Optimal replacement scenarios for an average petrol passenger car using life-cycle assessment

Abstract

The reduction of the lifetime of vehicles, using scrappage schemes, has been identified as a transformation pathway in the target of reducing the environmental impacts of passenger transport. The energy-efficiency of manufacturing new automobiles needs to be measured in order to achieve environmental benefits when replacing old cars. Thus, the goal of the present study is to establish the environmentally optimal time in which to replace a petrol car, in five substitution scenarios that include a newer version of this car, a diesel car and an electric car. The average occupancy, annual mileage and the energy mix on the market for electricity were addressed in this approach. This research quantifies the GHG emissions from the selected vehicles, with the aim of determining the optimal number of years after which substitution should take place, by way of a novel contribution to the current literature. The results show that the base vehicle can be efficiently replaced after 8.88 years if an electric car is selected as the substitute. However, this period would decrease to 6.55 years if the new vehicle were powered with 100% renewable energy. Moreover, an environmentally optimal replacement could be made at 3.29 years, if the substitute were an electric car run with an average occupancy of 3 passengers and a 100% renewable energy mix. It was also demonstrated that the EURO 5 diesel car could be a replacement option for the base vehicle after 13.65 years, considering GWP impacts exclusively. By contrast, there are no environmental benefits related to diesel cars when considering PM2.5 emissions, hence they are not a feasible environmentally optimal substitution. This article concludes that the substitution could be up to 69.94% sooner if a cleaner energy mix is used to run the replacement car.