Assessment of mobility decarbonization with carbon tax policies and electric vehicle incentives in the US

On-road transportation electrification shows a significant stride toward achieving the low-carbon emission targets in the United States. Similarly, decarbonizing electricity generation technologies is crucial to prevent the transfer of CO2 emissions from the transportation sector to the power generation sector. The realization of nationwide emission mitigation goals undoubtedly depends on collaborative efforts from all U.S. states. However, in the presence of heterogeneous low-carbon policies, the state-level decarbonization landscape, which includes the electric vehicle (EV) adoption process and the choice of local renewable portfolios, blurs the national-level path toward the decarbonization target from a long-term planning perspective. To address this knowledge gap, this study employs an Integrated Assessment Model (IAM), specifically GCAM-USA, which is a state-level representation of the U.S. energy system embedded within the Global Change Analysis Model (GCAM). The aim is to present a blueprint illustrating how the U.S. decarbonization process is influenced by differentiated state-level EV purchase incentives and/or carbon tax policies. The modeling results reveal a heightened sensitivity of the effectiveness of decarbonization in midwestern states to the implementation of various low-carbon strategies, leading to a proposal to establish an interstate collaborative energy strategy for electricity generation in the face of the emerging era of electrified transportation. The insights derived from this study can contribute to raising awareness among federal and state policymakers about the importance of tailored state strategies for decarbonization while simultaneously striving to facilitate the harmonization of national-level progress in achieving climate goals.