Reduction of life-cycle CO emissions by expanding car-sharing services: A case study on Japan.

Carbon neutrality is a growing concern for all global economies. We considered the number of new and used cars registered during 2009-2018 in Japan and estimated the total number of private and shared cars, assuming that when owners abandoned their old cars, a certain percentage of the owners chose to use a car-sharing service (i.e., car rental service), instead of buying a new private car. We estimated the CO emissions generated during the manufacturing, driving, and disposal stages of cars, to analyze the impact of car sharing on CO emissions. Then, we determined the changes in the life-cycle CO emissions of all the cars for three car-sharing penetration rates (0, 5, and 100%), assuming that all the cars were gasoline-powered. Additionally, we analyzed how electric vehicles can optimize the proposed strategy. An increase in car-sharing services significantly reduced vehicular CO emissions; the decrease in CO emissions from private cars when owners switched to car services significantly exceeded the increase in the CO emissions associated with the increased number of cars. The proposed model can serve as a reliable framework to analyze the current status of CO emissions and simulate the future changes in car-sharing services.