Maritime routing and speed optimization with emission control areas

Strict limits on the maximum sulphur content in fuel used by ships have recently been imposed in some Emission Control Areas (ECAs). In order to comply with these regulations many ship operators will switch to more expensive low-sulphur fuel when sailing inside ECAs. Since they are concerned about minimizing their costs, it is likely that speed and routing decisions will change because of this. In this paper, we develop an optimization model to be applied by ship operators for determining sailing paths and speeds that minimize operating costs for a ship along a given sequence of ports. We perform a computational study on a number of realistic shipping routes in order to evaluate possible impacts on sailing paths and speeds, and hence fuel consumption and costs, from the ECA regulations. Moreover, the aim is to examine the implications for the society with regards to environmental effects. Comparisons of cases show that a likely effect of the regulations is that ship operators will often choose to sail longer distances to avoid sailing time within ECAs. Another effect is that they will sail at lower speeds within and higher speeds outside the ECAs in order to use less of the more expensive fuel. On some shipping routes, this might give a considerable increase in the total amount of fuel consumed and the CO₂ emissions.     

The effects of emission control area regulations on cruise shipping

To control SOx, NOx and particulate matter emission from ships, including cruise ships, emission control areas (ECAs) have been defined by the International Maritime Organization (IMO), which influences cruise planning. This paper investigates a mixed integer programming model to reschedule voyage plans by optimizing speeds, sailing patterns and ports-of-call sequences, hence reducing fuel costs. A tabu search based solution method is developed to solve the model. Computational tests on real-world data of cruise lines are conducted in order to explore the effects of ECA regulations on cruise shipping. The results show that the proposed model can save fuel costs under ECA regulations, and the designed solution method is efficient.     

Emission control areas: More or fewer?

As the global sulphur limit implemented by the International Maritime Organization (IMO) and the further development of sulphur emission reduction technologies, the effects of Emission Control Areas (ECAs) on reducing the sulphur emissions from ships will be reduced gradually. To explore the necessity of ECAs in the near future, this paper introduces the fictitious sulphur emission permit allocated to shipping carriers for our considered region. We propose an ECA location problem, which determines the location of ECAs in order to minimize the impact of sulphur emissions on human health, while satisfying the constraint on the fictitious sulphur emission permit. A mixed-integer linear programming model is proposed for our investigated problem. Numerical experiments are carried out by using our proposed model applied to China and Africa, where the sulphur emissions at different sites are estimated via the fuel consumption calculated by collecting data from liner carriers. Results show that, for the case of China, the Bohai Rim, the Yangtze River Delta and the Pearl River Delta have a high probability for establishing ECAs. For the case of Africa, the Guinea Bay and South Africa have a high probability for establishing ECAs.     

Benefit of speed reduction for ships in different weather conditions

Currently, the shipping industry is facing a great challenge of reducing emissions. Reducing ship speeds will reduce the emissions in the immediate future with no additional infrastructure. However, a detailed investigation is required to verify the claim that a 10% speed reduction would lead to 19% fuel savings (Faber et al., 2012).This paper investigates fuel savings due to speed reduction using detailed modeling of ship performance. Three container ships, two bulk carriers, and one tanker, representative of the shipping fleet, have been designed. Voyages have been simulated by modeling calm water resistance, wave resistance, propulsion efficiency, and engine limits. Six ships have been simulated in various weather conditions at different speeds. Potential fuel savings have been estimated for a range of speed reductions in realistic weather.It is concluded that the common assumption of cubic speed-power relation can cause a significant error in the estimation of bunker consumption. Simulations in different seasons have revealed that fuel savings due to speed reduction are highly weather dependent. Therefore, a simple way to include the effect of weather in shipping transport models has been proposed.Speed reduction can lead to an increase in the number of ships to fulfill the transport demand. Therefore, the emission reduction potential of speed reduction strategy, after accounting for the additional ships, has been studied. Surprisingly, when the speed is reduced by 30%, fuel savings vary from 2% to 45% depending on ship type, size and weather conditions. Fuel savings further reduce when the auxiliary engines are considered.     

Have Emission Control Areas (ECAs) harmed port efficiency in Europe?

Ports in the European Union and North America have enforced environmental regulations on controlling SO_x and NOx emissions from ships in their coastal areas known as Emission Control Areas (ECAs). This study uses two-stage approaches to examine whether ECA regulations impact the efficiency of ports operating in such areas. First, port efficiencies are estimated using non-radial slacks-based measure (SBM) Data Envelopment Analysis (DEA) models. The efficiency scores estimated by the SBM DEA models are then regressed on explanatory variables, including the ECA factor, and macroeconomic indicators using bootstrapped truncated regression (BTR) models. Panel data is collected on countries in EU ECAs and non-ECAs regarding such input variables as capital and labor, with cargo as an output variable. The results indicate that ECA regulations can harm port efficiency, reflecting concerns of policy-makers and industrial managers: the average efficiency loss from an ECA designation amounts to 0.058–0.066 on a scale of 0–1, accounting for a 15–18% loss from ECA ports’ average efficiency scores.     

The desulphurisation of shipping: Past,present and the future under a global cap

As from January 2020, the International Maritime Organization (IMO) is implementing a global 0.5% limit on the sulphur content of fuel, commonly known as the global sulphur cap. This limit is the latest policy in the efforts to reduce sulphur emissions from shipping, following the designation of emission control areas (ECAs) and other regional regulations. In this paper, a literature review is conducted of academic studies that have dealt with issues relating to the reduction of maritime sulphur emissions. Various recurring research themes are identified, spanning the areas of operations research, maritime economics and transport policy. The effects and implications of available compliance options are then analyzed from the perspectives of ship operators, shippers and consumers. Using lessons learned from the enforcement of ECA regulations, this is followed by an appraisal of various potential issues related to the enforcement of these new global regulations. It is found that a homogeneous enforcement regime is required to ensure a level playing field amongst ship operators and that the global sulphur cap may lead to serious market distortion, due to the potential short term rise of fuel prices. The paper concludes with a set of recommendations for future research on sulphur emissions from shipping in the aftermath of the global cap and, looking forward, to its relationship to the IMO strategy on the reduction of greenhouse gas (GHG) shipping emissions.     

Assessment of cost as a function of abatement options in maritime emission control areas

This paper assesses cost as a function of abatement options in maritime emission control areas (ECA). The first regulation of air pollutions from ships which came into effect in the late 1990s was not strict and could easily be met. However the present requirement (2015) for reduction of Sulfur content for all vessels, in combination with the required reduction of nitrogen and carbon emissions for new-built vessels, is an economic and technical challenge for the shipping industry. Additional complexity is added by the fact that the strictest nitrogen regulations are applicable only for new-built vessels from 2016 onwards which shall enter US or Canadian waters. This study indicates that there is no single answer to what is the best abatement option, but rather that the best option will be a function of engine size, annual fuel consumption in the ECA and the foreseen future fuel prices. However a low oil price, favors the options with the lowest capex, i.e. Marine Gas Oil (MGO) or Light Fuel Oil (LFO), while a high oil price makes the solutions which requires higher capex (investments) more attractive.     

Effect of a speed reduction of containerships in response to higher energy costs in Sulphur Emission Control Areas

The objective of this paper is to explore the possible consequences of the future low-sulphur fuel requirements in Sulphur Emission Control Areas (SECA) on vessel speed, from the standpoint of the container shipping industry. Rational energy use, speed reduction, and revenues are closely related in the container shipping sector because speed reductions may provide substantial energy and cost savings. The operators could consider reducing their speed in SECA in order to save on fuel that will become relatively expensive. However, to maintain a weekly frequency without adding new ships, such a behaviour implies that the required speed at sea outside the SECA area increases. This paper aims to investigate if such a difference in speed is cost-effective, and if the increase in speed outside SECA may result in an increase in CO₂ emissions of the total cycle. We propose a cost model that estimates the cost-minimising combination of speeds inside and outside SECA, and the resulting CO₂ emissions of the liner service. Applying this model to representative liner services serving North Europe, we find that differentiating speed accordingly slightly decreases total costs and increases CO₂ emissions in a similar way. The results are sensitive to the price of low-sulphur fuels, the part of the cycle in SECA and the number of ships deployed in the service.     

Sulphur abatement globally in maritime shipping

In 2016, the International Maritime Organization (IMO) decided on global regulations to reduce sulphur emissions to air from maritime shipping starting 2020. The regulation implies that ships can continue to use residual fuels with a high sulphur content, such as heavy fuel oil (HFO), if they employ scrubbers to desulphurise the exhaust gases. Alternatively, they can use fuels with less than 0.5% sulphur, such as desulphurised HFO, distillates (diesel) or liquefied natural gas (LNG). The options of lighter fuels and desulphurisation entail costs, including higher energy consumption at refineries, and the present study identifies and compares compliance options as a function of ship type and operational patterns.The results indicate distillates as an attractive option for smaller vessels, while scrubbers will be an attractive option for larger vessels. For all vessels, apart from the largest fuel consumers, residual fuels desulphurised to less than 0.5% sulphur are also a competing abatement option. Moreover, we analyse the interaction between global SO_X reductions and CO₂ (and fuel consumption), and the results indicate that the higher fuel cost for distillates will motivate shippers to lower speeds, which will offset the increased CO₂ emissions at the refineries. Scrubbers, in contrast, will raise speeds and CO₂ emissions.     

风帆助航对船舶主机油耗率的影响

加装风帆是船舶节能的有效途径,但风帆助航会影响船舶主机和其他系统的运行状况,对船舶能效的影响主要来自主机工况的改变。本文通过分析加装风帆后对螺旋桨工作特性的影响,推导出了计算主机油耗率的方法,并使用某超大型油轮(VLCC)的相关参数进行验证计算,证明此方法简单实用,可为计算风帆助航船舶能效指数EEOI等相关参数提供参考。     

Real option analysis for environmental compliance: LNG and emission control areas

A wide array of technical and operational solutions is available to shipowners in order to comply with existing and upcoming environmental regulation within Emission Control Areas (ECAs). Liquefied Natural Gas (LNG) is a promising alternative since it offers potential cost savings in addition to ensuring compliance with ECA regulation. But investment to retrofit existing vessels to be able to use LNG carries significant upfront costs, and a high degree of uncertainty remains on the differential between the prices of LNG and conventional maritime fuels, as well as on the availability of LNG and the reliability of its supply chain. New technologies such as LNG inherently carry substantial risk and an ill-chosen investment strategy may have irreversible consequences that could jeopardise the future of the shipping company. One important question is whether interested owners should invest in LNG now to comply with ECA rules in 2015 and reap the benefits of lower LNG prices, or whether it would be advisable to wait until some of the uncertainty is resolved.While traditional discounted cash flow techniques are unable to account for the value of managerial flexibility linked, for example, to the possibility of deferring an investment, real option analysis can be used to analyse such cases. The paper discusses the optimal time for investment in LNG retrofit and takes specific account of the value of an investment deferral strategy versus the advantages obtainable from the immediate exploitation of fuel price differentials. Through the use of a real option model the paper shows that there is a trade-off between low fuel prices and capital expenses for investment in LNG retrofit. The development in LNG is critically dependent on its future price as well as the reduction in capital costs and ship retrofitting costs. In this respect, policy makers can play a critical role in providing support to advance technical knowledge, maintain LNG prices at favourable levels and in avoiding ambiguity on regulation.     

Shipping log data based container ship fuel efficiency modeling

Container shipping lines have been initiating various ship fuel efficiency management programs because bunker fuel costs always dominate the daily operating costs of a container ship. As the basis of these kinds of programs, we develop a viable research methodology for modeling the relationship between the fuel consumption rate of a particular container ship and its determinants, including sailing speed, displacement, sea conditions and weather conditions, by using the shipping log data available in practice. The developed methodology consists of an outlier-score-based data preprocessing procedure to tackle the fuzziness, inaccuracy and limited information of shipping logs, and two regression models for container ship fuel efficiency. Real shipping logs from four container ships (two with 13000 TEUs and two with 5000 TEUs) over a six-month sailing period are used to exhibit the applicability and effectiveness of the proposed methodology. The empirical studies demonstrate the performance of three models for fitting the fuel consumption rate of a ship and the industrial merits of ship fuel efficiency management. In addition, we highlight the potential impacts of the models developed in this study on liner shipping network analysis, as these models can serve as base models for additionally considering the influence of displacement and weather conditions on ship fuel efficiency and exhaust emissions.     

A joint optimization model for liner container cargo assignment problem using state-augmented shipping network framework

This paper proposes a state-augmented shipping (SAS) network framework to integrate various activities in liner container shipping chain, including container loading/unloading, transshipment, dwelling at visited ports, in-transit waiting and in-sea transport process. Based on the SAS network framework, we develop a chance-constrained optimization model for a joint cargo assignment problem. The model attempts to maximize the carrier’s profit by simultaneously determining optimal ship fleet capacity setting, ship route schedules and cargo allocation scheme. With a few disparities from previous studies, we take into account two differentiated container demands: deterministic contracted basis demand received from large manufacturers and uncertain spot demand collected from the spot market. The economies of scale of ship size are incorporated to examine the scaling effect of ship capacity setting in the cargo assignment problem. Meanwhile, the schedule coordination strategy is introduced to measure the in-transit waiting time and resultant storage cost. Through two numerical studies, it is demonstrated that the proposed chance-constrained joint optimization model can characterize the impact of carrier’s risk preference on decisions of the container cargo assignment. Moreover, considering the scaling effect of large ships can alleviate the concern of cargo overload rejection and consequently help carriers make more promising ship deployment schemes.     

Emissions of NOX and particles from manoeuvring ships

Ship exhausts contain high levels of particles and nitrogen oxides due to the heavy fuel oil normally used for combustion and the combustion characteristics of most ship engines. The quantification of exhaust gases during ships’ manoeuvring has not received a lot of attention. This work presents results from emission measurements for the main engines onboard two ships and characterises quantities and potential impacts of emissions from manoeuvring. The observed nitrogen oxides levels vary throughout the manoeuvring period but at lower levels than at cruising speed. With a selective catalytic reduction system in operation, however, the situation is reversed. Elevated levels of particle emissions, measured as number concentrations, are detected throughout the manoeuvring. There are also peak concentrations of particles, at both the start-up and the shut-down of the engines. The increase is big enough to suspect a notable impact on air quality in port cities over the short period that manoeuvring at reduced speeds takes place.     

The viability of pure vegetable oil as an alternative fuel for large ships

Heavy fuels are likely to remain the dominant fuel source for two-stroke, low-speed diesel engines for large ship propulsion for the next decade or more. There is however, potential for increased use of pure vegetable oils (PVO) as an alternative and, by emitting lower levels of several pollutants, this can help the attainment of Annex VI of the MARPOL 73/78 convention aimed at large ships using fuels with less than 4.5% sulphur or 1.5% sulphur in SO_X emission control areas The use of alternative fuels can also influence the attainment of the Kyoto protocol that requires greenhouse gas emissions to be reduced by 5% by 2010 compared to 1990. This paper analyses the physical and chemical properties of various pure vegetable oils as an alternative to heavy fuel oil for large ship propulsion.     

Routing and scheduling of RoRo ships with stowage constraints

Roll-on/Roll-off ships are used for international transport of vehicles and other rolling equipment. We consider the problem where a ship sails between two geographical regions, picking up cargo in the first and making deliveries to the second. Several variations are considered with optional cargoes, flexible cargo quantities, and ship stability restrictions. Decisions must be made regarding the route and schedule of the ship as well as the stowage of cargo onboard. The problem is modeled as a mixed integer program, which has been solved using Xpress. In addition, a tailor made heuristic procedure is built using components from tabu search and squeaky wheel optimization. Extensive computational results are presented, showing that the heuristic is able to handle realistically sized problem instances.     

Operational profiles of ships in Norwegian waters: An activity-based approach to assess the benefits of hybrid and electric propulsion

Various regulations are imposed on shipping to increase energy efficiency and reduce environmental impacts. Alternative fuels and power systems are among the solutions for compliance with these regulations. The power system of a ship may not operate optimally because of the diversity of the operational profile during its lifetime. This article uses an activity-based approach and big data from the Automatic Identification System (AIS) to study the operational profiles of eight ship types operating in Norwegian waters around mainland Norway in 2016. The aim is to identify ship types that can benefit from electric and hybrid propulsion through analysis of their operational profiles. Close to shore, the operational profiles of various ship types are similar, and all ships spend a great proportion of their time with lower loads. As the distance from shore increases, the operational profiles of various ship types follow distinct trends. Among the considered ship types, reefers spend more operational time close to the diesel engine design condition. On the other hand, offshore and passenger ships show the most dynamic operational profiles and spend a large percentage of their operational time with a partial load, away from diesel engine design conditions. Such ships can benefit from hybridisation, diesel-electric propulsion, and other electric concepts, such as batteries and fuel cells. Another option is to downsize diesel engines for better operation while fuel cells and batteries supply peak and partial loads. Operational profiles are plotted and details of the approach are presented in the article.     

Dynamic optimization of ship energy efficiency considering time-varying environmental factors

Nowadays, optimization of ship energy efficiency attracts increasing attention in order to meet the requirement for energy conservation and emission reduction. Ship operation energy efficiency is significantly influenced by environmental factors such as wind speed and direction, water speed and depth. Owing to inherent time-variety and uncertainty associated with these various factors, it is very difficult to determine optimal sailing speeds accurately for different legs of the whole route using traditional static optimization methods, especially when the weather conditions change frequently over the length of a ship route. Therefore, in this paper, a novel dynamic optimization method adopting the model predictive control (MPC) strategy is proposed to optimize ship energy efficiency accounting for these time-varying environmental factors. Firstly, the dynamic optimization model of ship energy efficiency considering time-varying environmental factors and the nonlinear system model of ship energy efficiency are established. On this basis, the control algorithm and controller for the dynamic optimization of ship energy efficiency (DOSEE) are designed. Finally, a case study is carried out to demonstrate the validity of this optimization method. The results indicate that the optimal sailing speeds at different time steps could be determined through the dynamic optimization method. This method can improve ship energy efficiency and reduce CO₂ emissions effectively.     

Adapting the shipping sector to stricter emissions regulations: Fuel switching or installing a scrubber?

This paper examines how the existing fleet in the shipping industry can be adapted to the new emission regulations through the two main techniques that currently exist: (a) the use of low-sulphur marine diesels; and (b) the installation of scrubbers. A method is presented here for drawing up an economic assessment of both these techniques under uncertainty. It enables the best option to be selected at any given time taking into account fuel prices (spot and futures), scrubber installation costs, the time that the vessel operates in an Emission Control Area (ECA) and the remaining useful lifetime of the vessel. The paper also considers the possibility of an unexpected change from a non-ECA navigation area to an ECA. The assessment is carried out in a manner consistent with marine diesel and crude oil spot and futures market quotes. Our results show the net present value of investing in the installation of scrubbers and investing in changing fuel types for different assumptions on how vessels are operated. We also analyse increases in fuel consumption and CO₂ emissions as a consequence of using scrubbers and how they affects the financial analysis if such incremental emissions must be paid under a CO₂ pricing mechanism.     

Liner ship route schedule design with port time windows

This paper examines a practical tactical liner ship route schedule design problem, which is the determination of the arrival and departure time at each port of call on the ship route. When designing the schedule, the availability of each port in a week, i.e., port time window, is incorporated. As a result, the designed schedule can be applied in practice without or with only minimum revisions. This problem is formulated as a mixed-integer nonlinear nonconvex optimization model. In view of the problem structure, an efficient holistic solution approach is proposed to obtain global optimal solution. The proposed solution method is applied to a trans-Atlantic ship route. The results demonstrate that the port time windows, port handling efficiency, bunker price and unit inventory cost all affect the total cost of a ship route, the optimal number of ships to deploy, and the optimal schedule.