Life cycle assessment of passenger cars fed with a blend of LPG, bio-LGP, and renewable DME, and comparison with conventional and electric passenger cars

Life Cycle Assessment (LCA) methodology was applied to comparatively assess the environmental impacts of B and C segments passenger cars with spark-ignition (SI) engine and with electric motor. Cars complied with the Euro 6d emission standard and were fuelled with petrol or a mixture of liquefied petroleum gas (LPG) (60% m/m), bio-LPG (20% m/m), and renewable dimethyl ether (20% m/m). Exhaust emissions and fuel consumptions for SI cars were obtained from chassis dynamometer laboratory measurements of Innovhub-SSI, with WLTC driving tests, and included regulated pollutants (CO, total hydrocarbons [THC], non-methane hydrocarbons [NMHC], NOx, particulate matter [PM], and solid particle number [PN]) as well as other conventional and trace compounds of significance for traffic environmental evaluations (CO2, CH4, PM soot, total PN (via EEPS), NH3, N2O, 1,3-butadiene, formaldehyde, and benzene). Main results show an increase in absolute impacts across all categories when transitioning from the B-segment to the C-segment car, with the use of innovative blends arising in a reduction of effects over petrol in five impact categories, including climate, with reductions ranging from 13% to 36% in the indicator adopted. The use of electric cars, for both segments, also shows improvement over petrol in five impact categories but deterioration in ten, especially for water use, ionising radiation, non-carcinogenic human toxicity, and freshwater eutrophication. With respect to conventional SI vehicles, climate change results in a decrease for innovative fuels blend of GPL, bio-GPL, and rDME, on average by 21% in B-segment cars and 16% in C-segment car, whilst the electric car lowers impacts by 36% and 38% in the same segments. The impact on climate change is primarily due to fossil CO2 and CH4 emissions from petrol and LPG combustion and to the activities related to the production of energy carriers and cars. In the case of petrol cars, more than half of the impact is due to exhaust emissions, with the corresponding reduction resulting for the innovative blend originated by the inclusion of biofuels. The electric car emerges as the best option for climate change because the absence of exhaust emissions is more than capable to offset the higher impacts associated with car production and with battery recharging.