Environmental Efficiency Assessment of Tunisian Thermal Power Plants in the Presence of Technological Heterogeneity: Non-Parametric Meta-Frontier

This paper assesses the environmental efficiency (EE) of 18 thermal power plants (TPPs) in Tunisia from 2005 to 2013, considering technological heterogeneity and CO2 emissions. Using a non-parametric meta-frontier approach based on the hyperbolic distance function with undesirable outputs, the study evaluates both environmental and technological performance. Results indicate that all TPPs exhibit inefficiency, with Meta-Environmental Efficiency (MEE) scores below 1. Combined-cycle plants achieve the highest efficiency (MEE = 0.967), followed by GAS TURBINE TGE9000 (0.780) and GAS TURBINE 20/30 (0.531). The decomposition of MEE into group environmental efficiency (GEE) and technology gap (TGP) scores suggests that inefficiency in GAS TURBINE TGE9000 plants stems from technological constraints, while the underperformance of GAS TURBINE 20/30 plants is linked to operational management. Combined-cycle plants serve as benchmarks, underscoring the need to transition toward this technology to enhance efficiency and sustainability. Econometric analysis reveals that meta-environmental efficiency is significantly influenced by plant characteristics and external factors. The post-revolution period and fuel consumption negatively impact efficiency, whereas plant age and size exhibit a positive effect. The robustness of these findings is confirmed through two econometric models - the random effects Tobit regression and truncated regression bootstrap - both yielding consistent results. These insights provide valuable guidance for policymakers in designing strategies to improve environmental efficiency in Tunisia’s electricity sector.