Derivate Techniques Of Harvesting Sea And Ocean Wave Energy: Literature Review

Literature Review

What Are Some Of The Derivate Techniques Of Harvesting Or Capturing Sea And Ocean Wave Energy?

What Are Some Of The Available Techniques Of Deriving The Efficient Location For Setting Up A Plant Of Energy Generation Which Can Provide Minimum Maintenance And Setup Cost With Maximum Power?

How Can The Environmental Challenges Such As The Extreme Impact Of Waves Under The Sea And Ocean Water And Carrion Be Solved?(Takahashi, 2011)

The consumption of power all over the world is estimated to increase over the coming years. The traditional methods of power generation are contributing to the extreme environmental effects that are still ambiguous. The problems associated with the use of fossil fuels have brought the technologies of renewable energy under the spotlight. Some of the management energy sources for the renewable energy include geothermal, biomass, ocean, solar, and wind. The ocean energy sources are one of the most imminent energy source for biomass, solar, and wind sources. Approximately 70% of the surface of the earth is covered with oceans which involve the abundant quantity of energy in the form of thermal gradient, marine current, tidal, and wave.

The wave power can be generated in the entire year compared to other renewable energy sources. The attainable energy flux in the wave energy is greater than the energy flux attainable from wind or solar renewable sources. The literature review below evaluate the available past and present literature regarding the ocean wave power generation and provides the possible gaps and information to do development implementation, and further research in the future (Baddour, 2010).

The waves referred to in this proposal are ocean waves generated by the wind. During the shinning of the sun on the world, there is heating of the air resulting to the difference in pressure that are the engines that propagate the winds. The energy from the sun can then be concentrated in or transferred to the wind. The wave energy can be captured at either onshore or offshore. There are numerous types of potentially efficient devices that have been identified which require not larger compared to the commonplace in shipbuilding. There are numerous methods that can be used in concentrating ocean wave energy which is commonly known as Wave Energy Converters. The generators can be positioned on the seashore to protect it from extreme waves of the sea surface (Charlier, 2011).

At Uppsala University in Sweden, the Renewable Electric Energy Conversion project using the permanent magnet linear generated positioned on the coastal region where the wave energy converters are impelled by point absorbing floating buoy to produce electricity. In the current experiment, a wave energy converter has been joined to the diverse resistive loads, ultra-capacitors, and diode rectifier. The outcomes denote that the generator loads is beneficial when the generation of power is to be maximized. The average power absorbed increases with a decreasing resistive load (Danielsson, 2008).

Derivate Techniques of Harvesting Sea and Ocean Wave Energy

Some of the factors that have affected the development of the systems of wave energy include testing huge prototypes under severe environmental conditions, deploying, and high costs of construction. The efficient power or energy pulling from the waves composed of psychology and technical; challenges and the most perplexing is to derive the wave behaviour accurately as it relies on the friction between the surface water and wind of the ocean. The extracted power from the ocean waves by the WEC depends on the control strategy, power off-shore site, hydrodynamic characteristics of the device, and also the wave conditions at the site off-shore (Gerald, 2009).

The process of energy harvesting is attained through converting the wave energy of Transverse Ocean to the electrical energy through the piezoelectric patches attached on the cantilevers secured on the buoy. A point absorber wave extractor is then established with two systems of the coaxial cylinder. The system is composed of the outer cylinder which oscillates vertically and the inner cylinder which performs under tension. The harvester is made of a system of mass-spring used for wave motions transfer to mechanical vibrations and tow devices of piezoelectricity-lever used for the purposes of transferring and amplification of the mechanical vibration collected to electrical power (Goldin, 2012).

The controller of MCWT is an optimum power point tracking controller amended to account for the wave conditions incoming and also WEC output power. This controller is used for controlling latching of a water column oscillating with Wells turbine, maximizing the time of latching based on the state of the sea. This design can be used in capturing the vibrations of low frequency by incorporating the boats and buoys (Justus, 2013). Australia is surrounded by the Pacific Ocean in the Easter side and the Indian Ocean in the western side making the country to be known as the most promising region for harvesting wave energy globally. States such as South Australia, Western Australia, Victoria, and Tasmania are known for their high levels of annual wave energy of approximately 30kW per meter along,

This section analyzes the theoretical basis of the ocean power generation and also the impacts of the approaches on the ocean wave generation process. The wave power derivate techniques are normally grouped by the method used in capturing the wave energy, power take-off system, and by the location. The categories of power take-off system include linear electrical generator, air turbine, hydroelectric turbine, pump-to-shore, elastomeric hose pump, and hydraulic ram (Lynn, 2013).

Pressure Differential Converters

This derivate technique is based on the converters and is relatively new technology using the reinforced rubber membranes in extracting wave energy. The converters use the pressure difference at diverse positions beneath a wave to generate a difference in pressure within a system of closed power take-off fluid. The difference in pressure is generally used in the generation of flow, which drives an electrical generator and a turbine. The pressure differential converters submerged frequently apply flexible membranes as the surface for working amongst the system of power take-off and the ocean (Lynn, 2013).

This device is a long structure that utilize the velocity of the wave to fill a reservoir to a higher level of water compared to the ocean or sea surrounding. The potential energy in the height of the reservoir is then harvested with turbines of the low head. Devices can be either floating offshore or on shore. The devices floating pose environmental worries regarding the mooring system affecting electromagnetic force generated from the subsea cable, organisms becoming entangled, and benthic organisms are also affected (Mehrangiza, 2011).

These devices can be positioned in deeper waters offshore or on shore. With an air chamber integrated into the oscillating water column, it swells the air compressed in the chambers compelling air to the turbine of air to generate electricity. Substantial noise is generated as air is forced in the turbines, this affects the marine organisms and birds potentially within the device vicinity (Multon, 2013).

The surface attenuator performs just like the point absorber buoys, with numerous segments floating coupled to each other and are perpendicularly oriented to the waves incoming. A flexing movement is produced by waves that propagate hydraulic pumps to produce energy. The impacts of this device to the environment are related to those of the point absorber buoys, with an extra anxiety that micro-organisms could be strained in the joints (Neill, 2018).

The point absorber buoy floats on the water surface, attached in position by cables joined to the seabed. Buoys utilize the fall and rise of the seabed to produce electric energy in numerous techniques such as directly through linear generators or through generators propelled by hydraulic pumps or linear-to-rotary converters. The generated EMF by acoustics and electrical cables for transmission may be an anxiety for the micro-organisms in marine environment. The existence of buoys is likely to interfere with birds, fish, and marine mammals since there is a potential for risks of collision (Patel, 2012).

Overtopping Device

One of the available technique techniques of deriving the efficient location for setting up a plant of energy generation which can provide minimum maintenance and setup cost with maximum power is the use of wave energy converter (WEC). There are numerous types of wave energy converters and these are used depending on the magnitude, location, and requirements of the given project. The Wave Energy Converters are devices which harvest the energy from waves and transforms it into electricity. These devices are classified according to their directional characteristics, operating principle, and the location where they are installed. The principle of operation refers to the approach of energy extraction (Peche, 2016).

The wave energy converters are developed progressively and they are recognized to be grouped in productions dependent on their installed location. The initial production of the wave energy converters was installed on the shoreline and hence these categories of WEC were referred to as shoreline WECs. The following generation of wave energy converters was installed at locations nearshore and also referred to as nearshore wave energy converter. The third generation wave energy converters were installed offshore and are referred to as offshore wave energy converters and also installed under conditions that are tougher and harsher and these factors bring their operation and installation at higher levels compared to the rest of the wave energy converters (Peppas, 2009).

The operation principles of the wave energy converter can be categorized into three major parts, namely, oscillating water columns, wave activated bodies, and overtopping devices. The wave activated bodies devices oscillate as a result of the actions of the wave and majority of them use hydraulic systems for the purposes of electricity generation. The overtopping devices apply the overtopping of water from the waves into a reservoir which takes the water at higher heights compared to the height of sea and propel the hydro-power to generate electricity. The oscillating water column uses the waves to expand and compress air so as to rotate an air turbine which is used in the generation of electricity (Peppas, 2009).

The extreme waves under the sea and ocean water do not modify the coastal and marine ecosystems at the sites in which they impact but may also produce larger-scale effects through the alteration of connectivity, the movement of energy, materials, and organisms between habitat units within seascapes. The extreme waves under the sea modify connectivity through alteration of trophic connectivity and creation of barriers to the movement of some organisms. The ecological connectivity refers to the manner in which the landscape impedes or enables the movement of energy, materials, and organisms between the habitat units (Wright, 2017).

Oscillating Water Column

In the aquatic environment, connectivity can be a specifically significant determinant of the ecosystem functionality and structure of the community since numerous organisms display diverse stages in life history that utilize different habitats and shows positive and negative interactions with other organisms that live across the boundaries of the habitat (Plummer, 2009). The extreme waves also affect the passive and active movement of the reproductive propagules, adult organisms, or early-stages from the source population to sink population, this prevents demographic extinction and decline of sink population. Such moves are not only significant in the determination of the distribution, survival, and growth of species and their interaction but also can redistribute resources such as nitrogenous waste from marine mammals and birds (Seymour, 2009).

One of the ways through which the environmental challenges such as the extreme impact of waves under the sea and ocean water and carrion can be solved in through creation of barriers to the movement of the waves. The artificial structures can prevent the extreme waves from washing away the habitats of marine organisms and also affecting the ecological connectivity of this organism. Physical structures can also be erected so as to stabilize shorelines and also to establish physical barriers to the movement of extreme waves. Structures such as groynes can be constructed perpendicularly to the shoreline basically to reduce the wave action and tidal currents on their landward side. The technologies used onshore should also use environmentally friendly materials to reduce the ecological stress and promote the development of natural communities (Seymour, 2009).

The field set-up of the research will be an empirical study to examine opinions from diverse ocean wave power generation companies in Australia. The targeted companies include Bombora Wave Power based in Western Australia, Oceanlinx based in South Australia, Ocean Power Technologies based in Victoria, and the CETO wave farm based in Western Australia. These companies are responsible for harvesting energy from wind waves to perform the useful work of a generation of electricity by the use of Wave Energy Converter. The study will not be limited to any technology used by the companies during the process of ocean wave energy power generation, or the geographical position of the station or even a specific industry since the research sought to determine these technologies and their wave of operation (Stelzer, 2012).

All the relevant information pertaining the technologies, methods, and techniques of ocean wave power generation will be stained during the field set-up. Just like any other field set-up, there is no guarantee that the rate of response for the survey will be 100%. Through cooperation with diverse ocean wave power generation companies, the researcher can ensure that the data acquired and analyzed is as precise as possible. The survey would apply closed-ended questions to advance the data collection method since they are easy to respond compared to open-ended questions (TRW, 2009).

Surface Attenuator

The table below simplifies the relevance of each hypothesis in answering the research questions.

No	Research Questions		Relevant Hypothesis
Q1	What are some of the derivate techniques of harvesting or capturing sea and ocean wave energy?	H1 H2 H3 H4 H5 H6	Submerged pressure differential Surface attenuator Point absorber buoy Overtopping device Oscillating water column Oscillating wave surge converter
Q2	What are some of the available techniques of deriving the efficient location for setting up a plant of energy generation which can provide minimum maintenance and setup cost with maximum power?	H7	Wave Energy Converter (WEC) which can further be categorized into three parts, namely wave activated bodies, overtopping devices, and oscillating water columns
Q3	How can the environmental challenges such as the extreme impact of waves under the sea and ocean water and carrion be solved?	H8 H9	Creation of barriers to the movement of the waves Construction of groynes perpendicularly to the shoreline

Table 1: Summary of Relevance between Research Questions and Hypotheses.

The data that this research will be working at is basically concerning the quantitative empirical data attained from responses during survey for the process of ocean wave power generation companies and professionals. Since the research deals with field experts, the data analysis method is a non-probabilistic purposive sampling type. Upon collection of the responses, it will be possible to point the best technology that can be used during energy harvesting. Majority of responses consider Point absorber buoy as the derivate technique of harvesting or capturing sea and ocean wave energy. Majority of the companies apply the wave energy converter when deriving the efficient location for setting up a plant of energy generation with minimum maintenance and maximum power output (Takahashi, 2011).

The project plan has been developed and provides care to take into consideration all the undertakings stated in the preceding parts that will be required to achieve the empirical study. The duration projected of the proposed project is 23 working months.

Conclusion

The waves referred to in this proposal are ocean waves generated by the wind. During the shinning of the sun on the world, there is heating of the air resulting to the difference in pressure that are the engines that propagate the winds. The energy from the sun can then be concentrated in or transferred to the wind. The wave energy can be captured at either onshore or offshore. Majority of responses consider Point absorber buoy as the derivate technique of harvesting or capturing sea and ocean wave energy. The extreme waves under the sea modify connectivity through alteration of trophic connectivity and creation of berries to the movement of some organisms. The ecological connectivity refers to the manner in which the landscape impedes or enables the movement of energy, materials, and organisms between the habitat units.

References

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