Assessment of ethanol blended fuels for gasoline vehicles in China: Fuel economy, regulated gaseous pollutants and particulate matter

Abstract

The government of China has announced an ambitious plan to expand the mandatory use of ethanol blended gasoline fuels by 2020. Given the dissimilarity in fuel properties between China and other countries with ethanol blending practices, it is necessary to assess the energy and environmental impacts of ethanol blending. In this study, we prepared two types of ethanol blended fuels (E10, with ethanol contents of approximately 10%) with lower contents of aromatics (ELA) and olefins (ELO), respectively, compared with the market China 5 gasoline. Nine in-use gasoline vehicles varying by manufacturer, engine technology, model year, and emission standard level were analyzed using a chassis dynamometer, which followed the Worldwide Harmonized Light Vehicles Test Cycle (WLTC). Two major positive effects from using E10 fuels could be observed in this study. First, tested turbocharged gasoline direct injection (GDI) vehicles could gain reductions in CO2 emission, fuel consumption and energy consumption by switching to the higher-octane-number ELO. This finding, along with the engine development trends in the automotive industry (e.g., downsizing and higher compression ratio), may have a synergistic effect to deliver greater energy efficiency in the future. Second, the two ethanol blended fuels could be more effective in reducing the particle mass (PM) and particle number (PN) emissions than the levels of using China 5 gasoline. Notably, the benefit of using ELO was more significant, with average emission reductions of 35% for the PM and of 44% for the PN. However, ELA and ELO possibly increased emissions of gaseous pollutants for certain vehicles in the study, but the intra-vehicle differences between the various fuel groups were not statistically significant (not significant, p > 0.05, t-test). We suggest that more measurements under various environmental conditions and comprehensive air quality simulations should be conducted to better understand the environmental impacts of ethanol blending in China.