The Development of Wave Energy in China
With the growing concern over the emission of greenhouse gas and the depletion of fossil in roughly a hundred years (Guo, 2010), greater emphasis are placed on the utilization the renewable clean energy, such as solar energy, wind energy, hydro energy, biomass energy.Wave power, as one of inexhaustible clean energies, stands out prominently due to high efficiency and low capital cost.As a result, Sea wave power has been increasingly viewed in many countries as a competitive and promising energy resource(You, 2003).
China’s engagement in the study of wave energy conversion since 1970’s has made significant progress in fueling China’s fast growing economy.
And there is still great potential of further exploitation of wave energy as about 7? 1010 W of wave energy is technological accessible in the near shore of China. Development and deployment of wave power help phase in the energy structure swift ‘from coal-dominance to more shares of clean energy types’ to tackle the problem of energy crisis and environmental pollution in a cost-effective manner (reference from Beijing Foreign Affairs Office).
This term paper focuses on the conditions, progress and challenges of utilizing wave energy in China. Firstly it discusses the physical concepts of sea wave energy, including the basic process, relative merits and several common converters. The main part then elaborates on the reasons and situations for China to exploit wave power. It finally concludes from the progress of utilization that wave power has a vast developing foreground and an infinite market potential in China. Physical Features of Wave Power
As one of the mechanical waves, the ocean waves are generated by wind blowing vastly enough over the sea surface and transferring energy from wind to wave(Guo, 2010). Specifically, the formation of waves is due to ‘the tangential stress on the interface between the wind and sea’(Guo, 2010), intensified by ‘the wind blows on the upwind side of the wave which cause pressure different between upwind and downwind of wave(Guo, 2010). While energy transformation takes place in macrocosm and transverse aspect, changes of energy magnitude exist in microcosm and longitudinal regard.
Under the action of wind and gravity, the particle moves in circle in deep water while moves elliptically in shallow water. Dimensions of particle trajectories decrease exponentially as the depth increase in both deep water and shallow water(Guo, 2010). Typically these paths will become very small at a water depth larger than a few wavelengths in the deep water (Chow, 2012), which means that the larger orbits on the sea surface contain more wave energy than those in the deeper location.
Consequently, ‘the wave energy is stored in the ocean worldwide and highly concentrated near the ocean surface’(Guo, 2010). The above-mentioned kinetic energy and potential energy generated by sea surface waves is referred to as ocean wave energy(“Wave Energy Development,” 2006). Huge amount of energy is stored in waves, consisting of 94% energy of the ocean stored in the waves and the other 6% in tidal energy(Guo, 2010). Generally speaking, wave power cannot convert to electricity directly like wind energy. Wave energy should first be captured and converted into useful mechanical energy and then use this form of mechanical energy to generate electricity’(Guo, 2010), which might cause energy loss during conversion. Three determinants of energy output are wave height, wave speed, wavelength, and water density. … Relative Advantage and Disadvantages The technology of producing electricity from sea waves is innovative and a leading method worldwide.
Environmental pollution and global warming as a result of fossil fuel consumption have turned people to make use of largest world resource to create electricity, namely, sea waves. Comparing with other renewable clean energies, wave power has relative high-lightened merits as follows(Kloosterman, 2010): High Density Wave power is the densest power among renewable energy resources, namely about 5kW/m to 100kW/m(Guo, 2010). The high density of wave power implies that considerable amounts of electricity may be yielded at relatively small sites. Certain Continuity
The second feature that makes wave power suitable for electricity production is that the wave power can produce electricity continuously Unlike most of renewable energy resources (Guo, 2010). By contrast, nuclear power plants and hydroelectric stations are hi ghly susceptible to earthquake damage and China is hit by more than 4 typhoons a year on average, making the building of wind farms extremely difficult but wave electrical devices promising(Aviv, 2008). High Efficiency Besides high density and continuity in production, wave energy also is characterized by its high efficiency.
According to S. D. E, wave energy has the potential to provide 4 times more energy per square meter than wind, leading to rendering 500 times more than the electricity requirements of the whole world population if fully harnessed which ‘offers a solution to the severe global shortage of electricity that is estimated to cost billions of dollars’(Aviv, 2008). Multi-purpose Utilization Plenty of other purposes can be realized by wave energy besides providing electricity. The low temperature water in deep seas can replace Freon for the refrigeration of air-conditioners in summer.
Desalination of sea water on islands lacking of fresh water can also be achieved by wave power. As with You (2003), ‘Multi-purpose utilization of wave energy can increase its commercial values’. Some Drawbacks As a rather new field with most of the technology under development, the practical efficiency of the wave power device is not high enough. Basically, wave power is ready to be used at low speed and high force and the motion of forces is not in a single direction, raising difficulties for most electric generators that operate at higher speeds and turbines that need a constant, steady flow(“Powered by the Sea,”).
Conversely, the cost for construction is high. Since the devices used for capturing the sea waves, ‘the structure need to be withstanding the rough weather and the corrosive sea water’(Guo, 2010). ‘The total cost includes the primary converter, the power take-off system, the mooring system, installation and maintenance cost, and electricity delivery costs(“Powered by the Sea,”)’, boosting costs of generation in this way.
Also, the wave power electricity generation is highly dependent on the sea characteristics, putting limits of the construction of wave power devices exclusively to the high wave power density coastlines(Guo, 2010). Moreover, wave electricity devise can exert potential negative influence on the marine environment. Large-scale implementation of wave energy converts (WECs) is likely to introduce an anthropogenic activity in the ocean(Patricio, 2009). This in turn may contribute to underwater noise which is detrimental to certain marine fauna with acoustic sensibility.
Proper and continuous monitor of the noise can help abate the negative effect on marine species. Consequently, the advantages of wave energy far outweigh its drawbacks which mostly can be mitigated with further technological development. Potential Worldwide and in China ‘The realistically usable worldwide resource of wave energy has been estimated to be greater than 2 TW’, equivalent to an annual amount of 6000TWh(Wikipedia). The practical potential to harness the wave power to generate electricity would be much less given some constraints like technical and economic difficulties(Guo, 2010).
Waves generate approximately 2,700 gig watts of power. According to Wikipedia, of those 2,700 gig watts, only about 500 gig watts can be utilized with the technology currently. This huge potential and applicability of wave power concentrate especially on the regions along coastlines, including the western seaboard of Europe, the northern coast of the UK, and the Pacific coastlines of North and South America, Southern Africa, Australia, and New Zealand(Wikipedia).
South-eastern China has an obvious comparative advantage in regard of wave resources, with excellent conditions for mineralization, and there are 130 types of minerals with proven reserves. Recent Progress of utilization of wave power in China Although the first known patent on wave energy conversion was issued as early as 1799, extensive researches have not been carried out until the early 1970s(“Wave Energy Development,” 2006). Extracting the power of the waves is ‘moving out of the realms of sea mythology and into scientific reality’(“Powered by the Sea,”).
Representative countries that pioneered in this field are United Kingdom,Norway,Portugal,China,India and so on(You, 2003). ‘Various kinds of wave energy conversion devices have been proposed and many prototype wave power stations have been constructed, such as Salter duck, clam, Cockerel raft, oscillating water column (OWC)(You, 2003). ’ Had it not been due to certain technical and economic constraints, the huge reserve of power stored in oceans covering 71% of the earth’s surface is bound to have a promising foreground.
For example, most of the studies on other influencing devices have been called off in light of low conversion efficiency and poor sustainability, leaving the OWC system of wave energy conversion to be the major direction of researches(You, 2003). Therefore, wave power generation is not currently a widely employed commercial technology comparing with other renewable green energies(“Powered by the Sea,”). In tune with the world trend, China is in the first rank of countries in studying wave energy conversion at present with a history also dated back to 1970s. Actually, the application of wave power in a real sense started in 1982(Guo, 2010).
Developments in establishing small marine wave power devices like lighthouse or small power devices equipped in ships laid foundation for the completion of the first wave power station in 2005 with capacity of 50kW and yields roughly 26MWh every year(Guo, 2010). The next milestone is also established in 2005 which is the largest wave power station in china with capacity of 100kW. Both of the power stations are located in the southern province Guangdong with 4,300 km in costline. China has established Department of Energy in 2009, and will focus on development of renewable energy include wave power.
Glorious past contributes to the present development of wave energy in China. It is one of the most influencing countries in studying wave energy conversion at present. Up to now, three types of facilities utilizing wave power have been developed, including shoreline OWC wave power plants, floating OWC buoys and pendulous wave power plants(You, 2003). Besides, one of the two power plants in Guangdong province is under construction with 150kW capacity and the other one of 500Kw capacity is planed to start in the near future(Psenak, 2012).
A third plant was built in Yangjiang City in 2011. Applicability of different wave power technologies in China can be summarized into five kinds, that is Oscillating water column(OWC), Pelamis wave power converter, Oyster wave power conerter, wave dragon converter and Finavera wave power converter(Guo, 2010). The main disadvantages with OWC are low efficiency and high capital cost, which canbe addressed with the development of OWC technology. According to the Chinese wave power company, the estimated total efficiency of the OWC system can reach 20%(Guo, 2010).
Although covering the shortages of OWC, Pelamis wave power convertor with long and narrow (snake-like) shape pointing into the waves, is not suitable for China as it can only be applied to high power density area. The same situation applies to the Finavera power converter. The Oyster system ‘consists of a hinged mechanical flap connected to the seabed at a depth of 10 metres. Each passing wave moves the flap which drives hydraulic pistons to deliver high pressure water via a pipeline to an onshore turbine which generates electricity’(“Powered by the Sea,”).
Unlike Pelamis wave power converter, ‘Oyster wave converter has relative low limitation in wave power density and it is near-shore fixed in shallow water’(Guo, 2010). Moreover, the capital cost of Oyster wave power convertor is lower than OWC systems. It is considered suitable for China, according to Guo(2010). The wave dragon technology is not mature enough to be put into practice in full size. … The future of wave power in China Chinese policy is open to developing comprehensive renewable energy resources, including wind power, solar power and wave power.
Although wave power is currently the least used in China, it is widely believed that wave power has a big potential because of some advantageous natural conditions(Guo, 2010). …good wave climate in Guangdong, Fujian and some other provinces. The potential capacities of wave power in China are 500GW approximately(Liu). Wave energy is considered to be the large useful wave power resource in China. The technologies of wave power have been developed for a long time, though not very mature due to the high cost of the existing wave power plant.
Continous experiments with new equipments to harness ocean wave energy as well as efforts to attract sizeable foreign investments would be the major goals of this giant developing country(“Wave Power Projects in US, Scotland and China “, 2010). It is reasonably estimated that the cost for wave power generation will decrease to a rational level if wave power is largely used for commercial generation(Guo, 2010). As analyzed preceedingly, the on land Oyster systems suit China best and improved OWC will be the most widely adopted wave power generation system in China.
According to Guo, ‘if they are combined with newer systems off-shore wave power generation system such as Wave Dragon and Pelamis, these will form the future Chinese wave power generation system’. In this way, the time volatility of wave energy can also be smoothed by interconnection of large numbers of devices(Falnes, 1991). Hence, wave energy is expected to have a great potential to be economically competitive with the development of new designs and technical improvements over time(Falnes, 1991).
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