scholarly journals A HOLISTIC METHOD TO SELECT TIDAL STREAM ENERGY HOTSPOTS

2017 ◽  
pp. 5
Author(s):  
Angela Vazquez ◽  
Gregorio Iglesias
Keyword(s):  
Ad Hoc ◽  
Holistic Approach ◽  
Tidal Energy ◽  
Energy Development ◽  
Potential Conflict ◽  
Cost Of Energy ◽  
Tidal Turbine ◽  
Tidal Stream ◽  
Tidal Stream Energy

Potential areas for tidal stream energy development are conventionally selected on the basis of resource assessments. For all the importance of the resource, there are other elements (technological, economic, spatial, etc.) that must be taken into account in this selection. The objective of the present work is to develop a new methodology to select tidal stream hotspots accounting for all these relevant elements, and to apply it to a case study, showing in the process how the potential for tidal energy development can be fundamentally altered by technological, economic and spatial constraints. The case study is conducted in the Bristol Channel and Severn Estuary (UK), one of the regions with the largest tidal resource in the world. First, the most energetic areas are identified by means of a hydrodynamics model, calibrated and validated with field data. Second, the method calculates the energy that can be harnessed in these areas by means of a geospatial Matlab-based program designed ad hoc, and on the basis of the power curve and dimensions of a specific tidal turbine. Third, the spatial distribution of the levelised cost of energy (LCOE) is calculated, and a number of locations are selected as potential tidal sites. The fourth element in the approach is the consideration of restrictions due to overlap with other marine uses, such as shipping. As a result, potential conflict-free areas for tidal stream energy exploitation at an economical cost are identified. Thus, the case study illustrates this holistic approach to selecting tidal stream sites and the importance of elements other than the resource, which – for all its relevance – is shown to not guarantee by itself the potential for tidal stream energy development.

scholarly journals Tidal current power effects on nearby sandbanks: a case study in the Race of Alderney

2020 ◽  
Vol 378 (2178) ◽  
pp. 20190503 ◽  
Author(s):  
Luke S. Blunden ◽  
Stephen G. Haynes ◽  
AbuBakr S. Bahaj
Keyword(s):  
Sediment Transport ◽  
Tidal Energy ◽  
Sand Wave ◽  
Sand Transport ◽  
Tidal Dynamics ◽  
Tidal Flows ◽  
Tidal Turbine ◽  
Turbine Arrays ◽  
Sediment Model

A validated numerical model of tidal flows and sediment transport around the Alderney South Banks was used to investigate the potential effects of large (300 MW) tidal turbine arrays at different locations in Alderney territorial waters. Two methods were used, firstly looking at hydrodynamic changes only and secondly modelling sediment transport over a non-erodible bed. The baseline hydrodynamic model was validated relative to ADCP velocity data collected in the immediate vicinity of the sandbank. Real-world sand transport rates were inferred from sand-wave migrations and agree favourably with sediment transport residuals calculated from model outputs. Outputs from the sediment model reproduced realistic morphological behaviours over the bank. Seventeen different locations were considered; most did not result in significant hydrodynamic changes over the South Banks; however, three array locations were singled out as requiring extra caution if development were to occur. The results provide a case for optimizing the array locations for twin objectives of maximizing array power and minimizing impacts on the sandbanks. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

scholarly journals Lifetime Analysis of IGBT Power Modules in Passively Cooled Tidal Turbine Converters

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1875
Author(s):  
Faisal Wani ◽  
Udai Shipurkar ◽  
Jianning Dong ◽  
Henk Polinder ◽  
Antonio Jarquin-Laguna ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Surface Waves ◽  
Stream Velocity ◽  
Insulated Gate Bipolar Transistor ◽  
Cost Of Energy ◽  
Igbt Modules ◽  
Lifetime Analysis ◽  
Tidal Turbine ◽  
Tidal Stream ◽  
The Impact

Thermal cycling is one of the major reasons for failure in power electronic converters. For submerged tidal turbine converters investigating this failure mode is critical in improving the reliability, and minimizing the cost of energy from tidal turbines. This paper considers a submerged tidal turbine converter which is passively cooled by seawater, and where the turbine has fixed-pitch blades. In this respect, this study is different from similar studies on wind turbine converters, which are mostly cooled by active methods, and where turbines are mostly pitch controlled. The main goal is to quantify the impact of surface waves and turbulence in tidal stream velocity on the lifetime of the converter IGBT (insulated gate bipolar transistor) modules. The lifetime model of the IGBT modules is based on the accumulation of fatigue due to thermal cycling. Results indicate that turbulence and surface waves can have a significant impact on the lifetime of the IGBT modules. Furthermore, to accelerate the speed of the lifetime calculation, this paper uses a modified approach by dividing the thermal models into low and high frequency models. The final calculated lifetime values suggest that relying on passive cooling could be adequate for the tidal converters as far as thermal cycling is concerned.

scholarly journals Identifying economically viable tidal sites within the Alderney Race through optimization of levelized cost of energy

2020 ◽  
Vol 378 (2178) ◽  
pp. 20190500
Author(s):  
Z. L. Goss ◽  
D. S. Coles ◽  
M. D. Piggott
Keyword(s):  
Large Scale ◽  
Tidal Energy ◽  
Monte Carlo Analysis ◽  
Lessons Learned ◽  
Fixed Costs ◽  
Levelized Cost ◽  
Learning Rates ◽  
Cost Of Energy ◽  
Case Study Site ◽  
Tidal Stream

Costs of tidal stream energy generation are anticipated to fall considerably with array expansion and time. This is due to both economies of volume, where arrays comprising of large numbers of turbines can split fixed costs over a greater number of devices, and learning rates, where the industry matures and so arrays of the same size become cheaper due to lessons learned from previous installations. This paper investigates how tidal energy arrays can be designed to minimize the levelized cost of energy (LCOE), by optimizing not only the location but also the number of devices, to find a suitable balance between decreased costs due to economies of volume and diminishing returns due to global blockage effects. It focuses on the Alderney Race as a case study site due to the high velocities found there, making it a highly suitable site for large-scale arrays. It is demonstrated that between 1 and 2 GW could be feasibly extracted as costs in the tidal industry fall, with the LCOE depending greatly on the assumed costs. A Monte–Carlo analysis is undertaken to account for variability in capital and operational cost data used as inputs to the array optimization. Once optimized, the estimated P50 LCOE of an 80 MW array is £110/MWh. This estimate aligns closely with the level of subsidy considered for tidal stream projects in the Alderney Race in the past. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

Development of a Simulation Tool to Accurately Predict Tidal Turbine Reliability

2016 ◽  
Author(s):  
Benson Waldron ◽  
Alexandros Zymaris ◽  
Claudio Bittencourt ◽  
Nikolaos Kakalis
Keyword(s):  
Systems Engineering ◽  
Tidal Energy ◽  
Operating Conditions ◽  
Simulation Tool ◽  
Commercial Development ◽  
Diverse Range ◽  
Repair Costs ◽  
Cost Of Energy ◽  
Tidal Turbine ◽  
Work Done

The pre-commercial development of the tidal energy sector is characterized by a diverse range of technology concepts. Within the spectrum of proposed and developed solutions the three-bladed Horizontal Axis Tidal Turbine (HATT) is one of the more dominant configurations. However, even within this “narrow” classification technology developers have chosen different design solutions and strategies. Major influences on design decisions are the maintenance and repair costs and their impact on Levelised Cost of Energy (LCOE); therefore it is critical to accurately determine reliability to support the engineering and financial decision making. This paper is based upon work done to develop techniques for the reliability analysis of tidal turbines Power Take Off (PTO) systems and proposes a simulation tool for improved reliability prediction. In brief the proposal is to utilize available methodologies and software to demonstrate how the different loading and environmental conditions experienced in tidal impact on PTO reliability. The approach utilizes a system engineering model of the powertrain augmented with physics-of-failure models. Using available surrogate reliability data and the output from the systems engineering modelling a modified probability of failure for a system or component can be generated. The model is capable to simulate the system under nominal, off-design and faulty conditions. By utilizing this approach, the reliability of the turbine can be quantitatively analyzed taking into account realistic operating conditions. An indicative case-study is presented to demonstrate the proposed approach.

scholarly journals Characterization of the vertical evolution of the three-dimensional turbulence for fatigue design of tidal turbines

2020 ◽  
Vol 378 (2178) ◽  
pp. 20190495 ◽  
Author(s):  
Maxime Thiébaut ◽  
Jean-François Filipot ◽  
Christophe Maisondieu ◽  
Guillaume Damblans ◽  
Christian Jochum ◽  
...  
Keyword(s):  
Turbulence Intensity ◽  
Large Scale ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Tidal Energy ◽  
Tidal Turbines ◽  
Tidal Stream ◽  
Vertical Evolution ◽  
Tidal Stream Energy ◽  
Scale Turbulence

A system of two coupled four-beam acoustic Doppler current profilers was used to collect turbulence measurements over a 36-h period at a highly energetic tidal energy site in Alderney Race. This system enables the evaluation of the six components of the Reynolds stress tensor throughout a large proportion of the water column. The present study provides mean vertical profiles of the velocity, the turbulence intensity and the integral lengthscale along the streamwise, spanwise and vertical direction of the tidal current. Based on our results and considering a tidal-stream energy convertor (TEC) aligned with the current main direction, the main elements of turbulence prone to affect the structure (material fatigue) and to alter power generation would likely be: (i) the streamwise turbulence intensity ( I x ), (ii) the shear stress, v ′ w ′ ¯ , (iii) the normal stress, u ′ 2 ¯ and (iv) the vertical integral lengthscale ( L z ). The streamwise turbulence intensity, ( I x ), was found to be higher than that estimated at other tidal energy sites across the world for similar height above bottom. Along the vertical direction, the length ( L z ) of the large-scale turbulence eddies was found to be equivalent to the rotor diameter of the TEC Sabella D10. It is considered that the turbulence metrics presented in this paper will be valuable for TECs designers, helping them optimize their designs as well as improve loading prediction through the lifetime of the machines. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

scholarly journals The Tidal Stream Energy Resource of the Fromveur Strait—A Review

2020 ◽  
Vol 8 (12) ◽  
pp. 1037
Author(s):  
Nicolas Guillou ◽  
Jean-Frédéric Charpentier ◽  
Mohamed Benbouzid
Keyword(s):  
Energy Resource ◽  
Tidal Energy ◽  
Energy Output ◽  
Wake Interactions ◽  
Tidal Stream ◽  
Technical Specifications ◽  
Tidal Stream Energy ◽  
Key Steps ◽  
A Site

Refined assessments of the available tidal stream energy resource are required to optimize turbines design and guarantee successful implementations and operations of devices in the marine environment. Investigations primary focused on identifying areas with maximum current speeds. However, further information may be reached by exhibiting (i) resource temporal variability, (ii) superimposed effects of meteo-oceanographic conditions (including especially wind-generated surface-gravity waves), and (iii) potential environmental impacts of operating turbines at the regional (e.g., changes in sediment transport and surrounding seabed features, effects on marine water quality, etc.) and local (wake-wake interactions and energy output) scales. These aspects are here investigated by reviewing a series of research studies dedicated to the Fromveur Strait off western Brittany, a region with strong potential for tidal array development along the coast of France. Particular attention is dedicated to the exploitation of combined in-situ and remote-sensing observations and numerical simulations. Beyond a site specific characterization of the tidal stream energy resource, this review promotes a series of original approaches and analysis methods for turbines optimization, thus complementing technical specifications to secure the key steps of a tidal energy project and promote the growth of a reliable tidal stream energy exploitation.

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