What fuels can be used in addition to hydrogen in some fuel cell systems?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Diagram of a proton exchange membrane (PEM) fuel cell showing labeled layers, including flow field plates, electrodes, and the proton exchange membrane, with arrows indicating hydrogen and oxygen inputs, electricity generation, and water and heat as outputs. — fuel cell Proton exchange membrane (PEM) fuel cell
The proton exchange membrane is one of the most advanced fuel cell designs. Hydrogen gas under pressure is forced through a catalyst, typically made of platinum, on the anode (negative) side of the fuel cell. At this catalyst, electrons are stripped from the hydrogen atoms and carried by an external electric circuit to the cathode (positive) side. The positively charged hydrogen ions (protons) then pass through the proton exchange membrane to the catalyst on the cathode side, where they react with oxygen and the electrons from the electric circuit to form water vapour (H₂O) and heat. The electric circuit is used to do work, such as power a motor.

In addition to hydrogen, some fuel cell systems utilize other fuels, most notably carbon monoxide.12

In specific types of fuel cells, such as molten carbonate fuel cells and solid oxide fuel cells, the fuel is often a mixture of hydrogen and carbon monoxide. This mixture is typically generated from water and fossil fuels.12

Furthermore, other primary fuels used in current fuel cell systems include:

Reformed natural gas: Methane that has been converted into a hydrogen-rich gas.3
Methanol: A liquid fuel that can be used in fuel cell systems.3

While these fuels allow for operation, it is important to note that if fuels like natural gas must be altered in composition to be suitable for a fuel cell, the system's net efficiency is typically reduced.3