Investor Presentaiton
Energies 2019, 12, 3658
Global potential [EJ/yr] (log scale)
103
Theoretical
Technical
Jo
100
9 of 37
10-1
Wave
*
Tide
"Ocean Thermal Salinity
current gradient gradient
* Referred to the Gulf Stream
The bars depict the range of the estimated values
Figure 3. Summary of the global ocean renewable energy resources.
3.2. Conversion Technologies
3.2.1. Wave Energy Conversion
Currently, there are a large number of concepts and patents on the use of wave energy. As illustrated
in Figure 4, the process of the wave energy conversion can be divided into three main stages: the primary
conversion stage, the secondary conversion stage, and the tertiary conversion stage [72]. In the
primary conversion stage, the wave converter captures the kinetic energy of the waves through wave
body interactions (e.g., buoy oscillation, air flow, or water flow). The secondary conversion stage
converts the body motion energy into electricity through the power take-off (PTO) system, and the
tertiary stage adapts the characteristics of the produced power to the grid requirements with power
electronic interfaces.
Primary conversion stage Secondary conversion stage
Tertiary conversion stage
Wave
motion
Body
motion
PTO
Generator
PTO
Electricity
Power
electronic
interface
Grid
Figure 4. Main stages of wave energy conversion.
Based on the working principles of the WEC, from the primary conversion stage to the secondary
conversion stage, the general categories are classified as shown in Figure 5 [72-75]:
The oscillating water column (OWC), which compresses or decompresses the air in a chamber
using the wave elevation to drive a Wells or impulse turbine to convert wave power. Depending on
the location of installation, OWC devices can be fixed onshore [76-78], as shown in Figure 6a,
or floating, as shown in Figure 6b [79-81].
Wave activated bodies (WABs), which utilize the wave excitation motions between two bodies to
convert wave power into electric power. According to their dimension and orientation, WABS can
also be classified as terminators [82] (Figure 6c), positioned with large horizontal extensions
perpendicular to the wave propagation direction); attenuators [83,84] (Figure 6d), which have
a large horizontal extension parallel to the wave propagation direction; point absorbers [85,86]
(Figure 6e), which have small dimensions compared to the predominant wavelength and are
usually axisymmetric about their vertical axis; and submerged pressure differentials [87] (Figure 6f),
which are submerged buoys with large dimensions.View entire presentation