Renewable energy, innovations and environmental sustainability in Sub-Saharan Africa: The Environmental Kuznets Curve, policy thresholds and thresholds for complementary policies

Amid growing environmental challenges and development pressures, this study examines the dynamic relationship between renewable energy consumption, innovation, and environmental degradation in 24 Sub-Saharan African countries from 2000 to 2021. Using mixed-effects and logistic quantile regression models, we test the Environmental Kuznets Curve (EKC) hypothesis across carbon dioxide and methane emissions. The analysis confirms an EKC pattern, identifying critical turning points of 0.049 kt for CO2, 0.054 kt CO2-equivalent for methane, and 0.137 % of GDP for industrialization where emissions begin to increase as income levels rise. Innovation, proxied by non-resident patent activity, exhibits a non-linear effect: initially contributing to higher emissions at lower quantiles but significantly reducing emissions at higher quantiles, reflecting the time-lagged environmental benefits of technological diffusion. The study further reveals heterogeneous impacts of GDP and industrialization across the emissions distribution, suggesting that blanket policy interventions may be ineffective. Instead, we identify context-specific policy thresholds for renewable energy and innovation that can enhance environmental sustainability. These findings underscore the need for integrated, innovation-driven energy strategies tailored to the region's development stage, institutional capacity, and emission profiles.