Comparative evaluation of emission and fuel economy of an automotive spark ignition vehicle fuelled with methane enriched biogas and CNG using chassis dynamometer

The fuel economy and mass emission of an automotive spark ignition vehicle fuelled with the methane enriched biogas (93% CH4) and base CNG (89.14%) were evaluated using chassis dynamometer under modified Indian driving cycle (MIDC). The transient emissions were also measured with respect to time. The emissions such as CO, HC and NOx are marginally higher with the enriched biogas than base CNG. But, the experimental results indicate that the vehicle’s emission with the enriched biogas fuel meets to the BS IV Emission Norms. There is no significant change in fuel economy of the vehicle fuelled with the enriched biogas (24.11 km/kg) as compared to base CNG (24.38 km/kg). The experimental data indicates transient emission characteristics (CO, HC and NOx) of the vehicle with respect to time for both fuels are very higher with urban cycle (low speed) than extra urban cycle (high speed) and the findings could be useful to find out scopes of further improvement in transient emission and performance of the engine. As the methane enriched biogas gives similar performance like fossil CNG, the enriched biogas could be used as an auto fuel for spark ignition vehicles.