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Fuel Cell Science

At its most basic, a hydrogen fuel cell is just a device that allows substances to combine chemically, without burning, to produce electricity.

Most fuel cells look like small boxes composed of densely packed layers of a cloth-like material and metal or plastic. Hydrogen, the fuel, flows in through a port on one side and oxygen through a port on the other.

Those two gases, which can’t combine without help, meet in the presence of a catalyst, most commonly platinum, that’s embedded in the cell’s layers.

The chemical reaction that ensues produces electricity; the cell keeps generating power as long as the hydrogen and oxygen keep flowing. Most appealing: The only byproducts are a tiny bit of heat — and water.

Two of the main hurdles in turning hydrogen fuel cells into the power source of the future for cars and other commercial applications include the amount and cost of platinum — about $1,400 an ounce — and the cost and difficulty of producing large quantities of hydrogen, which has to be extracted from water, natural gas or plant materials and then distributed through networks of fueling stations.

Fuel Cells 101
In a fuel cell, hydrogen fuel isn’t burned. Instead, it reacts chemically with components inside the cell to produce electricity. The most common type of fuel cell is the PEM, short for proton exchange membrane. The membrane is a material that resembles kitchen plastic wrap.

» As air flows into one side of the fuel cell, hydrogen is fed into the other. The hydrogen interacts with a platinum-coated cloth or paper and splits into electrons, which have a negative electrical charge, and protons, which are positively charged.

» The protons pass through the membrane. The electrons cannot pass through the membrane. Instead, they form an electrical current that travels through an external circuit, powering a motor or other device.

» The oxygen in the air combines with the electrons and protons from the hydrogen fuel, creating exhaust in the form of water and heat.