Freight transport modal shifts in a TIMES energy model: Impacts of endogenous and exogenous modeling choice

The freight transportation sector accounted for 10.1% of global emissions and 16.2% of Quebec's greenhouse gas emissions in 2018. In this sector, the most salient yet little explored behavioral change opportunity is the modal shift from heavy trucks to trains. Current model developments are being made so that E4 modelers represent modal choices as endogenous variables in the models. However, if we want to continue to improve the realism of the models, it is important to know if this modeling technique is suitable for a world where radical changes are required. In this study, two types of modal shifts are implemented and compared in a TIMES-type energy model: exogenous modal shifts, with demand-side scenarios, and endogenous modal shifts, with the introduction of substitution elasticities as an endogenous behavioral feature of the model. The results of this study show that only the exogenous approach allows the modeling of disruptions: in demand, in energy consumption, and in system costs. With respect to vehicle type, the exogenous approach avoids investments in complex infrastructure (i.e., catenary), at least in the medium term, while the endogenous approach leads to results where electric trucks and catenaries appear in 2030. Only the scenario with a significant modal shift from heavy trucks to trains (Exog_max) avoids substantial energy consumption (17 PJ in 2030 and 10 PJ in 2050). The concluding recommendation is to use the exogenous approach in a disruptive modeling context. In a world where a paradigm shift is needed, the exogenous approach allows for a better representation of concepts that have been seldom modeled until now.