The cells produce about 1 million watts of electricity. That's more than enough to power the post office. Fuel cells are too expensive for most commercial uses. But costs are falling. Backers of this project say the goal is not to make money but to test on a large scale a technology that is gaining ground.
Fuel cells are essentially large batteries.
They strip hydrogen off fuels like natural gas and, through a chemical process, convert the hydrogen into electricity. The process produces steam and hot water, but no toxic emissions and little greenhouse gas. One cell produces about 44 pounds of carbon. A comparable amount of energy from a power plant would send 1,100 tons of carbon into the atmosphere. The post office will also use the cells' hot water by-product to heat the building.