Response Statistics of U-Oscillating Water Column Energy Harvesters Exposed to Extreme Storms: Application to the Case Study of Roccella Jonica (Italy)

2020 ◽  
Author(s):  
Felice Arena ◽  
Valentina Laface ◽  
Giovanni Malara ◽  
Saveria Meduri ◽  
Andrea Pedroncini
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Environmental Conditions ◽  
Extreme Event ◽  
Time History ◽  
Structural Safety ◽  
Sea Waves ◽  
Energy Harvesters ◽  
Storm Model

Abstract This article deals with the case study of a marina located in Roccella Jonica (Italy), where a wave energy harvester belonging to the family of U-Oscillating Water Columns (U-OWC) is going to be installed. U-OWCs are wave energy harvesters composed by a water column exposed to the action of random sea waves and an air pocket connected to the atmosphere by a Power Take - Off (PTO) system. In Roccella Jonica, this device is going to be embedded in a vertical breakwater expanding the main layout of the infrastructure. For ensuring the structural safety of the system, to characterize statistically its response peaks in severe environmental conditions is important. In this context, one of the main difficulties is utilizing appropriate environmental conditions representing real extreme events at the installation site. This article proposes to adopt the DNV trapezoidal storm model for representing the time history of an extreme event in conjunction with a nonlinear U-OWC model. Relevant Monte Carlo simulations show that the DNV storm model provides peak distributions that are rather close to the ones obtained by processing real storm time histories. Thus, it can be adopted for checking the performance of the system in extreme conditions.

Design Point Effect Due to Severe Storm Conditions on the Reliability Assessment of Offshore Structures: Case Study

2005 ◽  
Author(s):  
Ahmed Mostafa Tawfik
Keyword(s):  
Wave Height ◽  
Environmental Conditions ◽  
Current Velocity ◽  
Offshore Structures ◽  
Structural Safety ◽  
Design Stage ◽  
Design Point ◽  
Reliability Method ◽  
Storm Wave

Structural reliability is of an intense significance for the evaluation of failure probability and safety levels of offshore structures in their structural design stage, especially when the variables are eminently random. Hence, the environmental conditions are considered among the most important parameters in the design of offshore structures whose effect of great contribution to structural safety. The 100 year storm wave height and current velocity constitute the majority of uncertainty in the environmental conditions. Eventually, these values are used as stochastic values i.e. mean values in addition to standard deviation. This paper uses the stochastic values of 100 year storm wave height and current velocity to estimate the probability of failure. These simulations had been encountered in the structural analysis and design on practical case study representing an offshore structure located in the Mediterranean Sea to predict the reliability level. The outcome of these simulations uses the Response Surface Method with design point technique for both stress and displacement limit states. The results of this Reliability method lead to an acceptable level for reliability analysis and risk assessments.

scholarly journals Structural Safety Analysis for an Oscillating Water Column Wave Power Conversion System Installed in Caisson Structure

2020 ◽  
Vol 8 (7) ◽  
pp. 506
Author(s):  
Hsien Hua Lee ◽  
Thung-Yeh Wu ◽  
Chung-You Lin ◽  
Yung-Fang Chiu
Keyword(s):  
Water Column ◽  
Return Period ◽  
Wave Energy ◽  
Structural Model ◽  
Stokes Equations ◽  
Safety Analysis ◽  
Structural Safety ◽  
Oscillating Water Column ◽  
Caisson Breakwater ◽  
Energy Converting

In this study, an alternative way, a so called caisson based type of oscillating water column (OWC) wave energy converting system was proposed to capture and convert wave energy. Since the caisson structure is constructed to protect the coastal line or ports, it is important to know if a built-in associated OWC system will be a burden to affect the safety of the structure or it is safe enough to work appropriately. In this study, three steps of structural analysis were performed: firstly, the analysis for the structural safety of the whole caisson structure; secondly, performing the mechanic analysis for the chamber of the associated OWC system; and finally, performing the analysis for the wave induced air-pressure in the chamber under the design conditions of a local location during the wave-converting operation. For the structural safety analysis, a typical structural model associated with caisson breakwater was built and analyzed while the shape of the structure, material applied to the construction, and associated boundary conditions were all set-up according to the wave and structures. The motion and the strain distribution of the caisson structure subjected to designated waves of 50-year return period were evaluated and compared to the safety requirement by the code. For the analysis of the energy converting performance, a numerical method by using a theorem of unsteady Navier–Stokes equations in conservation form was used to analyze the proposed OWC model when the structure subjected to an incident wave of a 10-year return period.

The influence of three-dimensional effects on the performance of U-type oscillating water column wave energy harvesters

2017 ◽  
Vol 111 ◽  
pp. 506-522 ◽  
Author(s):  
G. Malara ◽  
R.P.F. Gomes ◽  
F. Arena ◽  
J.C.C. Henriques ◽  
L.M.C. Gato ◽  
...  
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Three Dimensional ◽  
Oscillating Water Column ◽  
Energy Harvesters ◽  
Dimensional Effects

scholarly journals A wave energy system based on peristaltic pumping of air by sea waves

2019 ◽  
Vol XXII (1) ◽  
pp. 269-277
Author(s):  
Ünsalan D.
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Air Flow ◽  
Energy System ◽  
Leeward Side ◽  
Channel Height ◽  
Oscillating Water Column ◽  
Sea Waves ◽  
Peristaltic Pumping ◽  
Calm Water

Oscillating water column type of wave energy converters have attracted researchers and engineers working on the field of renewable energy systems, despite the problems caused by the alternating direction of air flow through the turbines. This problem has been circumvented by the use of single direction of rotation turbines such as Wells, Denniss-Auld and omnidirectional impulse turbines, albeit with rather low efficiencies. The authors have considered the usage of near-sinusoidal (cnoidal) form of sea waves as the drivers for the linear peristaltic pumping of air along a channel. The conceived device is an inverted U-shaped channel on a barge, aligned in the direction of wave and serves as a channel for the progress of waveform. Air is driven through the channel by peristaltic action to achieve a unidirectional air flow at the leeward end of the channel. An end-wall operated by a float experiencing heaving and surging motions at the leeward side of the channel prevents the escape of pumped air, which instead is directed to an upward duct leading to a turbine. Since the air flow is unidirectional, the use of more convenient air turbines compared to the ones used in oscillating water column devices are enabled. Air flow parameters with wave amplitudes exceeding and less than channel height above the calm water line are analysed using the Airy wave to demonstrate the feasibility of the proposed system analytically. It was found that the optimum solution was achieved when the channel top is at the calm water level

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