Evaluation of the lifecycle environmental benefits of full battery powered ships : comparative analysis of marine diesel and electricity

The paper aims to investigate the holistic environmental benefits of using a battery system on a roll on/roll off (ro-ro) passenger ship which was originally fitted with a diesel engine engaged in Korean coastal service. The process of this research has multiple layers. First, the operating profiles of the case ship were collected, such as speed, output, operation time and the configuration of the diesel propulsion system. Second, the full battery propulsion system, in place of the diesel system, was modelled and simulated on a power simulation software (PSIM) platform to verify the adequacy of the proposed battery propulsion system. Then, the life cycle assessment method was applied to comprehensively compare the environmental footprint of the diesel-mechanical and fully battery-powered vessels. A focus was placed on the life cycle of the energy sources consumed by the case ship in consideration of the South Korea’s current energy importation and production status. Three life cycle stages were considered in the analysis: ‘production’, ‘transport’ and ‘use’. With the aid of Sphera GaBi Software Version 2019 and its extensive data library, the environmental impacts at the energy production and transport stages were evaluated, while the same impacts at the use stage were determined based on actual laboratory measurements. The environmental performance of the two scenarios in four impact categories was discussed: global warming potential (GWP), acidification potential (AP), eutrophication potential (EP) and photochemical ozone creation potential (POCP). Results of the comparative analysis are presented based on estimates of the overall reduction in the environmental impact potential, thereby demonstrating the overall benefits of using a battery driven propulsion, with a decrease of the GWP by 35.7%, the AP by 77.6%, the EP by 87.8% and the POCP by 77.2%. A series of sensitivity analyses, however, has delivered the important message that the integration of batteries with marine transportation means may not always be the best solution. The types of energy sources used for electricity generation will be a key factor in determining whether the battery technology can ultimately contribute to cleaner shipping or not. By casting doubts on the benefits of battery propulsion, this paper is believed to offer a meaningful insight into developing a proper road map for electrifying ship propulsion toward zero emission of shipping

Notes on Supersymmetry Enhancement of ABJM Theory

We study the supersymmetry enhancement of ABJM theory. Starting from a ${\cal N}=2$ supersymmetric Chern-Simons matter theory with gauge group U(2)$\times$U(2) which is a truncated version of the ABJM theory, we find by using the monopole operator that there is additional ${\cal N}=2$ supersymmetry related to the gauge group. We show this additional supersymmetry can combine with ${\cal N}=6$ supersymmetry of the original ABJM theory to an enhanced ${\cal N}=8$ SUSY with gauge group U(2)$\times$U(2) in the case $k=1,2$. We also discuss the supersymmetry enhancement of the ABJM theory with U($N$)$\times$U($N$) gauge group and find a condition which should be satisfied by the monopole operator.Comment: 23 pages, no figure, minor corrections, version to appear in JHE

Myricetin improves endurance capacity and mitochondrial density by activating SIRT1 and PGC-1α

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A study on the weak points of stator windings of high voltage rotating machinery for ships

ABSTRACTReliability studies of existing rotating machine insulation systems mainly focused on reliability evaluation for diagnosis and life prediction of generators and motors of various onshore power plants. However, with the increase in commercial rated voltage of marine rotating machine, accidents related to insulation systems occur frequently, and since many difficulties are caused in repair and replacement, the demand for improved reliability of marine high-voltage rotating machine is increasing.Accordingly, several international classification societies have begun to require tests to confirm the reliability of the insulation system of high-voltage rotating machine for ships. For the first time among them, in accordance with Rule Proposal No.2015/EL01 (Rules and Regulations for the Classification of Ships, 2016) at Lloyd, international classification for generators and motors contracted after July 2016 is required. It was requested to present the insulation deterioration reliability results of the rotating machines insulation system according to the standards (IEC 60,034-18-31, IEC 60,034-18-32, IEC 60,034-18-33, IEC 60,034-18-34).In this paper, in order to check the weak points of the high-voltage rotating machinery of a ship against voltage deterioration among the above four standards, a test procedure was developed in accordance with the IEC 60,034-18-32 standard, and the weak points were identified and analyzed through testing did

Large-Scale Electric Propulsion Systems in Ships Using an Active Front-End Rectifier

In the case of the electric propulsion system on the vessel, Diode Front End (DFE) rectifiers have been applied for large-sized ships and Active Front End (AFE) rectifiers have been utilized for small and medium-sized ships as a part of the system. In this paper, we design a large electric propulsion ship system using AFE rectifier with the proposed phase angle detector and verify the feasibility of the system by simulation. The phase angle derived from the proposed phase angle detection method is applied to the control of the AFE rectifier instead of the zero-crossing method used to detect the phase angle in the control of the conventional AFE rectifier. We compare and analyze the speed control, Direct Current (DC)-link voltage, harmonic content and measurement data of heat loss by inverter switch obtained from the simulation of the electric propulsion system with the 24-pulse DFE rectifier, the conventional AFE rectifier, and the proposed AFE rectifier. As a result of the simulation, it was confirmed that the proposed AFE rectifier derives a satisfactory result similar to that of a 24-pulse DFE rectifier with a phase shifting transformer installed according to the speed load of the ship, and it can be designed and applied as a rectifier of a large-sized vessel

A study on the development of job training curriculum for operation of electric propulsion ships

ABSTRACTIn order to reduce the emission of pollutants from ships, the need to introduce eco-friendly ships is gradually increasing. Recently built ships are being applied with eco-friendly ship propulsion systems that can replace the existing propulsion systems. The number of ships to which an electric propulsion system, which is a kind of eco-friendly ship propulsion system, is applied is increasing. In addition, an electric propulsion system is attracting attention as a propulsion system suitable for autonomously operated ships to which the digital twin system is applied. Electric propulsion ships have many differences from ships to which the existing propulsion system is applied in terms of equipment and systems mounted thereon. Overseas, job training is being conducted for seamen who onboard electric powered ships for the safe operation of ships, but there is no systematic training course for electric powered ships in Korea. In this paper, we analyze in detail the current educational cases related to electric powered ships in various countries, and propose a curriculum and contents for the mandatory dutied of electric powered ships that can be applied in Korea based on the standard education curriculum of the International Maritime Organization

Lifecycle environmental benefits with a hybrid electric propulsion system using a control algorithm for fishing boats in Korea

In Korea, fishing boats account for 65,452 out of 71,174 coastal ships, and aging ships are a leading cause of environmental problems and economic loss. To solve this problem, the government has enacted a policy to promote the development and distribution of environmental vessels. Electric propulsion systems and hybrid systems are suggested as alternatives. However, to study whether this hybrid system is environmentally friendly, a system for measuring the performance of conventional diesel-powered ships was developed and measured. A case study applying the battery hybrid system was analyzed through a Matlab/Simulink simulation, and the effect of reducing the carbon dioxide emissions by 7.6% was verified. In addition, comparing with a case where the load-sharing optimal control was introduced, we proved that the carbon dioxide reduction with the controller was 10.7%. By applying the results of this study to various countries with different fuel production processes through the LCA technique, it was confirmed that the battery hybrid system is eco-friendly from the energy production stage, rather than unconditionally, according to the national power production method. Additional research is needed to reflect the aging trend of the entire fleet and to create a detailed category classification through future research

Effectiveness of the Speed Reduction Strategy on Exhaust Emissions and Fuel Oil Consumption of a Marine Generator Engine for DC Grid Ships

Recent developments in power electronics, energy storage systems, and renewable energy; increased market demands for more efficient and cleaner electric power to meet stricter environmental regulations; and development in gigawatt (GW)-class DC (direct current) transmission systems for transmission of greater power over longer distances than similar alternative current (AC) systems, have supported the development of the DC grid, making it a promising solution for both the onshore and offshore industries. This paper presents an experimental study on the effectiveness of an engine speed reduction strategy on exhaust gas emission and fuel consumption when applied to a 4-stroke generator engine equipped with a cam-driven plunger diesel injection system. The experiments were performed on an 8-cylinder V-type 4-stroke generator engine installed in the MASTC laboratory, which is the only demonstration testbed for the ship’s electric propulsion system in Korea. Experimental results showed that fuel consumption decreased, but emission mass fraction in exhaust gas increased when maintaining engine power while reducing engine speed. This study has shown economic benefits in reducing fuel consumption, but incurred penalties for the emission performance of 4-stroke generator engines equipped with cam-driven plunger diesel injection systems when applying the engine speed reduction strategy