*3.2. Power Electrification Potential for Decarbonization of Road Freight Transport*

Results for TTW energy consumption along with historical data [16] are presented in Figure 10. Differences between results for the Base scenario and historical data are lower than 4%. TTW energy consumption in the Base scenario increases, reaching the peak at 1074 PJ/year in 2020, to decrease until reaching 613 PJ/year by 2050. Drivers for TTW energy consumption reduction in the Base scenario are vehicle stock reduction, vehicle fuel consumption improvement and HEV adoption. Since BEV and FCEV diffusion is small, diesel and gasoline account for 99.0% of TTW energy consumption.

**Figure 10.** Road freight vehicle fleet tank to wheel energy consumption: (**a**) total energy consumption; (**b**) fossil fuel consumption.

In the alternative scenarios, TTW energy consumption remains identical to the Base scenario until EDV diffusion starts, 2020 in the HBB and HFF scenarios, and 2025 in the FBB scenario. By 2050, TTW energy consumption is reduced 15.1%, 10.7% and 26.7% in the HBB, HFF and FBB scenarios, compared with the baseline value. As fuel shift occurs in the alternative scenarios, reductions for fossil fuel consumption are larger than reductions for energy consumption; up to 20.8% in the HBB and HFF scenarios and 44.7% in the FBB scenario, compared with the 2050 baseline values.

Powertrain electrification increases electricity and/or hydrogen consumption in road freight transport. Electricity consumption and hydrogen consumption reach 3.3 and 2.6 PJ/year in the Base scenario by 2050, respectively. In contrast, electricity consumption increases up to 39.7 PJ/year in the HBB and FBB scenarios; while hydrogen consumption increases up to 66.6 and 73.6 PJ/year in the HFF and FBB scenarios. Since the stock share and vehicle fuel consumption of ICEVs and HEVs are larger than the values for BEVs and FCEVs, diesel and gasoline represent more than 74% of TTW energy consumption in all alternative scenarios by 2050, despite the large increments in electricity and hydrogen consumption.

Even though the fuel cycle is out of the scope of this research, CO2 emissions are presented both on TTW and WTW basis, with the aim of providing more insights on the impact of powertrain electrification on the road freight vehicle fleet. TTW CO2 emissions along with historical data [83] are presented in Figure 11a. Differences between the modeling results for the Base scenario and historical data are lower than 3%. In the Base scenario, TTW CO2 emissions increase until reaching the peak in 2020 at 79.8 Mt-CO2/year; to decrease thereafter, until reaching 44.9 Mt-CO2/year by 2050. Since BEV and FCEV diffusion is small and CO2 emission factors for diesel and gasoline are constant throughout the time horizon, TTW CO2 emissions reduction is caused by the same drivers that cause TTW energy consumption reduction: vehicle stock reduction, vehicle fuel consumption reduction and HEV adoption.

**Figure 11.** Road freight vehicle fleet CO2 emissions. (**a**) Tank to wheel CO2 emissions; (**b**) Well to wheel CO2 emissions.

TTW CO2 emissions can be reduced up to 20.1% in the HBB and HFF scenarios and 44.6% in the FBB scenario, compared with the 2050 baseline value. The Japanese government aims to achieve two CO2 emissions reduction targets: one for the medium-term, proposed at the 21st Conference of the Parties (COP21), corresponding to 26% CO2 emissions reduction compared with the 2013 values by 2030; and one for the long-term, proposed in the Forth Basic Environmental Plan, corresponding to 80% CO2 emissions reduction compared with the 1990 values by 2050. Results for the road freight vehicle fleet TTW CO2 emissions show that none of the CO2 emissions reductions target can be achieved in any of the alternative scenarios considering powertrain electrification. In that sense, meeting CO2 emissions reduction targets that involve proportional CO2 emissions reductions across all sectors in road freight transport requires measures other than powertrain electrification.

WTW CO2 emissions are shown in Figure 11b. Compared with TTW CO2 emissions, WTW CO2 emissions are larger in all scenarios, since CO2 is emitted during the production of electricity and hydrogen is included. In the Base scenario, WTW CO2 emissions decrease from 98.8 Mt-CO2/year in 2012 to 56.9 MT-CO2/year in 2050. Even including the CO2 emitted to produce electricity and hydrogen, powertrain electrification yields lower WTW CO2 emissions than the Base scenario; with maximum CO2 emissions reductions of 17.3%, 13.4% and 32.6% in the HBB, HFF and FBB scenarios, respectively. Since WTW CO2 emissions are determined by the energy resources used to produce electricity and hydrogen, it is necessary to focus on the simultaneous decarbonization of electricity and hydrogen production to enhance CO2 emissions reductions from powertrain electrification in road freight transport.

CO2 emissions reductions for powertrain electrification estimated in this research represent the maximum 'technologically realizable' CO2 emissions reduction potential; and they correspond to the upper limit of the CO2 emissions reductions achievable by replacing ICEVs with EDVs in road freight transport. However, in practice, powertrain electrification in road freight transport will lead to lower CO2 emissions reductions than estimated here due to barriers that prevent EDV diffusion such as public acceptance, vehicle use diversity, short payback times, and risk aversion. It is recommended to endogenize these barriers in future modeling of the road freight vehicle fleet.
