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1 Oceanic Energy Professor S.R. Lawrence Leeds School of Business University of Colorado Boulder, CO 80305

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  • Oceanic EnergyProfessor S.R. LawrenceLeeds School of BusinessUniversity of ColoradoBoulder, CO 80305

  • Course OutlineRenewableHydro PowerWind EnergyOceanic EnergySolar PowerGeothermalBiomassSustainableHydrogen & Fuel CellsNuclearFossil Fuel InnovationExotic TechnologiesIntegrationDistributed Generation

  • Oceanic Energy OutlineOverviewTidal PowerTechnologiesEnvironmental ImpactsEconomicsFuture Promise

    Wave EnergyTechnologiesEnvironmental ImpactsEconomicsFuture PromiseAssessment

  • Overview of Oceanic Energy

  • Sources of New EnergyBoyle, Renewable Energy, Oxford University Press (2004)

  • Global Primary Energy Sources 2002Boyle, Renewable Energy, Oxford University Press (2004)

  • Renewable Energy Use 2001 Boyle, Renewable Energy, Oxford University Press (2004)

  • Tidal Power

  • Tidal MotionsBoyle, Renewable Energy, Oxford University Press (2004)

  • Tidal ForcesBoyle, Renewable Energy, Oxford University Press (2004)

  • Natural Tidal BottlenecksBoyle, Renewable Energy, Oxford University Press (2004)

  • Tidal Energy Technologies1. Tidal Turbine Farms2. Tidal Barrages (dams)

  • 1. Tidal Turbine Farms

  • Tidal Turbines (MCT Seagen)750 kW 1.5 MW15 20 m rotors3 m monopile10 20 RPMDeployed in multi-unit farms or arraysLike a wind farm, butWater 800x denser than airSmaller rotorsMore closely spacedhttp://www.marineturbines.com/technical.htmMCT Seagen Pile

  • Tidal Turbines (Swanturbines)Direct drive to generatorNo gearboxesGravity baseVersus a bored foundationFixed pitch turbine bladesImproved reliabilityBut trades off efficiencyhttp://www.darvill.clara.net/altenerg/tidal.htm

  • Deeper Water Current TurbineBoyle, Renewable Energy, Oxford University Press (2004)

  • Oscillating Tidal TurbineOscillates up and down150 kW prototype operational (2003)Plans for 3 5 MW prototypesBoyle, Renewable Energy, Oxford University Press (2004)http://www.engb.com

  • Polo Tidal TurbineVertical turbine bladesRotates under a tethered ring50 m in diameter20 m deep600 tonnesMax power 12 MWBoyle, Renewable Energy, Oxford University Press (2004)

  • Power from Land Tides (!)http://www.geocities.com/newideasfromtelewise/tidalpowerplant.htm

  • Advantages of Tidal TurbinesLow Visual ImpactMainly, if not totally submerged.Low Noise Pollution Sound levels transmitted are very lowHigh PredictabilityTides predicted years in advance, unlike windHigh Power DensityMuch smaller turbines than wind turbines for the same powerhttp://ee4.swan.ac.uk/egormeja/index.htm

  • Disadvantages of Tidal TurbinesHigh maintenance costsHigh power distribution costsSomewhat limited upside capacityIntermittent power generation

  • 2. Tidal Barrage Schemes

  • DefinitionsBarrageAn artificial dam to increase the depth of water for use in irrigation or navigation, or in this case, generating electricity. FloodThe rise of the tide toward land (rising tide)Ebb The return of the tide to the sea (falling tide)

  • Potential Tidal Barrage SitesBoyle, Renewable Energy, Oxford University Press (2004)Only about 20 sites in the world have been identified as possible tidal barrage stations

  • Schematic of Tidal BarrageBoyle, Renewable Energy, Oxford University Press (2004)

  • Cross Section of a Tidal Barragehttp://europa.eu.int/comm/energy_transport/atlas/htmlu/tidal.html

  • Tidal Barrage Bulb TurbineBoyle, Renewable Energy, Oxford University Press (2004)

  • Tidal Barrage Rim GeneratorBoyle, Renewable Energy, Oxford University Press (2004)

  • Tidal Barrage Tubular TurbineBoyle, Renewable Energy, Oxford University Press (2004)

  • La Rance Tidal Power BarrageRance River estuary, Brittany (France)Largest in worldCompleted in 19662410 MW bulb turbines (240 MW)5.4 meter diameterCapacity factor of ~40%Maximum annual energy: 2.1 TWhRealized annual energy: 840 GWhElectric cost: 3.7/kWhTester et al., Sustainable Energy, MIT Press, 2005Boyle, Renewable Energy, Oxford University Press (2004)

  • La Rance Tidal Power Barragehttp://www.stacey.peak-media.co.uk/Brittany2003/Rance/Rance.htm

  • La Rance River, Saint Malo

  • La Rance Barrage SchematicBoyle, Renewable Energy, Oxford University Press (2004)

  • Cross Section of La Rance Barragehttp://www.calpoly.edu/~cm/studpage/nsmallco/clapper.htm

  • La Rance Turbine Exhibit

  • Tidal Barrage Energy CalculationsR = range (height) of tide (in m)A = area of tidal pool (in km2)m = mass of waterg = 9.81 m/s2 = gravitational constant = 1025 kg/m3 = density of seawater 0.33 = capacity factor (20-35%)kWh per tidal cycleAssuming 706 tidal cycles per year (12 hrs 24 min per cycle)Tester et al., Sustainable Energy, MIT Press, 2005

  • La Rance Barrage Example = 33%R = 8.5 mA = 22 km2GWh/yrTester et al., Sustainable Energy, MIT Press, 2005

  • Proposed Severn Barrage (1989)Boyle, Renewable Energy, Oxford University Press (2004)Never constructed, but instructive

  • Proposed Severn Barrage (1989)Severn River estuaryBorder between Wales and England216 40 MW turbine generators (9.0m dia)8,640 MW total capacity17 TWh average energy outputEbb generation with flow pumping16 km (9.6 mi) total barrage length8.2 ($15) billion estimated cost (1988)

  • Severn BarrageLayoutBoyle, Renewable Energy, Oxford University Press (2004)

  • Severn Barrage ProposalEffect on Tide LevelsBoyle, Renewable Energy, Oxford University Press (2004)

  • Severn Barrage ProposalPower Generation over TimeBoyle, Renewable Energy, Oxford University Press (2004)

  • Severn Barrage ProposalCapital CostsBoyle, Renewable Energy, Oxford University Press (2004)Tester et al., Sustainable Energy, MIT Press, 2005

  • Severn Barrage ProposalEnergy CostsBoyle, Renewable Energy, Oxford University Press (2004)

  • Severn Barrage ProposalCapital Costs versus Energy CostsBoyle, Renewable Energy, Oxford University Press (2004)1p 2

  • Offshore Tidal LagoonBoyle, Renewable Energy, Oxford University Press (2004)

  • Tidal FenceArray of vertical axis tidal turbinesNo effect on tide levelsLess environmental impact than a barrage1000 MW peak (600 MW average) fences soonBoyle, Renewable Energy, Oxford University Press (2004)

  • Promising Tidal Energy Siteshttp://europa.eu.int/comm/energy_transport/atlas/htmlu/tidalsites.html

    CountryLocationTWh/yrGWCanadaFundy Bay174.3Cumberland41.1USAAlaska6.52.3Passamaquody2.11ArgentinaSan Jose Gulf9.55RussiaOrkhotsk Sea12544IndiaCamby157.6Kutch1.60.6Korea10Australia5.71.9

  • Tidal Barrage Environmental FactorsChanges in estuary ecosystemsLess variation in tidal rangeFewer mud flatsLess turbidity clearer waterMore light, more lifeAccumulation of siltConcentration of pollution in siltVisual clutter

  • Advantages of Tidal BarragesHigh predictabilityTides predicted years in advance, unlike windSimilar to low-head damsKnown technologyProtection against floodsBenefits for transportation (bridge)Some environmental benefitshttp://ee4.swan.ac.uk/egormeja/index.htm

  • Disadvantages of Tidal TurbinesHigh capital costsFew attractive tidal power sites worldwideIntermittent power generationSilt accumulation behind barrageAccumulation of pollutants in mudChanges to estuary ecosystem

  • Wave Energy

  • Wave StructureBoyle, Renewable Energy, Oxford University Press (2004)

  • Wave Frequency and AmplitudeBoyle, Renewable Energy, Oxford University Press (2004)

  • Wave Patterns over TimeBoyle, Renewable Energy, Oxford University Press (2004)

  • Wave Power CalculationsHs2 = Significant wave height 4x rms water elevation (m) Te = avg time between upward movements across mean (s) P = Power in kW per meter of wave crest lengthExample: Hs2 = 3m and Te = 10s

  • Global Wave Energy Averageshttp://www.wavedragon.net/technology/wave-energy.htmAverage wave energy (est.) in kW/m (kW per meter of wave length)

  • Wave Energy PotentialPotential of 1,500 7,500 TWh/year 10 and 50% of the worlds yearly electricity demandIEA (International Energy Agency)

    200,000 MW installed wave and tidal energy power forecast by 2050 Power production of 6 TWh/yLoad factor of 0.35DTI and Carbon Trust (UK) Independent of the different estimates the potential for a pollution free energy generation is enormous. http://www.wavedragon.net/technology/wave-energy.htm

  • Wave Energy Technologies

  • Wave Concentration EffectsBoyle, Renewable Energy, Oxford University Press (2004)

  • Tapered Channel (Tapchan)http://www.eia.doe.gov/kids/energyfacts/sources/renewable/ocean.html

  • Oscillating Water Columnhttp://www.oceansatlas.com/unatlas/uses/EnergyResources/Background/Wave/W2.html

  • Oscillating Column Cross-SectionBoyle, Renewable Energy, Oxford University Press (2004)

  • LIMPET Oscillating Water ColumnCompleted 2000Scottish IslesTwo counter-rotating Wells turbinesTwo generators500 kW max powerBoyle, Renewable Energy, Oxford University Press (2004)

  • Mighty Whale Design Japanhttp://www.jamstec.go.jp/jamstec/MTD/Whale/

  • Might Whale DesignBoyle, Renewable Energy, Oxford University Press (2004)

  • Turbines for Wave EnergyBoyle, Renewable Energy, Oxford University Press (2004)http://www.jamstec.go.jp/jamstec/MTD/Whale/Turbine used in Mighty Whale

  • Ocean Wave Conversion Systemhttp://www.sara.com/energy/WEC.html

  • Wave Conversion System in Action

  • Wave Dragonhttp://www.wavedragon.net/technology/wave-energy.htmWave DragonCopenhagen, Denmarkhttp://www.WaveDragon.netClick Picture for Video

  • Wave Dragon Energy Outputin a 24kW/m wave climate = 12 GWh/year in a 36kW/m wave climate = 20 GWh/year in a 48kW/m wave climate = 35 GWh/year in a 60kW/m wave climate = 43 GWh/year in a 72kW/m wave climate = 52 GWh/year. http://www.wavedragon.net/technology/wave-energy.htm

  • Declining Wave Energy CostsBoyle, Renewable Energy, Oxford University Press (2004)

  • Wave Energy Power DistributionBoyle, Renewable Energy, Oxford University Press (2004)

  • Wave Energy Supply vs. Electric DemandBoyle, Renewable Energy, Oxford University Press (2004)

  • Wave Energy Environmental Impacts

  • Wave Energy Environmental ImpactLittle chemical pollutionLittle visual impactSome hazard to shippingNo problem for migrating fish, marine lifeExtract small fraction of overall wave energyLittle impact on coastlinesRelease little CO2, SO2, and NOx11g, 0.03g, and 0.05g / kWh respectivelyBoyle, Renewable Energy, Oxford University Press (2004)

  • Wave Energy Summary

  • Wave Power AdvantagesOnshore wave energy systems can be incorporated into harbor walls and coastal protectionReduce/share system costsProviding dual useCreate calm sea space behind wave energy systemsDevelopment of mariculture Other commercial and recreational uses; Long-term operational life time of plantNon-polluting and inexhaustible supply of energyhttp://www.oceansatlas.com/unatlas/uses/EnergyResources/Background/Wave/W2.html

  • Wave Power DisadvantagesHigh capital costs for initial constructionHigh maintenance costsWave energy is an intermittent resourceRequires favorable wave climate. Investment of power transmission cables to shoreDegradation of scenic ocean front views Interference with other uses of coastal and offshore areas navigation, fishing, and recreation if not properly sitedReduced wave heights may affect beach processes in the littoral zonehttp://www.oceansatlas.com/unatlas/uses/EnergyResources/Background/Wave/W2.html

  • Wave Energy SummaryPotential as significant power supply (1 TW) Intermittence problems mitigated by integration with general energy supply systemMany different alternative designsComplimentary to other renewable and conventional energy technologieshttp://www.oceansatlas.com/unatlas/uses/EnergyResources/Background/Wave/W2.html

  • Future Promise

  • World Oceanic Energy Potentials (GW)SourceTidesWavesCurrentsOTEC1SalinityWorld electric2World hydroPotential (est)2,500 GW2,70035,000200,0001,000,000

    4,000Practical (est)20 GW5005040NPA42,8005501 Temperature gradients2 As of 19983 Along coastlines

    4 Not presently available

    Tester et al., Sustainable Energy, MIT Press, 2005

  • Solar Power Next Weekhttp://www.c-a-b.org.uk/projects/tech1.jpg

    Marine current turbines work, in principle, much like submerged windmills, but driven by flowing water rather than air. They can be installed in the sea at places with high tidal current velocities, or in a few places with fast enough continuous ocean currents, to take out energy from these huge volumes of flowing water. These flows have the major advantage of being an energy resource which is mostly as predictable as the tides that cause them, unlike wind or wave energy which respond to the more random quirks of the weather system. The technology under development by MCT consists of twin axial flow rotors of 15m to 20m in diameter, each driving a generator via a gearbox much like a hydro-electric turbine or a wind turbine. The twin power units of each system are mounted on wing-like extensions either side of a tubular steel monopile some 3m in diameter which is set into a hole drilled into the seabed.

    The submerged turbines, which will generally be rated at from 750 to 1500kW per unit (depending on the local flow pattern and peak velocity), will be grouped in arrays or "farms" under the sea, at places with high currents, in much the same way that wind turbines in a wind farm are set out in rows to catch the wind. The main difference is that marine current turbines of a given power rating are smaller, (because water is 800 times denser than air) and they can be packed closer together (because tidal streams are normally bi-directional whereas wind tends to be multi-directional).

    Environmental Impact Analyses completed by independent consultants have confirmed our belief that the technology does not offer any serious threat to fish or marine mammals. The rotors turn slowly (10 to 20 rpm) (a ship's propeller, by comparison, typically runs 10 times as fast and moreover our rotors stay in one place whereas some ships move much faster than sea creatures can swim). The risk of impact from our rotor blades is extremely small bearing in mind that virtually all marine creatures that choose to swim in areas with strong currents have excellent perceptive powers and agility, giving them the ability to successfully avoid collisions with static or slow-moving underwater obstructions.The "Swanturbines" design is different to other devices in a number of ways. The most significant is that it is direct drive, where the blades are connected directly to the electrical generator without a gearbox between. This is more efficient and there is no gearbox to go wrong. Another difference is that it uses a "gravity base", a large concrete block to hold it to the seabed, rather than drilling into the seabed. Finally, the blades are fixed pitch, rather than actively controlled, this is again to design out components that could be unreliable.

    http://www.darvill.clara.net/altenerg/tidal.htmStingray is designed to extract energy from water that flows due to tidal effects - tidal stream energy. It consists of a hydroplane which has its attack angle relative to the approaching water stream varied by a simple mechanism. This causes the supporting arm to oscillate which in turn forces hydraulic cylinders to extend and retract. This produces high pressure oil which is used to drive a generator. http://www.engb.comFrom http://www.geocities.com/newideasfromtelewise/tidalpowerplant.htm

    The tidal activity in land is much smaller than that of in the sea because of its less flexibility and high density. With the help of a hydraulic system, it is possible to extract energy from land tidal activity. When the tide occur, the top surface of the Earth will move up and down and the body structure of the mechanism fixed on the top surface will also move up and down (see diagrams below). But there occurs a relative motion between the top surface of the Earth and the bottom of the supporting stand because of the density difference between the top and bottom (density will be less on the top surface), flexibility (elasticity) difference between the top and bottom (flexibility will be more on the top surface). The large two-way head piston is rigidly connected to the strong rigid-supporting stand and which is rigidly fixed in the bottom of the deep well.

    During the upward motion of the cylinder (assume that the relative movement between the top and bottom is about 1cm), as the large two- way head piston is remaining stationary related to the bottom, the inside volume of lower chamber will decrease and the fluid in it will experience a high pressure, that causes the fluid in it with a volume of 0.0824m3 to escape through the 32.3cm diameter cylinder (Sc4 - see.fig) provided on the body structure. Since there is a small piston 4(Sp4) which can slide through its small cylinder, the fluid will push this pistonin 1meter and the one way piston 2 (Lp2) connected on the other end will also moves 1meter. Since the diameter of the one way cylinder2 (Lc2) is 1meter then, the volume of the displaced fluid by Lp2 will be 0.785m3 and this fluid will escape through 37.7 cm diameter cylinder 3 (Sc3). This causes, the small piston 3 (Sp3) and the small piston 2 (Sp2) with the rack slides through the small cylinder 2(Sc2) and small cylinder 3 (Sc3) in 7meter. As the rack is meshing with the pinions P1 & P2, it will rotate and through the gear train of the required gear ratio the power will be transferred to the rotor of the generator; and by its rotation, electricity will be produced.

    Similarly, during the down ward motion of the cylinder, in the tidal-fall, the inside volume of upper chamber will decrease and the fluid in it will experience a high pressure that causes the fluid in it with a volume of 0.1m3 to escape through the 35.6cm diameter cylinder (Sc1 - see.fig) provided on the body structure. Since there is a small piston 1(Sp1) which can slide through its small cylinder, the fluid will push this pistonin 1meter and the one way piston 1 (Lp1) connected on the other end will also moves 1meter. Since the diameter of the one way cylinder1 (Lc1) is 1meter then, the volume of the displaced fluid by Lp1 will be 0.785m3 and this fluid will escape through 37.7 cm diameter cylinder 2(Sc2). This causes the small piston 2 (Sp2) and small piston 3 (Sp3) with the rack, slides through the small cylinder 2(Sc2) and small cylinder 3 (Sc3) in 7meter. As the rack is meshing with the pinions P1 & P2, it will rotate and through the gear train of the required gear ratio the power will be transferred to the rotor of the generator and by its rotation, electricity will be produced.

    The construction of this barrage began in 1960. The system used consists of a dam 330m long and a 22km2 basin with a tidal range of 8m, it incorporates a lock to allow passage for small craft. During construction, two temporary dams were built on either side of the barrage to ensure that it would be dry, this was for safety and convenience. The work was completed in 1967 when 24, 5.4m diameter Bulb turbines, rated at 10MW were connected to the 225kV French Transmission network.Blue Energy Power System - For large scale power production, multiple turbines are linked in series to create a tidal fence across an ocean passage or inlet. These are large scale, site specific, custom engineered energy installations which will vary in size and output by location. These structures have the added benefit as a transportation solution.

    Mega Power System - A scaled-up version of the Blue Energy Power System, the mega class is a tidal fence capable of producing thousands of megawatts of power. These tidal fences can be many kilometers long and can operate in depths of up to 70 metres.

    http://www.bluenergy.com/technology.htmlThe potential energy of a set of waves is proportional to wave height squared times wave period (the time between wave crests). Longer period waves have relatively longer wavelengths and move faster. The potential energy is equal to the kinetic energy (that can be expended). Wave power is expressed in kilowatts per meter (at a location such as a shoreline).

    The formula below shows how wave power can be calculated. Excluding waves created by major storms, the largest waves are about 15 meters high and have a period of about 15 seconds. According to the formula, such waves carry about 1700 kilowatts of potential power across each meter of wavefront. A good wave power location will have an average flux much less than this: perhaps about 50 kw/m.

    Formula: Power (in kw/m) = k H2 T ~ 0.5 H2 T,

    where k = constant, H = wave height (crest to trough) in meters, and T = wave period (crest to crest) in seconds.

    Potential world-wide wave energy contribution to the production of electricity is estimated by IEA (International Energy Agency) to be between 10 and 50% of the worlds yearly electricity demand of 15,000 TWh

    A recent study by the DTI and Carbon Trust in UK is stating some 200,000 MW installed wave and tidal energy power by 2050 which with a load factor of 0.35 is resulting in a power production of 6 TWh/y. Independent of the different estimates the potential for a pollution free energy generation is enormous http://www.wavedragon.net/technology/wave-energy.htmAnother promising type of wave energy power plant is a shoreline-based system called the Tapered Channel (Tapchan). The principle here is capital intensive yet has potential due to its ruggedness and simplicity. A tapering collector funnels incoming incoming waves in a channel. As the wave travels down the narrowing channel it increases in height till the water spills into an elevated reservoir. The water trapped in the reservoir can be released back to the sea similar to conventional hydroelectric power plants to generate electricity [1]. The advantage of this particular system lies in its ability to buffer storage which dampens the irregularity of the waves. However, the Tapchan system does require a low tidal range and suitable shoreline topography -limiting its application world-wide. A demonstration prototype of this design has been running since 1985 and plans are under consideration to build a commercial scale plant in Java [8].

    http://www.oceansatlas.com/unatlas/uses/EnergyResources/Background/Wave/W2.htmlThe Oscillating Water Column generates electricity in a two step process. As a wave enters the column, it forces the air in the column up the closed column past a turbine, and increases the pressure within the column. As the wave retreats, the air is drawn back past the turbine due to the reduced air pressure on the ocean side of turbine.

    Much research is occurring internationally to develop oscillating water columns which require less stringent siting conditions, including the OSPREY and floating columns, such as the Japanese Mighty Whale Another notable example of an OWC is the Mighty Whale. It is the worlds largest offshore floating OWC and was launched in July 1998 by the Japan Marine Science and Technology Center. This prototype, moored facing the predominant wave direction, has a displacement of 4,400 tons and measures 50m long. The Mighty Whale has three air chambers that convert wave energy into pneumatic energy. Wave action causes the internal water level in each chamber to rise and fall, forcing a bi-directional flow over an air-turbine to generate energy. The resulting electricity is supplied mainly to the nearby coastal areas. Storage batteries onboard ensure that electricity is available even during periods of reduced wave activity. It is projected that a row of such devices could be used to supply energy to fish farms in the calm waters behind the devices, and aeration/purification of seawater [7].

    http://www.oceansatlas.com/unatlas/uses/EnergyResources/Background/Wave/W2.htmlThis technology builds upon SARA's pioneering Ocean Wave Energy Conversion system, awarded US Patent 5,136,173; 1992. Unlike alternative concepts that make use of cumbersome intermediate mechanical stages, SARA's approach uses direct conversion of mechanical fluid energy into electricity, via a highly efficient magnetohydrodynamics (MHD) process. Product:Rapidly-deployable Wave-powered MHD Electric Generator for the US NavyLow-cost commercial power for coastal communities. Benefits:Almost no moving parts. No gears, no levers, no turbines, no drive belts, no bearings, etc. Direct, local, and efficient conversion of fluid motion into electricity, with no intermediate mechanical stages. Highly-compatible with very-strong, but slow-moving, driving forces (ocean waves, for example).

    High capital costs for initial construction [9] to resist exposure to strong wave forces, storms, and corrosion [10]; Wave energy is an intermittent resource [2]; Requires favorable wave climate. The highest concentration of wave energy occurs between the latitudes 40 and 60 in each hemisphere, which is where the winds blow most strongly. Latitudes of around 30 of the equator due to the regular trade winds may also be suitable for exploitation of wave energy [11]; Offshore wave energy systems require investment power transmission cables for electrical connections to shore [11]; Degradation of scenic ocean front views from wave energy devices located near or on the shore, and from onshore overhead electric transmission lines [10]; Potential interference with other uses of coastal and offshore areas such as navigation, fishing, and recreation if not properly sited [2]; By reducing the height of waves they may affect beach processes in the littoral zone [2].

    Ocean waves have the potential to contribute up to one TW to the global energy supply. The problems associated with the intermittence of wave energy can be smoothed by integration with the general energy supply system. Many different wave power plants, some of them multi-purpose, have been proposed, assessed, and cost-estimated With the development of large-scale demonstration and commercial power plants underway, wave energy will begin to play an increasing role in complementing other renewable and conventional energy technologies to meet global needs.