Spatial-domain changes in the proportion of thermal power in the power grids of China and the duality of PHEV-driven energy have increased the complexity of research on the CO2 emissions of plug-in hybrid electric vehicles (PHEVs). 130000 km of driving data from 50 PHEV vehicles operating in Shanghai is studied to derive methods to evaluate the carbon dioxide emission of PHEV vehicles. The electric drive distance ratio of the PHEV and its influencing factors are analyzed. The effects of the electric range, charging frequency, and power grid composition on the carbon emission intensity of PHEV are analyzed, and the effect of the level of progress for PHEV in 2020 on CO2 emission reductions is forecast. The results of the study show that the daily vehicle kilometers travelled by PHEV passenger cars in China's first-tier cities are mainly concentrated within a range of 50 km, accounting for 70% of total trips. Under the national grid structure in 2016, PHEVs with a driving range of more than 50 km emit at least 15% less carbon dioxide than conventional vehicles. In areas with a high proportion of renewable energy grid structure, PHEV carbon dioxide emissions can be reduced to below 100.0 g·km-1, which is more than 28% lower than that achieved using the national grid structure. Based on the national grid structure and technical level in 2016, increasing the all-electric range (50-100 km) and the charging frequency (0.5 times·d-1 to 2 times·d-1) has no obvious effect on reducing CO2 emissions. The PHEV fuel economy and electricity consumption levels in 2020 could reduce carbon dioxide emissions by 32% compared to those in 2016.
Keywords: carbon dioxide emissions; electric distance ratio; grid structure; plug-in hybrid electric vehicle (PHEV); travel pattern.