“…Following the work of Dong, Sun, Hochman, Zeng, et al (), by taking various fossil fuels (i.e., coal, petroleum, and natural gas) as new explanatory variables, this study has extended the existing EKC model. The empirical framework is as follows: Considering the potential risk of heteroskedasticity, each variable is converted to logarithmic form (Dong, Sun, Li, & Liao, ) and, thus, Equation is rewritten as follows: where subscripts i = 1, 2, ⋯, 30 and t = 1997, 1998, ⋯, 2015 denote province and year, respectively.…”