Electrifying Long-Haul Freight—Part II: Assessment of the Battery Capacity

Recently, electric heavy-duty tractor-trailers (EHDTTs) have assumed significance as they present an immediate solution to decarbonize the transportation sector. Hence, to illustrate the economic viability of electrifying the freight industry, a detailed numerical model to estimate the battery capacity for an EHDTT is proposed for a route between Washington, DC, to Knoxville, TN. This model incorporates the effects of the terrain, climate, vehicular forces, auxiliary loads, and payload in order to select the appropriate motor and optimize the battery capacity. Additionally, current and near-future battery chemistries are simulated in the model. Along with equations describing vehicular forces based on Newton’s second law of motion, the model utilizes the Hausmann and Depcik correlation to estimate the losses caused by the capacity offset of the batteries. Here, a Newton-Raphson iterative scheme determines the minimum battery capacity for the required state of charge. Consequently, the model demonstrates different combinations of battery capacities and payloads while checking minimum conditions of brake torque, motor torque, and current draw. Most importantly, battery life and aging effects are included to account for extreme driving and climatic conditions. Overall, all advanced lithium-based battery chemistries are able to meet the required route using a standard payload of 16 tons after significant reductions in drag, rolling resistance, and weight prior to electrification with the vehicle remaining under the maximum weight limit. However, all need to employ their pulse setting except for the lithium iron phosphate option that operates the route successfully under its continuous maximum amperage selection. Finally, mass production of lithium-air batteries could significantly lower the cost and weight of the EHDTT, possibly revolutionizing the trucking industry.