than a century.
She had Mark close down the fuel cells as well.
This was the first commercial use of a fuel cell.
These fuel cells are at an early stage of development.
The first fuel cells were created in the 19th century.
Less than two hours' worth of energy was left in their fuel cells.
Learn about whether the cost of fuel cells is a major problem in this article.
Fuel cells for cars, however, are 10 to 20 years away.
The companies have set a target of 2004 for a commercial fuel cell.
Only five years ago, fuel cells were at least 50 times more expensive than they are today.
