Efisiensi Biaya dan Skala Ekonomi PLTA dan PLTP PT PLN Indonesia Power: Pendekatan Frontier Stokastik

The transition toward a low-carbon electricity system has made the cost efficiency of renewable energy power plants, particularly hydropower (PLTA) and geothermal power plants (PLTP), a strategic issue. This study aims to measure cost efficiency, estimate cost–input elasticities and economies of scale, and identify the determinants of inefficiency in power plants managed by PT PLN Indonesia Power. The study uses a balanced panel dataset comprising 22 power plant units over the 2016–2025 period, yielding 220 unit-year observations. The analysis employs the Generalized True Random Effects Stochastic Frontier Analysis (GTRE-SFA), combined with a linearly homogeneous translog cost function and a heteroskedastic inefficiency model. The results indicate that the translog function combined with GTRE-SFA is the most appropriate specification. The average cost efficiency across all units is 0.832, with hydropower plants achieving 0.879 and geothermal plants 0.743. The economies of scale value of 1.247 indicates the potential to reduce average costs through capacity expansion. Plant age, installed capacity, capacity factor, equivalent availability factor, and technology type are significant determinants of inefficiency. These findings provide insights for optimizing asset management, maintenance strategies, and renewable energy capacity planning to improve operational cost efficiency.