Many ports and terminals endeavor to enhance energy efficiency as energy prices have increased through years and climate change mitigation is a key target for the port industry. Stricter environmental regulations are adopted by authorities to limit pollutants and GHG emissions arising from energy consumption. Increasingly, port operational strategies and energy usage patterns are under scrutiny. To ingrain sustainability and environmental protection of ports, the use of innovative technology appears as a critical conduit in achieving a transition from a carbon-intensive port industry (dependent on fossil fuels) to a low-carbon port model by harnessing renewable energy, alternative fuels (e.g. LNG, hydrogen, biofuel), smarter power distribution systems, energy consumption measurement systems. In this context, this paper conducts a systematic literature review to analyze operational strategies (e.g. peak shaving, operations optimization), technology usage (e.g. electrification of equipment, cold-ironing, energy storage systems), renewable energy, alternative fuels and energy management systems (e.g. smart grid with renewable energy) for improving the energy efficiency and environmental performance of ports and terminals. Research gaps and future research directions are identified. Analysis shows that there is a great potential for ports to achieve further energy efficiency and researchers have many impactful research opportunities.

A review of energy efficiency in ports: Operational strategies, technologies and energy management systems

Experimental and numerical hydrodynamic analysis of a stepped planing hull

In this paper, we investigate the verification and validation (V&V) procedures for the URANS simulations of the turbulent cavitating flow around a Clark-Y hydrofoil. The main focus is on the feasibility of various Richardson extrapolation-based uncertainty estimators in the cavitating flow simulation. The unsteady cavitating flow is simulated by a density corrected model (DCM) coupled with the Zwart cavitation model. The estimated uncertainty is used to evaluate the applicability of various uncertainty estimation methods for the cavitating flow simulation. It is shown that the preferred uncertainty estimators include the modified Factor of Safety (FS1), the Factor of Safety (FS) and the Grid Convergence Index (GCI). The distribution of the area without achieving the validation at the Vv level shows a strong relationship with the cavitation. Further analysis indicates that the predicted velocity distributions, the transient cavitation patterns and the effects of the vortex stretching are highly influenced by the mesh resolution.

Verification and validation of URANS simulations of the turbulent cavitating flow around the hydrofoil

Energy-related approach for reduction of CO2 emissions: A strategic review on the port-to-ship pathway

This paper deals with power control strategies for a fixed-pitch direct-drive marine current turbine (MCT) when the marine current speed exceeds the rated value corresponding to the MCT nominal power. At overrated marine current speed, the MCT control strategy is supposed to be changed from maximum power point tracking (MPPT) stage to constant power stage. In this paper, flux-weakening strategy is investigated to realize appropriate power control strategies at high marine current speeds. During flux-weakening operations, the generator can be controlled to produce nominal or overnominal power for a specific speed range (constant power range). These two power control modes are compared, and the constant power range is calculated. The relationship between the expected constant power range and generator parameter requirements [stator inductance, permanent magnet (PM) flux, and nominal power coefficient] is analyzed. A Torque-based control with a robust feedback flux-weakening strategy is then carried out in the simulation. The proposed control strategies are tested in both high tidal speed and swell wave cases; the results validate the analysis and show the feasibility of the proposed control method.

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Power Control of a Nonpitchable PMSG-Based Marine Current Turbine at Overrated Current Speed With Flux-Weakening Strategy

In the context of marine application of computational fluid dynamic (CFD), it is well known that the numerical simulations of planing craft are significantly less reliable than that of displacement ships. For this reason, it is important to perform a comprehensive approach to the verification and validation (V&V) methodology and procedures for simulating CFD planing craft. In the first part of this paper, an assessment of the accuracy and effectiveness of different simulation setups and techniques for planing craft is performed. In the second part, the results of the V&V study are reported for three different hull models at four Froude numbers (Fr). The Unsteady Reynolds-Averaged Navier-Stokes code results were validated using benchmark experimental data obtained for three hull models characterized by systematic variation of the length to beam ratio. Grid independence, iteration, and time-step convergence analysis for response variables (resistance coefficients, wetted surfaces, and dynamic trim angles) were conducted using the main error and uncertainty estimation methods available in the literature. The same procedures were followed for the profiles of the wave patterns. The results showed that there was improved reliability of the numerical simulation of the planing craft in terms of the errors and uncertainties, related to the predictions of resistance, running attitude, and wave pattern. The results of the V&V study highlighted the fact that modeling of the planing craft is a critical point to improve the reliability of the numerical simulation.

An Extended Verification and Validation Study of CFD Simulations for Planing Hulls

One of the most promising fields in energy production from renewable sources is related to the intensive exploitation of marine and river current power. This paper will illustrate the design and the performances of a shrouded hydro turbine to harness clean energy from marine and river currents. This system has been developed and tested at the University of Naples, to explore the feasibility of plants based on such idea. Two different diffusers have been designed, realized and tested. A simple designed method has been carried out in order to define the diffuser pitch angle. In order to evaluate the design diffuser angle in more accurate way a numerical simulation has been carried out. The experimental test results were compared with the bare wind turbine. The data were non-dimensionalized with respect to the disc turbine area in order to compare the ducted turbine performances with a bare turbine with the same overall size of the ducted wind turbine.

Numerical and experimental analysis of a shrouded hydroturbine

In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by an analytical method and compared against towing tank tests. Using the 2D + T theory, the pressure distribution over the wedge section entering the water and the normal forces acting on the 2D sections have been computed. By integrating the 2D sectional normal forces over the entire wetted length of the vessel, the lift force acting on it has been obtained. Using lift forces as well as the consequence pitch moment, the equilibrium condition for the single-stepped planing hull is found and then resistance, dynamic trim, and the wetted surface are computed. The obtained hydrodynamic results have been compared against the experimental data and it has been observed that the presented mathematical model has reasonable accuracy, in particular, up to Froude number 2.0. Furthermore, this mathematical model can be a useful and fast tool for the stepped hull designers in the early design stage in order to compare the different hull configurations. It should also be noted that the mathematical model has been developed in such a way that it has the potential to model the sweep-back step and transverse the vertical motions of single-stepped planing hulls in future studies.

https://www.mdpi.com/2077-1312/6/4/136/pdf

A Validation of Symmetric 2D + T Model Based on Single-Stepped Planing Hull Towing Tank Tests

Certain class of offshore structures exhibit highly intense nonlinear behavior called springing and ringing. Dynamic response of compliant structures like Tension Leg Platforms (TLP) under impact and non-impact waves responsible for ringing and springing phenomenon is of large interest to marine engineers. This paper develops a mathematical formulation of impact and non-impact waves and discusses the method of analysis of TLPs of triangular geometry under these wave effect; response of square and equivalent triangular TLPs are compared. Heave response in square TLPs show bursts but there are no rapid build-ups; gradual decays are seen in most cases looking like a beat phenomenon while such results are not predominantly noticed in case of equivalent triangular TLPs. Ringing, caused by impact waves in pitch degree-of-freedom and springing, caused by non-impact waves in heave degree-of-freedom in both the platform geometries are undesirable as they pose serious threat to the platform stability. Analytical studies conducted show that equivalent triangular TLPs positioned at different water depth are less sensitive to these undesirable responses thus making it as a safe alternative for deepwater oil explorations.

Salvatore Miranda

Papers

Experimental and numerical hydrodynamic analysis of a stepped planing hull

An Extended Verification and Validation Study of CFD Simulations for Planing Hulls

Numerical and experimental analysis of a shrouded hydroturbine

A Validation of Symmetric 2D + T Model Based on Single-Stepped Planing Hull Towing Tank Tests

Ringing and springing response of triangular TLPs