Optimal turning points of sustainability: New curves for a green future in BRICS-T countries

Recently, the globe has become an eyewitness to severe challenges and is trying to sort out some key solutions. Under these challenges, rising environmental stress and energy demand have become more prominent, particularly in emerging economies. Undoubtedly, these nations (BRICS-Türkiye) have made significant efforts, but problems persist. In the case of specified nations, this study attempts to illustrate a deep association between economic growth, environmental sustainability, environmental policies, and renewable energy throughout 1990-2020. A significant innovation of this study is the introduction of the Renewable Energy Capacity Curve Hypothesis (RCC) by revising the Renewable Energy Kuznets Curve (RKC) and linking it to the Load Capacity Curve (LCC). Using the most robust estimators, this study validates the existence of EKC, LCC, and RCC hypotheses for BRICS-T economies. This story does not end here; the present theme focuses on core contributions to future thoughts and works for the "Optimal Turning Point Hypothesis." Under the turning point perspective, RKC/RCC occurred before EKC, and RCC occurred before LCC. These outcomes elaborated that promoting renewable energy may accelerate the turning points of the EKC and the LCC more rapidly. To compare, this study identifies the turning points of all relevant hypotheses; specifically, RKC/RCC(5.43) is less than EKC (9.89) and less than LCC (10.32). The results provide valuable insights to policymakers on whether renewable energy investments should be a priority for environmental quality. Moreover, the mediating effect of policy support and renewable energy pushed the turning points earlier. The results provide valuable insights to policymakers on whether renewable energy investments should be a priority for environmental quality.