The purpose of this paper is to revisit speed optimization and speed reduction models for liner shipping in a multi/flexible fuel context with regards to the current ongoing speed limit debate at the International Maritime Organization (IMO). The focus is mainly on analyzing the influence of a maximum average speed limit on the optimal speeds, carbon intensity and emissions in conjunction with fleet deployment for dual fuel (DF) Neopanamax container vessels utilizing liquefied natural gas (LNG).
This report is a background report to the MarE-Fuel project financed by the Maritime Fund and the Lauritzen Fund. Partners of the project has been DTU, Anker Invest, Mærsk Line, Copenhagen Economics, OMT and DFDS. In the report, potential decarbonization roadmaps or pathways for the maritime industry are presented, as well as the methodology of deriving them. Different future fuels and their emissions are highlighted. In addition, biomass availability plays an essential role in climate mitigation efforts towards net-zero by 2050, and thus we examined different biomass availability scenarios alongside greenhouse-gas emissions cap scenarios. The assumptions related to the underlying emissions can be found in the first chapter of the report. Besides the underlying emissions for a decarbonized maritime industry, the ship stock and the underlying transport demand play an essential role for a future decarbonized maritime industry. In the second chapter of the report, we address this issue by explaining how ship stock and shipping demand have been incorporated into the model. Finally, we present the optimization ship stock model developed to generate roadmap scenarios. We show the objective function and the underlying constraints of the model. The results of this work are presented and discussed. We also show some sensitivity analysis, which will shed light on the relevant parameters for the futureof the maritime industry. Our main findings can be found in the end of the report.
The reduction of Greenhouses gasses (GHG) and other air emissions represents a major challenge for ports. The world over, however, ports vary considerably in their efforts to reduce air emissions, and the causes for this variation remain under-researched. This paper examines the drivers for the adoption of air emissions abatement measures in a sample of 93 of the world’s largest ports, covering all continents and mobile emitters. We test five hypotheses with a Linear Probability Model to disentangle the impacts of key port characteristics on the current adoption of abatement measures and identify three key drivers for adoption: Population density, the port landlord business model, and a specialization in servicing container shipping. We also find that ports are more likely to implement specific bundles of measures, in particular combining pricing and new energy sources. Our work has implications for ports, as we suggest that they should coordinate abatement efforts to achieve effectiveness in their work.
This report provides an assessment on the prospects for offshore energy hubs. Four use cases have been developed and evaluated by respondents in a survey instrument for their forecasted time horizon to implementation and their business potential as opportunities for the maritime and offshore
industries. The report is produced by the PERISCOPE Group at Aarhus University for the PERISCOPE network.
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.
This paper studies the design of a mid-scale maritime supply chain for distribution of liquefied natural gas (LNG) from overseas sourcing locations, via a storage located at the coast, before transporting the LNG on land to industrial customers. The case company has signed contracts with a number of initial customers and expect that there will be more customers and increased demand in the years to come. However, it is currently uncertain whether and when new contracts will be signed. To capture this uncertainty with regard to which and how many future customers there will be, which directly affects the demand, we propose a multi-stage stochastic programming model, which maximizes the expected profits of the supply chain. The model aims at aiding decisions concerning the import of LNG, investments in floating storage units and customer distribution systems, and it has been applied on a real case study for distributing LNG to customers in a Brazilian state. It is shown that explicitly considering uncertainty in the modeling of this problem is very important, with a Value of Stochastic Solution of 13.2%, and that there are significant economies of scale in this supply chain. Most importantly, the multi-stage stochastic programming model and the analysis presented in this paper provided valuable decision support and managerial insights for the case company in its process of setting up the LNG supply chain.
This study concerns nitrogen based emissions from a hydrogen enriched ammonia fueled SI engine. These emissions deserve special attention as their formation may differ from conventional HC combustion due to the nitrogen content in the fuel. A range of experiments are conducted with a single cylinder 0.612 l CFR engine with a compression ratio varying from 7 to 15 using a fuel composition of 80 vol% NH3 and 20 vol% H2. Wet exhaust samples are analysed with an FT-IR. Emission measurements reveal that nitric oxide stem from other reaction paths than the dissociation of molecular nitrogen. This causes the NO emissions to peak around 35% rather than 10% excess air, as is typical in HC fueled SI-engines. However the magnitude of NO emissions are comparable to that of measurements conducted with gasoline due to lower flame temperatures. Nitrogen dioxide levels are higher when comparing with gasoline, but has a relatively low share of the total NOx emissions (3–4%). Nitrous oxide is a product of NH2 reacting with NO2 and NH reacting with NO. The magnitude is largely affected by ignition timing due to the temperature development during expansion and the amount of excess air, as increased oxygen availability stimulates the formation of the NH2 radical and the levels of NO2 are higher. Under ideal operating conditions (MBT ignition timing) N2O levels are very low. The dominating contributors to unburned ammonia are chamber crevices as the magnitude of these emissions is greatly affected by the compression ratio. However, levels are lower than required in order to eliminate all NOx emissions with a SCR catalyst.
Existing energy management strategies (EMSs) for hybrid power systems (HPSs) in hydrogen fuel cell vessels (FCVs) are not applicable to scenarios with multiple hydrogen fuel cells (FCs) and lithium batteries (LBs) in parallel, and are difficult to achieve real-time control and optimization for multiple objectives. In this paper, a bi-layer real-time energy management strategy (BLRT-EMS) is proposed. Compared with existing EMSs, the proposed BLRT-EMS implements different control/optimization objectives distributed in the execution layer EMS (EL-EMS) and the decision layer EMS (DL-EMS), which can significantly reduce bus voltage fluctuations, decrease hydrogen consumptions, improve the system efficiency, and have potential for engineering applications. In the first EL-EMS, a decentralized optimal power allocation strategy is proposed, which allows each FC system to allocate the output power ratio according to their generation costs, ensuring consistent performance of multiple FC systems (MFCS) under long-term operating conditions, and thus delaying the degradation rate of FCs. In the second EL-EMS, a distributed cooperative control strategy is proposed to achieve dynamic SoC equalization, proportional output power allocation, and accurate bus voltage restoration among multiple battery storage systems (MBSS) to extend the service life of batteries. In the DL-EMS, an energy coordination optimization strategy between MFCS and MBSS is proposed to achieve hydrogen consumption reduction and system efficiency improvement, thus enhancing the endurance performance of FCV. Finally, test results based on the StarSim experimental platform show that the proposed BLRT-EMS has faster SoC convergence speed, smaller bus voltage deviation, lower hydrogen consumption, higher system efficiency, and lower operation stress than the state-of-the-art methods.
As of January 2015, the new maximum limit of fuel sulfur content for ships sailing within emission control areas has been reduced to 0.1%. A critical decision for ship owners in advance of the new limits was the selection of an abatement method that complies with the regulations. Two main options exist: investing in scrubber systems that remove sulfur dioxide emissions from the exhaust and switching to low-sulfur fuel when sailing in regulated waters. The first option would involve significant capital costs, while the latter would lead to operating cost increases because of the higher price of the fuel used. This paper presents a literature review of emissions abatement options and relevant research in the field. A cost–benefit methodology to assess emission reduction investments from ship owners is also presented. A study examined the effects of recent drops in bunker fuel price to the payback period of a potential scrubber investment. The results show that lower prices would significantly delay the payback period of such investments, up to two times in some cases. The case studies present the emissions generation through each option for representative short sea shipping routes. The repercussions of low-sulfur policies on large emission reduction investments including cold ironing are examined, along with implications of slow steaming for their respective payback periods. Recommendations are made for research in anticipation of future regulations and technological improvements.