From the Ballard information page:
The core of the Ballard® fuel cell consists of a membrane electrode assembly (MEA), which is placed between two flow-field plates.
The MEA consists of two electrodes, the anode and the cathode, which are each coated on one side with a thin catalyst layer and separated by a proton exchange membrane (PEM). The flow-field plates direct hydrogen to the anode and oxygen (from air) to the cathode.
When hydrogen reaches the catalyst layer, it separates into protons (hydrogen ions) and electrons.
The free electrons, produced at the anode, are conducted in the form of a usable electric current through the external circuit. At the cathode, oxygen from the air, electrons from the external circuit and protons combine to form water and heat.
I understand that. The question is how you obtain the hydrogen.