Co-located wave and offshore wind farms: A preliminary approach to the shadow effect

In recent years, with the consolidation of offshore wind technology and the progress carried out for wave energy technology, the option of combine both technologies has arisen. This combination rest mainly in two main reasons: in one hand, to increase the sustainability of both energies by means of a more rational harnessing of the natural resources; in the other hand, to reduce the costs of both technologies by sharing some of the most important costs of an offshore project. In addition to these two powerful reasons there are a number of technology synergies between wave and wind systems which makes their combination even more suitable. Co-located projects are one of the alternatives to combine wave-wind systems, and it is specially for these project were so-called shadow effect synergy becomes meaningful. In particular, this paper deals with the co-location of Wave Energy Conversion (WEC) technologies into a conventional offshore wind farm. More specifically, an overtopping type of WEC technology was considered in this work to study the effects of its co-location with a conventional offshore wind park. This study aims to give a preliminary approach to the shadow effect and its implications for both wave and offshore wind energies

CO-LOCATED WAVE AND OFFSHORE WIND FARMS: A PRELIMINARY CASE STUDY OF AN HYBRID ARRAY

In recent years, with the consolidation of offshore wind technology and the progress carried out for wave energy technology, the option of co-locate both technologies at the same marine area has arisen. Co-located projects are a combined solution to tackle the shared challenge of reducing technology costs or a more sustainable use of the natural resources. In particular, this paper deals with the co-location of Wave Energy Conversion (WEC) technologies into a conventional offshore wind farm. More specifically, an overtopping type of WEC technology was considered in this work to study the effects of its co-location with a conventional offshore wind park

Modelling Concept to Reality

This is a presentation part of the Joint PRIMaRE and UK&CHN|CORE Summer School, which was held in Plymouth and Falmouth in 10-14 September 2018

A Novel Hybrid Wind-Wave Energy Converter for Jacket-Frame Substructures

The research dataset supporting this publication can be accessed at http://hdl.handle.net/10026.1/11045.The growth of the offshore wind industry in the last couple of decades has made this technology a key player in the maritime sector. The sustainable development of the offshore wind sector is crucial for this to consolidate within a global scenario of climate change and increasing threats to the marine environment. In this context, multipurpose platforms have been proposed as a sustainable approach to harnessing different marine resources and combining their use under the same platform. Hybrid wind-wave systems are a type of multipurpose platform where a single platform combines the exploitation of offshore wind and wave energy. In particular, this paper deals with a novel hybrid wind-wave system that integrates an oscillating water column wave energy converter with an offshore wind turbine on a jacket-frame substructure. The main objective of this paper is to characterise the hydrodynamic response of the WEC sub-system of this hybrid energy converter. A 1:50 scale model was tested under regular and irregular waves to characterise the hydrodynamic response of the WEC sub-system. The results from this analysis lead to the proof of concept of this novel hybrid system; but additionally, to characterising its behaviour and interaction with the wave field, which is a requirement for fully understanding the benefits of hybrid systems

Hybrid Wave and Offshore Wind Farms: a Comparative Case Study of Co-located Layouts

Marine energy is one of the most promising alternatives to fossil fuels due to the enormous energy resource available. However, it is often considered uneconomical and difficult. Co-located offshore wind turbines and wave energy converters have emerged as a solution to increase the competitiveness of marine energy. Among the benefits of colocated farms, this work focuses on the shadow effect, i.e. the reduction in wave height in the inner part of the farm, which can lead to significant savings in operation and maintenance (O&M) costs thanks to the augmented weather windows for accessing the wind turbines. The aim of this study is to quantify the wave height reduction achieved within a co-located wave-wind farm. Different locations and a large number of layouts are analysed in order to define the optimum disposition

Report of final project conference, Aalborg, Denmark

The Streamlining of Ocean Wave Farms Impact Assessment (SOWFIA) Project (IEE/09/809/ SI2.558291) is an EU Intelligent Energy Europe (IEE) funded project that draws together ten partners, across eight European countries, who are actively involved with planned wave farm test centres. The SOWFIA project aims to achieve the sharing and consolidation of pan-European experience of consenting processes and environmental and socio-economic impact assessment (IA) best practices for offshore wave energy conversion developments. Studies of wave farm demonstration projects in each of the collaborating EU nations are contributing to the findings. The study sites comprise a wide range of device technologies, environmental settings and stakeholder interests. Through project workshops, meetings, on-going communication and networking amongst project partners, ideas and experiences relating to IA and policy are being shared, and co-ordinated studies addressing key questions for wave energy development are being carried out. The overall goal of the SOWFIA project is to provide recommendations for approval process streamlining and European-wide streamlining of IA processes, thereby helping to remove legal, environmental and socio-economic barriers to the development of offshore power generation from waves. By utilising the findings from technology-specific monitoring at multiple sites, SOWFIA will accelerate knowledge transfer and promote European-wide expertise on environmental and socio-economic impact assessments of wave energy projects. In this way, the development of the future, commercial phase of offshore wave energy installations will benefit from the lessons learned from existing smaller-scale developments

Monopile-mounted wave energy converter for a hybrid wind-wave system

Multipurpose platforms are innovative solutions to combine the sustainable exploitation of multiple marine resources. Among them, hybrid wind-wave systems stand out due to the multiple synergies between these two forms of marine renewable energy. The objective of this work is to develop a hybrid system for monopile substructures, which are currently the prevailing type of substructure for offshore wind turbines, and more specifically to focus on the wave energy converter sub-system, which consists in an oscillating water column. For this purpose, an in-depth experimental campaign was carried out using a 1:40 scale model of the wave energy converter sub-system and the monopile substructure, considering regular and irregular waves. Based on the experimental results the performance of the device and its interaction with the wave field were characterised – a fundamental step to fully understand the benefits and limitations of this hybrid wind-wave system, which sets the basis for its future development. Regarding the performance, the best efficiency was obtained with the turbine damping corresponding to a 0.5% orifice size, and two resonance peaks were identified (T = 9 and 6 s). As for the interaction of the hybrid system with the wave field, between 5% and 66% of the incident wave power is reflected and between 3% and 45%, transmitted. The wave period was found to be the parameter that most influenced wave run-up on the substructure. This characterisation of the behaviour of the hybrid system shows that it is indeed a promising option for further development.University of Plymout

Power extraction in regular and random waves from an OWC in hybrid wind-wave energy systems

A mathematical model is developed to analyse the hydrodynamics of a novel oscillating water column (OWC) in a hybrid wind-wave energy system. The OWC has a coaxial cylindrical structure in which the internal cylinder represents the mono-pile of an offshore wind turbine while the external cylinder has a skirt whose scope is to guide the wave energy flux inside the chamber. This layout is not casual, but consistent with the current approach to harnessing wave energy through hybrid systems. The device shape is rather complex and the boundary value problem is solved by applying the matching-method of eigenfunctions. Within the framework of a linearised theory, we model the turbine damping effects by assuming the airflow to be proportional to the air chamber pressure. Consequently, the velocity potential can be decomposed into radiation and diffraction problems. We study the effects of both skirt and internal radius dimensions on the power extraction efficiency for monochromatic and random waves. We show that the skirt has strong effects on the global behaviour, while the internal cylinder affects the values of the sloshing eigenfrequencies. Finally, we validate the analytical model with laboratory data and show a good agreement between analytical and experimental results