Progress and future prospects in anaerobic digestion of agricultural waste in Türkiye

Despite growing interest in valorizing agricultural waste through anaerobic digestion (AD), full-scale implementation in developing countries remains insufficiently explored. This study evaluates the development, performance, and technological characteristics of agricultural waste AD plants in Türkiye between 2011 and 2024, identifying key drivers and barriers to the biogas sector. Data were collected through surveys, regulatory databases, and operator interviews covering all 103 AD facilities. During the study period, 102 electricity-generating AD plants and one biomethane facility were commissioned, reaching a total installed electrical capacity of 301 MW in Türkiye. In 2024, these plants generated 1,244 GWh electricity (average power: 142 MW), corresponding to a 47% capacity factor. Although most facilities had capacities between 1 and 4 MW, larger plants (>3 MW) generated 68% of total electrical output. Cattle manure as the dominant feedstock accounted for 64% of energy production, followed by poultry manure (24%) and agro-industrial wastes (12%). Regionally, 70% of capacity is concentrated in Central Anatolia and the Aegean. Beyond energy recovery, the widespread use of AD in Türkiye contributes pollution mitigation by reducing uncontrolled manure disposal, greenhouse gas emissions, and nutrient pollution. Nationwide, approximately 11% of cattle manure and 18% of poultry manure undergo AD treatment. All plants operate as wet, mesophilic systems, with 97 using CSTR digesters and 5 employing plug-flow lagoons. The findings highlight the role of policy incentives and livestock distribution in shaping the development of the biogas sector, providing practical insights for sustainable agricultural waste management in developing countries.