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A Student's Guide to Alternative Fuel Vehicles

Hydrogen - a very special type of gas

The Fuel of the Future, or Futuristic Looking Fuel?

One of the most interesting, and in some ways promising, alternative transportation fuels is hydrogen. While only experimental vehicles are operating on this fuel now, the potential for this unique energy source is excellent. Anyone who has taken a chemistry class knows that hydrogen is number one on the periodic chart of elements and the lightest of all elements. It is easy to produce through electrolysis, simply splitting water (H20) into oxygen and hydrogen by using electricity. However, these days, nearly all hydrogen is made from natural gas.

Because hydrogen burns nearly pollution-free, it has been looked at as the ultimate clean fuel. When burned, it turns into heat and water vapor. When burned in an internal combustion engine (the kind of engine in gasoline cars today), the combustion also produces small amounts of other gases. These other gases are mostly oxides of nitrogen because the hydrogen is being burned with air, which is about two-thirds nitrogen. Being a non-carbon fuel, the exhaust is free of carbon dioxide. Carbon dioxide, emitted from our burning of fossil fuels, is causing the world's climate to change.

Hydrogen is normally a gas and can be compressed and stored in cylinders. The main problem with hydrogen is bulk of the cylinders (fuel tanks). Compressed hydrogen contains less energy per volume compared to liquid fuels like gasoline or ethanol. Hydrogen can also be cooled to produce liquid hydrogen, but it is costly.

Hydrogen's clean burning characteristics may, one day, make it a popular transportation fuel. For now, the problem of how to store enough hydrogen on a vehicle for a reasonable range, and its high cost, compared to gasoline, are critical barriers to widespread commercial use.

Nearly all hydrogen currently is made from natural gas. For that reason, hydrogen usually costs more than natural gas.

Hydrogen fueled vehicles
There have only been a small number of prototype hydrogen vehicles made. Most of these have been experimental vehicles made by car manufacturers. Nearly all of these prototype cars were equipped with internal combustion engines, similar to ones that run on gasoline.

Hydrogen is also used in fuel cells. See the discussion on this in the fuel cell vehicle section below.

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Page updated: April 22, 2002
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