Automotive engines have been running for years with conventional or petroleum derived fuels (gasoline or diesel). Scarcely few automobiles have been using gaseous fuels such as liquefied petroleum gas (LPG) or compressed natural gas (CNG). Over the years, large scale use of conventional type of combustion engines namely spark ignition and compression engine with petroleum derived fuels has led to high rise in greenhouse gases with major being carbon dioxide. To circumvent the problem of automotive pollution, non-carbon or low carbon fuels are being encouraged. In this direction, hydrogen being high energy carrier is a good candidate for use in automobiles. Thus, hydrogen has been explored as an alternate fuel due to its good properties but resulted in high NO_x emissions. Also, in the advent of new combustion processes, a novel combustion process combining the good features of conventional combustion process is gaining increasing attention from combustion community. In this regard, homogeneous charge compression ignition (HCCI) engine concept has been evolved. HCCI mode derives good features of conventional engines yielding simultaneous reduction of NO_x and particulate emissions. Even much more benefits can be extracted with the use of hydrogen in HCCI mode of operation. In spite of its good features, HCCI opens challenges in terms of uncontrolled auto-ignition, high peak pressures and poor high load capability. Through, present review work, it is observed that many techniques are explored to achieve HCCI mode of operation and apart from experimental studies, multi-dimensional modelling works revealed much insights into its behaviour. Swirl along with other pertinent engine operating parameters could address challenges to a significant extent. Biomass resources are being seen as potential sources for production of hydrogen. Addition of hydrogen, with fuels such as DME, diesel, and bio-fuels could reduce harmful emissions substantially without any penalty on engine performance compared to its use in neat form.
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