The following factors have to be considered before selecting or building a nearshore WEC:
1. Wave Heights: As one can tell from the theory of wave energy the wave heights in a particular basin play the most crucial role in determining the amount of energy available for the WEC to extract. The available energy is directly proportional to the square of the wave height and thus the user has to make sure that the dominant wave heights in the area under consideration are large enough to have a profitable energy takeoff for the type of WEC.
2. Wave Frequency: Majority of the WECs derive their power from the oscillating parameters of the wave i.e the pressure variations, wave elevation, water particle velocities etc. The best power take off is found in case where the forcing frequency of the wave parameter is in resonance with the natural frequency of the moving part of the WEC. Although no sea state would have a single frequency but the spectrum of the basin should be studied for any narrow band sectors of frequency and the device could be designed accordingly. If the basin is a broad band spectrum then a dynamic WEC with active control would be best suited. In case the device is active controlled then it could alter its natural frequency by changing its mass (via altering water ballast) or stiffness constant to match the frequency for maximum energy take off.
3. Breaking severity: It is basically defined as the ratio between the energy lost in breaking to the total energy present. It is dependent on a variety of factors such as the wave steepness, wave length, density, cause of breaking viz. superposition, wave height to depth ratio, or obstruction etc. For the best results its best to keep the WEC out of the surf zone.
4. Breaker Type: In case the breaking in a field is occurring fairly offshore then the type of breaker will also affect the amount of energy available for the WEC. The loss of excess momentum flux and energy flux was measured and found to to range from 10% for single spilling events to as much as 25% for plunging breakers.
5. Structural Limits of the WEC: The WECs can stand to face significant damage from storms and swells. They have to be designed accordingly.
There are many other factors which may affect the WEC depending on the water basin under consideration. The reader is advised to do a through research of the area before selecting or building a WEC.
1. Wave Heights: As one can tell from the theory of wave energy the wave heights in a particular basin play the most crucial role in determining the amount of energy available for the WEC to extract. The available energy is directly proportional to the square of the wave height and thus the user has to make sure that the dominant wave heights in the area under consideration are large enough to have a profitable energy takeoff for the type of WEC.
2. Wave Frequency: Majority of the WECs derive their power from the oscillating parameters of the wave i.e the pressure variations, wave elevation, water particle velocities etc. The best power take off is found in case where the forcing frequency of the wave parameter is in resonance with the natural frequency of the moving part of the WEC. Although no sea state would have a single frequency but the spectrum of the basin should be studied for any narrow band sectors of frequency and the device could be designed accordingly. If the basin is a broad band spectrum then a dynamic WEC with active control would be best suited. In case the device is active controlled then it could alter its natural frequency by changing its mass (via altering water ballast) or stiffness constant to match the frequency for maximum energy take off.
3. Breaking severity: It is basically defined as the ratio between the energy lost in breaking to the total energy present. It is dependent on a variety of factors such as the wave steepness, wave length, density, cause of breaking viz. superposition, wave height to depth ratio, or obstruction etc. For the best results its best to keep the WEC out of the surf zone.
4. Breaker Type: In case the breaking in a field is occurring fairly offshore then the type of breaker will also affect the amount of energy available for the WEC. The loss of excess momentum flux and energy flux was measured and found to to range from 10% for single spilling events to as much as 25% for plunging breakers.
5. Structural Limits of the WEC: The WECs can stand to face significant damage from storms and swells. They have to be designed accordingly.
There are many other factors which may affect the WEC depending on the water basin under consideration. The reader is advised to do a through research of the area before selecting or building a WEC.