How hydrogen cars work

I wrote this summary to further inform readers who have questions about the Hyundai Tucson Fuel Cell Electric Vehicle and the article John wrote about its visit to The Drake hotel in Chicago.


Under the hood of Hyundai’s Tucson Fuel Cell Electric Vehicle. 

What’s in the car?

Inside the car are fuel cells, devices that convert the chemical energy of hydrogen (or another chemical) to electricity. Hydrogen is used because of its simplicity: “An atom of hydrogen consists of a single electron and a single proton.” With the hydrogen,

The fuel cell generates electricity by stripping the electrons from the protons and using the electrons to create a pure stream of electricity. The ionized hydrogen atoms then combine with oxygen to form water. The other byproduct of this process is heat, so this water generally takes the form of steam. (HowStuffWorks)

Also inside the car are hydrogen tanks; the Hyundai Tucscon has one tank holding 12.3 pounds of hydrogen. With the electricity from the fuel cells, a 134 horsepower motor drives the car.

Where does the hydrogen come from?

Hydrogen is extracted from hydrocarbons, mainly natural gas, a fossil fuel. In 2010, the United States produced 89.4% of the natural gas it consumed, importing the remainder from Canada, Trinidad, Egypt, Qatar, and Nigeria (top 5 by imported volume).

How is the hydrogen obtained?

There are two methods, and most hydrogen in the United States (95%) is obtained with steam-methane reforming. When natural gas is used to extract hydrogen*, the methane in natural gas reacts with steam  at a temperature of 1,292°F (700°C) to 1,832°F (1,000°C), in the presence of a nickel-based catalyst, and produces hydrogen, carbon monoxide, and a relatively small amount of carbon dioxide.

In the second process, called water-gas shift reaction, “the carbon monoxide and steam are reacted using a catalyst to produce carbon dioxide and more hydrogen” (U.S. DOE). In the final process, called pressure-swing adsorption, the carbon monoxide and carbon dioxide are removed, leaving the hydrogen.

*Alternatives to natural gas as a source for hydrogen include methanol, ethanol, propane, or gasoline (U.S. DOE).

Sources are linked and comprise HowStuffWorks, United States Energy Information Administration (EIA), and the United States Department of Energy (DOE), Haldor Topsoe (a catalyst research company), and Car & Driver.