Reduction of life-cycle CO₂ 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 CO₂ emissions generated during the manufacturing, driving, and disposal stages of cars, to analyze the impact of car sharing on CO₂ emissions. Then, we determined the changes in the life-cycle CO₂ 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 CO₂ emissions; the decrease in CO₂ emissions from private cars when owners switched to car services significantly exceeded the increase in the CO₂ emissions associated with the increased number of cars. The proposed model can serve as a reliable framework to analyze the current status of CO₂ emissions and simulate the future changes in car-sharing services.