Extreme heat effects on electric vehicle energy consumption and driving range

It is well-known that cold climates impact battery electric vehicle (BEV) performance, but less is known about the effect of extremely high temperatures. This study quantifies the effect of high temperature on energy consumption and driving range using a dataset of 345,622 trips from 300 BEVs, excluding plug-in hybrids, owned by 278 customers of the Salt River Project (SRP) utility in the Phoenix, AZ metropolitan region between May 1, 2020 and August 31, 2022. We compare results from two methods to estimate energy consumption rate per km for auxiliary, propulsion, and total energy and driving range for different ambient temperature bins ranging from −21 °C to 53 °C. The first method is a straightforward average for each bin. The second is a regression model that uses continuous and dummy variables to control for make, model, year, average speed, and trip length. The two methods produce similar U-shaped curves, although the regression that controls for other factors shows a more pronounced effect for extremely high temperatures. For trips at an ambient temperature between 46 °C (115 °F) and 50 °C (122 °F), the energy consumption rate increases by 28.43 % compared with 26–30 °C (79–86 °F), all else being equal. The auxiliary load increases by 50.3 %, while energy for propulsion increases by only 23.6 %. For driving range, the decrease is 16 % for 46–50 °C and 22 % for 51–53 °C, compared with the driving range at 26–30 °C. We then estimate that the impact of summer heat on the electrical load, if SRP were to meet its goal of 500,000 BEVs by 2035, would add an additional 4.6 GWh per day (6.5 %) during shoulder months and 4.94GWh per day (4.2 %) during summer months. On the hottest days, the estimated BEV electricity consumption is 5.3 GWh per day, 3.9 % above the average daily demand for the peak days. This research contributes to our understanding of how BEVs perform at very high ambient temperatures. The findings highlight the need to plan for higher summer demand from BEVs in future power investments in hot climates, especially since expected peak demand from BEVs will coincide with existing peak demand.