Why are molten carbonate fuel cells unsuitable for most vehicles?
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.
Molten carbonate fuel cells are generally unsuitable for use in vehicles primarily due to their high operating temperature of approximately 650 °C (1,200 °F). Because of this, the cells require a significant warm-up period that can last several hours before they reach operational temperatures, making them impractical for the quick-start requirements of most vehicles.1
Additionally, the high-temperature operation creates significant engineering challenges regarding the durability of system parts and joints, particularly when the cells are subjected to frequent heating and cooling cycles. Due to these factors, this technology is better suited for stationary applications, such as local or large-scale power stations, rather than mobile transportation.1