Techno-Economic Assessment of an Ammonia-Based Gas Turbine

Abstract

Abstract. The crucial role of gas turbines (GTs) in the power production field, within a continuos evolving energy market and needs to reduce carbon emissions, is nowadays becoming increasingly important. In this context, gas turbine manufacturers are actively working to retrofit natural gas (NG)-based turbines to enable operation with alternative fuels. Among the various options, ammonia stands out as a promising solution to promote the decarbonization of the energy sector, particularly because it is a carbon-free compound and an excellent hydrogen carrier. It can be used directly as a fuel or decomposed to produce pure hydrogen, which can be utilized in GTs or other power generation technologies. This study presents an energetic and economic analysis focusing on the retrofitting of a commercial open cycle GT fed by ammonia as primary fuel. To achieve a hydrogen-rich fuel mixture, a fuel conditioning unit has been introduced that exploits the GT exhaust gas heat improving thermal energy recovery. The system includes a high-temperature gaseous ammonia generator, and a cracking reactor to decompose ammonia into hydrogen and nitrogen. After the reactor, a separation step is implemented to obtain a purified hydrogen outlet. Then, a fuel booster is used to increase the fuel pressure to the level required by the GT. A comprehensive thermodynamic analysis is conducted to assess the energy flows within the system, with a focus on integrating heat exchangers for ammonia preheating and sizing the ammonia cracking reactor. Additionally, the requirements for efficient catalytic NH3 conversion and the role of separation technologies in hydrogen purification are evaluated. In particular, pressure swing adsorption (PSA) and hydrogen-permeable membrane systems are analyzed and compared. The costs of the GT retrofitting, including capital expenditure (CAPEX) and operating expenditure (OPEX) of the fuel conditioning unit, have been estimated, and the levelized cost of electricity (LCOE) has been calculated as an economic performance parameter, compared against the current benchmark. Moreover, a sensitivity analysis has been carried out to evaluate the impact of different factors (e.g., ammonia and natural gas price, carbon taxation) on the economic feasibility of the proposed solution. The results provide insights into the operational efficiency and cost-effectiveness of adopting ammonia as a carbon-free fuel for gas turbines, contributing to the efforts to decarbonize the industrial power generation sector.