Hydrodynamic Model Tests With a Large Floating Hydrocarbon Storage Facility

The paper presents model tests with a floating hydrocarbon storage facility performed in SINTEF Ocean’s basin. The system may be considered a very large floating structure with a footprint of 300m × 310m. Hydrocarbons are stored into independent tanks, which are soft moored to a modular floating frame which is kept in station by dolphins. The system is composed of 14 tanks and 21 frame barge modules, therefore 35 connected floating bodies. The objective of the model tests was twofold. First, to verify the feasibility of the global system, namely in terms of tank and frame motions, connection loads, station keeping loads and relative wave elevations. Second, to acquire data for tuning and validation of numerical models, i.e. to investigate effects that cannot be reliably established by simulations alone. The model tests were performed in wave, current and wind conditions corresponding to 1 year and to 100 years return periods, in addition to a set a simplified wave conditions. The paper describes the model test setup, the experimental program, the procedures for analysis of test data, it presents representative results and discusses the main observations.

New Engineering Approach for the Development and Demonstration of a Multi-Purpose Platform for the Blue Growth Economy

Aquaculture is currently the fastest growing food sector in the world and the open oceans are seen as one of the most likely areas for large-scale expansion [1], [2], [3]. The global demand for seafood is continuing to rise sharply, driven by both population growth and increased per capita consumption, whilst wild-capture fisheries are constrained in their potential to produce more seafood. A recently funded EC project, the Blue Growth Farm – BGF (GA n. 774426, 1st June 2018 – 30th September 2021) aims at contributing to this world need with an original solution. The Blue Growth Farm proposes an efficient, cost-competitive and environmentally friendly multi-purpose offshore farm concept. It is based on a modular floating structure, moored to the seabed, meeting requirements of efficiency, cost-competitiveness and environmental friendless, where automated aquaculture and renewable energy production systems are integrated and engineered for profitable applications in the open sea. In the present paper, the overall engineering approach developed to carry out the research work is presented, described and justified. Different technical and scientific challenges are addressed through an integrated industrial engineering design approach, where all disciplines are tuned to achieve the Blue Growth Farm main targets. These are represented by: i) guaranteeing expected nominal fish production thanks to advanced automation and remote control capabilities; ii) minimizing the pollution introduced at marine ecosystem level when exploiting the marine natural resources, whilst increasing the social acceptance and users community agreement; iii) maximizing the electricity production in the Blue Growth Farm potential installation area ecosystem to provide energy supply to the on-board electrical equipment and to dispatch the extra produced electric energy to the land network. Preliminary engineering design results are promising to demonstrate effective increase of safety and efficiency by reducing on-board human effort and consequently risks at offshore, thus to make commercial-scale open ocean farming a reality. The present paper introduces overall concepts and design methodology whilst other companion works submitted at OMAE2019 [4], [5], [6] provide insight of specific aspects of the Blue Growth Farm project elaborated during the first six months activity.

Development of Wireless Control System With Underwater Fish-Eye Camera to Monitor Fish at the Test Site of Marine Renewable Energy

Environmental impact assessment is important when marine renewable energy device is installed. Fishermen concern the effect of device on local fish. To confirm the effect before and after installation of marine renewable energy device, we developed wireless monitoring system using an underwater fish eye camera. The camera system is composed of a dome-shaped fish eye lens, a container, and a float. Two thrusters are attached on the container to change the monitoring directions. In the current research, this system was developed to monitor underwater situation around device remotely and in real time. We tested to monitor a target and fish in a fish case at the site off Kamaishi city. The recorded video showed the target and fish. Effectiveness of this system was shown through the field test for real time monitoring around marine renewable energy device.

Three-Dimensional Physical Environment Modelling for Integrated Multi-Trophic Aquaculture (IMTA) Implementation in Onagawa Bay, Japan

Continually increasing demands on aquaculture products drive the current monoculture to upgrade and upscale because of not only economic but environmental sustainability reasons. Over the past decade, open water integrated multi-trophic aquaculture (IMTA) practiced as a potential alternative has been demonstratively illustrated from both scientific and public attention. Basing on previous studies of this synergistic aquaculture system, we, here, studied the physical environment in Onagawa Bay as the cornerstone for further IMTA implementation. Onagawa Bay locates in Miyagi Prefecture, Japan, and because of its mature practice on polyculture, it is recognized as a suitable site for IMTA. Unfortunately, the earthquake and tsunami in 2011 caused a huge uncertainty on physical environment changes. Still insufficient researches have been conducted on physical environment study, especially through modelling method. Here, adopting the three-dimensional Marine Environmental Committee (MEC) ocean model, we described the setup and validation for Onagawa Bay in this research. At the present stage, simulation results can best fit observation data on the tidal elevation with the correlation coefficient between observed and simulated tidal elevation reaching 0.96, captured the main characteristic of flow velocity, and exhibited homogenous tendency towards water temperature. Furthermore, through the plot of the residual velocity field and statistical seasonal velocity distribution, potential aquaculture configuration has been discussed spatio-temporally on the hypothesis that high current speeds contribute to the further implementation.

A Fundamental Study on Tsunami Protection Measures for a Vessel Moored at a Wharf Considering the Backwash Influence

When a tsunami attacks in harbors, a vessel moored at a wharf is occurred a serious damage. The first wave of the tsunami has two forms and those are called the leading wave and the backwash. And, it is difficult to predict the form of the first wave of tsunamis. Authors have been studying about damage protection measures against the leading wave of vessels moored at wharves. However, it is also necessary that a damage protection measure against the backwash of vessels moored at wharves is considered. In this study, it is examined the damage status of a vessel at a wharf due to the backwash. Then, it is examined the influence of the backwash to the author’s proposal tsunami protection measures. The three dimensional MPS (Moving Particle Semi-implicit) method is used. The Backwash is simulated as the dam break phenomenon. Outflow angles, flow velocities, mooring conditions and with and without of tsunami protection measures are considered.

A Multipurpose Framework for Modelling and Simulation of Marine Aquaculture Systems

Research within marine aquaculture has either focused on technology (e.g. farming structures, autonomous systems, harvesting and transport technologies) or biology (e.g. biomass control, feeding process, fish behavior and welfare). Here, we present a computational framework allowing the integrated analysis of these two aspects in a flexible and evolutive way. This framework is called FhSim which was originally developed for the modelling and simulation of fisheries operations and aquaculture structures, but its application domain has been continuously extended through different research projects. In this paper, we present the basic design principles and functionality of the FhSim framework with the focus on modelling and simulation of marine aquaculture systems. The basic theories and methods used for the modelling of open net cages, closed cages, fish behavior, feeding processes, and ROV operations in net cages are introduced, respectively. It is also shown how the technological and biological aspects of fish farming can be considered in a specialized or integrated analysis. Furthermore, approaches for combining numerical models with monitoring sensor data, techniques for real-time simulation of fish farming operations and the coupling of FhSim with other simulation programs are discussed.

Introduction of Virtual Structural Boundary for Collision Force Analysis of Tsunami Drifting Objects in Particle Method

One of the reasonable methods to analyze the collision force of a tsunami drifting object against a structure is a particle method. However, when both the structure and the drifting body are composed of particles, there are various problems such as particles of the collision object slipping through particles of the structure. Therefore, the authors have constructed a particle method - analytical solution hybrid method which can analyze the collision force of a tsunami drifting object to an elastic member by constructing a structure as a boundary condition acting on a drifting object. However, since this boundary was introduced as a virtual boundary that acts only on drifting particles, the collision force of the tsunami drifting object to the structure can be analyzed, but the fluid force can’t be analyzed. Therefore, in this study, in addition to the boundary condition as the structure, we further reconstructed the collision force and the fluid force as a method that can analyze the collision force and the fluid force simultaneously by setting the mirror particle boundary condition for the fluid particle. By developing this method, it became possible to calculate the collision force in a situation where a stagnation point occurs like a flow field at the front of the wall type structure, and the drifting object is decelerating.

Development of Elemental Technologies for Seafloor Mineral Processing of Seafloor Massive Sulfides

Seafloor Massive Sulfides have been expected to be future mineral resources. The grade of valuable metallic elements in ores of Seafloor Massive Sulfides is usually small percentage. If valuable minerals can be extracted from the ores on deep seafloor, the total mining cost can be reduced significantly. The authors proposed Seafloor Mineral Processing, where ores are to be ground into fine particles and separated into concentrates and tailings on seafloor. The Seafloor Mineral Processing system consists of processing units for unit operations such as grinding and separation. To investigate the applicability of flotation, which is a method to separate ore particles by using the difference in wettability of minerals, to the separation unit, measurements of contact angles of sulfide minerals at high pressures were carried out. The results suggested that the contact angles of the minerals would have relationships with pressure in depending on the kind of minerals and solutions. In addition, applying Laser-Induced breakdown Spectroscopy (LIBS), an optical method for elemental analysis, to measurement of metal grade of ore particles handled as slurry in the processing units was also investigated. Signals assigned to copper, zinc, and lead were successfully detected in the spectra obtained from ore particles in slurry flow.

Design and Inclusion of a Desalination System in a Floating Offshore Wind Farm

This paper investigates the techno-economic feasibility of integrating a desalination system to an offshore wind farm. The first part of the paper involves a proposal for the design of a desalination system fitted inside the WindFloat Atlantic hull. Taking into account of the power, footprint, volume and weight requirements of the desalination system, the desalination capacity is chosen to be 10,000 m3/d per platform2. A 3D model of the system is also presented. The second part of the paper focuses on the development of an economic model that gives as output the levelized cost of water (LCOW) for the studied technology. At first, a methodology to estimate capital expenditure (Capex) and operational expenditure (Opex) of an offshore desalination system with the above-mentioned characteristics is presented. Then, three locations with high wind speeds and with frequent exposure to droughts (Gran Canaria, California and South Africa) are chosen and the model is applied. Particularly interesting results are found for Gran Canaria, isolated system with favorable conditions (high electricity price, high water production cost and good offshore wind resource).

Hydrodynamic Load Modeling for Offshore Free-Floating Macroalgal Aquaculture Under Extreme Environmental Conditions

This article describes a preliminary study of an on-going ARPA-E (Advanced Research Projects Agency-Energy) MARINER Phase I project. The hydrodynamic load and dynamic response of an innovative offshore macroalgae cultivation system, Nautical Offshore Macroalgal Autonomous Device (NOMAD), under extreme environmental conditions is examined. The high strength, extremely durable, recyclable carbon fiber (rCF) free-floating long-line is applied with polyculture (Nereocystis luetkeana (bull kelp) and Saccharina latissima (sugar kelp)) in the NOMAD system. This novel macroalgal farming system is designed to free float from Washington State to California along the west coast of the US to avoid anchoring costs and the failure of earlier offshore growth trials. In this study, we expect to identify possible failure modes for the preliminarily design of NOMAD free-floating long-line macroalgal farming system based on the preliminary numerical predictions. We developed a 1km system-scale NOMAD free-floating long-line numerical model and performed a dynamic response analysis on the long-line to determine the behaviors of the long-line under extreme environmental conditions. The 1km free-floating rCF long-line responses very flexible due to wave and current activities even for large bending stiffness. Therefore, the potential entanglement of free-floating long-line on a global scale may cause the system failure even when the tensions and bending moments are in the safe range. Three cases include 10m NOMAD free-floating long-line with sugar kelp, bull kelp, and polyculture numerical models are developed, and the simulation results are analyzed. The tensions at the holdfast of the kelps in these cases are found to be below the breakage limit approximately. However, the severe clumping of the kelps and potential entanglement of adjacent lines may result in damage to the farming system.