Accounting for more than 90% of the molecules and more than 75% of the mass [1], hydrogen is the most abundant element in the universe. Due to the small molecule size and high buoyancy, it is not available in it’s free form on Earth. In recent years, hydrogen has gained the attention of the automotive industry [2–12] as an environmentally friendly alternative fuel.
As a fuel, hydrogen is unique - it is odorless, colorless, tasteless, and burns invisibly in sunlight. Detection solutions such as the odorants used in natural gas are not yet feasible for automotive hydrogen because the available additives can poison the fuel cell catalyst. Additionally, the lower flammability limit of hydrogen is lower, and the flammability range wider, than fuels such as gasoline [13]. Hydrogen detection and its concentration measurement is usually done using hydrogen concentration sensors [13]. For special purposes alternate methods are being developed to overcome the deficiencies of hydrogen sensors operating in harsh environments [14], such as inside of a fuel cell system.
In this paper, we present a method for estimating the composition of the anode gas in the fuel cell system. This method is based on indirect measurements and usage of already available signals inside the fuel cell system. Successful implementation of this method makes direct hydrogen concentration measurement unnecessary yielding significant savings in cost (≈ $100 per unit) and increase in reliability and robustness.