Demand for fossil fuels is increasing day by day with the increase in industrialization and
energy demand in the world. For this reason, many countries are looking for alternative
energy sources against this increasing energy demand. Hydrogen is an alternative fuel with
high efficiency and superior properties. The development of hydrogen-powered vehicles in
the transport sector is expected to reduce fuel consumption and air pollution from exhaust
emissions. In this study, the use of hydrogen as a fuel in vehicles and the current experimental
studies in the literature are examined and the results of using hydrogen as an
additional fuel are investigated. The effects of hydrogen usage on engine performance and
exhaust emissions as an additional fuel to internal combustion gasoline, diesel and LPG
engines are explained. Depending on the amount of hydrogen added to the fuel system, the
engine power and torque are increased at most on petrol engines, while they are decreased
on LPG and diesel engines. In terms of chemical products, the emissions of harmful
exhaust gases in gasoline and LPG engines are reduced, while some diesel engines increase
nitrogen oxide levels. In addition, it is understood that there will be a positive effect on the
environment, due to hydrogen usage in all engine types.