Figure shows decision boundaries considering different battery ranges, and key cost components: electricity and battery unit costs. We also include isolines for various battery energy densities and powertrain efficiencies to visualize potential improvements in powertrain core components. The region in gray corresponds to the output space where BETs are more expensive than long-term diesel baseline at 1.15 USD/mile 31 (0.72 USD/km), while the feasible region is shown in yellow. Electricity costs above ∼ 0.1 USD/kWh prohibit BETs from being cost-competitive regardless of advances in energy density or battery range. At this electricity cost, the fuel expenses of BETs with a fuel consumption of 3 kWh/mi (1.86 kWh/km) equates to those of diesel trucks with a projected fuel economy of 10.46 mpg and a without-tax diesel cost of 3.13 USD/gallon in the long-term scenario by Jones et al. . Our present-day and future scenarios fall in the infeasible region with an electricity cost of 0.32 and 0.15 USD/kWh, respectively. If the electricity cost drops below 0.1 USD/kWh, BETs with battery ranges below 600 miles become cost-competitive with diesel with today's battery energy density. As battery energy densities increase over time, the decision boundary extends to encompass a feasible region for BETs with ranges longer than 600 miles, as they no longer suffer from carrying heavy batteries and losing payload. The unit cost of batteries is expected to drop to 70 USD/kWh by 2050, which can be further reduced through economic credits for secondary use in other trucks or stationary applications, as discussed in the scenarios above. However, due to the large uncertainty in the monetary value of second-hand batteries, we vary the battery cost within a broad range between 30 and 110 USD/kWh to capture variations in BET's capital cost arising from these economic credits. We thus identify the feasible region where BETs outcompete diesel trucks. To achieve cost parity with diesel in the long term, trucks driving 600 miles on a single charge would require a battery unit cost close to 30 USD/kWh, assuming highly efficient powertrains (∼ 98%) and our optimistic value of 0.15 USD/kWh for electricity unit cost.