The location of natural gas emergency response team centers (NGERTCs) is critical in terms of addressing natural gas notifications that require a timely emergency response. The selection of NGERTCs in Istanbul has an important place in terms of providing better service, due to the necessity of responding to emergency natural gas notifications within 15 min, in addition to the over 200,000 natural gas notifications per year and heavy traffic conditions. Therefore, this study proposes a solution based on GIS and FAHP to determine suitable NGERTC locations in Istanbul Metropolitan Area. In the first stage of the study, the required 15-min coverage areas for emergency calls for 36 existing NGERTCs in Istanbul were extracted and the adequacy of their locations was analyzed. In the second stage of the study, the weights of seven criteria determined for new NGERTC site selection were calculated by the FAHP method. With spatial analysis made, 12 new NGERTC locations were proposed. Finally, re-coverage analysis was performed for proposed and existing NGERTCs, and changes in coverage area within a 15 min response time were analyzed. Natural gas network coverage increased from 70.04% to 83.86%, and natural gas subscriber coverage increased from 91.03% to 96.27%. The results show that GIS and FAHP are worth using in selecting suitable NGERTC locations.

This study evaluates the technological, economic, environmental, and natural-gas-infrastructure integration potential of biomethane production in Türkiye. Based on the national biomass resource assessment, animal, plant, forest, and municipal waste streams correspond to approximately 289,821,769.70 tons/year of biomass-based waste, a theoretical biogas capacity of about 13,364.04 x 10^6 m³/year, and a technically convertible biomethane potential of approximately 8.3 billion m³/year. Under the upper scenario, total biomethane capacity reaches nearly 10.4 billion m³/year, equivalent to almost 20% of Türkiye's 2024 natural gas consumption of about 53 billion m³. The technology comparison indicates that anaerobic digestion is the most mature near-term option, with 55-65% CH4 in biogas, a gas yield of 2.5-6.0 kWh/kg organic dry matter (ODM), and 60-80% overall efficiency when coupled with combined heat and power (CHP). Hydrothermal gasification offers higher long-term conversion potential with an 8-12 kWh/kg ODM gas yield and 40-70% efficiency, whereas hydrothermal carbonization remains a complementary pathway with a 1-3 kWh/kg ODM gas yield and limited direct biomethane output. The economic analysis shows approximate CAPEX/OPEX values of €580,000/€286,000 per year for the reference HTG facility, €1.80 million/€832,984 per year for HTC, and €460,000/€271,000 per year for AD. Payback periods are estimated at around 3-4 years for lower-investment conversion cases and 5-6 years for new biomethane plant cases, indicating AD as the most feasible short-term pathway. The results show that biomethane can support natural gas substitution, import reduction, rural development, and greenhouse gas mitigation, provided that gas-quality standards, grid-injection rules, certification systems, investment incentives, and site-specific planning are implemented within the 2025-2053 roadmap.