Download Investigation of Seasonal Variation of Wave Energy Density around

Proceedings of The Fifteenth (2005) International Offshore and Polar Engineering Conference
Seoul, Korea, June 19−24, 2005
Copyright © 2005 by The International Society of Offshore and Polar Engineers
ISBN 1-880653-64-8 (Set); ISSN 1098-6189 (Set)
Investigation of Seasonal Variation of Wave Energy Density around
Jeju Sea based on Long-Term Simulated Wave Data
Keyyong Hong, Seung-Ho Shin, Seok-Won Hong
Ocean Development System Research Division, Korea Research Institute of Ships and Ocean Engineering, KORDI, Daejeon, Korea
Hwangjin Ryu
Department of Naval Architecture and Ocean Engineering, Hongik University, Yeongi-Gun, Chungcheongnam-Do, Korea
shortage in resource owing to the excessive use of fossil fuels. The
wave energy is also renewable, which is easily available at most of
coastal waters. However, the serious disadvantage of high cost of wave
power generation makes the practical use of wave power difficult.
Though its cost has gone down along with technical advance in wave
power generation, the wave power generation still costs much higher
than other power generations based on fuel fossils.
ABSTRACT
Wave power distribution is investigated to find out the optimal sites for
wave power generation at Jeju sea which is considered to contain the
highest wave energy density in Korean coastal waters. The spatial and
seasonal variation of wave power per unit length is calculated in Jeju
sea area based on monthly mean wave data from 1979 to 2002 which
was produced by SWAN wave model simulation. The selected
favorable locations for wave power generation are compared in terms
of magnitude of wave energy density and distribution characteristics of
wave parameters, suggesting that Chagui-Do is the most optimal site
for wave power generation at Jeju sea. The seasonal distribution of
wave energy density reveals that the highest wave energy density
occurs at northwest sea in the winter and it is dominated by wind waves,
while the second highest one happens at south sea in the summer and it
is dominated by swell sea. The annual average of wave energy density
gradually increases from east to west of Jeju sea. At Chagui-Do, the
energy density of swell sea is relatively uniform while the energy
density of wind waves is fluctuating. The distribution of wave
directions implies that except the rear region of island influenced by
wave refraction, the northwest wave direction is dominant in summer
and the southeast in winter. Wave periods are longer in summer and
winter and it appears relatively longer at the west sea of Jeju than east's.
The longest wave period occurs at the west sea in winter, and in
summer it appears relatively homogeneous with a little longer period at
the south sea.
The economic efficiency of wave power generation is greatly subject to
wave power density at the installation site though other parameters
such as mechanical efficiency of wave energy converter, construction
expense and operation cost are also significant. Therefore the accurate
understanding of the wave energy distribution at the target sea area is
important for cost-effective wave power generation. This study aims to
find out the detail characteristics of wave power distribution at Jeju sea
which is considered to have the highest average wave energy density in
Korean coastal region and where the installation of an OWC(oscillating
water column) wave energy converter is planned. Eventually, we try to
identify an optimal site for wave power generation around Jeju sea by
investigating wave height, wave period and direction in terms of their
monthly averages and seasonal variations.
Since the wave power is given as a function of wave height and period,
those parameters are directly related to the efficiency of wave power
generation. In addition, because the operation of wave energy converter
has an optimal direction in general, wave direction plays an important
role in overall efficiency of wave power generation, too. The wave
parameters in the ocean vary depending on location and time and thus
both spatial average and periodical variation of wave properties should
be considered for the selection of optimal location for wave power
generation.
KEY WORDS: Wave energy density; wave power distribution; wave
climate; wave hindcasting; SWAN(Simulating Waves Nearshore) wave
model; Jeju sea
Song et al.(2004) analyzed the wave characteristics at Korean costal
water based on long-term wave data generated by Jeon et al.(2003)
using the HYPA wave model with relatively large mesh of 15km. They
showed that the coastal area of Jeju, which is the southern island of
Korean peninsula, has the highest average wave energy density in
Korean coastal region. Ryu et al.(2004) investigated the spatial and
INTRODUCTION
Ocean waves are considered to be one of the most important alternative
energy resources that can overcome the environmental harm and the
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