I. Introduction
The automobile industry is facing the ultimate stage approaching zero regulated emissions as well as substantial reductions in CO2 emissions. As the most plentiful element in the universe, hydrogen has long been recognized as a desirable fuel in engines[1]. Its combustion does not produce any of the major pollutants such as CO2, HC and smoke. NOx is the noly pollutant needs to be carefully controlled. Thus, hydrogen is probably the unique versatile fuel which provides permanent solutions to fuel depletion and global environmental problems.