G. de F. Retief

Bio: G. de F. Retief is an academic researcher from Stellenbosch University. The author has contributed to research in topics: Energy transformation & Electric power. The author has an hindex of 2, co-authored 3 publications receiving 15 citations.

Detailed Design of a Wave Energy Conversion Plant

Abstract: A preliminary assessment of wave energy conversion by means of the Stellenbosch Wave Energy Converter (SWEC) has indicated the viability of this system as a supplementary source of electric power. In order to refine the preliminary estimates of the cost of power delivered, detailed design of a 770 MW (rated output) installation at a site 60 km north of Cape Town has been undertaken. This paper describes the power conversion characteristics of the SWEC at the proposed site, structural design of the collector arms and generating tower for both mass gravity or piled solutions, a construction scenario involving a casting harbour in nearby Saldanha Bay and the towing and placement of 53 m long precast modules, and finally an assessment of the environmental impact of the proposed 40 km array on the adjacent coastline. The proposed system is found to be both technically and economically feasible and offers a useful contribution towards future electric power supply.

A proposal for wave energy conversion near cape town

Abstract: The South African wave energy program has been underway for several years and has included an analysis of the temporal and spatial distribution of wave energy along the full coast-line, determination of energy attenuation perpendicular to the coast-line at a site on the south western coast, and the development of a wave energy converter which is most suited to local conditions and requirements. The resource analysis has shown that the inshore power levels occurring along the south western coast are as promising as any elsewhere in the world. A bottom mounted, V-shaped wave energy conversion device driving an air turbine has been found to be most suited to prevailing conditions. The conversion characteristics of the device are presented, based on 1:100 scale three dimensional and 1:50 scale two dimensional model studies. Preliminary design studies of the proposed conversion system have underlined its potential viability as a cost effective supplementary source of power.

Gansbaai Fishing Harbour – The Design and Construction of a Breakwater on a Hostile Coast

Abstract: This paper describes the design and construction of a fishing harbour on a rocky coastline exposed to the prevailing south westerly swell of the South Atlantic and to severe westerly gales. Because of economic pressure the first phase of the development was undertaken without adequate knowledge of the wave regime or the topography of the sea-bed in the area and resulted in a virtually unusable harbour. The second phase of construction was therefore only embarked upon after extensive hydrographic surveys, wave recording and analyses, and probably the most exhaustive series of model tests ever undertaken for such a small project. These investigations and the good co-operation between research staff, engineers and contractors resulted in the elimination of most of the initial problems and the creation of a functional fishing harbour,

Wave energy device and breakwater integration: A review

Abstract: One of the most abundant energy sources exists in this world is the ocean wave energy. By far, it has shown to be the most clean, renewable, predicted energy and has raised the potential to compete with the current use of non-renewable energy sources. Recent research conducted on wave energy invention has opened a new dimension to slowly reduce the dependency on fossil fuel by introducing new technology on the renewable world but relatively lacking in economical aspect. This review brings the latest status on integration of wave energy device with other marine facilities, which is the breakwater structure that may possibly aid to cost sharing. Most researches done on this field highlighted countries experiencing rough sea condition and focused less on countries with medium wave condition as faced by the Asian continent. The potential for energy extraction and wave dissipation for medium wave condition will be discussed in this review by considering several aspects including reliability, effectiveness and performance. Finally, this review shows that the integration opens up a new dimension to acknowledge the technology harnessing ocean wave, especially for the Asian countries experiencing medium wave condition.

Development of multi-oscillating water columns as wave energy converters

Abstract: Wave energy development continues to advance in order to capture the immense ocean energy available globally. A large number of wave energy conversion concepts have been developed and researched to date but we are still not able to see a convergence of technologies. This provides the requirement and additional opportunity for further research. This paper provides a review and discusses the development of the OWC concept of wave energy converters in general and the evolved variation of the M-OWC more specifically. The review outlines the increased potential of the M-OWC concept and its current state through its advancement in recent years. Although still under development the M-OWCs have the potential to provide promising results, through the various innovative concepts under consideration, and support the progression and further development of wave energy as another serious contender in the renewables energy mix.

Comparison of the Experimental and Numerical Results of Modelling a 32-Oscillating Water Column (OWC), V-Shaped Floating Wave Energy Converter

Abstract: Combining offshore wind and wave energy converting apparatuses presents a number of potentially advantageous synergies. To facilitate the development of a proposed floating platform combining these two technologies, proof of concept scale model testing on the wave energy converting component of this platform has been conducted. The wave energy component is based on the well-established concept of the oscillating water column. A numerical model of this component has been developed in the frequency domain, and the work presented here concerns the results of this modelling and testing. The results of both are compared to assess the validity and usefulness of the numerical model.

Design and Construction of Rubble Mound Breakwaters

Abstract: The principal function of a rubble mound breakwater is to protect a coastal area from excessive wave action. The dissipation of wave energy through absorbtion rather than reflection distinguishes rubble mound breakwaters from other types of fixed breakwater. A principal design objective is to determine the size and layout of the components of the cross-section. Designing and constructing a stable structure with acceptable energy absorbing characteristics continues to rely heavily on past experience and physical modelling. This paper outlines key design and construction issues, with particular regard to armour stability.