Wave power

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Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work — for example, electricity generation, water desalination, or the pumping of water (into reservoirs). Machinery able to exploit wave power is generally known as a wave energy converter (WEC).

Wave power is distinct from the diurnal flux of tidal power and the steady gyre of ocean currents. Wave power generation is not currently a widely employed commercial technology although there have been attempts at using it since at least 1890.[1] In 2008, the first experimental wave farm was opened in Portugal, at the Aguçadoura Wave Park.[2]

Contents

Physical concepts

See Energy, Power and Work for more information on these important physical concepts. See Wind wave for more information on ocean waves.

Waves are generated by wind passing over the surface of the sea. As long as the waves propagate slower than the wind speed just above the waves, there is an energy transfer from the wind to the waves. Both air pressure differences between the upwind and the lee side of a wave crest, as well as friction on the water surface by the wind, making the water to go into the shear stress causes the growth of the waves.[3]

Wave height is determined by wind speed, the duration of time the wind has been blowing, fetch (the distance over which the wind excites the waves) and by the depth and topography of the seafloor (which can focus or disperse the energy of the waves). A given wind speed has a matching practical limit over which time or distance will not produce larger waves. When this limit has been reached the sea is said to be "fully developed".

In general, larger waves are more powerful but wave power is also determined by wave speed, wavelength, and water density.

Oscillatory motion is highest at the surface and diminishes exponentially with depth. However, for standing waves (clapotis) near a reflecting coast, wave energy is also present as pressure oscillations at great depth, producing microseisms.[3] These pressure fluctuations at greater depth are too small to be interesting from the point of view of wave power.

The waves propagate on the ocean surface, and the wave energy is also transported horizontally with the group velocity. The mean transport rate of the wave energy through a vertical plane of unit width, parallel to a wave crest, is called the wave energy flux (or wave power, which must not be confused with the actual power generated by a wave power device).

Wave power formula

In deep water where the water depth is larger than half the wavelength, the wave energy flux is[A 1]

P = \frac{\rho g^2}{64\pi} H_{m0}^2 T \approx \left(0.5 \frac{\text{kW}}{\text{m}^3 \cdot \text{s}} \right) H_{m0}^2\; T,

with P the wave energy flux per unit of wave-crest length, Hm0 the significant wave height, T the wave period, ρ the water density and g the acceleration by gravity. The above formula states that wave power is proportional to the wave period and to the square of the wave height. When the significant wave height is given in meters, and the wave period in seconds, the result is the wave power in kilowatts (kW) per meter of wavefront length.[4][5][6]

Example: Consider moderate ocean swells, in deep water, a few kilometers off a coastline, with a wave height of 3 meters and a wave period of 8 seconds. Using the formula to solve for power, we get

P \approx 0.5 \frac{\text{kW}}{\text{m}^3 \cdot \text{s}} (3 \cdot \text{m})^2 (8 \cdot \text{s}) \approx 36 \frac{\text{kW}}{\text{m}},

meaning there are 36 kilowatts of power potential per meter of coastline.

In major storms, the largest waves offshore are about 15 meters high and have a period of about 15 seconds. According to the above formula, such waves carry about 1.7 MW of power across each meter of wavefront.

An effective wave power device captures as much as possible of the wave energy flux. As a result the waves will be of lower height in the region behind the wave power device.

Wave energy and wave energy flux

In a sea state, the average energy density per unit area of gravity waves on the water surface is proportional to the wave height squared, according to linear wave theory:[3][7]

E=\frac{1}{16}\rho g H_{m0}^2, [A 2][8]

where E is the mean wave energy density per unit horizontal area (J/m2), the sum of kinetic and potential energy density per unit horizontal area. The potential energy density is equal to the kinetic energy,[3] both contributing half to the wave energy density E, as can be expected from the equipartition theorem. In ocean waves, surface tension effects are negligible for wavelengths above a few decimetres.

As the waves propagate, their energy is transported. The energy transport velocity is the group velocity. As a result, the wave energy flux, through a vertical plane of unit width perpendicular to the wave propagation direction, is equal to:[9][3]

P = E\, c_g, \, \

with cg the group velocity (m/s). Due to the dispersion relation for water waves under the action of gravity, the group velocity depends on the wavelength λ, or equivalently, on the wave period T. Further, the dispersion relation is a function of the water depth h. As a result, the group velocity behaves differently in the limits of deep and shallow water, and at intermediate depths:[3][7]

Deep water characteristics and opportunities

Deep water corresponds with a water depth larger than half the wavelength, which is the common situation in the sea and ocean. In deep water, longer period waves propagate faster and transport their energy faster. The deep-water group velocity is half the phase velocity. In shallow water, for wavelengths larger than twenty times the water depth, as found quite often near the coast, the group velocity is equal to the phase velocity.[10]

The regularity of deep-water ocean swells, where "easy-to-predict long-wavelength oscillations" are typically seen, offers the opportunity for the development of energy harvesting technologies that are potentially less subject to physical damage by near-shore cresting waves.[11]

History

The first known patent to utilize energy from ocean waves dates back to 1799 and was filed in Paris by Girard and his son.[12] An early application of wave power was a device constructed around 1910 by Bochaux-Praceique to light and power his house at Royan, near Bordeaux in France.[13] It appears that this was the first Oscillating Water Column type of wave energy device.[14] From 1855 to 1973 there were already 340 patents filed in the UK alone.[12]

Modern scientific pursuit of wave energy was however pioneered by Yoshio Masuda's experiments in the 1940s.[15] He has tested various concepts of wave energy devices at sea, with several hundred units used to power navigation lights. Among these was the concept of extracting power from the angular motion at the joints of an articulated raft, which was proposed in the 1950s by Masuda.[16]

A renewed interest in wave energy was motivated by the oil crisis in 1973. A number of university researchers reexamined the potential of generating energy from ocean waves, among whom notably were Stephen Salter from the University of Edinburgh, Kjell Budal and Johannes Falnes from Norwegian Institute of Technology (now merged into Norwegian University of Science and Technology), Michael E. McCormick from U. S. Naval Academy, David Evans from Bristol University, Michael French from University of Lancaster, John Newman and Chiang C. Mei from MIT.

Stephen Salters 1974 invention became known as Salter's Duck or Nodding Duck, although it was officially referred to as the Edinburgh Duck. In small scale controlled tests, the Duck's curved cam-like body can stop 90% of wave motion and can convert 90% of that to electricity giving 81% efficiency.[17]

In the 1980s, as the oil price went down, wave-energy funding was drastically reduced. Nevertheless, a few first-generation prototypes were tested at sea. More recently, following the issue of climate change, there is again a growing interest worldwide for renewable energy, including wave energy.[18]

Modern technology

Wave power devices are generally categorized by the method used to capture the energy of the waves, by location and by the power take-off system. Method types are point absorber or buoy; surfacing following or attenuator oriented parallel to the direction of wave propagation; terminator, oriented perpendicular to the direction of wave propagation; oscillating water column; and overtopping. Locations are shoreline, nearshore and offshore. Types of power take-off include: hydraulic ram, elastomeric hose pump, pump-to-shore, hydroelectric turbine, air turbine,[19] and linear electrical generator. Some of these designs incorporate parabolic reflectors as a means of increasing the wave energy at the point of capture. These capture systems use the rise and fall motion of waves to capture energy.[20] Once the wave energy is captured at a wave source, power must be carried to the point of use or to a connection to the electrical grid by transmission power cables.[21] The table contains descriptions of some wave power systems:

Device Proponent Country of Origin Capture Method Category Location Category Power take off Category Year Announced Notes
ProteanTM Energy Wave Energy Converter Protean Energy Ltd Australia Point-absorber wave-buoy device Offshore Direct drive energy conversion 2004 The Protean™ WEC technology is a unique type of wave buoy or point absorber. When deployed, it sits on the ocean surface where the energy density is the highest. The Protean™ WEC technology works on a buoy and tethering system. The buoy converts relative movement between the static ocean floor and the floating buoy into energy. The innovative tension mooring system uses a combination of cables running from an ocean floor mounted clump weight to the WEC buoy on the ocean surface. The Protean™ technology has no exposed turbines or moving parts that are dangerous to marine life and each unit has a small environmental footprint.
PowerBuoy Ocean Power Technologies US Buoy Offshore Hydroelectric turbine 1997 In the United States, the Pacific Northwest Generating Cooperative is funding construction of a commercial wave-power park at Reedsport, Oregon that will utilize this technology which consists of modular, ocean-going buoys.[22] The rise and fall of the waves moves hydraulic fluid within the buoy and spins a generator. The electricity is transmitted to shore over a submerged transmission line. A 150 kW buoy has a diameter of 36 feet (11 m) and is 145 feet (44 m) tall, with approximately 30 feet of the unit rising above the ocean surface. Using a three-point mooring system, they are designed to be installed one to five miles (8 km) offshore in water 100 to 200 feet (60 m) deep.[23]
Pelamis Wave Energy Converter Pelamis Wave Power UK (Scottish) Surface-following attenuator Offshore Hydraulic 1998 The Pelamis machine consists of a series of semi-submerged cylindrical sections linked by hinged joints. As waves pass along the length of the machine, the sections move relative to one another. The wave-induced motion of the sections is resisted by hydraulic cylinders which pump high pressure oil through hydraulic motors via smoothing hydraulic accumulators. The hydraulic motors drive electrical generators to produce electricity.[24] Pelamis Wave Power first tested and grid connected a Pelamis machine in 2004 at the European Marine Energy Center.[25] The first of a second generation of machines, the P2 started grid connected tests off Orkney in 2010, the machine is owned by E.ON.[26].
Wave Dragon Erik Friis-Madsen Denmark Surface-following attenuator Offshore Hydroelectric turbine 2003 With the Wave Dragon wave energy converter large wing reflectors focus waves up a ramp into an offshore reservoir. The water returns to the ocean by the force of gravity via hydroelectric generators.
Anaconda Wave Energy Converter Checkmate SeaEnergy.[25] UK Surface-following attenuator Offshore Hydroelectric turbine 2008 In the early stages of development, the device is a 200 metres (660 ft) long rubber tube which is tethered underwater. Passing waves will instigate a wave inside the tube, which will then propagates down its walls, driving a turbine at the far end.[27][28]
AquaBuOY Finavera Wind Energy, later SSE Renewables Limited Ireland-Canada-Scotland Buoy Offshore xxx 2003 In 2009 Finavera Renewables surrendered its wave energy permits from FERC.[27] In July 2010 Finavera announced that it had entered into a definitive agreement to sell all assets and intellectual property related to the AquaBuOY wave energy technology.[29][30][31][32]
FlanSea (Flanders Electricity from the Sea) FlanSea Belgium Buoy Offshore Hydroelectric turbine 2010 A point absorber buoy developed for use in the southern North Sea conditions.[31][32][33] It works by means of a cable that due to the bobbing effect of the buoy, generates electricity.[33][34][35]
SeaRaser Alvin Smith (Dartmouth Wave Energy) UK Buoy Nearshore Hydraulic ram 2008 Uses pumping technique to gather wave energy.[36]
CETO Wave Power Carnegie Australia Buoy Offshore Pump-to-shore 1999 Currently being tested off Fremantle, Western Australia,[35] the device consists of a single piston pump attached to the sea floor with a float (buoy) tethered to the piston. Waves cause the float to rise and fall, generating pressurized water, which is piped to an onshore facility to drive hydraulic generators or run reverse osmosis water desalination.[37][38]
Unnamed Ocean Wave-Powered Generator SRI International US Buoy Offshore Electroactive polymer artificial muscle 2004 A type of wave buoys, built using special polymers, is being developed by Stanford Research Institute.[39][40]
Wavebob Wavebob Ireland Buoy Offshore Direct Drive Power Take off 1999 Wavebob have conducted some ocean trials, as well as extensive tank tests. It is an ccean-going heaving buoy, with a submerged tank which captures additional mass of seawater for added power and tunability, and as a safety feature (Tank "Venting")
Oyster wave energy converter Aquamarine Power UK (Scots-Irish) Oscillating wave surge converter Nearshore Pump-to-shore (hydro-electric turbine) 2005 The wave energy device captures the energy found in nearshore waves and converts it into electricity. The systems consists of a hinged mechanical flap connected to the seabed at around 10m depth. 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. In November 2009, the first full-scale demonstrator Oyster began producing power when it was launched at the European Marine Energy Centre (EMEC) on Orkney.[41]
OE buoy Ocean Energy Ireland Buoy Offshore xxx 2006 In September 2009 completed a 2-year sea trial in one quarter scale form. The OE buoy has only one moving part.[42]
Lysekil Project Uppsala University Sweden Buoy Offshore Linear generator 2002 Direct driven linear generator placed on the seabed. The generator is connected to a buoy at the surface via a line. The movements of the buoy will drive the translator in the generator. The advantage of this setup is a less complex mechanical system with potentially a smaller need for maintenance. One drawback is a more complicated electrical system.[43][44]
Oceanlinx Oceanlinx Australia Buoy Offshore Hydroelectric turbine 1997 An Australian firm is developing this deep-water technology to generate electricity from, ostensibly, easy-to-predict long-wavelength ocean swell oscillations. Oceanlinx recently began installation of a third and final demonstration-scale, grid-connected unit near Port Kembla, near Sydney, Australia, a 2.5 MWe system that is expected to go online in early 2010, when its power will be connected to the Australian grid. The company's much smaller first-generation prototype unit, in operation since 2006, was since disassembled.[11]
SDE Sea Waves Power Plant SDE Energy Ltd. Israel Buoy Inshore Hydroelectric turbine xxx A breakwater-based wave energy converter, this device is built close to the shore and utilizes the vertical motion of buoys for creating hydraulic pressure which in turn operates the system's generators. In 2010 it began construction of a new 250 kWh model in the port of Jaffa, Tel Aviv and preparing to construct its standing orders for a 100mWh power plants in the islands of Zanzibar and Kosrae, Micronesia.
WaveRoller AW-Energy Oy Finland Surface-following attenuator Offshore Pump-to-shore 1994 The WaveRoller is a plate anchored on the sea bottom by its lower part. The back and forth movement of surge moves the plate. The kinetic energy transferred to this plate is collected by a piston pump. Full-scale demonstration project built off Portugal in 2009.[45][46]

Potential

The realistically usable worldwide resource has been estimated to be greater than 2 TW.[47][48] Locations with the most potential for wave power include 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. The north and south temperate zones have the best sites for capturing wave power. The prevailing westerlies in these zones blow strongest in winter. Waves are very predictable; waves that are caused by winds can be predicted five days in advance.

Challenges

There is a potential impact on the marine environment. Noise pollution, for example, could have negative impact if not monitored, although the noise and visible impact of each design varies greatly.[5]. Other biophysical impacts (flora and fauna, sediment regimes and water column structure and flows) of scaling up the technology is being studied.[49] In terms of socio-economic challenges, wave farms can result in the displacement of commercial and recreational fishermen from productive fishing grounds, can change the pattern of beach sand nourishment, and may represent hazards to safe navigation.[50] Waves generate about 2,700 gigawatts of power. Of those 2,700 gigawatts, only about 500 gigawatts can be captured with the current technology.[20]

Wave farms

Main article: Wave farm

The Aguçadoura Wave Farm was the world's first wave farm. It was located 5 km (3 mi) offshore near Póvoa de Varzim north of Oporto in Portugal. The farm was designed to use three Pelamis wave energy converters to convert the motion of the ocean surface waves into electricity, totalling to 2.25MW in total installed capacity. The farm first generated electricity in July 2008[51] and was officially opened on the 23rd of September 2008, by the Portuguese Minister of Economy.[52][53] The wave farm was shut down two months after the official opening in November 2008 as a result of the financial collapse of Babcock & Brown due to the global economic crisis. The machines were off-site at this time due to technical problems, and although resolved have not returned to site and were subsequently scrapped in 2011 as the technology had moved on to the P2 variant as supplied to Eon and Scottish Power Renewables.[54] A second phase of the project planned to increase the installed capacity to 21MW using a further 25 Pelamis machines[55] is in doubt following Babcock's financial collapse.

Funding for a 3MW wave farm in Scotland was announced on 20 February 2007 by the Scottish Executive, at a cost of over 4 million pounds, as part of a £13 million funding package for marine power in Scotland. The first of 66 machines was launched in May 2010.[56]

Funding has also been announced for the development of a Wave hub off the north coast of Cornwall, England. The Wave hub will act as giant extension cable, allowing arrays of wave energy generating devices to be connected to the electricity grid. The Wave hub will initially allow 20MW of capacity to be connected, with potential expansion to 40MW. Four device manufacturers have so far expressed interest in connecting to the Wave hub.[57][58]

The scientists have calculated that wave energy gathered at Wave Hub will be enough to power up to 7,500 households. Savings that the Cornwall wave power generator will bring are significant: about 300,000 tons of carbon dioxide in the next 25 years.[59]

A CETO wave farm off the coast of Western Australia has been operating to prove commercial viability and, after preliminary environmental approval, is poised for further development. [60][61]

Patents

See also

  • Renewable energy portal
  • Energy portal

Notes

  1. ^ The energy flux is P = \tfrac{1}{16} \rho g H_{m0}^2 c_g, with c_g the group velocity, see Herbich, John B. (2000). Handbook of coastal engineering. McGraw-Hill Professional. p. A.117, Eq. (12). ISBN 9780071344029.  The group velocity is c_g=\tfrac{g}{4\pi}T, see the collapsed table "Properties of gravity waves on the surface of deep water, shallow water and at intermediate depth, according to linear wave theory" in the section "Wave energy and wave energy flux" below.
  2. ^ For a small-amplitude sinusoidal wave \scriptstyle \eta=a\,\cos\, 2\pi\left(\frac{x}{\lambda}-\frac{t}{T}\right) with wave amplitude \scriptstyle a,\, the wave energy density per unit horizontal area is \scriptstyle E=\frac{1}{2}\rho g a^2, or \scriptstyle E=\frac{1}{8}\rho g H^2 using the wave height \scriptstyle H\,=\,2\,a\, for sinusoidal waves. In terms of the variance of the surface elevation \scriptstyle m_0=\sigma_\eta^2=\overline{(\eta-\bar\eta)^2}=\frac{1}{2}a^2, the energy density is \scriptstyle E=\rho g m_0\,. Turning to random waves, the last formulation of the wave energy equation in terms of \scriptstyle m_0\, is also valid (Holthuijsen, 2007, p. 40), due to Parseval's theorem. Further, the significant wave height is defined as \scriptstyle H_{m0}=4\sqrt{m_0}, leading to the factor 1⁄16 in the wave energy density per unit horizontal area.
  3. ^ For determining the group velocity the angular frequency ω is considered as a function of the wavenumber k, or equivalently, the period T as a function of the wavelength λ.

References

  1. ^ Christine Miller (August 2004). "Wave and Tidal Energy Experiments in San Francisco and Santa Cruz". http://www.outsidelands.org/wave-tidal3.php. Retrieved 2008-08-16. 
  2. ^ Joao Lima. Babcock, EDP and Efacec to Collaborate on Wave Energy Projects Bloomberg, September 23, 2008.
  3. ^ a b c d e f Phillips, O.M. (1977). The dynamics of the upper ocean (2nd ed.). Cambridge University Press. ISBN 0 521 29801 6. 
  4. ^ "Wave Power". University of Strathclyde. http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/wave%20power.htm. Retrieved 2008-11-02. 
  5. ^ a b "Wave Energy Potential on the U.S. Outer Continental Shelf" (PDF). United States Department of the Interior. http://www.ocsenergy.anl.gov/documents/docs/OCS_EIS_WhitePaper_Wave.pdf. Retrieved 2008-10-17. 
  6. ^ http://www.scotland.gov.uk/Publications/2006/04/24110728/10
  7. ^ a b Goda, Y. (2000). Random Seas and Design of Maritime Structures. World Scientific. ISBN 978 981 02 3256 6. 
  8. ^ Holthuijsen, Leo H. (2007). Waves in oceanic and coastal waters. Cambridge: Cambridge University Press. ISBN 0521860288. 
  9. ^ Reynolds, O. (1877). "On the rate of progression of groups of waves and the rate at which energy is transmitted by waves". Nature 16: 343–44. Bibcode 1877Natur..16R.341.. doi:10.1038/016341c0. 
    Lord Rayleigh (J. W. Strutt) (1877). "On progressive waves". Proceedings of the London Mathematical Society 9 (1): 21–26. doi:10.1112/plms/s1-9.1.21.  Reprinted as Appendix in: Theory of Sound 1, MacMillan, 2nd revised edition, 1894.
  10. ^ R. G. Dean and R. A. Dalrymple (1991). Water wave mechanics for engineers and scientists. Advanced Series on Ocean Engineering. 2. World Scientific, Singapore. ISBN 978-9810204204.  See page 64–65.
  11. ^ a b Adee, Sally (2009-10-21). "This Renewable Energy Source Is Swell". IEEE Spectrum Inside Technology. http://spectrum.ieee.org/energy/renewables/this-renewable-energy-source-is-swell. Retrieved 2009-10-22. 
  12. ^ a b Clément et al. (2002). "Wave energy in Europe: current status and perspectives". Renewable and Sustainable Energy Reviews 6 (5): 405–431. doi:10.1016/S1364-0321(02)00009-6. 
  13. ^ "The Development of Wave Power" (PDF). http://www.mech.ed.ac.uk/research/wavepower/0-Archive/EWPP%20archive/1976%20Leishman%20and%20Scobie%20NEL.pdf. Retrieved 2009-12-18. 
  14. ^ Morris-Thomas et al.; Irvin, Rohan J.; Thiagarajan, Krish P. (2007). "An Investigation Into the Hydrodynamic Efficiency of an Oscillating Water Column". Journal of Offshore Mechanics and Arctic Engineering 129 (4): 273–278. doi:10.1115/1.2426992. 
  15. ^ "Wave Energy Research and Development at JAMSTEC". Archived from the original on July 1, 2008. http://web.archive.org/web/20080701162330/http://www.jamstec.go.jp/jamstec/MTD/Whale/. Retrieved 2009-12-18. 
  16. ^ Farley, F. J. M. and Rainey, R. C. T. (2006). "Radical design options for wave-profiling wave energy converters". International Workshop on Water Waves and Floating Bodies. Loughborough. http://www.iwwwfb.org/Abstracts/iwwwfb21/iwwwfb21_15.pdf. Retrieved 2009-12-18. 
  17. ^ "Edinburgh Wave Energy Project" (PDF). University of Edinburgh. http://www.mech.ed.ac.uk/research/wavepower/EWPP%20archive/duck%20efficiency%20&%20survival%20notes.pdf. Retrieved 2008-10-22. 
  18. ^ Falnes, J. (2007). "A review of wave-energy extraction". Marine Structures 20 (4): 185–201. doi:10.1016/j.marstruc.2007.09.001. 
  19. ^ Embedded Shoreline Devices and Uses as Power Generation Sources Kimball, Kelly, November 2003
  20. ^ a b McCormick, Michael E., and R. Cengiz Ertekin. Mechanical Engineering-CIME 131.5 (2009): 36. Expanded Academic ASAP. Web. 5 October 2009.
  21. ^ Underwater Cable an Alternative to Electrical Towers, Matthew L. Wald, New York Times, 2010-03-16. Retrieved 2010-03-18.
  22. ^ "Agreement to Develop Wave Power Park in Oregon". www.renewableeneregyaccess.com. http://www.renewableenergyaccess.com/rea/news/story?id=47546. Retrieved 2008-10-15. 
  23. ^ "Reedsport OPT Wave Park FERC Project No. 12713 Application for a Major License". Federal Energy Regulatory Commission. http://www.mediafire.com/?sharekey=9a0349b792f8b2c25bf1f12f1ff3f30a07d42b6bc27c364ef1940a51b339e393. Retrieved 2010-02-15. 
  24. ^ Jenny Haworth (24 September 2008). "If Portugal can rule the waves, why not Scotland?". The Scotsman. http://news.scotsman.com/opinion/If-Portugal-can-rule-the.4520629.jp. Retrieved 2008-10-09. 
  25. ^ "Update on EMEC activities, resource description, and characterisation of wave-induced velocities in a tidal flow". http://www.emec.org.uk/EWTEC7_EMEC.pdf'. Retrieved 2010-12-03. 
  26. ^ "Making Waves". Scottish Government. http://www.scotland.gov.uk/News/Releases/2010/05/17144639. Retrieved 2011-04-07. 
  27. ^ Anaconda WEC
  28. ^ Article about Anaconda on physics.org
  29. ^ http://www.sustainablebusiness.com/index.cfm/go/news.display/id/20617 Sustainable Business.com Finavera Renewables To Sell Ocean Energy Division
  30. ^ Stock Markets Review Finavera Renewables To Sell Finavera Renewables Ocean Energy - Quick Facts
  31. ^ Announcement of definitive agreement for sale of Finavera Ocean Energy Limited
  32. ^ Finavera To Surrender Wave Energy Permits
  33. ^ FlanSea "optimal for use in southern North Sea"
  34. ^ Image of FlanSea
  35. ^ FlanSea project page
  36. ^ Lewis Smith (November 17, 2008). "Searaser device in uphill battle for clean energy". The Sunday Times. http://www.timesonline.co.uk/tol/news/environment/article5167812.ece. Retrieved 2010-11-13. 
  37. ^ "CETO Overview". carnegiecorp.com.au. http://www.carnegiecorp.com.au/index.php?url=/ceto/ceto-overview. Retrieved 2008-11-03. 
  38. ^ Stephen Cauchi (October 5, 2008). "New wave of power in renewable energy market". The Age (Melbourne). http://www.theage.com.au/national/new-wave-of-power-in-renewable-energy-market-20081004-4tyd.html. Retrieved 2008-10-10. 
  39. ^ SRI Demonstrates Ocean Wave-Powered Generator off California Coast, SRI International, 08.12.2008
  40. ^ Carolyn Said (14 December 2008). "Researchers wring energy out of ocean waves". San Francisco Chronicle. http://articles.sfgate.com/2008-12-14/business/17131881_1_ocean-energy-roger-bedard-sri-technology. Retrieved 9 November 2010. 
  41. ^ Heather Clancy (December 30, 2009). "Wave energy's new pearl: University begins testing Oyster tech off Scottish coast". ZDNet. http://www.zdnet.com/blog/green/wave-energys-new-pearl-university-begins-testing-oyster-tech-off-scottish-coast/9576. Retrieved 2010-11-13. 
  42. ^ Ocean Energy press release
  43. ^ Leijon, Mats et. al (9 April 2008). "Wave Energy from the North Sea: Experiences from the lysekil Research site". http://www.springerlink.com/content/8634116882r00t13/fulltext.pdf. Retrieved 24 June 2009. 
  44. ^ Leijon, Mats et. al (January/February 2009). "Catch the Wave to Electricity". IEEE power energy magazine 7 (1): 50–54. doi:10.1109/MPE.2008.930658. 10.1109/MPE.2008.930658. http://ieeexplore.ieee.org/search/searchresult.jsp?SortField=Score&SortOrder=desc&ResultCount=25&maxdoc=100&coll1=ieeejrns&coll2=ieejrns&coll3=ieeecnfs&coll4=ieecnfs&coll5=ieeestds&coll6=preprint&coll7=books&coll8=modules&coll9=aip&srchres=0&history=yes&queryText=((Catch+the+wave+to+electricity)%3CIN%3Emetadata)&oldqrytext=((the+conversion+of+wave+motions+to+electricity)%3Cin%3Emetadata)&imageField.x=0&imageField.y=0&imageField=((the+conversion+of+wave+motions+to+electricity)%3Cin%3Emetadata)&radiobutton=cit. Retrieved 29 June 2009. 
  45. ^ Susan Kraemer (3 November 2009). "WaveRoller uses swinging door for underwater wave energy". Scientific American. http://www.scientificamerican.com/article.cfm?id=waveroller-uses-swinging-door-for-u-2009-11. Retrieved 9 December 2010. 
  46. ^ AW-Energy Oy
  47. ^ Tom Thorpe. "An Overview of Wave Energy Technologies: Status, Performance and Costs" (PDF). wave-energy.net. http://www.wave-energy.net/Library/An%20Overview%20of%20Wave%20Energy.pdf. Retrieved 2008-10-13. 
  48. ^ Cruz J.; Gunnar M., Barstow S., Mollison D. (2008). Joao Cruz. ed. Green Energy and Technology, Ocean Wave Energy. Springer Science+Business Media. p. 93. ISBN 978-3-540-74894-6. 
  49. ^ Marine Renewable Energy Programme, NERC Retrieved 2011-08-01
  50. ^ Steven Hackett:Economic and Social Considerations for Wave Energy Development in California CEC Report Nov 2008 Ch2, pp22-44 California Energy Commission|Retrieved 2008-12-14
  51. ^ "First Electricity Generation in Portugal". http://www.pelamiswave.com/news?archive=1&mm=7&yy=2008. 
  52. ^ "23 de Setembro de 2008". Government of Portugal. http://www.portugal.gov.pt/portal/pt/comunicacao/agenda/20080923.htm. Retrieved 2008-09-24. 
  53. ^ Jha, Alok (2008-09-25). "Making waves: UK firm harnesses power of the sea ... in Portugal". London: The Guardian. http://www.guardian.co.uk/technology/2008/sep/25/greentech.alternativeenergy. Retrieved 2008-10-09. 
  54. ^ "Pelamis Sinks Portugal Wave Power". cleantech.com. http://cleantech.com/news/4276/pelamis-sinks-portugal-wave-power-p. Retrieved 2009. 
  55. ^ Joao Lima. "Babcock, EDP and Efacec to Collaborate on Wave Energy Projects". Bloomberg Television. http://www.bloomberg.com/apps/news?pid=20601081&sid=aSsaOB9qbiKE&refer=australia. Retrieved 2008-09-24. 
  56. ^ Fyall, Jenny (2010-05-19). "600ft 'sea snake' to harness power of Scotland". The Scotsman: pp. 10–11. http://news.scotsman.com/scotland/600ft-39sea-snake39-to-harness.6303096.jp. Retrieved 2010-05-19. 
  57. ^ James Sturcke (26 April 2007). "Wave farm wins £21.5m grant". London: The Guardian. http://www.guardian.co.uk/environment/2007/apr/26/energy.uknews. Retrieved 2009-04-08. 
  58. ^ "Tender problems delaying Wave Hub". BBC News. 2 April 2008. http://news.bbc.co.uk/2/hi/uk_news/england/cornwall/7326971.stm. Retrieved 2009-04-08. 
  59. ^ "Go-ahead for £28m Cornish wave farm". The Guardian (London). 2007-09-17. http://www.guardian.co.uk/environment/2007/sep/17/renewableenergy.uknews. Retrieved 2008-10-12. 
  60. ^ "Renewable Power from the Ocean's Waves". CETO Wave Power. http://www.ceto.com.au/home.php. Retrieved 9 November 2010. 
  61. ^ Keith Orchison (7 October 2010). "Wave of the future needs investment". The Australian. http://www.theaustralian.com.au/special-reports/climate-change/climate-change/story-fn5oikwf-1225935586957. Retrieved 9 November 2010. 

Further reading

External links

Wave power
Tidal power
Osmotic power
 
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Portals: Energy • Renewable energy • Sustainable development
 
Waves
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