In this paper, full-scale data for two ships have been used for the comparison of five different added resistance methods. The effect of using separate wave spectra for wind waves and swell on performance prediction has been explored. The importance of the peak enhancement factor(γ) in the JONSWAP spectrum for added resistance computation has been studied. Simulation model including calm water resistance, added resistance and wind resistance has been used. Ships have been simulated in the same weather conditions and propeller speed as in the case of full-scale ships using different methods for added resistance. The performance of these methods has been quantified by comparing speed and power predictions with the full-scale data. The paper also discusses the challenges involved in using full-scale data for such a comparison because of difficulty in isolating the effect of added resistance in full-scale data. It was observed that three out of five methods were able to predict added resistance even in high waveheights. Even though these methods showed significantly different RAOs, its effect on speed and power prediction was minor. Simulation results were not sensitive to the choice of peak enhancement factor(γ) in the JONSWAP spectrum. There was minor improvement in results by using separate wave spectra for wind waves and swell instead of single wave spectrum for combined wind waves and swell.
Although prevention of incidents leading to evacuations at sea is of vital importance, little is known about its causal patterns and demographic determinants. We investigated therefore relationships between age, occupation and nationality and causes of evacuations. The data were obtained from the Telemedical Assistance Service (TMAS) in Denmark between 2004 and 2014 supplemented with data on all seafarers from the Danish Maritime Authority (N = 73,344). These data included information on broad age groups, occupational position and nationality. The outcomes were evacuations from any cause and in four broad categories of causes leading to evacuations. A total of 403 evacuations were reported in the 11-year study period. 27% of the evacuations were due to external causes, 19% due to diseases of the circulatory system, 14% due diseases of the digestive system and 40% from other or undetermined causes. Age-adjusted all-cause evacuation rates varied between 1.4 and 3.4 incidents per 1000 person-years in 2004–2014 for officers and between 3.3 and 20.2 incidents for non-officers. An elevated risk of evacuations was found among both officers and non-officers aged ≥50 years, compared with those aged 30–49 years with odds ratios of 2.73 (95% confidence intervals 1.66, 4.50) and 2.59 (2.03, 3.31), respectively. The odds ratios for non-officers from non-Danish European Union and from non-European Union countries compared with Danish non-officers were 1.51 (1.12, 2.04) and 0.55 (0.42, 0.71), respectively. In conclusion, working as non-officer, older age and non-Danish EU nationality were associated with a higher risk of evacuations irrespective of the cause leading to evacuation.
Massive investments in offshore wind power generate significant challenges on how this electricity will be integrated into the incumbent energy systems. In this context, green hydrogen produced by offshore wind emerges as a promising solution to remove barriers towards a carbon-free economy in Europe and beyond. Motivated by the recent developments in Denmark with the decision to construct the world's first artificial Offshore Energy Hub, this paper investigates how the lowest cost for green hydrogen can be achieved. A model proposing an integrated design of the hydrogen and offshore electric power infrastructure, determining the levelised costs of both hydrogen and electricity, is proposed. The economic feasibility of hydrogen production from Offshore Wind Power Hubs is evaluated considering the combination of different electrolyser placements, technologies and modes of operations. The results show that costs down to 2.4 EUR per kg can be achieved for green hydrogen production offshore, competitive with the hydrogen costs currently produced by natural gas. Moreover, a reduction of up to 13 pct. of the cost of wind electricity is registered when an electrolyser is installed offshore shaving the peak loads.
The 76th session of the Marine Environment Committee (MEPC 76) of the International Maritime Organization adopted several mandatory measures in June 2021 to reduce carbon emissions from ships. One of the measures is the carbon intensity indicator (CII), which is the carbon emissions per unit transport work for each ship. Several options of CIIs are available and none of them is chosen to be applied yet. We prove that, at least in theory, requiring the attained annual CII of a ship to be less than a reference value, no matter which CII option is applied, may increase its carbon emissions. Therefore, more elaborate models, combined with real data, should be developed to analyze the effectiveness of each CII option and possibly to design a new CII.
The purpose of this paper is to provide an overview and discussion of potential Market Based Measures (MBMs) under the Initial IMO Strategy for the reduction of greenhouse gas (GHG) emissions from ships. In this context, some related developments are also seen as directly relevant, mainly in the context of the possible inclusion of shipping into the EU Emissions Trading System (ETS). A comparative evaluation of maritime MBMs is made using the following criteria: GHG reduction effectiveness, compatibility with existing legal framework, potential implementation timeline, potential impacts on States, administrative burden, practical feasibility, avoidance of split incentives between ship-owner and charterer, and commercial impacts. The paper breaks down potential MBMs into the following classes: Bunker levy/carbon levy MBMs, ETS (global and/or EU ETS) MBMs and other MBM proposals.
This study presents a novel approach to forecast freight rates in container shipping by integrating soft facts in the form of measures originating from surveys among practitioners asked about their sentiment, confidence or perception about present and future market development. As a base case, an autoregressive integrated moving average (ARIMA) model was used and compared the results with multivariate modelling frameworks that could integrate exogenous variables, that is, ARIMAX and Vector Autoregressive (VAR). We find that incorporating the Logistics Confidence Index (LCI) provided by Transport Intelligence into the ARIMAX model improves forecast performance greatly. Hence, a sampling of sentiments, perceptions and/or confidence from a panel of practitioners active in the maritime shipping market contributes to an improved predictive power, even when compared to models that integrate hard facts in the sense of factual data collected by official statistical sources. While investigating the Far East to Northern Europe trade route only, we believe that the proposed approach of integrating such judgements by practitioners can improve forecast performance for other trade routes and shipping markets, too, and probably allows detection of market changes and/or economic development notably earlier than factual data available at that time.
Exploring how transnational environmental governance and the operation of global value chains (GVCs) intersect is key in explaining the circumstances under which mandatory disclosure can improve the environmental footprint of business operations. We investigate how the governance dynamics of the tanker shipping value chain (a major emitter of greenhouse gases) limits the effectiveness of the European Union (EU) monitoring, reporting, and verification (MRV) regulation, which mandates the disclosure of greenhouse gas emissions for ships calling at EU ports. Although MRV seeks to help shipowners and ship managers save fuel and reduce emissions, it does not address the complexity of power relations along the tanker shipping value chain and currently cannot disentangle how different actors influence the design, operational, commercial, and ocean/weather factors that together determine fuel consumption. In particular, the EU MRV neglects to reflect on how oil majors exert their power and impose their commercial priorities on other actors, and thus co-determine fuel use levels. We conclude that, in its current form, the EU MRV is unlikely to lead to significant environmental upgrading in tanker shipping. More generally, we argue that regulators seeking to facilitate environmental upgrading need to expand their focus beyond the unwanted behaviors of producers of goods and providers of services to also address the incentive structures and demands placed on them by global buyers.
As the emission legislation becomes further constraining, all manufacturers started to fulfill the future regulations about the prime movers in the market. Lean-burn gas engines operating under marine applications are also obligated to enhance the performance with a low emission level. Lean-burn gas engines are expressed as a cleaner source of power in steady loading than diesel engines, while in transient conditions of sea state, the unsteadiness compels the engine to respond differently than in the steady-state. This response leads to higher fuel consumption and an increase in emission formation. In order to improve the stability of the engine in transient conditions, this study presents a concept implementing a hybrid configuration in the propulsion system. An engine model is developed and validated in a range of load and speed by comparing it with the available measured data. The imposed torque into the developed engine model is smoothed out by implementing the hybrid concept, and its influence on emission reduction is discussed. It is shown that with the hybrid propulsion system, the NOX reduces up to 40% because of the maximum load reduction. Moreover, eliminating the low load operation by a Power Take In during incomplete propeller immersion, the methane slip declines significantly due to combustion efficiency enhancement.
Increasing concerns related to fossil fuels have led to the introducing the concept of emission-free ships (EF-Ships) in marine industry. One of the well-known combinations of green energy resources in EF-Ships is the hybridization of fuel cells (FCs) with energy storage systems (ESSs) and cold-ironing (CI). Due to the high investment cost of FCs and ESSs, the aging factors of these resources should be considered in the energy management of EF-Ships. This article proposes a nonlinear model for optimal energy management of EF-Ships with hybrid FC/ESS/CI as energy resources considering the aging factors of the FCs and ESSs. Total operation costs and aging factors of FCs and ESSs are chosen as problem objectives. Moreover, a stochastic model predictive control method is adapted to the model to consider the uncertainties during the optimization horizon. The proposed model is applied to an actual case test system and the results are discussed.
Just as containerized goods appear to flow seamlessly across the planet's oceans, internationalized and standardized certificates present seafaring labor as uniform and seamless. But underneath these certificates are the intimate and unequal entanglements of local masculinity norms, age, and kinship ties that sustain the maritime labor supply chain. In this article, we follow how three young, male seafarers from eastern India find ways to contain piracy risks at work and poverty risks at home, and their sense of obligation as men, sons, husbands, and fathers. By delving into the unequal conditions for industrial male workers from the Global South, this article demonstrates how containerized maritime labor commodities are not uniform but are dependent upon economic inequality and intimate kinship ties to be productive.