What are fuel cells?

A fuel cell is an electrochemical device that extracts electricity directly from a fuel (typically hydrogen). A single cell consists of an electrolyte sandwiched between an anode and a cathode. Hydrogen is supplied to the anode and a catalyst separates the gas into negatively charged electrons (e-) and positively charged ions (H+). The electrons (e-) flow through an external load to the cathode. The hydrogen ions (H+) migrate through the electrolyte to the cathode where they combine with oxygen and the electrons (e-) to produce water. Each cell only produces a small voltage (typically 0.7V) and so many of these are stacked together to give the required level of power.

In contrast to a normal battery, a fuel cell does not become “flat” since new fuel is continuously supplied to the cell. It can therefore supply constant power like an engine or a turbine although it does not have any moving parts.

Fuel cells are inherently clean as the only emissions are electricity, water and heat (when fueled with pure hydrogen). They also offer significant improvements in efficiency over other energy generation technologies and with minimal noise (the cell is silent but peripheral equipment for pumping fuel etc produce some sound).

There are different types of fuel cells as shown in the table below. Currently the most popular ones are the PEM (for portable, automotive and stand-by power applications) and SOFC (for larger stationary power generation requirements).
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Types of fuel cells