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This paper investigates the possibility to reduce the emissions of CO2 in the Italian passenger transportation sector by increasing the share of internal combustion engine vehicles fed by natural gas. In fact, from an environmental point of view, natural gas is a better choice in comparison with traditional oil-based fuels, as it yields less CO2, NOx, and PM emissions per kilometer, than classical gasoline and diesel engines, due to its intrinsic characteristics. For this reason, natural gas vehicles can effectively contribute to the energy transition, especially in the short-medium term, as it can be in the energy production sector. Nonetheless, Italian institutions address most of the eco-incentives’ mechanism to promote hybrid and electric passenger vehicles, irrespective of the different types of fuel for the internal combustion engine. In this paper, a technical overview of the different available propulsion systems adopted in commercial vehicles is first presented.

Battery electric vehicles (BEVs) are considered one of the most promising solution to improve the sustainability of the transportation sector aiming at a progressive reduction of the dependence on fossil fuels and the associated local pollutants and CO2 emissions. Presently, the major technological obstacle to a large scale diffusion of BEVs, is the fairly low range, typically less than 300 km, as compared to classical gasoline and diesel engines. This limit becomes even more critical if the electric vehicle is operated in severe weather conditions, due to the additional energy consumption required by the cabin heating, ventilating, and air-conditioning (HVAC). The adoption of vapor-compression cycle, either in heat pump or refrigerator configuration, represents the state-of-the-art technology for HVAC systems in vehicles. Such devices typically employ an expansion valve to abruptly reduce the pressure causing the flash evaporation of the working fluid.