Assessment of the potential for critical metal recycling and economic effects in the electrification transition of public transportation in mega-cities: a case study of Shanghai

Under the domestic strategic guidance of promoting a green and low-carbon transition as outlined in the recommendations for the “15th Five-Year Plan”, coupled with the restructuring of industrial and supply chains triggered by global geopolitical developments, the electrification of public transportation has become a core pathway for the transformation of urban transportation systems. The large-scale advancement of this pathway relies on the stable supply and efficient recycling of critical metal resources. In this context, to describe the level of recycling and economic value assessment of critical metal resources in mega-cities during the process of public transportation electrification, this study takes pure electric taxis in Shanghai’s public transportation system as the research object. Based on dynamic material flow analysis, it calculates the recycling potential of four critical metals—lithium, nickel, cobalt, and manganese—in power batteries under different scenarios and assesses the economic effects. The study estimates the demand, scrappage, and recycling amounts of pure electric taxis and the associated critical metals between 2025 and 2050, and evaluates their economic impacts. The results indicate that with the advancement of public transportation electrification, the scale of pure electric taxis and the demand for critical metals in power batteries will grow rapidly. Between 2025 and 2050, as the demand and scrappage of critical metals in vehicles and power batteries gradually increase, the recycling potential for these metals is significant, with cumulative recycling amounts estimate at 157.02-365.75 t, 144.67-336.98 t, 50.83-118.40 t, and 46.92-109.29 t, respectively. The derived economic value is substantial, with the achievable economic effects of lithium, nickel, cobalt, and manganese expect to cumulatively reach 11.305 7 million to 26.333 9 million yuan, 15.407 9 million to 35.888 9 million yuan, 11.386 3 million to 26.521 6 million yuan, 1 407.65 to 3 278.77 yuan by 2050, respectively. Moreover, this study offers relevant recommendations for Shanghai to advance the electrification of public transportation, the recycling of critical metals, and the sustainable utilization of resources, and provides a reference for the comprehensive green transformation of similar and other types of cities.