The hydraulic wave generator, left. The pulling barrel with r = 3,5 cm, right.
The screen shows the test conditions.The wave generator delivers wave heights Hs = 20 cm in a cyclic time of 2.24 seconds. The rotation counter shows 465 RPM, which is ekvivalent to a rim velocity of 26 km/h. Each flywheel contains at the rims an inertia mass of 0.9 kg, i.e. 1.8 kg in total. The stored amount of energy in the flywheel system is thereby 47 Joule, which is obtained through a few wave periods of time. The mass of the float is 2.75 kg, and the diameter is 36 cm.
With float width B = 0,36 m the wave power hitting the float is
P_{inf} = 52 W/m € 0,36 m = 18,6 W
So the absorber efficiency in irregular waves is 16
%, which is fairly good considering that the theoretical maximum for one float
is 50 %.
Parameter | Model | Full scale |
Length | 1 | s |
Area | 1 | s^{2} |
Volume/Mass/Force | 1 | s^{3} |
Time | 1 | SQR s |
Speed (linear) | 1 | SQR s |
Power | 1 | s^{3.5} |
Scale 1:20 | Full scale | |
Float displacement | 0.20 m | 4 m |
Float volume | 3.66 m^{3} | 49 m^{3} |
Float mass | 2.75 kg | 22 tonne |
P_{abs} | 3 W | 107 kW |
Mechanical Eff. | 0.9 | 0.9 |
Generator Eff. | 0.9 | 0.9 |
With the known figures for mechanical and generator efficiency, the power obtained from this WaveSpinner unit will be P_{out} = 87 kW.
Waves of 4 m heights occur approximately 445 hours yearly at a
standard point of measurements in the North Sea 100 km West of Blaavand^{1)3)},
Denmark.
The yearly production of electric energy from one
WaveSpinner unit (float+generator)at that place would then be 38.7 MWh/y on 4 m wave heights
alone.
Multiple WaveSpinner units can
be joined together in a flexible structure, called WaveSpinners Connected,
and the total production can be summerized accordingly.
The possible amount of electric energy collection from the whole
spectrum of wave heights, depends on the number and the dimensions
and characteristics of the floats.
The goal is to cover as broad a spectrum as
possible.^{2)}
References:
1. Facts about
Wave Energy (Da: Fakta om Bølgeenergi)
2.
Absorption Width
3. IEA Ocean Energy
Systems Annex II Report 2003