Various combinations of ship propulsion systems have been developed with low-carbon-emission technologies to meet regulations and policies related to climate change, one of which is the combined gas turbine and steam turbine integrated electric drive system (COGES), which is claimed to be a promising ship propulsion system for the future. The objective of this paper is to perform a techno-economic and environmental assessment of the COGES propulsion system applied to liquefied natural gas (LNG) carriers. A propulsion system design for a 7500 m³ LNG carrier was evaluated through the thermodynamics approach of the energy system. Subsequently, carbon emissions and environmental impact analyses were carried out through a life cycle assessment based on the power and fuel input of the system. Afterwards, a techno-economic analysis was carried out by considering the use of boil-off gas for fuel and additional income from carbon emission incentives. The proposed propulsion system design produces 1832 kilowatts of power for a service speed of 12 knots with the total efficiency of the system in the range of 30.1%. The results of the environmental evaluation resulted an overall environmental impact of 10.01 mPts/s. The results of the economic evaluation resulted in a positive net present value and a logical payback period for investment within 8 years of operation. The impact of this result shows that the COGES has a promising technological commercial application as an environmentally friendly propulsion system. Last, for the economy of the propulsion system, the COGES design has a positive net present value, an internal rate return in the range of 12–18%, and a payback period between 6 and 8 years, depending on the charter rate of the LNG carrier.

Numerous studies have been conducted to minimize material costs and improve efficiency, one of which involves using the genetic algorithm (GA) for material selection. Although the GA provides the best solution, it is computationally intensive. To mitigate this issue, a simple method was proposed. The stiffened plate, a primary component of ship structure, was chosen as the optimization model for this study, with the objective of minimizing material costs using the proposed simple method. Two design variables, plate thickness (t) and plate material type (m), were selected with specific constraints. The simple method was used to determine the appropriate plate material types to reduce material costs. Additionally, size optimization was conducted using stress equations to produce the optimal thickness. The results showed that this method significantly reduced the computational time and material cost of the ship structure.

Studi Pengurangan Biaya Fabrikasi Struktur Dek Kapal dengan Hybrid GA

The increasing fuel price causes ships' operational costs to increase, which impacts the decreasing income of fishermen. This condition shows the need for a solution to reduce fishermen's dependence …