TY - JOUR TI - Effect of alternative fuel gases on performance gas turbine units AU - Iliev Iliya K AU - Zvereva Elvira AU - Marin George AU - Beloev Hristo I AU - Valeeva Yuliya JN - Thermal Science PY - 2026 VL - 30 IS - 3 SP - 2117 EP - 2128 PT - Article AB - The change in the energy characteristics of alternative fuels affects the operation of gas turbines designed to operate on natural gas as well as on the operation of the main and auxiliary equipment of a combined cycle gas turbine. In the future, the transition alternative gases will eliminate the use of natural gas for the operation of the gas turbine. The publication estimates the operating costs, initial investments in adapting the equipment and setting up the automatic control system of the gas turbine. Important recommendations are made regarding fuel combustion in gas turbines when switching to different types of fuels. An assessment of emissions after the gas turbine unit is made when switching to alternative fuels and adding hydrogen fuel to the fuel mixture. Mathematical modelling of the gas turbine unit was carried out in the software package "AS GRET" (automated system of gas-dynamic calculations of power turbomachines). A distinctive feature of this study is the analysis of gas turbine operation at a constant combustion chamber temperature, irrespective of the fuel type utilized. Maintaining this condition enables the gas turbine to be integrated into a combined-cycle power unit without necessitating modifications to the steam-water path. DO - 10.2298/TSCI250817236I ER -