Impact of carbon pricing on the cruise ship energy systems optimal configuration

The shipping industry has been facing increasing challenges due to the stringent regulations for anthropogenic emissions limits, the new targets for carbon emissions reduction and the potential carbon pricing introduction. These have led to an upsurge of activities towards improving the environmental footprint of cruise ships. This study investigates the impact of carbon pricing on the cruise ships optimal power plant configuration. Mathematical models are used to estimate the performance of the cruise ship energy systems. A novel bi-objective optimisation method for the cruise ship energy systems synthesis is developed, which employs the Non-Sorting Genetic Algorithm II optimisation algorithm and uses as objectives the Life Cycle Cost and the lifetime carbon emissions. Cruise ship configurations that perform optimally under carbon pricing scenarios whilst complying with the existing emissions regulations are identified. The derived results show that the baseline configuration does not belong to the optimal solutions, whereas solutions including carbon capture, waste heat recovery and dual fuel generator sets that operate with natural gas or methanol can reduce drastically the carbon emissions. The optimisation identified solutions that reduce the Life Cycle Cost by 40% compared to the baseline configuration despite increasing their capital cost whilst reducing of the carbon emissions more than 37

A comparative analysis of EEDI versus lifetime CO2 emissions

The Energy Efficiency Design Index (EEDI) was introduced as a regulatory tool employed at the ship design phase to reduce the carbon dioxide (CO2) emissions and increase the vessel’s operational efficiency. Although it stimulated the greening of the shipping operations, its effectiveness is considerably criticised from various shipping industry stakeholders. The aim of this study is to investigate the EEDI effectiveness on accurately representing the environmental performance of the next-generation ships power plants for two representative ship types, in specific, an ocean-going tanker and a cruise ship. The performance of the optimal power plant solutions identified in previous studies is analysed according to the existing EEDI regulatory framework and compared with the lifetime CO2 emissions estimated based on an actual operating profile for each ship. The results indicate that the EEDI underestimates the effect of technologies for reducing carbon emissions in all the investigated cases. In this respect, it is concluded that EEDI is classified as a conservative metric, which however can be used as an approximation to compare alternative solutions early in the design phase

A novel multi-objective decision support method for ship energy systems synthesis to enhance sustainability

The shipping industry has been facing great pressure to become more sustainable, emanating from the increasingly stringent environmental regulations, fuel prices volatility and societal needs. As a result, a variety of technologies have been developed aiming to improve the environmental and economic performance of the modern ship energy systems, however leading to additional challenges for the technology selection during the design process. This study introduces an innovative method that integrates the economic and environmental aspects of sustainability to support decisions on the synthesis of the modern ship energy systems. The method includes a simulation model for predicting the energy systems performance during the ship lifetime. The genetic algorithm NSGA-II, is employed to solve the multi-objective combinatorial optimisation problem of selecting the integrated ship energy systems configuration. The derived results are visualised to reveal the Pareto front and the trade-offs among the objectives. The method is novel in supporting the synthesis of the integrated ship energy systems, as it includes both environmental and economic objectives, as well as evaluates the performance of the systems over an expected operational profile. The developed method is implemented for the case study of an Aframax oil tanker and the derived results analysis indicates that the ship energy systems sustainability can be improved by adopting LNG fuel and dual fuel engines technology, as well as by introducing other emerging technologies like fuel cells and carbon capture, although the latter is associated with a high cost. It is concluded that the inclusion of both environmental and economic objectives highlights the trade-offs between more environmentally friendly or cost efficient configurations, thus supporting the multi-objective decision-making process

Environmental and economic sustainability assessment of emerging cruise ship energy system technologies

The environmental and the economic impact of ship energy systems is a rising concern for the shipping industry. A number of technologies to improve the sustainability of ship energy systems exists. The majority of previous research on ship energy systems selection focused on the techno-economic performance of one or two components. However, an approach of evaluating simultaneously the environmental and economic performance of the integrated ship energy systems is missing. In this respect, this work aims to identify the most sustainably performing configuration of cruise ship energy systems by quantifying and evaluating the life cycle cost and the CO2 lifetime gaseous emissions of the integrated ship energy systems. The machinery responsible for the propulsion, electric and thermal power production, as well as emission reduction and energy efficiency is included. The performance of existing and emerging technologies is modelled including fuel cells, carbon capture technology, waste heat recovery systems, as well as propulsion and auxiliary systems with alternative fuels such as LNG. Alternative system configurations of the investigated ship are generated and assessed based on on-board operational data of a cruise ship. A set of dominant solutions is derived by employing a multi-objective evolutionary algorithm and indicative results for the most sustainable configurations are presented. A sensitivity analysis is performed for future fuel prices and technologies capital cost for the year 2030. The derived results from the cruise ship case study indicate that the ship energy systems sustainability can be improved by adopting natural gas dual fuel technologies and fuel cells. In addition, introducing a carbon capture technology and a waste heat recovery in the ship energy systems can improve the carbon footprin

Safety and reliability analysis of an ammonia-powered fuel-cell system

Recently, the shipping industry has been under increasing pressure to improve its environmental impact with a target of a 50% reduction in greenhouse gas emissions by 2050, compared to the 2008 levels. For this reason, great attention has been placed on alternative zero-carbon fuels, specifically ammonia, which is considered a promising solution for shipping decarbonisation. In this respect, a novel ammonia-powered fuel-cell configuration is proposed as an energy-efficient power generation configuration with excellent environmental performance. However, there are safety and reliability concerns of the proposed ammonia-powered system that need to be addressed prior to its wider acceptance by the maritime community. Therefore, this is the first attempt to holistically examine the safety, operability, and reliability of an ammonia fuel-cell-powered ship, while considering the bunkering and fuel specifications. The proposed methodology includes the novel combination of a systematic preliminary hazard identification process with a functional and model-based approach for simulating the impact of various hazards. Furthermore, the critical faults and functional failures of the proposed system are identified and ranked according to their importance. This work can be beneficial for both shipowners and policymakers by introducing technical innovation and for supporting the future regulatory framework

Hydrogen vs batteries : comparative safety assessments for a high-speed passenger ferry

Batteries and hydrogen constitute two of the most promising solutions for decarbonising international shipping. This paper presents the comparison between a battery and a proton-exchange membrane hydrogen fuel cell version of a high-speed catamaran ferry with a main focus on safety. The systems required for each version are properly sized and fitted according to the applicable rules, and their impact on the overall design is discussed. Hazards for both designs were identified; frequency and consequence indexes for them were input qualitatively, following Novel Technology Qualification and SOLAS Alternative Designs and Arrangements, while certain risk control options were proposed in order to reduce the risks of the most concerned accidental events. The highest ranked risks were analysed by quantitative risk assessments in PyroSim software. The gas dispersion analysis performed for the hydrogen version indicated that it is crucial for the leakage in the fuel cell room to be stopped within 1 s after being detected to prevent the formation of explosive masses under full pipe rupture of 33 mm diameter, even with 120 air changes per hour. For the battery version, the smoke/fire simulation in the battery room indicated that the firefighting system could achieve a 30% reduction in fire duration, with firedoors closed and ventilation shut, compared to the scenario without a firefighting system

Decision support methods for sustainable ship energy systems : a state-of-the-art review

The shipping sector has been under great pressure since the last decade to improve its environmental footprint, more so recently with the International Maritime Organisation target for a 50% reduction in greenhouse gas emissions by 2050, benchmarked to 2008 levels. These challenging goals have increased the interest towards alternative fuels and ship energy systems that can offer a more sustainable performance. The variety of potential technological solutions along with the multiple criteria employed to evaluate the ship energy systems with respect to sustainability considerations, renders the decision-making process for selecting ship energy systems challenging and highlights the need for dedicated decision support methods. This study presents a state-of-the-art review of the literature on decision support methods for enhancing the ship energy systems sustainability. The trends and gaps in the literature are identified, based on which, recommendations for future research are proposed. This study findings indicate that, among others, further research is needed to adapt more holistic approaches that include safety and reliability indicators as well as the social aspect of sustainability. This review can be beneficial for the maritime industry stakeholders, including policy makers, academics and ship owners/operators