Examining Ethanol-Biodiesel-Diesel Blends: Impact on Diesel Passenger Car Performance and Emissions Under Legislative Test Cycles

Incorporating ethanol and biodiesel into diesel fuel offers substantial benefits from bioenergy perspective. This approach aligns with the National Policy on Biofuels by reducing dependency on fossil fuels, promoting sustainability, and strengthening the agricultural sector through increased demand for bio-based feedstocks. To assess the effect of these alternative fuels, a study was conducted with different Ethanol-Biodiesel-Diesel (B7, E2B7 and E5B7) fuel blends on the performance and exhaust emissions of a diesel passenger car under Modified Indian Driving Cycle (MIDC) and Worldwide Harmonized Light Vehicles Test Cycle (WLTC). A four-cylinder 1.5 L Common Rail Turbo based diesel passenger car was selected for the study. The test findings reveal that biodiesel blend (B7) produces higher CO emissions compared to neat diesel; however, these emissions decrease with the addition of ethanol (E2B7 and E5B7) due to its embedded oxygen content. Under MIDC, THC emissions decrease with biodiesel but increase when ethanol is blended with biodiesel. NOx emissions are elevated with biodiesel due to its higher cetane number and shorter ignition delay, and this increase persists with E5B7 blend also. Conversely, CO2 emissions decrease for both, biodiesel and ethanol-biodiesel blends due to their lower carbon content compared to neat diesel. There is a marginal improvement in fuel economy with these blends, though this improvement is within the margin of uncertainty compared to neat diesel. Under WLTC conditions, the trends are consistent. Biodiesel blend shows higher CO emissions, which are mitigated by adding ethanol. THC emissions decrease with biodiesel but rise again when ethanol is added. NOx emissions increase with biodiesel compared to neat diesel; a similar trend continues with ethanol blending. CO2 emissions are lower for both, biodiesel and ethanol-biodiesel blends compared to neat diesel, attributed to their reduced carbon content. Fuel economy demonstrates slight improvement, albeit within uncertainty margins, when using these blends compared to neat diesel. These research findings highlight the potential benefits of using ethanol-biodiesel-diesel blends, including reduced CO2 emissions and marginal fuel economy improvements, despite the challenges of increased NOx emissions. Further research is needed to ensure the long-term viability of utilizing biodiesel-ethanol-diesel blends in diesel vehicles by carrying out long duration trials on the vehicles with the focus on the overall performance of the vehicle including fuel supply system.