The design of decarbonized power systems is one of the most relevant and challenging problems that power system planners are facing nowadays. In this sense, the replacement of natural gas turbines by H 2 -fired gas turbines in future power systems may constitute a solution to reduce greenhouse gas emissions maintaining the dispatchability of the system. This work develops a novel generation capacity expansion formulation that considers the possibility of installing new H 2 -fired gas turbines, as well as renewable generation and different storage technologies. The proposed model also determines the investment decisions related to the installation of electrolyzers to produce H 2 , as well as H 2 storage facilities. The provision of reserve capacity by generating units, storage and electrolyzers is also considered to determine the optimal investment decisions. The uncertainty related to the demand growth and the capital costs of electrolyzers and H 2 storage is explicitly considered by using a stochastic programming formulation. A realistic case study based on an actual isolated power system is solved to test the proposed formulation. The obtained results indicate that H 2 power plants are installed in all cases in which this technology is available. Additionally, the capacity installed of electrolyzers is over 2.5 times higher than that of H 2 power units.INDEX TERMS batteries, hydrogen turbines, electrolyzers, hydrogen tanks, pumped storage hydropower, renewable generation, stochastic programming I. NOTATION