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.
The power output from many wave energy converters (WECs) is limited by a finite stroke length in the power take-off (PTO) mechanism. As the PTO approaches its maximum stroke length, an end-stop system needs to be engaged to avoid damage to the machinery. Still the on-set of the end-stop is a nonlinear trigger force, a stiff point in the system. In this respect it is similar to how snap loads in the mooring cables affect the system after a period of cable slack. This paper presents a detailed study into the dynamics of end-stop events and snap loads for a WEC. The WEC is a bottom-mounted linear generator connected to a surface buoy via a steel wire. By comparing a linear spring model with three dynamic mooring line models we conclude that large differences are observed in the low-tension and slack regions of the cable during moderate wave loads, while minor differences are seen in the estimated peak tension. By further varying end-stop parameters we observe that the peak tension in the line changes mildly with the axial stiffness for moderate wave heights. The peak tension is surprisingly unaffected by the introduction of a critical damping level to the end-stop system, despite the significant increase in end-stop force which causes the translator to come to a sudden stop. We discuss how the connection between maximum line force and end-stop parameters is highly dependent on the buoy position in the wave at the instant of end-stop onset.
The levelized costs of energy (LCoE) of wave power is still not fully competitive with other sources of renewable energy. However, wave energy is partly in a different phase than other renewable energy types and could thus contribute to a better predictability and smoothed power output. This work focuses on co-location of wave and wind power by investigating the intermittency of wind and waves power based on measured historical data from several hundreds of locations worldwide. Employing wind power curves and wave power matrices, the sites are evaluated based on several different metrics. The results indicate that there are several spots where wave power has a much lower intermittency than wind power providing reliable energy supply. Best sites for co-location in terms of energy yield were found in North-Western Europe. However, both wind and wave production have the same seasonal variability in these sites. Only a handful of sites found in California showed the possibility of seasonal power smoothing using the combination of wind and wave.
This article examines whether the concept of territorial governance (TG) accurately captures the nature of governance and policymaking in transboundary marine spatial planning (TMSP) activities in the Baltic Sea Region. The focus of analysis is on the DG Mare–funded Baltic SCOPE and Pan Baltic Scope projects, which brought together key marine spatial planning stakeholders in the Baltic Sea Region to find solutions to TMSP issues. The five key dimensions of TG are examined against the transboundary collaborations undertaken during these two projects. The article finds that TMSP in the Baltic Sea Region shares many of the key characteristics of TG, such as, promoting learning and establishing stronger links between institutions, sectors and stakeholders; however, the TG concept fails to accurately capture the power dynamics at play in TMSP, particularly the central role of national planning authorities and certain sea use sectors in determining the overall direction of policy.
In the European Union, Maritime Spatial Planning (MSP) has been regarded as a means of promoting the sustainable growth of the blue economy. Consequently, where the planning outcomes affect the business operations in marine areas, commercial and industry stakeholders should have an important role in the planning process. However, the business perspective in MSP has gained little attention in stakeholder involvement literature. The aim of this study is to elaborate on the business sector's interest and involvement in MSP in the Baltic Sea region. The findings are based on the first-hand experiences of MSP authorities and experts. Furthermore, perspectives from two sea-use sectors, maritime transport and marine tourism, have been investigated using online questionnaires to discover their views. The study focuses on the questions of who to involve and what are the driving forces promoting business sector involvement. Even though MSP is a form of broad-scale planning, the results indicate that all spatial and organizational scales from local to international and from small enterprises to umbrella organizations should be considered when designing approaches to business stakeholder participation. The planning authorities need to consider what are the benefits and challenges of involving different types of business stakeholders. Planners often rely on organizations that represent business stakeholders and individual companies. It is resource effective to interact with representatives as they are considered to have a broad and general knowledge of the respective sector's interests. However, in some cases it is beneficial to also integrate individual companies, especially in local or regional contexts.
The share of renewables in the power system is increasing rapidly. Large offshore wind power plants (OWPPs) are developed at a high pace and conventional fossil fuel-based plants are decommissioned. Consequently, there will be a risk of insufficient amount of power plants providing black start functionality for system restoration after a black out. This paper proposes a STATCOM with a battery energy storage that is located at the point of common connection to an OWPP that together can provide a reliable black start service to the power grid. The concept is demonstrated by using time domain simulations in PSCAD. The STATCOM functionality provides fast and dynamic reactive power management and the battery unit provides active power balancing capability to maintain the frequency within a tolerable range specified by the system operator. The simulation results fulfill the success criteria for the black start and confirm its feasibility for practical implementation.
Integrated community energy systems are an emerging concept for increasing the self-sufficiency and efficiency of local multi-energy systems. This idea can be conceptualized for the smart island energy systems due to their geographical and socioeconomic context, providing several benefits through this transformation. In this study, the energy system of the Ballen marina—located on the medium-sized Danish island of Samsø— is investigated. Particular consideration is given to the integration of PV, BESS, and—in the future—flexible loads. For this purpose, the BESS is modelled, incorporating the battery degradation process. The possibilities to improve energy utilization and maximize self-consumption from the marina's PV units are identified and evaluated, demonstrating a substantial enhancement of the local system operation.
The present paper deals with separation of long-crested regular waves into incident and reflected components. Such methods have been available for several decades for linear waves, but have recently been extended to cover nonlinear waves over horizontal foreshores. The overall goal of the present paper is to extend the separation method for nonlinear regular waves to also cover sloping foreshores. This requires the combination of the existing method with a nonlinear shoaling model. A nonlinear shoaling model was very recently found valid for the shoaling of the primary and bound components in regular waves when the slope angle is positive and mild. In the present paper this shoaling model is utilized and assumed valid also for the de-shoaling of the reflected waves, ie on a negative mild slope angle. However, if the reflected waves are nonlinear the de-shoaling process is much more complicated and will for example cause the release of free waves. Interactions among those free reflected wave components may cause nonlinear interactions not included in the mathematical model. For that reason, the applicability range is limited to mildly nonlinear reflected waves. Using numerical model data with various foreshore slopes, wave nonlinearities and reflection coefficients the reliability of the developed model is examined in detail.
Highly accurate and precise heave decay tests on a sphere with a diameter of 300 mm were completed in a meticulously designed test setup in the wave basin in the Ocean and Coastal Engineering Laboratory at Aalborg University, Denmark. The tests were dedicated to providing a rigorous benchmark dataset for numerical model validation. The sphere was ballasted to half submergence, thereby floating with the waterline at the equator when at rest in calm water. Heave decay tests were conducted, in which the sphere was held stationary and dropped from three drop heights: a small drop height, which can be considered a linear case, a moderately nonlinear case, and a highly nonlinear case with a drop height from a position where the whole sphere was initially above the water. The precision of the heave decay time series was calculated from random and systematic standard uncertainties. At a 95% confidence level, uncertainties were found to be very low — on average only about 0.3% of the respective drop heights. Physical parameters of the test setup and associated uncertainties were quantified. A test case was formulated that closely represents the physical tests, enabling the reader to do his/her own numerical tests. The paper includes a comparison of the physical test results to the results from several independent numerical models based on linear potential flow, fully nonlinear potential flow, and the Reynolds-averaged Navier–Stokes (RANS) equations. A high correlation between physical and numerical test results is shown. The physical test results are very suitable for numerical model validation and are public as a benchmark dataset.
In tramp shipping, a preliminary route is required for voyage planning at the pre-fixture stage (before a chartering contract is agreed). Such routes are conventionally designated by using pilot charts or software considering long-term statistical weather. However, it has been experienced by tramp operators that such route solutions often poorly estimated sailing distances for long journeys and thereby cause inappropriate cost estimation and bad voyage plan. To fill this gap, a data-driven methodology is proposed in this paper to establish a practical route library with the consideration of ship sizes, load conditions and seasonality. In this method, it first requires a dividing of ship trajectories into local sea passage and open sea passage. The voyage trajectories made of AIS points are then simplified to pattern nodes based on a speed-weighted geolocation method. Afterwards, the KMeans algorithm is deployed to properly classify these pattern nodes, identifying the most representative nodes (routes) in open sea passages. Simultaneously, the connection points are identified by DBSCAN algorithm, representing local sea passages. Combining the representative routes in open sea passages and the connection points in local sea passages, the most navigated routes between two ports are obtained. Finally, case studies are conducted for the Pacific Ocean and the Atlantic Ocean respectively using global AIS data from tanker vessels to demonstrate the feasibility and effectiveness of this methodology. The proposed route library is capable of providing reliable route references to support the decision-making at the pre-fixture stage.