Performance and Emissions Comparison between Biomethane and Natural Gas Fuel in Passenger Vehicles

Bio-methane as fuel in a natural gas engine is a viable solution to reduce greenhouse gas emissions. The present paper illustrates the results of the first set of measurements carried out in the BiomethER project (EULIFE). BiomethER aimed to design and build two innovative bio-methane production plants, located in Emilia Romagna region (Italy), fed by different feedstock: the first one with sewage sludge and the other with landfill waste. Biogas extracted by the anaerobic digester was cleaned and upgraded to biomethane for road vehicles application. To verify the compatibility of biomethane in conventional compressed natural gas engine (CNG) vehicles, three passenger cars have been tested with two gases: conventional natural gas and bio-methane coming by BiomethER sewage sludge plant. Test concerned dynamic performances and exhaust emissions and was operated on the chassis dynamometer facility, in ENEA Casaccia Research Centre. Preliminary results showed no appreciable deviation was noticeable for fuel consumption and CO2 emissions between the two fuels, acceleration and maximum power were almost the same for the three vehicles tested. The WTW evaluation of GHG emissions for the biomethane resulted in up to 79% lower in comparison with natural gas provided by the Italian pipeline.