Fuel Cell Technology

A fuel cell is a relatively simple device for separating electrons from their atoms via a chemical process and thereby deriving electricity from the flow of electrons. Hydrogen is the best-known source of fuel cell electricity, but other elements are also viable in certain circumstances. Fuel cells are attractive because they constitute an energy process that contributes no pollution, and especially no greenhouse gases. They generate only electricity, heat, and small amounts of water. For this reason, they will continue to be prominent in discussions of our energy future. In addition, they have very high levels of potential efficiency for converting the power source to useful energy. It is not unusual for fuel cells to have efficiency rates of 40% or more; an incandescent lightbulb, by contrast, has a rate of only 5% of its energy converted to light. The other 95% is lost.

William Grove, a Welsh physicist, built the first working fuel cell in 1839. While this technology was gradually developed over more than a century, it gained serious attention when the U.S. National Aeronautics and Space Administration used fuel cells in the Gemini and Apollo spacecraft of the 1960s. This demonstrated that sources of electricity can be used that weigh much less than conventional batteries.

A hydrogen fuel cell works by injecting pressurized hydrogen into a series of small channels on one side of the cell (the anode), which is separated from the channels on the other side (the cathode) by a platinum-coated membrane. This membrane permits the protons of the hydrogen atoms to pass through to the other side, but not the electrons. Thus, it is known as a proton-emitting membrane, or PEM. The electrons are channeled externally to a circuit to yield electricity, and they are then recombined on the other side with the protons and some oxygen. This combination of hydrogen and oxygen creates a small quantity of water. The fuel cell also generates heat during this process. Sometimes the heat is problematic because it degrades the efficiency of the fuel cell, but in other cases, this by-product is captured and used to heat water or buildings.

Fuel cell technology has three principal kinds of applications: vehicular, stationary, and portable. Vehicular applications have received more attention than the others as governments and industries seek alternatives to transportation powered by fossil fuels that cause global warming. Several leading auto companies have produced hydrogen fuel cell prototype vehicles. These are electric cars that run on hydrogen instead of batteries. It should be noted, however, that this kind of application has problems that should not be underestimated. An automobile needs a very large stack of fuel cells to generate enough electricity to move the vehicle, and this adds a lot of weight to the vehicle. It also needs a large tank of pressurized hydrogen if the vehicle is going to have more than a local range. Finally, hydrogen fueled vehicles need an infrastructure of refueling stations. This is far from impossible, but it confronts us with a chicken-and-egg situation: People will not own hydrogen fuel cell vehicles if they cannot refuel conveniently, but refueling stations will not be attractive investments until there is a critical mass of hydrogen fuel cell vehicles. Several cities in several countries now have refueling stations, and it remains to be seen how many more will be added in the near future.

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