An investigation of the wave energy resource on the South African Coast, focusing on the spatial distribution of the South West coast
Date
2008-03
Authors
Joubert, J. R.
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
This thesis is an investigation of the wave power resource on the South African coast,
focusing on the spatial distribution of wave power of the coastal region exposed to the
highest wave power. The study’s main objective is to provide a detailed description of the
spatial distribution of wave power to assist in the selection of locations for deployment of
Wave Energy Converter (WEC) units in this zone. The study methodology employed to
achieve this main objective entails an analysis of measured wave data recorded at wave
recording stations distributed along the South African coast. The analysis provided a
general description of wave power at locations for which wave data exist. From this analysis
it was found that the South West Coast is exposed to the highest wave power, with an
average wave power of approximately 40 kW per meter wave crest. The rest of the South
African coast is exposed to average wave power between approximately 18 kW/m to 23
kW/m.
The wave power characteristics on the South West Coast region (from Cape Point to Elands
Bay) were therefore the focus of this thesis. The study objective was achieved by
transferring deep sea wave data into the nearshore South West Coast study area with the
Simulating WAves Nearshore (SWAN) wave model. The deep sea wave data was obtained
from a 10 year period of available hindcast data. A simplified simulation procedure was
required in order to make the study practically feasible. A sensitivity analysis was carried
out to determine the validity of the simplified simulation procedure and it was found that the
procedure slightly overestimate wave power in the shallower water regions due to the
underestimation of energy dissipation processes. This overestimation was deemed
acceptable for the dominant wave conditions and the simplified model was therefore applied
in the study. An appropriate programming system was developed and used to transfer the
available 10 year deep sea wave data into the selected South West Coast region. From this
exercise spatial distribution of wave power and related statistical parameters were obtained
for the study area. The accuracy of the modelled output was investigated by directly
comparing it to wave data recorded during the overlapping recording period. It was found
that the model slightly overestimates the monthly wave power resource compared to the
measured data with a maximum overestimation of 9%; which is sufficiently accurate for the
purpose of the study.
The results of this investigation can be used for the identification of areas of high wave
power concentration within the study area for the location of WEC units. Further numerical modelling is required for the detailed design of wave farms, especially if potential
sites are located in shallow water (shallower than approximately 50 m).
Description
Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2008.
Keywords
Wave energy, Ocean wave power, Wave energy conversion, Spatial distribution, Dissertations -- Civil engineering, Theses -- Civil engineering