In addition to the growing engagement in environmental issues, and the following search for a reduction in emission of pollutants and increased energy efficiency, Brazil is experiencing a reheating of the Oil and Gas industry, which expects increases in the production of national natural gas. Since natural gas is an energy transition fuel, cleaner than traditional alternatives such as diesel and fuel oil, this work intends to study the technical-economic feasibility of different generation technologies (diesel en-gines, natural gas engines and cogeneration with fuel cells fuel fueled by natural gas) to evaluate the fuel competitivity in the distributed generation market. In more details, it is proposed to evaluate a study case in which the electric power generation from vessels moored at the port terminal in Rio de Janeiro, traditionally of high consumption and low efficiencies, is shifted to an onshore system consisting in a generator and a Lithium-ion battery bank. Two methodologies are presented for the simulation of a typ-ical month of service with demands provided by the instrumentation results of a vessel, one for traditional generators, with an on/off operation strategy, and one for the fuel cell bank, with a monthly cost minimization. The economic evaluation, carried out using the Net Present Value (NPV) and financial return techniques, shows that the higher investment cost of fuel cells does not make them competitive yet. Furthermore, it is observed that batteries are not economically justified for situations where there is not a large variation of load factors, however, an alternative scenario seeks to show the effects of the generation sizing and storage sizing relationship on the economic bene-fits. Finally, it is shown that, in addition to the pure economic criteria, which in many cases can still point to diesel technologies as more advantageous, considerations such as reduced emissions, ease of access to infrastructure and projections of fuel price drops should also be relevant.