The Solution
Waves4Power green energy solutions are based on harvesting the free power of the ocean waves. The power is converted into electricity and distributed to the end user. It’s as simple as that…
The Waves4Power WaveEL system is based on many years of experience, testing, and countless marine service operations. The heart of the wave power system is our point absorber, the WaveEL buoy, where the energy of the waves is converted into electrical power.
The WaveEL buoy – a gigantic pump
- A buoy with a long vertical tube (the acceleration tube) passing through it
- A water piston inside the tube connected to a power conversion system
- A mooring system allowing the buoy free vertical movement while securing it on station
- A dynamic cable connecting the buoy to the connection hub and then via sea cable to the end user
The power generating buoy is a Point Absorber and as such is defined as a device with small horizontal dimensions in relation to the wavelength of the waves from which it is extracting energy. Due to their size, point absorbers are known to survive well in the ocean as they do not fight the waves, but ride them.
The device is best described as a very large pump where two masses are acting against each other. One mass is the buoy itself, including the acceleration tube, and the other is the mass of the water column inside the tube. Due to the difference in natural period for these masses – driven by the waves – they want to oscillate out of phase. By damping the relative movement – forcing them towards the same phase – energy can be captured by the conversion system. There are various sophisticated ways to establish this damping, thus improving the energy output.
WORKING PRINCIPLE of the WaveEL buoy
The characteristic feature of the WaveEL buoy is the patented long acceleration tube. The tube – which is open at both ends – goes directly through the buoy and extends 30-35 meters below.
As waves rise and lower the buoy with the attached tube, they will move differently – slightly out of phase – with the water column in the tube. By placing a piston in the tube, connected to a hydraulic conversion system, a gigantic pump is created.
Flexibility
The solution W4P offers is very flexible. A minimum depth of 40 meters is required, but the power converting buoys may be moored at essentially any depth or bottom conditions, just like a weather buoy.
Simplicity
Waves4Power focuses on simplicity. An inexpensive solution is created with well-tested components (as much as possible of which are industry standard) that are thoroughly tested with documented characteristics from established, reliable suppliers.
When the buoy is still, the water line inside the tube will be at the same level as the waterline outside the buoy. The tube’s lower opening is at such a depth that there is practically no turbulence from surface waves. Therefore, the water column in the tube is barely affected by ocean wave action.
The buoy/tube unit represents one body of a two-body oscillating system where the other body is the inert water mass present in the acceleration tube.
The conversion system utilizes a hydraulic cylinder as its pump. Its piston rod is connected to a large water piston placed inside the tube. The water piston’s motion relative to the buoy/tube is dampened by applying pressure in the hydraulic system, forcing the water piston to somewhat follow the buoy while pulling the water column along. The dampening force on the water piston needs to be set correctly between the two extremes – A: free floating with no dampening and B: totally locked – to efficiently harvest the wave energy.
A: Without damping of the water piston the buoy/tube unit will move freely while the water mass and water piston essentially stand still. The amplitude of the buoy/tube will be as great as the wave height. In this scenario no energy is captured.
B: If the water piston is locked completely to the buoy/tube it will force the water in the tube to follow the wave induced movement of the buoy/tube unit. The weight of the water mass that is now a part of the moving unit will reduce the speed and the amplitude of the motion of the system, with the same result – as in A, above – that no energy is captured from the waves.
However, between these two extreme conditions energy can be tapped by pressurizing the hydraulic system so that the movement of the water piston is dampened but not locked, thus making the water piston pull the water mass along but not quite being able to keep up with the buoy. The two masses will be moving out of phase, making the hydraulic cylinder act as a gigantic hydraulic pump.
The hydraulic pump is connected to an accumulator feeding a hydraulic motor with a generator. This converts the hydraulic pressure into electric power.
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