Do Energy Types Matter for Environmental Quality? Evidence from Disaggregated Energy Use and Institutional Factors in MINT Economies Under the EKC Framework

Climate change represents a major threat to environmental sustainability by accelerating ecological degradation and undermining long-term economic resilience, particularly in emerging economies. Motivated by the growing policy need to understand how energy structure and socioeconomic conditions shape environmental outcomes, this study examines the impact of energy consumption, structural change, human capital, financial development, and political risk on the ecological footprint of Mexico, Indonesia, Nigeria, and Türkiye (MINT economies). Guided by an extended Environmental Kuznets Curve (EKC) framework, the study examines whether environmental degradation follows a nonlinear trajectory in response to energy consumption, rising at the initial stages of energy expansion due to dominant scale effects, but declining beyond a critical threshold as efficiency gains, technological progress, and structural adjustments begin to offset environmental pressures. Energy consumption is disaggregated into oil-based energy, natural gas, and renewable energy to capture their distinct environmental effects. The empirical analysis employs the Panel-Corrected Standard Errors estimator as the baseline approach, complemented by Feasible Generalized Least Squares and Generalized Method of Moments estimators to ensure robustness and to address potential endogeneity and cross-sectional dependence. The results show that renewable energy and oil consumption exhibit inverted U-shaped relationships with environmental degradation, indicating nonlinear threshold effects consistent with EKC-type adjustments. In contrast, natural gas consumption demonstrates a predominantly linear and environmentally deteriorating effect, with no statistically significant turning point. Economic growth consistently intensifies environmental pressure, confirming the dominance of scale effects in rapidly industrializing economies. Structural change and human capital contribute to environmental improvement under certain specifications, while political risk exacerbates environmental degradation. Meanwhile, financial development shows an insignificant negative impact on environmental degradation. The results emphasize the importance of accelerating renewable energy expansion beyond critical penetration thresholds while progressively reducing fossil fuel dependence and strengthening institutional frameworks to ensure that economic growth translates into sustained environmental improvement.