Technology

Often thought of as new technology, fuel cells have long history: Here's how they work:

July 18, 2005

Scientists are working to make fuel cells a viable energy source for the 21st century. But, in fact, the technology dates back more than 150 years.

Research began in the mid-1800s, but with the onset of the Industrial Revolution, fuel cells were abandoned in favor of more powerful alternatives, said Jack Brouwer, associate director of the National Fuel Cell Research Center in Irvine, Calif.

"They didn't think fuel cells could contribute," he said.

The technology sat dormant until the beginning of the space program in the 1950s. Seeking an efficient power source that produced no emissions, scientists turned to fuel cells to send rockets into orbit. The astronauts, in turn, drank the water emitted from the fuel cells.

Here's how a fuel cell works, according to the U.S. Department of Energy:

Proton exchange membrane fuel cells are the type typically used in automobiles. A PEM fuel cell uses hydrogen fuel and oxygen from the air to produce electricity.

Hydrogen fuel is channeled through field flow plates to an anode on one side of the fuel cell, while oxygen from the air is channeled to a cathode on the other side of the cell.

At the anode, a platinum catalyst causes the hydrogen to split into positively charged hydrogen ions [protons] and negatively charged electrons. The steep cost of platinum is one reason the technology is expensive.

The PEM allows only the positive ions to pass through it to the cathode. The negative electrons must travel along an external circuit to the cathode, creating an electric current.

At the cathode, the electrons and hydrogen ions combine with oxygen to form water, which flows out of the cell.

Most fuel cells designed for use in cars produce fewer than 1.16 volts of electricity-far from enough to power a vehicle. So multiple cells must be assembled into a fuel cell stack. The power generated by a stack depends upon the number and size of the fuel cells in the stack and the surface area of the PEM.
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