Research on the correction method to the projected capture area of horizontal axis tidal energy converters

Horizontal axis tidal turbines (HATTs) are efficient in converting tidal energy. Improvements in the design of the HATTs require a thorough understanding of the energy conversion process. In this paper, the design of a HATT with two blades is conducted by blade element momentum theory (BEM). In this simplified method, the eddy current induced by the rotors hub and tips were considered while ignoring the blade elements drag items. Based on the assumption of maximum power of blade elements, the distribution of blade elements flow angle and the chord length coefficient along the radius can be assumed to be associated only with the blade elements tip speed ratio (TSR) which is dimensionless. This approach was validated by comparing the simulation results with computational fluid dynamics (CFD). A good qualitative match between the expected value and simulation results was observed, indicating that the design method is feasible and reasonable.

Download Full-text

Increasing the Competitiveness of Tidal Systems by Means of the Improvement of Installation and Maintenance Maneuvers in First Generation Tidal Energy Converters—An Economic Argumentation

Energies ◽

10.3390/en12132464 ◽

2019 ◽

Vol 12 (13) ◽

pp. 2464 ◽

Cited By ~ 3

Author(s):

Eva Segura ◽

Rafael Morales ◽

José A. Somolinos

Keyword(s):

High Performance ◽

First Generation ◽

Tidal Energy ◽

General Purpose ◽

Technological Advances ◽

Automated Installation ◽

Definition Of ◽

The Cost ◽

Near Future ◽

Energy Converters

The most important technological advances in tidal systems are currently taking place in first generation tidal energy converters (TECs), which are installed in areas in which the depth does not exceed 40 m. Some of these devices are fixed to the seabed and it is, therefore, necessary to have special high performance ships to transport them from the base port to the tidal farm and to subsequently recover the main units of these devices. These ships are very costly, thus making the installation costs very high and, in some cases, probably unfeasible. According to what has occurred to date, the costs of the installation and maintenance procedures depend, to a great extent, on the reliability and accessibility of the devices. One of the possible solutions as regards increasing system performance and decreasing the costs of the installation and maintenance procedures is the definition of automated maneuvers, which will consequently influence: (i) an increase in the competitiveness of these technologies; (ii) a reduction in the number and duration of installation and maintenance operations; (iii) less human intervention, or (iv) the possibility of using cheaper general purpose ships rather than high cost special vessels for maintenance purposes, among others. In this research, we propose a definition of the procedures required for the manual and automated installation and maintenance maneuvers of gravity-based first generation TECs. This definition will allow us to quantify the costs of both the manual and automated operations in a more accurate manner and enable us to determine the reduction in the cost of the automated installation and maintenance procedures. It will also enable us to demonstrate that the automation of these maneuvers may be an interesting solution by which to improve the competitiveness of tidal systems in the near future.

Download Full-text

A multi-parametric criteria for Tidal Energy Converters siting in marine and fluvial environments

Energy Procedia ◽

10.1016/j.egypro.2017.12.052 ◽

2017 ◽

Vol 142 ◽

pp. 328-336 ◽

Cited By ~ 1

Author(s):

G.Lo Zupone ◽

S. Massaro ◽

S. Barbarelli ◽

R. Sulpizio

Keyword(s):

Tidal Energy ◽

Fluvial Environments ◽

Energy Converters

Download Full-text

Analysis of the optimal deployment location for tidal energy converters in the mesotidal Ria de Vigo (NW Spain)

Energy ◽

10.1016/j.energy.2016.06.055 ◽

2016 ◽

Vol 115 ◽

pp. 1179-1187 ◽

Cited By ~ 7

Author(s):

Marc Mestres ◽

Maria Griñó ◽

Joan Pau Sierra ◽

César Mösso

Keyword(s):

Tidal Energy ◽

Nw Spain ◽

Ría De Vigo ◽

Optimal Deployment ◽

Energy Converters

Download Full-text

Optimization of Hydrofoils for Horizontal Axis Marine Current Turbines Using Genetic Algorithm

Volume 6B: Energy ◽

10.1115/imece2013-66416 ◽

2013 ◽

Cited By ~ 1

Author(s):

Krishnil R. Ram ◽

Jai N. Goundar ◽

Deepak Prasad ◽

Sunil Lal ◽

Mohammed Rafiuddin Ahmed

Keyword(s):

Genetic Algorithm ◽

Reynolds Number ◽

Fossil Fuels ◽

Energy Resource ◽

Tidal Energy ◽

Horizontal Axis ◽

Geometric Constraints ◽

Algorithm Optimization ◽

Tidal Turbines ◽

Marine Current

As fossil fuels near depletion and their detrimental side effects become prominent on ecosystems, the world is searching for renewable sources of energy. Tidal energy is an emerging and promising renewable energy resource. Tidal turbines can extract energy from the flowing water in a similar way as wind turbines extract energy from the wind. The upside with tidal turbines is that the density of water is approximately 800 times greater than that of air and a tidal turbine harnessing the same amount of power as a wind turbine can be considerably smaller in size. At the heart of the horizontal axis marine current turbines are carefully designed hydrofoil sections. While there is a growing need to have hydrofoils that provide good hydrodynamic and structural performances, the hydrofoils also have to avoid cavitation for safe operation. This study uses a genetic algorithm optimization code to develop hydrofoils which have the desired qualities mentioned above. The hydrofoil problem is parameterized using a composite Bezier curve with two Bezier segments and 11 control points. Appropriate curvature conditions are implemented and geometric constraints are enforced to maintain the hydrofoil thickness between 16 to 18%. XFOIL is used as the flow solver in this study. The hydrofoils are optimized at Reynolds number of 2 million and for angles between 4 to 10 degrees. The best foil from the results, named USPT4 is tested for performance with the CFD code ANSYS CFX. The CFX results are validated with experimental results in a wind tunnel at the same Reynolds number. The hydrofoil’s performance is also compared with a commonly used NACA foil.

Download Full-text

Reliability-Based Calibration of Partial Safety Factors for the Horizontal Axis Tidal Turbine Standard for Certification

Volume 9B: Ocean Renewable Energy ◽

10.1115/omae2014-24109 ◽

2014 ◽

Author(s):

Gaizka Zarraonandia Simeon ◽

Claudio Bittencourt Ferreira

Keyword(s):

Design Process ◽

Extreme Values ◽

Numerical Models ◽

Tidal Energy ◽

Failure Criteria ◽

Offshore Structures ◽

Horizontal Axis ◽

Safety Factors ◽

Tidal Turbine ◽

Partial Safety Factors

Tidal energy is nowadays one of the fastest growing types of marine renewable energy. In particular, horizontal axis tidal turbines (HATT) are the most advanced designs and the most appropriate for standardisation. It is however, in the interest of the industry to provide a set of standard practises in order to help in the process of designing this type of marine converters. DNV GL is producing this standard with the support of Alstom and as part of the ReDAPT project commissioned and co-funded by the ETI (Energy Technologies Institute). The work undertaken by DNV GL to produce this standard involves the identification of the uncertainties that designers need to address during the design process. Unlike other marine structures, HATTs are usually located in very energetic areas where no other marine structure has been before. Site characterisation is one of the largest sources of uncertainty e.g. turbulence. Key inputs like turbine inflow conditions or predictions of extreme values are still grey areas due to the limited site measurements and the uncertainty of the metocean models. Numerical models of HATTs are still quite uncertain often dependent on experience of the people running them. As part of ReDAPT project there is an ongoing effort in validation and evaluation of the accuracy of these numerical models and some of the results are used in this calibration study. The new standard for HATTs deals with the loading uncertainty in a whole new way by introducing a new parameter that is added to the traditional partial safety factors for loads. This new standard uses the traditional safety factors from the offshore structures standards and allows changing them based on the level of uncertainty that was introduced during the design process. This paper describes the process of calibration of the partial safety factors in ULS for loads of HATTs that was part of the work in the creation of the new standard. The reliability based calibration involved the formulation of failure criteria, the identification of stochastic variables in the failure criteria, calculation of reliability against failure and ultimately the new set of partial safety factors for loads and a methodology for adjustment of the factors in a case by case basis.

Download Full-text

A panel method for both marine propulsion and renewable energy

Journal of Naval Architecture and Marine Engineering ◽

10.3329/jname.v16i2.35984 ◽

2019 ◽

Vol 16 (2) ◽

pp. 61-76

Author(s):

Yiyi Xu ◽

Pengfei Liu ◽

Irene Penesis ◽

Guanghua He

Keyword(s):

Renewable Energy ◽

Tidal Energy ◽

Energy Performance ◽

Panel Method ◽

Horizontal Axis ◽

Computational Hydrodynamics ◽

Design And Optimization ◽

Pressure Distributions ◽

Marine Propulsion ◽

Tidal Turbine

A computational hydrodynamics method was formulated and implemented as a tool from screw propeller propulsion to renewable energy performance prediction, design and optimization of horizontal axis turbines. As an example for tidal energy generation, a comparative analysis between screw propellers and horizontal axis turbines was presented, in terms of geometry and motion parameters, inflow velocity analysis and the implementation methodologies. Comparison and analysis are given for a marine propeller model and a horizontal axis turbine model that have experimental measurements available in literature. Analysis and comparison are presented in terms of thrust coefficients, shaft torque/power coefficients, blade surface pressure distributions, and downstream velocity profiles. The effect of number of blades from 2 to 5, of a tidal turbine on hydrodynamic efficiency is also obtained and presented. The key implementation techniques and methodologies are provided in detail for this panel method as a prediction tool for horizontal axis turbines. While the method has been proven to be accurate and robust for many propellers tested in the past, this numerical tool was also validated and presented for both tidal and wind turbines.

Download Full-text