How a fuel cell works

It seems that even popcorn makers are too complicated nowadays. Image courtesy of mypages.iit.edu

Fuel cells are a type of power source only seen in a few cars, such as the Honda FCX, but are part of an interesting concept which may be the future of reducing emissions while driving: the fuel cell-electric hybrid. These types of vehicles use both an electric battery and a fuel cell for power, and operate much like current gas-electric hybrids, except that they use hydrogen as a power source instead of gasoline. In order to better understand this revolutionary type of car, you must first learn how a fuel cell works.

A fuel cell can be thought of like a sandwich, with a cathode and an anode terminal on either end, and an electrolyte in the middle. A cathode is an electrical terminal from which an electric current departs, and an anode is a terminal where electric current arrives. The electrolyte is simply a substance which allows ions to pass through while blocking electrons. At the points where the cathode and anode touch the electrolyte, chemical reactions take place resulting in electrical generation, as well as the generation of water and carbon dioxide as waste.

For these types of vehicles, hydrogen is used as a fuel, and fed into the anode. This turns the hydrogen into pairs of positively charged ions and negatively charged electrons. The idea then is that the ions can pass through the electrolyte, but the electrons cannot, so they instead travel through an attached wire, creating electrical power. To complete the circuit, the electrons which have traveled to do work through the car return to the cathode, where they react with the hydrogen ions and oxygen to form water.

This type of fuel cell requires large amounts of hydrogen in order to provide this power, and like a gas engine, cannot actually store energy, which is why the additional electrical battery and motor have been added in the Honda FCX. Future improvements in the material the electrolyte is composed of could perhaps increase fuel efficiency and reduce hydrogen and electrons lost to waste, which could eventually make these types of vehicles economically viable in addition to being environmentally friendly.

—Seth Berger

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