Electric vehicles will contribute to emissions reductions in the United States, but their charging may challenge electricity grid operations. We present a data-driven, realistic model of charging demand that captures the diverse charging behaviours of future adopters in the US Western Interconnection. We study charging control and infrastructure build-out as critical factors shaping charging load and evaluate grid impact under rapid electric vehicle adoption with a detailed economic dispatch model of 2035 generation. We find that peak net electricity demand increases by up to 25% with forecast adoption and by 50% in a stress test with full electrification. Locally optimized controls and high home charging can strain the grid. Shifting instead to uncontrolled, daytime charging can reduce storage requirements, excess non-fossil fuel generation, ramping and emissions. Our results urge policymakers to reflect generation-level impacts in utility rates and deploy charging infrastructure that promotes a shift from home to daytime charging.
The use of electric vehicles (EVs), coupled with an electricity grid that is decarbonizing, can help the United States achieve emissions reduction targets1,2. Industry analysts forecast that the number of light-duty EVs and their charging plugs will multiply to over 300 million and 175 million, respectively, worldwide by 2035, an order of magnitude increase when compared with 20213. EV charging couples transportation to the grid, yet the two sectors’ transformations are largely uncoordinated, despite their shared objectives of lowering emissions4,5,6,7,8,9,10. While the implications of transportation electrification for the grid have been studied at low, near-term levels of adoption, identifying and mitigating system consequences at deep levels of EV adoption has remained a critical challenge as it requires models that capture the diverse behaviours and conditions of future drivers11.