Development of Türkiye's Electricity Generation and Installed Capacity Mix by Source and 2040 Outlook: ILR–RegARIMA, Diversity Indices, and Exact LMDI Analysis

This study focuses on analyzing the transition in the sources of electricity generation and installed capacity mix in Türkiye between 2000 and 2023 and presents a forecast of its probable development until 2040. The ILR transformation and regARIMA models were used in the framework of compositional data analysis, while model reliability was tested using the rolling backtest method. Accordingly, the results indicated an average MAPE of 0.37% and a coverage of 0.78 in the 95% confidence interval. Resource-based efficiency trends were determined by the capacity factor proxy, and diversity and structural breaks were analyzed using indicators of Shannon entropy, HHI, and efficient source number. The REF and SCN scenarios show that fossil fuels will decline while renewables will increase significantly in the 2035–2040 period. The study provides a transparent, reproducible, and policy-compatible forecasting framework in terms of energy diversity, supply security, and sustainability.