Revisiting environmental Kuznets curve: an investigation of renewable and non-renewable energy consumption role.

Empirical studies on the environmental Kuznets curve (EKC) hypothesis have not reached a consensus on their findings because different environmental indicators are used, among other reasons. So, this study proposes using a composite index encompassing all dimensions of environmental pollution, using the composite environmental quality index (CEQI) which is introduced by Fakher et al. (Environ Sci Pollut Res 28(43): 61096-61114, 2021b). To do so, continuously updated fully modified (CUP-FM) and continuously updated bias-corrected (CUP-BC) techniques are used for the panel of selected Organisation for Economic Co-operation and Development (OECD) countries and Organization in the Petroleum Exporting Countries (OPEC) from 2000 to 2019. The findings show that the EKC hypothesis is confirmed in the inverted N-patterned relationship for the OPEC countries and an inverted U-patterned relationship for the OECD countries. Our findings also declare that consumption of renewable energies (REC) significantly increases environmental quality (EQ) while consumption of non-renewable energies (NREC) adds to environmental degradation (ED). Further, the role of financial development (FD) in our composite index is respectively negative and positive for sampled OPEC and OECD economies. The positive coefficient of combined trade share (CTS) in both groups of studied countries indicates that this variable works to reduce ED. Lastly, the implications of these findings for economic-environmental policies are discussed.