Carsharing: mitigation strategy for transport-related carbon footprint

Abstract

Carsharing (CS) plays an important role in environmental improvements and can be managed as a low-carbon transportation innovation to mitigate the transportation-related carbon footprint. By conducting a questionnaire survey regarding people’s willingness to adopt CS, as well as constructing metrological models to estimate the environmental consequences of the People’s Republic of China’s (hereinafter “China”) CS market, we find that environmental consequences are closely associated with the CS market. The present study makes a significant breakthrough in the field by building a bridge between them. Previous studies only estimated the environmental impact of CS independently. Analysis shows that a high level of people’s acceptance of CS predetermines the market trend and its continuity. Environmental benefits increase with market size. Results suggest that in 2017 alone, 1.69 × 10⁹ million joules ( MJ) of energy savings and an equivalent carbon dioxide (CO₂) emission reduction of 13,6000 tons were due to China’s CS market. During the same period, China’s CS market size increased from 430 million Renminbi (RMB) in 2016 to 1.729 billion RMB in 2017. A greater magnitude of the impact is predicted in 2020 and 2025, according to an analysis of China’s lasting CS market. The impact of CS on parking land use can be quantified through a metrological model. Notably, this is the first study to build a combined dynamic and static model for estimating the reduced parking demands with regard to land use due to CS. Results suggest that in 2017, 4.68 × 10⁹ square meters (m²) of land use savings was theoretically due to China’s CS market. While previous studies have qualitatively linked reduced vehicle ownership and parking demand, few studies have quantified the magnitude of that impact, and no models have been developed. Such complementarity makes it possible to use multiple methods in a single research program, including a mixture of quantitative and qualitative approaches. While CS originated in Europe and America, numerous studies have examined the environmental impact of CS operations worldwide. Surveys in Europe indicate that per CS user reduces CO₂ emissions by 50% and that the local environmental quality has been improved by CS. An estimated annual reduction of 0.58 tons of CO₂-equivalent (CO_2e) per household member per year was reported in North America due to observed changes in household driving. Analysis shows that mode shifts from public transit or private car usage to CS vehicles result in an average of 146–312 kilograms (kg) of CO₂ reduction per member per year in Ulm, Germany, and that employing hybrid vehicles and electric vehicles (EVs) can reduce CO₂ emissions by approximately 35% and 65%, respectively, in Lisbon, Portugal. Additionally, CS users reduce transportation-related carbon dioxide emissions by up to 45–55% per household. Results suggest that upon joining a CS organization, current CS members in the United States of America (USA) reduce their average individual transportation energy use and greenhouse gas (GHG) emissions by approximately 51%. With regard to the impact of CS on parking demands, results suggest that overall parking needs are reduced owing to the reduced volume of the vehicles caused by the adoption of CS. Additionally, policy implications affect CS operations greatly. Keen interest from policymakers gives a further boost to CS with regard to parking space and synergies with other mobility modes. Accordingly, recommendations for sustainable improvement of CS’s environmental benefits are as follows: CS systems should complement public transportation, as well as the proliferation of fuel-efficient CS EVs; CS operations should share preferential policies on energy savings and emission reductions; the induction of collateral environmental benefits in the context of intermodal supply, in consideration of the possible rebound effects of CS; the certification of credits for CS environmental impacts. The analysis presented herein is aimed at helping policymakers better appreciate the environmental contributions of the CS market, support the market continuously, and provide a platform for the exchange of experience (e.g., arguably, generalization of China’s CS’s operation pattern characteristic of a large proportion of new EV use in the CS market) and learn from each other in mitigating climate change in the transportation sector. We conclude with a summary of key findings and recommendations for policy formulation and future research.