Technical Assessment of Diesel-to-Hydrogen Hybrid Propulsion Conversion in Nautical Vessels: Energy Performance, Operating Costs, and CO₂ Reduction

Abstract: The study evaluated the conversion of diesel propulsion systems to hybrid configurations with hydrogen fuel cells in three nautical vessels: the Ferretti 72ht, Ferretti 660, and Intermarine 600 Full. Fuel consumption, costs (Capex and Opex), and carbon dioxide emissions were analyzed, with results presented in seven tables that included operational performance, annual savings, installation and maintenance costs, carbon credits, and economic viability. The results demonstrated significant reductions in diesel consumption, ranging from 8.13% to 16.06%, equivalent to 10 to 31 liters per hour, with annual savings of US$ 266.904.00 and a reduction in CO₂ emissions of 447.66 tons per year. The Santos–Paraty route was also analyzed, where the conversion to the hybrid system resulted in a reduction of 304 liters of diesel per trip across the three vessels, with financial savings of US$ 485.88 and the avoidance of 815 kg of carbon dioxide emissions. The total cost of installing the cells was US$ 6.781.02, with an estimated lifespan of 10 years, resulting in an annual net Capex of US$ 678.10. The operational costs of refilling were US$ 37.71, maintenance US$ 20.47, and carbon credits US$ 40.74/year. The annual diesel savings of US$ 486.40 made the Opex US$ - 468.96. The estimated payback period was 14.5 years. It is concluded that conversion to hybrid fuel systems is technically feasible, economically advantageous, and environmentally sustainable, offering an effective alternative to reduce carbon emissions and costs in the nautical sector.