Did transportation electrification help to reduce transportation sector CO2 emissions? A study considering the dynamic electricity carbon emission factor

Transportation electrification is a key strategy for achieving carbon neutrality goals. However, the contributions of transportation electrification to carbon emissions (CRE) depend on the degree of power grid decarbonization. This study employed the Kaya Identity, the Logarithmic Mean Divisia Index (LMDI) model, and Moran's Index to examine CRE and its spatial clustering characteristics across China's seven power grid regions from 2004 to 2022, covering 30 provinces. Results indicated that the transportation electrification rate (EE) remained stable in the early years but increased gradually after 2016, reaching 12.35 % by 2022. Transportation electrification primarily impacts carbon emissions through three aspects: electricity substitution, electricity decarbonization, and energy efficiency improvement. Transportation electrification resulted in an additional 9.94 Mt of carbon emissions from 2004 to 2022, with the electricity substitution effect being the primary contributing factor. Most provinces have not achieved carbon reductions through transportation electrification. This outcome is mainly because these provinces have placed greater emphasis on the quantity of transportation electrification (rapid EE increase) rather than its quality (lagging grid decarbonization). Furthermore, regarding spatial distribution, CRE exhibits a clear pattern of “high in the north and low in the south”, indicating spatial clustering. This study provides valuable insights for advancing transportation electrification strategies.