Traditional Rubble Mound Breakwaters Research Articles

Crown Wall Modifications as Response to Wave Overtopping under a Future Sea Level Scenario: An Experimental Parametric Study for an Innovative Composite Seawall

The overtopping phenomenon at the rear side of breakwaters has particular importance in harbor protection. Undoubtedly, this topic needs to be taken even more seriously, considering the sea level rise. The present study focuses on the effectiveness in the reduction of the wave overtopping of a triangular parapet placed on the top of an innovative concrete superstructure. The last is part of the OBREC device (Overtopping BReakwater for wave Energy Conversion), an overtopping structure which is integrated into a traditional rubble-mound breakwater, to convert wave energy into electricity. Parametric laboratory tests, including the influence of water depth, have led to the evaluation of the accuracy of the main literature formulations and to the introduction of a new overtopping formula to take into account the influence of the parapet geometry. The results highlight the capability of the parapet in significantly increasing the hydraulic protection compared to a breakwater with a traditional crown wall. The findings from this work are expected to support in promoting and developing adaptive management strategies for existing coastal defenses and smart approaches in the construction and maintenance of new ones, with special reference to future sea-level-rise scenarios.

NUMERICAL MODELING OF WAVE INTERACTION WITH A NON-CONVENTIONAL BREAKWATER FOR WAVE ENERGY CONVERSION

The hybrid non-conventional breakwaters are innovative coastal structures, which have as a primary function the coastal and harbours protection, but with the important benefit of electricity production, due to their combination with Wave Energy Converters. The most recent example of a non-conventional breakwater is called OBREC, standing for Overtopping Breakwater for Energy Conversion (Vicinanza et al., 2014). The device consists of a traditional rubble mound breakwater, in which the seaward armour layer in the upper part is replaced with a frontal sloping ramp and a reservoir. The structure is designed to capture and gather the water that overtops the crest ramp. The potential energy of the water stored in the reservoir is converted into kinetic energy and then into electrical energy by flowing through low head hydraulic turbines coupled with generators, exploiting the different water levels between the reservoir and the sea level.

FULL-SCALE PROTOTYPE OF AN OVERTOPPING BREAKWATER FOR WAVE ENERGY CONVERSION

The Overtopping BReakwater for Energy Conversion (OBREC) is a new typology of overtopping wave energy converter (OTD) integrated into a traditional rubble mound breakwater. The device can be considered as an innovative non-conventional breakwater that has the same functions as the traditional structures with the added-valued of the energy production. The paper presents a comprehensive overview of the OBREC, offering a synthesis of the complete design process, from the results of the two complementary test campaigns in small scale carried out in 2012 and 2014 at Aalborg University, to the description of the full-scale device installed in Naples in 2016. The device represents the first OTD device in full-scale integrated into an existing rubble mound breakwater and it has been equipped by an instrumental apparatus to measure its response to the wave interaction. The monitoring of the full-scale device in the port of Naples, particularly during storm conditions, is aimed to study the scaling effects in wave loading and the overall performance of this breakwater-integrated OTD, included performance in terms of the energy production.

Wave loadings acting on innovative rubble mound breakwater for overtopping wave energy conversion

The Overtopping BReakwater for Energy Conversion (OBREC) is an overtopping type wave energy converter, totally embedded into traditional rubble mound breakwaters. The device consists of a reinforced concrete front reservoir designed with the aim of capturing the wave overtopping in order to produce electricity. The energy is extracted through low head turbines, using the difference between the water levels in the reservoir and the sea water level. This paper investigates the nature and magnitude of wave loadings exerting on various parts of the structure. The results improve the overall knowledge on the device behavior, completing the highlights from the complementary test campaign carried out in the same wave flume in 2012 (Vicinanza et al., 2014). The formulas provided have been used to design the first OBREC prototype breakwater in operation since January 2016 at Naples Harbour (Italy).

Economic Assessment of Overtopping BReakwater for Energy Conversion (OBREC): A Case Study in Western Australia

This paper constructs an optimal configuration assessment, in terms of the financial returns, of the Overtopping BReakwater for wave Energy Conversion (OBREC). This technology represents a hybrid wave energy harvester, totally embedded in traditional rubble mound breakwaters. Nine case studies along the southern coast of Western Australia have been analysed. The technique provides tips on how to estimate the quality of the investments, for benchmarking with different turbine strategy layouts and overlapping with the costs of traditional rubble mound breakwaters. Analyses of the offshore and nearshore wave climate have been studied by a high resolution coastal propagation model, forced with wave data from the European Centre for Medium-Range Weather Forecasts (ECMWF). Inshore wave conditions have been used to quantify the exploitable resources. It has been demonstrated that the optimal investment strategy is nonlinearly dependent on potential electricity production due to outer technical constraints. The work emphasizes the importance of integrating energy production predictions in an economic decision framework for prioritizing adaptation investments.

Hydraulic Performance of an Innovative Breakwater for Overtopping Wave Energy Conversion

The Overtopping BReakwaterfor Energy Conversion (OBREC) is an overtopping wave energy converter, totally embedded in traditional rubble mound breakwaters. The device consists of a reinforced concrete front reservoir designed with the aim of capturing the wave overtopping in order to produce electricity. The energy is extracted through low head turbines, using the difference between the water levels in the reservoir and the sea water level. This paper analyzes the OBREC hydraulic performances based on physical 2D model tests carried out at Aalborg University (DK). The analysis of the results has led to an improvement in the overall knowledge of the device behavior, completing the main observations from the complementary tests campaign carried out in 2012 in the same wave flume. New prediction formula are presented for wave reflection, the overtopping rate inside the front reservoir and at the rear side of the structure. Such methods have been used to design the first OBREC prototype breakwater in operation since January 2016 at Naples Harbor (Italy).

Wave loadings acting on Overtopping Breakwater for Energy Conversion

ABSTRACT Vicinanza, D., Norgaard, J.H., Contestabile, P. and Andersen, T.L., 2013. Wave loadings acting on Overtopping BReakwater for Energy Conversion. Any kind of Wave Energy Converter (WEC) requires information on reliability of technology and on time required for the return of the investment (reasonable payback). The structural response is one of the most important parameters to take in to account for a consistent assessment on innovative devices. This paper presents results on wave loading acting on an hybrid WEC named Overtopping BReakwater for Energy Conversion (OBREC). The new design is based on the concept of an integration between a traditional rubble mound breakwater and a front reservoir designed to store the wave overtopping from the incoming wave to produce electricity. 2D hydraulic model tests were carried out at the Department of Civil Engineering, Aalborg University (Denmark). The analyses of hydraulic model tests have identified the main shapes assumed by wave surfaces at the breakwater ...

BERM BREAKWATERS—STATE OF THE ART

ABSTRACT The Berm breakwater concept in its form is relatively new with regard to design of traditional rubble mound breakwaters. Unlike conventional breakwaters requiring heavy armouring, smaller armour stones could be utilized in berm breakwater, eliminating the use of heavy machinery in construction. There is also substantial energy dissipation due to the presence of the berm. A wider berm is provided at or around the mean water level which allows reshaping of the armour slope due to wave action until equilibrium profile is attained. The research work available to the authors till date, on the various aspects of the berm breakwaters has been presented in this paper. The literature presented includes state of the art on berm width, berm elevation, armour size criteria, crest elevation of the breakwater etc.