Symbiotic ship propulsion innovation technology: Uncertainty analysis on combined hydrofoil and LNG gas engine

Recent restrictive measures on emissions control and energy saving by the International Maritime Organization (IMO) necessitate a cost-effective technological approach that addresses the challenges of conventional powertrain systems. This study addresses the financial feasibility of incorporating a dual-fuel (DF) liquified natural gas (LNG) engine with a flapping foil system designed to harness wave energy. The study examines two cases, one involving the proposed system of the DF engine and the other featuring a hybrid DF system with a foil. Both cases are compared against the baseline case of a conventional diesel engine in the analyzed vessel. The wave structure, including wave height (Hs) and wavelength ratio (λ/l), along with the vessel speed (Vs) are considered for evaluating the hydrodynamic wing performance. The objective of this research is to explore the energy, emission, and economic scenarios when the DF engine is the sole power source propelling the vessel. The sensitivity and uncertainty analyses are conducted to pinpoint the range of economic feasibility. The findings revealed that Hs = 5 m and λ/ l = 1.2 wave characteristics are ideal for employing the foil in the propulsion system and achieving fuel savings. The DF LNG-powered vessel makes 12 % fuel savings compared to a conventional diesel engine, with additional fuel savings varying depending on the wave characteristics. According to the sensitivity analysis, under desirable wavelength conditions, the hybrid propulsion system is financially viable if diesel cost decreases by +30 % and LNG cost increases by -30 %.