*3.5. Sensitivity Analysis*

Since the time scales involved in technology diffusion in road transport are long, a time horizon between 2012 and 2050 was selected to study the role of powertrain electrification in the decarbonization of road freight transport. However, using a long time horizon implies large uncertainties in the parameters used to characterize the elements of the energy system. A sensitivity analysis was performed to understand the impact of those uncertainties on the modeling results. The impact of changes in fossil fuel price, hydrogen price, electricity price, annual traveled distance, new vehicle sales, discount rate, BEV fuel consumption, FCEV fuel consumption, BEV capital cost, FCEV capital cost, and technology diffusion span on the results for the FBB scenario was assessed. A variation of ±20% was considered for all the parameters. Results of the sensitivity analysis for the TTW CO2 emissions and net cash flow are presented in Figure 14.

**Figure 14.** Results of the sensitivity analysis: (**a**) Tank to wheel CO2 emissions; (**b**) net cash flow.

TTW CO2 emissions are most sensitive to variations in annual traveled distance and technology diffusion span, as they affect the stock of ICEVs in the road freight vehicle fleet. Other parameters produce small or no variations on TTW CO2 emissions. This is a consequence of the 'silver bullet' approach used to determine the maximum 'technologically realizable' CO2 emissions reduction potential of powertrain electrification, which considers EDV diffusion independent of the vehicle fleet RCO. Linking EDV diffusion and cost in the vehicle stock turnover model of the road freight vehicle fleet is recommended for future work.

The net cash flow is most sensitive to variations in annual traveled distance. Changes in the discount rate, fossil fuel price, BEV capital cost, and new vehicle sales also affect significantly the results for the net cash flow. Since the ICEV stock is larger than the EDV stock and fuel consumption is higher for ICEVs than for EDVs, the net cash flow is more sensitive to variations in the fossil fuel price than to variations in electricity and hydrogen price. In that sense, variations in fossil fuel price have a larger impact on the economic competitiveness of EDVs than variations in hydrogen and electricity price. Variations in the capital cost of FCEVs and BEVs change both the value and timing for the net cash flow peak; with the effect of BEV capital cost being larger than the effect of FCEV capital cost.
