Vehicles using a variable mixture of Compressed Natural Gas (CNG) and hydrogen (H2) could reduce certain pollutant emissions by more than 80% in comparison to petrol-driven cars, according to the JRC report 'Evaluation of a Euro 4 vehicle with various blends of CNG/H2-fuel'.
A prototype bi-fuel vehicle was tested, designed to operate either on petrol or on various H2-CNG-blends, with a maximum percentage of 30% hydrogen. The gaseous and particulate emissions analyses showed that such fuel mixtures in comparison to petrol could reduce pollutant and exhaust greenhouse gas emissions significantly, as the 30% hydrogen variant would lead to a 90% drop of particle number emissions, a reduction of more than 60% of nitrogen oxides and non-methane hydrocarbons and a 55% decrease of particulate matter. CO2 emissions would fall by 35%. The report also provides a methodology to estimate the unburned hydrocarbon’s density, the fuel density, the fuel consumption, and the heating value of each hydrogen and compressed natural gas blend.
With this report, the JRC provides a scientific and technical basis for type-approval methods for vehicles running on a mixture of hydrogen and compressed natural gas, in relation to their exhaust emission levels, as no methods were previously established. The report presents an experimental evaluation programme whose results have already been incorporated into the Commission's legislation on EU type-approval (Regulation 630/2012) and could help develop new approval methods for other types of vehicles.