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Why are phosphoric acid fuel cells expensive to build?

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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.

Phosphoric acid fuel cells are expensive to build primarily due to the materials required for their construction and the challenges posed by their operating environment.

The framing structure for the assembly of these cells is made of graphite, which significantly increases overall costs. Furthermore, the cells operate at temperatures up to approximately 200 °C (400 °F), and the presence of aggressive hot phosphoric acid creates complex structural design problems. These conditions necessitate specialized engineering for critical components, including joints, supporting pumps, and sensors, to ensure durability and stable operation.12