Abstract: Promoting plug-in hybrid vehicles (PHEV) is one important option to mitigate greenhouse gas emissions and air pollutants for road transportation sector. In 2015, more than 220,000 new PHEVs were registered across the world, indicating a 25-fold growth during 2011–2015. However, more criticizes have been put forward against the current energy efficiency regulations for vehicles that are mostly depended on laboratory measurements. To better understand the real-world energy-saving and emission mitigation benefits from PHEVs, we conducted on-road testing experiments under various operating conditions for two in-use PHEVs in Beijing, China. Our results indicate that air condition usage, congested traffic conditions, and higher loading mass could significantly increase energy consumption and shorten actual all-electric distance for PHEVs. For example, the worst case (14.1 km) would occur under harshest usage conditions, which is lower by at least 35% than the claimed range over 20 km. In charge sustaining (CS) mode, real-world fuel consumption also presents a large range from 3.5 L/100 km to 6.3 L/100 km because of varying usage conditions. Furthermore, various vehicle users have significantly different travel profiles, which would lead to large heterogeneity of emission mitigation benefits among individual PHEV adopters. Therefore, this study suggests that the global policy makers should use real-world energy efficiency of emerging electrified powertrain techniques as criteria to formulate relevant regulations and supportive policies.
Abstract: The gap between certified and real-world passenger vehicle emissions is widening and has driven vehicle policy transitions in the US and in Europe, particularly in the wake of emissions measurement scandals. Since carbon dioxide emissions are highly correlated with fuel consumption (FC), fuel consumption regulation is a useful policy instrument to combat climate change. Although the Chinese government set fuel economy standards in 2004, like many countries it does not conduct testing to confirm real-world FC rates comply with the standards. This paper employs a dataset of real-world FC measurements self-reported by over 1 million vehicle owners in China between 2008 and 2017 through a dedicated mobile phone application. By comparing this user-generated FC data with FC certification, the study provides an indication of discrepancies of FC gap and its characteristics, including: vehicle model year, transmission type, segment, weight bin, and market share. The study finds that while average certified FC decreased by 15% between 2008 and 2017, real-world FC remained unchanged, resulting in FC gap increase from 12% to 30%. The paper concludes that use of a local test-cycle, authoritative data collection, and stronger enforcement, may be useful policy tools for reducing China's real-world vehicle energy consumption.
Abstract: The increasing adoption of intelligent transportation system (ITS) data in smart-city initiatives worldwide has offered unprecedented opportunities for improving transportation air quality management. In this paper, we demonstrate the effective use of ITS and other traffic data to develop a link-level and hourly-based dynamic vehicle emission inventory. Our work takes advantage of the extensive ITS infrastructure deployed in Nanjing, China (6600 km2) that offers high-resolution, multi-source traffic data of the road network. Improved than conventional emission inventories, the ITS data empower the strength of revealing significantly temporal and spatial heterogeneity of traffic dynamics that pronouncedly impacts traffic emission patterns. Four urban districts account for only 4% of the area but approximately 30%–40% of vehicular emissions (e.g., CO2 and air pollutants). Owing to the detailed resolution of road network traffic, two types of emission hotspots are captured by the dynamic emission inventory: those in the urban area dominated by urban passenger traffic, and those along outlying highway corridors reflecting inter-city freight transportation (especially in terms of NOX). Fine-grained quantification of emissions reductions from traffic restriction scenarios is explored. ITS data-driven emission management systems coupled with atmospheric models offer the potential for dynamic air quality management in the future.
Abstract: It is of great importance to test and evaluate the on-road energy use characteristics and its impact factors of the new energy vehicles to support the industrial policies and national energy saving and emission control strategy making. This research have collected 180,000 km high frequent travel data of 30 new energy vehicle samples belonging to 4 typical models, building the database of travel characteristics and energy consumption. The energy use characteristics and its impact analysis of electric and plug-in hybrid vehicles are done in terms of trip chain and short trip perspective. The results show that, the trip chains of electric vehicles mainly distribute between 60~90 km, which has large probability to travel in low speed with AC on in downtown and the mileage anxiety exists; for the plug-in, they could cover daily city travel averagely but, all the conditions should be advantaged to enlarge the mileage ratio of electrified range to reach the current type-approval fuel economy.