The Impact of Natural Gas-Hydrogen Blends on Internal Combustion Engines Performance and Emissions

The fossil fuel consumption and the related environmental impact are important issues for the world research community: hydrogen seems to be a good alternative to fossil fuels provided that it is produced from renewable energy sources.

The aim of the present work is the comparison between natural gas and a hydrogen-natural gas blend (HCNG in the following) in terms of exhaust emissions and fuel consumption. A passenger car has been tested on a chassis dynamometer according to the European emission regulations, without any change on engine calibration (i.e. spark advance). The HCNG blend used during the test has a 12% vol. of hydrogen content.

CO emissions showed a reduction of about 19% when HCNG blend is used, while HC emissions remained constant. A 70% increase was observed for NOx emissions with HCNG. A 3% reduction for CO₂ emission was observed using HCNG because of the lower carbon content in the blend and the reduced fuel consumption on a mass basis. There is not significant variation of fuel consumption on energy basis, probably due to the effect of a non optimal ignition timing.