Wave Power Definition, Principle, Applications, and Comparison
Wave power is power derived from wave energy, which is converted and used to do work. It works by the conversion of kinetic wave energy from the oscillation of water molecules on the ocean surface. This article discusses wave power definition, principle, applications, and comparison from the following perspectives;
-Wave Power Definition: 6 Ways to Define Wave Power and Wave Energy
-Wave Power Working Principle: The 3 Steps in Wave Power Generation
-Wave Power Uses: 3 Applications of Wave Power
-Wave Power and Tidal Power: A Comparison
Wave Power Definition: 6 Ways to Define Wave Power and Wave Energy
There are various factors which can be used to define wave power.
One of these factors is the source(s) of wind power, as portrayed below;
Wave power is power which originates from ocean waves, that are formed as a result of solar heating, wind and gravity, among other factors [12].
It is well known that wave power is a product of the conversion of wave energy [1]. This conversion can be used to define the concept;
Wave power is power which is produced from the kinetic wave energy, using a wave energy converter (WEC) [13].
Another factor that can be used to describe wave power is electricity generation;
Wave power is electricity produced from wave energy, using electric generators [6], that convert the wave energy (kinetic) to mechanical energy, and subsequently to power.
Because wave power is derived from renewable sources, it can be described within the context of renewable energy, as follows;
Wave power is power derived from wave energy, which is a renewable form of energy like solar, bioenergy, wind and geothermal [3].
The wave power concept can be defined from the perspective of technology;
Wave power is the product of conversion by wave energy technologies like wave energy converters (WECs), which capture and harness renewable kinetic energy from waves.
Lastly, wave power can be defined based on potential uses;
Wave power is a product of wave energy conversion, which can be used for water pumping, desalination, and municipal electricity supply.
Wave Power Working Principle: The 3 Steps in Wave Power Generation
The source of wave power is wave energy, which is a renewable form of energy that occurs as a result of the influence of factors like wind currents, Earth’s rotation, geomagnetism and solar radiation on ocean water, and the settling effect of gravity.
Wave power is generated from wave energy, through a series of steps.
The steps in wave power generation are wave energy capture, wave energy conversion and electricity generation.
1). Wave Energy Capture (Step 1)
Due gravity, wind and changes in solar radiation intensity, the ocean is constantly in a state of oscillation.
This oscillation results in a form of kinetic energy called wave energy or tidal energy.
The first step in the process of generating wave power, is the capture of wave energy. When wave energy has been captured, it may then be converted and used to do work.
In order for wave energy to be captured, some equipment and technologies are usually required. An example of such equipment is the wave energy buoy; a floating device which is equipped with moveable parts [11].
Wave energy is transmitted to the moveable parts of the buoy or any other technological system, in the form of continuous oscillation. This energy which has been captured, can now be converted.
Aside the buoy method, overtopping wave power device is yet another technological tool that is used to capture wave energy [5].
The device basically comprises of an elevated inlet, low-head turbines, and a reservoir.
When waves rise above the sea level, these waves break against the overtopping device, such that water flows into the storage tank through the inlet.
The kinetic energy of the waves is captured in this water which flows into the reservoir. Before flowing back into the sea, the water passes through the turbine system, causing the low-head turbines to rotate, and thereby generating electricity.
2). Wave Energy Conversion (Step 2)
Wave conversion occurs when kinetic wave energy is converted to mechanical energy.
The exact manner in which this occurs, depends on the type of technology that is being used.
For the wave energy buoy, conversion occurs when wave energy is captured by the system and used to cause oscillatory motion of the moveable parts.
Overtopping devices convert wave energy by making the wave currents to pass through the turbine system, causing the low-head turbines to rotate.
Generally, when motion of a designated component of a wave energy system occurs under the influence of wave energy, it implies that conversion has occurred.
3). Electricity Generation (Step 3)
Electricity generation is the final step in the process of producing wave power.
Basically, electricity is generated when mechanical energy (derived from wave energy conversion) is used to move a conductor material in a magnetic field. This phenomenon is also known as electromagnetism [9].
Electricity is produced by a generator, which is usually a component of the wave energy system, and is equipped with all the necessary parts required for electromagnetic induction.
There are slight variations in the mechanism of electricity generation for different wave energy technologies.
The buoy system, for example, usually has a component which works like a piston [4]. This component rises and falls with the oscillation of the buoy, and drives a generator to produce electricity.
On the other hand, the overtopping device generates electricity by using the mechanical energy to drive a set of low-head turbines, which creates an electromagnetic field and current flow.
Wave power works by capturing wave kinetic energy, converting it to mechanical energy, and using this mechanical energy to drive an electric generator, using the electromagnetic induction principle.
This process is capable of generating significant amount of energy.
Wave Power Uses: 3 Applications of Wave Power
Wave power is good for a number of applications, including water desalination, water pumping and electricity supply.
These uses are discussed briefly as follows;
1). Wave Power for Water Desalination
Wave energy is one of various types of renewable energy that are used for the desalination of seawater. Others include solar, wind and geothermal [2].
The use of wave power (derived from wave energy) to desalinate water, has some advantages.
These advantages include the fact that when wave power is used for desalination, it simplifies the desalination process, especially in comparison to other forms of energy.
Desalination may then occur in situ, eliminating the need for offshore plants and pipeline systems. This is exemplified by the floating desalination buoy, which uses electricity generated from ocean waves, to purify seawater.
In other cases, wave power is used to transport seawater from the ocean, to an offshore plant where it is desalinated.
For most wave energy-driven desalination processes, the method of water purification used is reverse osmosis. Here, wave power is used to drive the RO system that carries out desalination
The product of desalination is usually potable water that is free of most of the dissolved constituents found in seawater.
2). Wave Power for Water Pumping
Where high pressure is needed to pump seawater to an onshore or offshore location, wave power can be applied.
One of the common scenarios in which this is used is seawater desalination. Wave power can help to drive the pump systems that are responsible for transporting seawater from the ocean, to the desalination plant.
In some cases the desalination process may be relatively complex. It may involve pumping the seawater through a filter and conditioner before sending it to the RO system [8].
Such cases may require more wave power, to be performed efficiently.
3). Wave Power for Electricity Supply
Although wave power is not widely used for electricity supply at the present, current developments could make it a common source of electricity in the future [10].
In terms of electricity generation, we may consider wave power to be similar to other renewable energy forms like wind and solar. This is because solar radiation and wind currents are known to play a role in the production of wave energy.
Wave Power and Tidal Power: A Comparison
Tidal power is power derived from the conversion of tidal energy.
The difference between wave power and tidal power, lies in the type of energy from which they are derived.
While both wave and tidal energy exist in the ocean, they are different from each other.
Tidal energy comes from the rise and fall of water levels in the ocean. Wave energy comes from the oscillation of ocean water under the influence of gravity, wind and solar radiation.
Also, some of the technologies used for tidal power generation, differ from those used for wave power generation. Tidal turbines, used to harness tidal energy [7], are not used for wave power generation.
Conclusion
Wave power is power derived from wave energy.
The following three steps summarize how wave power is generated;
- Wave Energy Capture
- Wave Energy Conversion
- Electricity Generation
Uses of Wave power include;
- Desalination
- Water Pumping
- Electricity Supply
References
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