Hydrogen fuel cells are all the rage in the current alternative energy euphoria. Here’s a primer on hydrogen fuel cells.

Hydrogen Fuel Cells

Hydrogen fuel cell technologies are complex, but the basics of this new technology can be explained in ways that make it understandable. Hydrogen is the lightest and most abundant element in the universe. It is an energy carrier, not an energy source, meaning that it stores and delivers energy in a usable form. In its pure form (H2), it is a colorless and odorless gas. However, since it combines easily with other elements, hydrogen is rarely found by itself in nature and is usually found as a part of other compounds, including fossil fuels, plant material, and water.

A fuel cell is a device that uses hydrogen (or a hydrogen-rich fuel) and oxygen to create an electric current. The amount of power produced by a fuel cell depends on several factors, including fuel cell type, cell size, the temperature at which it operates, and the pressure at which the gases are supplied to the cell. A single fuel cell produces enough electricity for only the smallest applications. Therefore, to provide the power needed for most applications, individual fuel cells are combined in series into a fuel cell stack. A typical fuel cell stack may consist of hundreds of fuel cells.

Fuel cells can be used to provide propulsion or auxiliary power for many transportation applications. Aside from spacecraft, which typically use alkaline fuel cells for onboard power, polymer electrolyte membrane (PEM) fuel cells are the primary type used in transportation.


Few fuel-cell-powered transportation products are currently in use today; even fewer are available commercially. A handful of fuel-cell-based passenger cars have been leased to government and universities, but they are not yet available for sale to the public. About 200 auxiliary power units have been used in U.S. and Russian spacecraft.