Several governments are increasing the blending mandate of renewable fuels to reduce the life-cycle greenhouse gas emissions of the road transport sector. Currently, ethanol is a prominent renewable fuel and is used in low-level blends, such as E10 (10 %v/v ethanol, 90 %v/v gasoline) in many parts of the world. However, the exact concentration of ethanol amongst other renewable fuel components in commercially available fuels can vary and is not known.
To understand the impact of the renewable fuel content on the emissions from Euro 6d-TEMP emissions specification vehicles, this paper examines the real-driving emissions (RDE) from four 2020 to 2022 model-year vehicles run on E0 and E10 fuels. CO, CO2, NO, and NO2 were measured through a Portable Emissions Measuring System (PEMS). In addition, N2O, formaldehyde, acetaldehyde, volatile organic compounds (VOCs), and other gaseous and particulate tailpipe emissions were measured and categorized in cold-start, urban, rural, and motorway segments with a proprietary system developed by Emissions Analytics. Engine-out emissions were also measured from a single-cylinder engine at steady-state low speed and load conditions.
The results show that the aldehydes, VOCs, and N2O emissions were greatest at cold-start and lowest at motorway conditions. The formaldehyde real-driving emissions increased by 14 % on average between the E0 and E10 fuels. However, the formaldehyde engine-out emissions were reduced for E10. Acetaldehyde real-driving emissions were below the detectable threshold for both E0 and E10 fuels, whereas, engine-out emissions increased for the E10. Whilst CO emissions presented inconsistent results across the cars and driving conditions, a reduction in CO2 emissions with the E10 fuel was observed across all conditions. NOx emissions increased for E10 compared to the E0 fuel in urban conditions and the opposite was observed for the motorway conditions. These findings highlight the need for the co-development of emissions regulations as greater ethanol and other renewable fuel content is blended into gasoline.
