Estimation of CO concentration in high temperature PEM fuel cells using electrochemical impedance

Storing electrical energy is one of the main challenges for modern society grid systems containing increasing amounts of renewable energy from wind, solar and wave sources. Although batteries are excellent storage devices for electrical energy, their usage is often limited by a low energy density, a possible solution, an avoidance of the long recharging time is combining them with the use of fuel cells. Fuel cells continuously deliver electrical power as long as a proper fuel supply is maintained. The ideal fuel for fuel cells is hydrogen, which in it’s pure for has high volumetric storage requirements. One of the solutions to this fuel storage problem is using liquid fuels such as methanol that through a chemical reformer converts the fuel into a hydrogen rich gas mixture. Methanol is a liquid fuel, which has low storage requirements and high temperature polymer electrolyte membrane (HTPEM) fuel cells can eciently run on the reformed hydrogen rich gas, although with reduced performance depending on the contaminants, such as CO, in the gas.
By estimating the amount of CO in the fuel cell, it could be possible to adjust the fuel cell system operating parameters to increase performance of the reformer and fuel cell stack. This work focus on the estimation of CO percentage in the hydrogen rich anode gas in a fuel cell, by combining signal processing ideas with impedance information of the fuel cell while it is running. The presented approach functions during in the normal operating range of an HTPEM fuel cell.