Search Results (105)

The analysis conducted in this paper observes long-term trends in the LNG transportation market with a tendency to predict its future development by applying market patterns and variables that follow changes in the historical period. The basis of this paper is a previous study that provided an analysis of this sector until the end of 2024 using linear regression. A comparison of the predictions with the results obtained showed that these predictions were mostly accurate, with a small deviation in LNG trade volume (10.9%), LNG fleet size (12.7%), and the number of countries exporting LNG (5%). The largest deviation was in the propulsion systems for new ships, where a new system (ME-GA) was introduced but later abandoned. Based on previous studies and current data, a forecast was made until the end of 2029, which shows that the LNG market will continue its growth and the LNG trade volume will exceed 450 MT by the end of this decade. As a result, the LNG fleet will grow to over 900 vessels. The data on the propulsion types of the LNG fleet show that the trend shown in previous studies will continue, namely that this LNG fleet will be powered by XDF and MEGI plants. Full article

Wood heat treatment is considered by many to be an eco-friendly wood modification method, given that only heat is applied during the treatment. However, it is essential to recognize that energy consumption can give rise to various environmental challenges. Quantitative evaluation of the environmental performance of a wood modification technology is always a challenge faced by the wood processing industry. To perform a comprehensive assessment, it is imperative to adopt a life-cycle-based approach, which is still very limited for heat-treated wood in China. This study investigated the mass and energy consumption of heat-treated radiata pine lumber in life cycle stages from forest management in New Zealand to wood heat treatment in East China and calculated its environmental impacts using the ReCiPe method. Two heat supply scenarios, i.e., on-site wood-fired boilers and off-site coal-fired power plants, were compared to evaluate the influence of national policy on environmental performance. Transoceanic shipping and lumber drying were found to be the life cycle stages dominating the environmental impacts level, and human-health-related impacts, mainly fine particulate matter, photochemical ozone formation, human toxicity, and global warming, were the major environmental impacts of heat-treated radiata pine lumber. With on-site heat supply, more heat and electricity were consumed due to a lower boiler efficiency and more energy demands. However, the impact assessment showed lower environmental impacts in this scenario. The non-fossil and carbon-neutral nature of wood is the key to the environmental advantages of this heat supply scenario. Full article

At present, shipping companies are aiming to meet better energy and environmental requirements when designing large cruise ships, thus decreasing emissions, increasing efficiency and reliability and greatly reducing maintenance time and costs. This paper provides a technical–economic comparison for a real case study, including a complete feasibility study regarding the sizing of a generation system to supply base hotel loads, between two power plant architectures focused on fuel cells and diesel generators for a cruise ship. The paper describes, in detail, an innovative solid oxide fuel cell (SOFC) generation system, which offers high efficiency and low emissions, assessed for its technical, economic and environmental performance. This study examines generators for hotels, requiring continuous service at constant load and a 1 MW power supply. The work relates to ships with a tonnage of more than 100,000 tons. Subsequently, considering that, in the case study, the diesel generators are powered by LNG (liquefied natural gas), there will also be a comparison with a case where both systems are simply powered by LNG. The main technical specifications required by shipbuilders for choosing the most suitable system for on-board generation (weight, volume, maintenance intervals and operations, as well as investment and operational expenses) are analyzed and described. The economic comparison is based on two extreme assumptions of the purchase and operating costs of the fuel cell system and returns a different result depending on the assumption adopted. The usefulness of the proposed solution based on fuel cells is demonstrated on the basis of an accurate technical, energetic and economic comparison with the conventional technologies based on diesel generators. The work is completed by evaluating the overall power-generating reliability improvement achievable with the new technology, in comparison with the traditional system. The comparison between the fuel cell system and the diesel system shows that the former has a higher weight (+40%), volume (+75%) and initial investment cost (3–6 times higher). However, the lower LNG consumption reduces the annual operating cost and the size and weight of the on-board tanks or, with the same tank capacity, increases the system’s range. The overall reliability of the fuel cell system is significantly higher than that of the traditional system. Full article

Marine reactors have been applied to floating nuclear power plants, naval vessels such as submarines, and civilian ships such as icebreakers. Nuclear-powered shipping is gaining increased interest because of decarbonization goals motivated by climate change. Enhanced reactor safety can potentially reduce regulatory and liability challenges to the adoption of nuclear propulsion systems for merchant ships. This gives strong impetus for reviewing past use of nuclear reactor systems in marine environments, especially from the perspective of any accident scenarios, lest planners be caught unaware of historical incidents. To that end, a loss of coolant accident (LOCA) in a Lenin icebreaker reactor in 1965 and disposal at sea of some of its damaged fuel and reactor vessel as well as the entire tri-reactor compartment is recounted. Full article

This research aims to assess the integration of different fuel cell (FC) options with battery and waste heat recovery systems through a mathematical modelling process to determine the most feasible retrofit solutions for a marine electricity generation plant. This paper distinguishes itself from existing literature by incorporating future cost projection scenarios involving variables such as carbon tax, fuel, and equipment prices. It assesses the environmental impact by including upstream emissions integrated with the Energy Efficiency Existing Ship Index (EEXI) and the Carbon Intensity Indicator (CII) calculations. Real-time data have been collected from a Kamsarmax vessel to build a hybrid marine power distribution plant model for simulating six system designs. A Multi-Criteria Decision Making (MCDM) methodology ranks the scenarios depending on environmental benefits, economic performance, and system space requirements. The findings demonstrate that the hybrid configurations, including solid oxide (SOFC) and proton exchange (PEMFC) FCs, achieve a deduction in equivalent CO₂ of the plant up to 91.79% and decrease the EEXI and the average CII by 10.24% and 6.53%, respectively. Although SOFC-included configurations show slightly better economic performance and require less fuel capacity, the overall performance of PEMFC designs are ranked higher in MCDM analysis due to the higher power density. Full article

The reactor pressure vessel (RPV) in onshore nuclear power plants is typically analysed for fatigue life by considering the temperature, internal pressure, and seismic effects using a simplified time-domain fatigue analysis. In contrast, the frequency-domain fatigue analysis method is commonly employed to assess the fatigue life of ship structures. The RPV of a floating nuclear power plant (FNPP) is subjected to a combination of temperature, internal pressure, and wave loads in the marine environment. Consequently, it is essential to effectively integrate the frequency-domain fatigue analysis method used for hull structures with the time-domain fatigue analysis method for RPVs in FNPPs or, alternatively, to develop a suitable method that effectively accounts for the temperature, internal pressure, and wave loads. In this study, a quasi-time-domain method is proposed for the fatigue analysis of RPVs in FNPPs. In this method, secondary components of marine environmental loads are filtered out using principal component analysis. Subsequently, the stress spectrum induced by waves is transformed into a stress time history. Fatigue stress under the combined influence of temperature, internal pressure, and wave loads is then obtained through a stress component superposition method. Finally, the accuracy of the quasi-time-domain method was validated through three numerical examples. The results indicate that the calculated values obtained by the quasi-time-domain method are slightly higher than those obtained by the traditional time-domain method, with a maximum deviation of no more than 24%. Additionally, the computation time of the quasi-time-domain method is reduced by 98.67% compared to the traditional time-domain method. Full article

Efficiency estimation of a propeller behind a vessel’s hull while sailing through ice floes, together with the ship’s resistance to motion, is a key factor in designing the power plant and determining the safety measures of a ship. This paper encloses the results from the experiments conducted at the CEHINAV towing tank, which consisted of analyzing the influence of the concentration at the free surface of artificial blocks, simulating ice, in propeller–block interactions. Thrust and torque were measured for a towed self-propelled ship model through simulated broken ice blocks made of paraffin wax. Three block concentrations of different block sizes and three model speeds were studied during the experimentation. Open-water self-propulsion tests and artificial broken ice towed self-propulsion tests are shown and compared in this work. The most relevant observations are outlined at the end of this paper, as well as some guidelines for conducting artificial ice-towed self-propulsion tests in traditional towing tanks. Full article

The study examined the potential changing roles of ports in terms of diversifying their revenue through the expansion of new markets in the Port of Ngqura. This is by means of the production and sales of renewable hydrogen as marine fuel produced from a wavefarm in Nelson Mandela Bay. A key objective of the study was to conduct a comprehensive techno-economic analysis of the feasible hydrogen production technologies based on the analysis performed, including alkaline electrolysis of seawater and renewable-powered electrolysis of seawater. The produced hydrogen aligns with global decarbonisation of ships and ports and will be used to supply the port with electricity, serve to refuel tugboats, and provide green hydrogen bunkering fuel for commercial shipping vessels. The Port of Ngqura is geographically well positioned to lead the production of zero carbon shipping fuel. This work considers the CAPEX and OPEX of a hydrogen plant using electrolysers and evaluates the current cost of production and selling price of hydrogen. The primary aim of this study was to examine the feasibility of hydrogen production through electrolysis of seawater at the Port of Ngqura. Through assessing resource and technological options, determining advantageous economic assumptions, and identifying existing limitations and potential opportunities, a feasibility study was conducted with special consideration of the site characteristics of Ngqura. The output of this study is a model that simulates the production, storage, and transportation of hydrogen gas from the Port of Ngqura, which was further used to analyse different case study scenarios. This approach directly addresses the main goal of the study. The results found showed that with wave energy convertors in a row of three next to each other, the energy produced by the wave farm was 2.973 TJ per month, which is equivalent to 18.58 tons of produced hydrogen when considering the lower heating value of hydrogen and assuming that hydrogen production efficiency is 75%. The anticipated hydrogen fuel will be able to refuel a tugboat with green hydrogen from the energy produced by the wave farm each month. It is predicted that the price of hydrogen is expected to drop, and the price of fossil fuel will gradually increase in the coming years. The fact that coal electricity can be produced on demand and wind and solar energy are weather dependent as a result lacks the ability to achieve a constant supply. There is currently an urgent need for energy storage and the efforts to study the production of hydrogen and ammonia. Hydrogen is still predicted to be more expensive than coal electricity; however, from this, maybe a critical cost for a kg of CO₂ could be calculated, which could make hydrogen competitive. The cost of green hydrogen production from wave energy in the Port of Ngqura was calculated as R96.07/kg (4.88 EUR/kg) of produced hydrogen, which is equivalent to 2.1 times the cost of the same energy supplied as Marine Diesel Oil (MDO) at current prices. Hydrogen from wave energy would thus become competitive with MDO; if a price is set for the emission of CO₂, this may also offset the difference in cost between MDO and hydrogen from wave energy. The carbon price necessary to make green hydrogen competitive would be approximately R6257/tonne CO₂, or 318 EUR/tonne CO₂, which is around 4.5 times the current trading price of carbon in the EU Emissions Trading Scheme. Full article

The objective of this study is to perform a thermodynamic analysis on a marine diesel engine waste heat-assisted cogeneration power plant modified with regeneration onboard a ship. The proposed system utilizes the waste heat from the main engine jacket water and exhaust gases to generate electricity and heat, thereby reducing the fuel consumption and CO₂ emissions. The methodology includes varying different turbine inlet pressures, extraction pressures, and fractions of steam extracted from the turbine to evaluate their effects on the efficiency, utilization factor, transformation energy equivalent factor, process heat rate, electrical power output, saved fuel flow rate, saved fuel cost, and reduced CO₂ emissions. The analysis demonstrates that the proposed system can achieve an efficiency of 48.18% and utilization factor of 86.36%, savings of up to 57.325 kg/h in fuel, 65.606 USD/h in fuel costs, and 180.576 kg/h in CO₂ emissions per unit mass flow rate through a steam turbine onboard a ship. Full article

Owing to global climate change or the ever-more frequent human activities in the offshore areas, it is highly probable that an imbalance in the offshore ecosystem has been induced. However, the importance of maintaining and protecting marine ecosystems’ balance cannot be overstated. In recent years, various marine disasters have occurred frequently, such as harmful algal blooms (green tides and red tides), storm surge disasters, wave disasters, sea ice disasters, and tsunami disasters. Additionally, overpopulation of certain marine organisms (particularly marine faunas) has led to marine disasters, threatening both marine ecosystems and human safety. The marine ecological disaster monitoring system in China primarily focuses on monitoring and controlling the outbreak of green tides (mainly caused by outbreaks of some Ulva species) and red tides (mainly caused by outbreaks of some diatom and dinoflagellate species). Currently, there are outbreaks of Cnidaria (Hydrozoa and Scyphozoa organisms; outbreak species are frequently referred to as jellyfish), Annelida (Urechis unicinctus Drasche, 1880), Mollusca (Philine kinglipini S. Tchang, 1934), Arthropoda (Acetes chinensis Hansen, 1919), and Echinodermata (Asteroidea organisms, Ophiuroidea organisms, and Acaudina molpadioides Semper, 1867) in China. They not only cause significant damage to marine fisheries, tourism, coastal industries, and ship navigation but also have profound impacts on marine ecosystems, especially near nuclear power plants, sea bathing beaches, and infrastructures, posing threats to human lives. Therefore, this review provides a detailed introduction to the marine organisms (especially marine fauna species) causing marine biological disasters in China, the current outbreak situations, and the biological backgrounds of these outbreaks. This review also provides an analysis of the causes of these outbreaks. Furthermore, it presents future prospects for marine biological disasters, proposing corresponding measures and advocating for enhanced resource utilization and fundamental research. It is recommended that future efforts focus on improving the monitoring of marine biological disasters and integrating them into the marine ecological disaster monitoring system. The aim of this review is to offer reference information and constructive suggestions for enhancing future monitoring, early warning systems, and prevention efforts related to marine ecological disasters in support of the healthy development and stable operation of marine ecosystems. Full article

Day after day, stricter environmental regulations and rising operating costs and fuel prices are forcing the shipping industry to find more effective ways of designing and operating energy-efficient ships. One of the ways to produce electricity efficiently is to create a waste heat-driven liquid metal–water binary vapor power plant. The liquid metal Rankine cycle systems could be considered topping cycles. Liquid metal binary cycles share characteristics like those of the steam Rankine power plants. They have the potential for high conversion efficiency, they will likely produce lower-cost power in plants of large capacity rather than small, and they will operate more efficiently at design capacity rather than at partial load. As a result, liquid metal topping cycles may find application primarily as base-load plants onboard ships. In this study, a waste heat-driven liquid metal–water binary vapor power plant onboard a ship is designed and thermodynamically analyzed. The waste heat onboard the vessel is the exhaust gas of the LM2500 marine gas turbine. Mercury and Cesium are selected as liquid metals in the topping cycle, while water is used in the bottoming cycle in binary power plants. Engineering Equation Solver (EES) software (V11.898) is used to perform analyses. For the turbine inlet temperature of 550 °C, while the total net work output of the binary cycle system is calculated to be 104.84 kJ/kg liquid metal and 1740.29 kJ/kg liquid metal for mercury and cesium, respectively, the efficiency of the binary cycle system is calculated to be 31.9% and 26.3% for mercury and cesium as liquid metal, respectively. This study shows that the binary cycle has a thermal efficiency of 26.32% and 31.91% for cesium and mercury, respectively, depending on liquid metal condensing pressure, and a binary cycle thermal efficiency of 25.9% and 30.9% for cesium and mercury, respectively, depending on liquid metal turbine inlet temperature, and these are possible with marine engine waste heat-driven liquid metal–water binary vapor cycles. Full article

Solving strategic IMO tasks for the decarbonization of maritime transport and the dynamics of its controlling indicators (EEDI, EEXI, CII) involves the comprehensive use of renewable and low-carbon fuels (LNG, biodiesel, methanol in the mid-term perspective of 2030, ammonia, and hydrogen to achieve zero emissions by 2050) and energy-saving technologies. The technology of regenerating secondary heat sources of the ship’s power plant WHR in the form of an Organic Rankine Cycle (ORC) is considered one of the most promising solutions. The attractiveness of the ORC is justified by the share of the energy potential of WHR at 45–50%, almost half of which are low-temperature WHR (80–90 °C and below). However, according to DNV GL, the widespread adoption of WHR-ORC technologies, especially on operating ships, is hindered by the statistical lack of system prototypes combined with the high cost of implementation. Developing methodological tools for justifying the energy efficiency indicators of WHR–ORC cycle implementation is relevant at all stages of design. The methodological solutions proposed in this article are focused on the initial stages of comparative evaluation of alternative structural solutions (without the need to use detailed technical data of the ship’s systems, power plant, and ORC nodes), expected indicators of energy efficiency, and cycle performance. The development is based on generalized results of variation studies of the ORC in the structure of the widely used main marine medium-speed diesel engine Wärtsilä 12V46F (14,400 kW, 500 min⁻¹) in the operational load cycle range of 25–100% of nominal power. The algorithm of the proposed solutions is based on the established interrelationship of the components of the ORC energy balance in the P-h diagram field of thermodynamic indicators of the cycle working fluid (R134a was used). The implemented strategy does allow, in graphical form, for justifying the choice of working fluid and evaluating the energy performance and efficiency of alternative WHR sources for the main engine, taking into account the design solutions of the power turbine and the technological constraints of the ORC condensation system. The verification of the developed methodological solutions is served by the results of comprehensive variation studies of the ORC performed by the authors using the professionally oriented thermoengineering tool “Thermoflow” and the specification data of Wärtsilä 12V46F with an achieved increase in energy efficiency indicators by 21.4–7%. Full article

Due to growing environmental concerns and stringent emissions regulations, optimizing the fuel consumption of marine propulsion systems is crucial. This work deals with the potential in an LNG ship propulsion system to reduce fuel consumption through controlled load distribution between engines in Dual-Fuel Diesel Electric (DFDE) plant. Based on cyclical data acquisition measured onboard and using an optimization model, this study evaluates different load distribution strategies between setups according to the optimization model results and automatic (equal) operation to determine their effectiveness in improving fuel efficiency. The analysis includes scenarios with different fuel types, including LNG, MDO and HFO, at different engine loads. The results indicate that load distribution adjustment based on the optimization model results significantly improves fuel efficiency compared to conventional methods of uniform load distribution controlled by power management systems in almost all load intervals. This research contributes to the maritime industry by demonstrating that strategic load management can achieve significant fuel savings and reduce environmental impact, which is in line with global sustainability goals. This work not only provides a framework for the implementation of more efficient energy management systems on LNG vessels, but also sets a benchmark for future innovations in maritime energy optimization as well as in the view of exhaust emission reduction. Full article

Liquefied natural gas carrier (LNGC) orders are increasing owing to marine environment regulations. The complexity of the integrated system applied to shipbuilding and software errors have increased with the high degree of automation. Direct on-site inspection methods are associated with high costs and safety risks, whereas software-based simulations rely heavily on the accuracy of the models of power system components. Hardware-in-the-loop simulation (HILS) can be utilized for designing and testing intricate real-time embedded systems. Specifically, HILS offers a reliable means of evaluating power management system (PMS) performance for LNGCs, which are high-value vessels commonly used in offshore plants. This study proposes a PMS–HIL test bed comprising a power supply unit, consumer, simulation control console, and main switchboard. The proposed HILS test bed utilizes the real equipment data of the shipbuilding industry to replicate the conditions associated with actual LNGCs. The proposed system is verified and validated through a software acceptance test procedure. Additionally, load-sharing, load-dependent start, blackout prevention, and preferential tests are performed for the PMS function evaluation. Test results indicate that the proposed system has great potential for conventional PMS commissioning. Therefore, it exhibits the potential to replace traditional factory acceptance tests. Additional development of the system will be conducted for ship automation, utilizing PMS control and an energy management system. Full article

In today’s era of heightened environmental awareness, industries and means of transport are under increasing pressure to minimize their ecological footprint. In particular, small-scale power plants for the marine sector pose environmental challenges due to their pollutant emissions. One promising technology to address this purpose is represented by small-scale gas turbines. In this work, the design of a radial turbine and a centrifugal compressor for a 5 MW engine to be employed onboard ships is developed. After a one-dimensional design, the project involves the aerodynamic and structural design optimization of the two machines using fluid dynamic and structural simulation software. The final configuration obtained by the optimization process and its performance are analyzed, demonstrating that the use of a radial architecture for the construction of a 5 MW small gas-turbine assembly for marine propulsion is feasible. Both the compressor and the turbine optimization procedures led to final values of polytropic efficiencies that were three percentage points larger than the first-guess design machine values, simultaneously allowing for reductions in stress usage factors by more than 38% and 32% for the compressor and the turbine, respectively. Full article