Fuel Cells: What are Fuel Cells?

Fuel cells can power almost about anything, from tiny microchips, to cars, to power plants. Getting the energy they produce is an interesting process.

A fuel cell is a device that takes stored chemical energy and converts it directly to electrical energy. Basically, it takes the chemical energy stored within the fuel (e.g. hydrogen, methane, and methanol) and converts it into electricity through electrochemical reactions.

The principal components of the fuel cell are: the electrodes, one positively and one negatively charged, that include catalysts where the electrochemical reactions occur; and the electrolyte, which carries electrically charged particles from one electrode to the other while keeping the reactants from mixing together.

There are different types of Fuel Cells: the Polymer Electrolyte Membrane or Proton Exchange Membrane (PEM), Alkaline (AFC), Phosphoric Acid (PAFC), Molten Carbonate (MCFC) and Solid Oxide (SOFC). These different types of fuel cells differ in their components materials, the operating temperatures, energy outputs, efficiency, and for what type of applications they are preferred.

The main difference between batteries and fuel cells is that batteries are what one could consider ‘batch’ electrochemical reactors, while fuel cells are considered ‘open’ electrochemical systems. In a ‘batch’ electrochemical reactor, the battery either has to be discarded or recharged when all the chemicals in it have reacted. In an ‘open’ fuel-cell system, the electrochemical reaction will continue as long as supplied with fuel and air (or oxygen), so in theory they have an unlimited life.

Batteries and fuel cells share many characteristics. Both convert chemical energy directly to electricity and can be connected in series or parallel to give the desired electrical characteristics.

Fuel cells are an attractive technology because they are highly efficient devices. They may convert fuel to useful energy at efficiencies as high as 60 percent; superior to internal-combustion machines that are limited to efficiencies near 40 percent or less. Fuel cells can also get the efficiency up to 90 percent in systems that recapture the energy in their waste heat. They also emit no noxious gases such as nitrogen dioxide and carbon monoxide; and produce virtually no noise during operation.

There are not any moving parts within fuel cells, so there is not anything mechanical to fail. Significant improvements in the service life of fuel cells under adverse conditions and cost reduction of the technology would contribute to the wider use of this technology, but it is getting there step by step.


Greenway, S., 2008, “The Fuel-Cell Decision” (An Article by Material Handling Management)

fuel cell, Encyclopædia Britannica Online, December, 2008. <https://www.britannica.com/EBchecked/topic/221374/fuel-cell>.

This post is part of the series: Fuel Cells

This is the series of articles on fuel cells describing what are fuel cells, types of fuel cells like hydrogen fuel cells and others.
  1. Fuel Cells
  2. Clean Energy from Hydrogen Fuel Cells
  3. Is Hydrogen Safe?