No doubt one of the most elegant solutions to the fueling problem would be to make fuel cells operate on a liquid fuel. This is particularly so for transportation and the portable sector. The direct methanol fuel cell (DMFC), a liquid- or vapor-fed PEM fuel cell operating on a methanol/water mix and air,
therefore deserves careful consideration. The main technological challenges are the formulation of better anode catalysts to lower the anode overpotentials (currently several hundred millivolts at practical current densities), and the improvement of membranes and cathode catalysts in order to overcome cathode
poisoning and fuel losses by migration of methanol from anode to cathode. Current prototype DMFCs generate up to 0.2 Wcm^–2 (based on the MEA area) of electric power, but not yet under practical operating conditions or with acceptable platinum loadings. However, the value is sufficiently close to what has been estimated to be competitive with conventional fuel cell systems including reformers and reformate cleanup stages.

A direct methanol fuel cell (DMFC) is an electrochemical cell that generates electricity based on the oxidation of methanol and reduction of oxygen. An aqueous methanol solution of low molarity acts as the reducing agent that traverses the anode flow field. Once inside the flow channel, the aqueous solution diffuses through the backing layer, comprised of carbon cloth or carbon paper. The backing layer collects the current generated by the oxidation of aqueous methanol and transports laterally to a land in the current collector plate. The global oxidation reaction occurring at the platinum-ruthenium catalyst of the anode is given by:

CH₃OH + H₂O→ CO₂ + 6H⁺ + 6e^-

The carbon dioxide generated from the oxidation reaction emerges from the anode backing layer as bubbles and is removed via the flowing aqueous methanol solution.