Academic literature on the topic 'Marine Renewable Energy'

The development of marine renewable energy is attracting increasing attention due to its great potential in meeting human energy demands with limited negative environment impact. Various wave energy converter concepts have been proposed in attempt to convert wave energy into usable energy. Both experimental and numerical methods have been widely used to investigate the hydrodynamic performance of these devices in operational conditions and their survival characteristics in extreme sea states. This study focuses on developing a numerical procedure that can predict wave loads and run-up on fixed and moving offshore and coastal structures more accurately. The wave induced motions of flap-type wave energy converter (WEC) and its efficiencies are also investigated. The ultimate objectives of the study are to develop a rigorous approach for the safe and cost efficient design of general offshore structures and leading to the better design of wave energy converters with increased efficiency, and provide best practice guideline to the wave energy converter developers and researchers and engineers in the field. Non-linear hydrodynamic modelling in viscous flow has been used in the simulations. Even for moderate waves, nonlinear effects are important due to wave-structure interaction and also the expected large motions under operational conditions. It seems likely that estimates of performance will be unreliable unless the nonlinear effects associated with such large amplitude motions are properly accounted for. Extreme conditions are also be analysed to ensure device integrity. OpenFOAM, a free, open-source CFD package, has been applied in this work due to its strong capability in coastal and offshore engineering. The built-in viscous solvers interFoam and interDyMFoam have been selected and extended to model wave interactions with fixed and moving offshore and coastal structures, respectively. The solvers have been firstly extended to generate various wave conditions, including regular waves, focused wave groups and tsunami waves etc. New module has also been developed to advance the wave absorption capability in attempt to reduce computational cost of the numerical model by using smaller computational domain. In order to simulate the motion of WECs in waves, the code has been further developed to have functions on determining the wave-induced motions of WECs and on updating the computational domain automatically according to the motion of the WEC. By comparing with published experimental data, theoretical and numerical results on various physical problems, including wave interactions with varied seabed, a fixed vertical circular cylinder, a rotating half-submerged rectangular barge and a flap-type wave energy converter etc. it is confident to say that OpenFOAM is very capable of modelling nonlinear wave interactions with coastal and offshore structures accurately.

Fishers are among the biggest commercial resource users in the marine environment. In order to meet international, national and local policies, the UK has to designate a suite of marine protected areas (MPAs) and reach marine renewable energy (MRE) targets. Inevitably, there will be conflict between these two industries and marine conservation. This study uses a multi-disciplinary approach to examine evaluate the suitability of various sources of data, which could be used to detect, assess, and ultimately predict, fishing effort displacement within the different sectors of the > 15 m fleet in the South West of the UK. Gear-specific Vessel Monitoring System (VMS) data from 2005-2008 was used to assess potential effort displacement due to Haig Fras, a proposed MPA and Wave Hub, a marine renewable energy installation (MREI). The spatial distribution of fishing activity was highly heterogeneous and distinct areas of intense fishing could be identified for all gear-types. A closure of Haig Fras would have the greatest impact on gillnetters. Scallop dredgers also occasionally use the area. The current closure at Wave Hub has the greatest impact on potters and whelkers whose geographic specialisation is most pronounced and who use the area extensively. Longliners also use the area disproportionately would be affected. A simple index of variability was developed in order to determine baselines and two other sources of data were used. High resolution seabed data and low resolution catch data. A semi structured interview was conducted with forty fishers to elicit further information on the challenges, barriers to progress and priority issues in relation to MRE those fishers face. The theme of discontent with the consultation process scored highly throughout. Fishers’ Knowledge (FK) another source of data also scored highly, although further work must be carried out to identify what aspects of this data are useful in assessment of fishing effort displacement.

Marine currents, i.e. water currents in oceans and rivers, constitute a large renewable energy resource. This thesis presents research done on the subject of marine current energy conversion in a broad sense. A review of the tidal energy resource in Norway is presented, with the conclusion that tidal currents ought to be an interesting option for Norway in terms of renewable energy. The design of marine current energy conversion devices is studied. It is argued that turbine and generator cannot be seen as separate entities but must be designed and optimised as a unit for a given conversion site. The influence of support structure for the turbine blades on the efficiency of the turbine is studied, leading to the conclusion that it may be better to optimise a turbine for a lower flow speed than the maximum speed at the site. The construction and development of a marine current energy experimental station in the River Dalälven at Söderfors is reported. Measurements of the turbine's power coefficient indicate that it is possible to build efficient turbines for low flow speeds. Experiments at the site are used for investigations into different load control methods and for validation of a numerical model of the energy conversion system and the model's ability to predict system behaviour in response to step changes in operational tip speed ratio. A method for wake measurements is evaluated and found to be useful within certain limits. Simple models for turbine runaway behaviour are derived, of which one is shown by comparison with experimental results to predict the behaviour well.

This thesis is concerned with the development of linear generators for use as the power take off mechanism in marine renewable energy converters. Delivering significant power at the low velocities demanded by wave and tidal stream energy converters requires a large force, which must be reacted by an electrical machine in a direct drive system. Attention is focused on the development of two novel topology linear permanent magnet machines suitable for use in this application. For each topology, models are presented that are capable of predicting the force characteristics and dynamic generator performance. The models, which are verified experimentally, reveal significant behavioural differences between the two topologies. The designer is thus provided with an interesting choice when considering a direct drive power take off strategy. In short, a variable reluctance machine is shown to develop a high shear force in its airgap, offering the potential of a compact generator, yet its performance is hindered by a poor power factor and the presence of significant airgap closure forces. The second machine, an air cored stator encompassing a permanent magnet translator, is shown to lend itself favourably as a generator, but only at the expense of requiring a large quantity of magnetic material and developing a significantly lower shear stress. Mechanical issues involved in the direct integration of linear electrical machines into the marine environment are examined. Details of two existing marine renewable energy devices are used to hypothesise about the characteristics of realistic sized generators of both the topologies investigated. Direct drive power take off is shown to represent a feasible alternative to the complex systems frequently proposed in these applications.

Human exploration of the hydrosphere is ever increasing as conventional industries grow and new industries emerge. A new emerging and fast-growing industry is the marine renewable energy. The last decades have been characterized by an accentuated development rate of technologies that can convert the energy contained in stream flows, waves, wind and tides. This growth benefits from the fact that human society has become notably aware of the well-being of the environment that we all live in. This brings a human desire to implement technologies which cope better with the natural environment. Yet, this environmental awareness poses difficulties in approving new renewable energy projects such as offshore wind, wave and tidal energy farms. Lessons have been learned that lack of consistent environmental data can become an impasse when consenting permits for testing and deployments marine renewable energy technologies. An example is the European Union in which a majority of the member states requires rigorous environmental monitoring programs to be in place when marine renewable energy technologies are commissioned and decommissioned. To satisfy such high demands and to simultaneously boost the marine renewable sector, long-term environmental monitoring framework that gathers multi-variable data are needed to keep providing data to technology developers, operators as well as to the general public. Technologies based on active acoustics might be the most advanced tools to monitor the subsea environment around marine manmade structures especially in murky and deep waters where divining and conventional technologies are cost. The main objective of this PhD project has develop and test an active acoustic monitoring system for offshore renewable energy farms, by integrating a multitude of appropriate monitoring sonar, hydrophones and cameras systems to be developed with standards suitable for subsea environmental monitoring. In this project, a first task was to identify, secondly acquire and test sonar systems, then a platform was designed and built, a data acquisition device control systems were developed, finally additional instruments such as video cameras and sonars were added. This systems integration followed by calibration of devices was conducted. The sonar systems were used for quantitative measurements of the occurrence of e.g. large marine animals and schools of fish near marine renewable energy converters. The sonar systems were also used for seabed inspections, depth measurements and capitating flow observations. So far, the combination of multibeam and dual-beam sonar systems produced good results of target detection, bottom inspection, depth measurements and biomass estimation. The multibeam sonar system was capable of resolving isolated targets located near high acoustic retroreflective objects. Panoramic acoustic images of wave and instream energy converters were acquired using a multibeam sonar operating at frequencies near 1 GHz. The Dual-beam and split-beam sonar systems produced data referent to acoustic background intensity of targets that helps to classify targets according to its size, composition and 3-Dimensional location within the water column. The next phase of this project will deploy the platform for longer periods in order to gather consistent acoustic and optical backscattering data of marine animal behaviour within marine renewable energy farms.

This thesis involves an examination of the main international, regional and national legal regimes regulating marine renewable energy in England and Wales. Deriving from a complex patchwork of law and policy, developments have ensued in the absence of a distinct governing ‘legal regime’ and within a number of competing paradigms. This original synthesis attempts to identify lacunae, conflicts and connections within and between the span of legal genres that MRE evokes. Against a backdrop of climate change mitigation, the key findings show that despite the presence of political will for offshore renewable energies, MRE development faces a number of legal obstacles, all of which seek to protect other important public and private interests. Although predominantly satisfactory at the international level (international law of the sea), national private property rights, environmental protection laws and regulatory development controls each encompass particular legal incongruities that have the potential to act as barricades to development. This thesis discusses these issues and reaches conclusions as to potential areas for reform.

As is the case with many countries, Namibia has an economy dependent on fossil fuels. The country is, however, blessed with abundant and diverse - but as yet unexploited - renewable energy (RE) resources that could be used for improving the livelihood of the vast majority of its 2.2 million people. Today the conflict between energy production from fossil fuels and protection of the environment is intensifying and this compels all countries to search for means of resolving this conflict. Developing RE through the enactment of enabling legislation and implementation of relevant policy is one important step towards attaining the ideal of an energy-secure future. This state of affairs is not unique to Namibia, as most countries with abundant RE sources are striving to promote and deploy RE in their respective regimes through appropriate policies and legal frameworks. This study examines Germany and Ghana from, respectively, the developed and developing world, as leading countries that have established a proactive RE regime. However, such a regime can only be successfully achieved if countries, including Namibia, adopt laws and policies that promote and encourage the use of RE in order to move away from fossil fuel dependence to a greener economy. Thus the study seeks to investigate RE resources in Namibia and their potential development. It outlines the current legislation pertaining to the regulation of RE in Namibia. As such, the study further examines the Organisation for Economic Cooperation and Development (OECD) guidelines and draws examples from other regimes, particularly Germany and Ghana, in order to provide a guideline for the enactment of a general Energy Act with a particular chapter on RE. It concludes with recommendations as to how Namibia can secure a sustainable energy future.

Approved for public release; distribution is unlimited.<br>The purpose of this thesis is to analyze Marine Corps installation energy consumption and the pursuit of increased renewable energy generation goals across Marine Corps installations. The main objective of this report is to determine the cost of interruption and the net present value (NPV) of renewable energy generation needed to meet the Marine Corps energy security objectives. First, we determine installation-specific energy consumption, resource requirements, and current renewable energy generation projects. Second, we analyze current Marine Corps installation energy portfolios to determine shortfalls from minimum energy targets and the cost to generate those shortfalls through renewable energy technologies. Finally, we identify installation energy security requirements, determine cost of interruption, and conduct a sensitivity analysis of the cost-benefit of renewable energy generation alternatives to meet energy security requirements. This study determines how investment in renewable energy to meet baseline energy consumption requirements increases energy security across Marine Corps installations. Furthermore, considering the cost of interruption, the investment in renewable energy technologies yields a positive NPV at the majority of Marine Corps installations. Based on this research, we recommend that the Marine Corps develops a quantitative method for assessing energy security and invest to meet energy security goals at each installation.

Marine renewable energy developments (MREDs) are becoming an increasing feature of the marine environment. Scotland has considerable potential for generating energy from the marine environment in the form of extensive wind, wave and tidal-stream resources. Scotland also hosts numerous internationally important breeding populations of seabirds and Scottish territorial waters represent a key overwintering area for many species. EU legislation requires that MREDs do not damage the integrity of protected seabird populations but potential effects of MREDs on seabirds are not yet fully understood. This thesis aims to address gaps in knowledge regarding how MREDs may affect seabird populations. I generate vulnerability and confidence indices to predict the effects of offshore wind, wave and tidal-stream renewable energy developments on Scottish seabird populations; track the movements of a seabird species identified as lacking in data to better understand overlap with MREDs; and investigate seabird use of a high current flow environment leased as a tidal-stream energy development site. Overall, this thesis indicates that seabird responses to MREDs are likely to be species-specific and will vary dependent on the development location and design of the energy generating technology. My findings indicate that effects of MREDs will differ dependent on individual foraging strategies, age and life stage of individuals, which implies that MREDs are likely to differently affect subsections of seabird populations.

This thesis uses data collected over three summers in 2010, 2011 and 2012 at the Isle of May National Nature Reserve, Scotland to examine top predator presence and behaviour in a moderately fast tidal stream site. Fieldwork consisted of an intensive land based observation survey of seabirds at sea, acoustic monitoring of small cetaceans and the deployment of a suite of oceanographical tools to simultaneously collect data on a fine temporal scale over a study area of ~1.5km2. The aim of the study was to examine the potential effects of marine renewable energy developments on top predator behaviour in a tidal stream site by addressing some of the key data gaps such as habitat use in tidal stream areas, dive behaviour and collision and disturbance risk assessment. Acoustic detections of harbour porpoises were investigated as a function of physical environmental variables. Strong links between porpoise presence and increased thermal stratification and chlorophyll levels were detected along with a very strong diurnal pattern with increased detections at night. There was no relationship with tidal state. The habitat use of five species of breeding birds at sea adjacent to breeding cliffs was examined to gauge what environmental factors drive habitat use at these sites. Counts of foraging kittiwakes were examined in relation to environmental variables and while strong temporal trends emerged there was no link with oceanographic features. The study site was predominately used for loafing (non foraging behaviour) and so species specific temporal variation in loafing behaviour was analysed. Strong seasonal and diurnal trends in loafing emerged for all species which could be linked to differences in their breeding phenology. These results can be used in assessing and mitigating disturbance to these birds from marine renewables developments. Age specific variation in dive behaviour in the European shag was examined to determine whether newly fledged juveniles were at a greater risk of collision with tidal turbines than adults. Juveniles initially demonstrated a shorter dive duration than adults but after 4-6 weeks their dive duration had significantly increased. However age specific difference in dive behaviour in relation to water depth iii remained unchanged over time with juveniles showing no relationship between dive duration and water depth while adults increased dive duration in deeper water. The implications of this result for assessing age specific collision risk for this species is discussed. Results from this study were used to populate a framework for assessing collision and disturbance risk to seabirds in the near shore area adjacent to the breeding colony from a small scale tidal turbine development scenario. A method was developed to quantify risk by combining relative abundance data, behavioural data and published data on activity budgets for four species; guillemots, razorbills, puffins and shags. The output from this thesis has practical applications for informing the temporal and spatial scale of data collection and survey design in environmental impact assessments regarding marine renewable energy developments with emphasis on understanding the mechanistic links driving predator behaviour. Results can also be used to design appropriate mitigation procedures to prevent disturbance to loafing or foraging birds.