Technologies for the reduction of bus engine emissions

In the past years, the emission standards of heavy duty engines were reduced in several steps to Euro 3 of today. Further, drastic reductions are planned with the introduction of Euro 4 and Euro 5 in the years 2005 and 2008 respectively. The combustion engine with the highest efficiency is the Diesel engine. This will not change for further years to come. However, it will be necessary to further reduce the exhaust emissions of these engines. Combustion optimisation with new injection systems, introduction of exhaust gas recirculations and the use of aftertreatment systems are possibilities to achieve this. CNG- and LPG-engines are already today able to meet the EEV (Enhanced Environmentally Friendly Vehicle) emission standard which is below Euro 5. Hydrogen engines are available for pilot projects. They have nearly no emissions.