oceanic energy - presentation

8/8/2019 Oceanic Energy - Presentation

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Renewable Energy VRenewable Energy V

Ocean Waves, Tide andOcean Waves, Tide andThermal Energy ConversionThermal Energy Conversion

Asim ZiaAsim Zia

Environmental Studies 133Environmental Studies 133

Alternative Energy StrategiesAlternative Energy StrategiesSan Jose State UniversitySan Jose State University

Spring 2007Spring 2007


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Overview [chapter 14]Overview [chapter 14] What are ocean energy resources?What are ocean energy resources? How tidal energy is extracted? What are itsHow tidal energy is extracted? What are its

technological limitations andtechnological limitations andeconomic/sustainability prospects?economic/sustainability prospects?

How wave energy is extracted? What are itsHow wave energy is extracted? What are itstechnological limitations andtechnological limitations andeconomic/sustainability prospects?economic/sustainability prospects?

How oceanHow ocean--thermal energy is extracted? Whatthermal energy is extracted? What

are its technological limitations andare its technological limitations andeconomic/sustainability prospects?economic/sustainability prospects? More information atMore information at

http://www.eere.energy.gov/consumer/renewabhttp://www.eere.energy.gov/consumer/renewable_energy/ocean/index.cfm/mytopic=50007le_energy/ocean/index.cfm/mytopic=50007


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Ocean Energy ResourcesOcean Energy Resources


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Tidal EnergyTidal Energy

http://www.energyquest.ca.gov/story/chapter14.html

At least16 feet

distanceneededbetweenhigh andlow tides


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Tidal Energy [Limited Sites]Tidal Energy [Limited Sites]


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Tidal Energy [Technologies]Tidal Energy [Technologies]

Barrage or damBarrage or damA barrage or dam is typically used to convert tidalA barrage or dam is typically used to convert tidal

energy into electricity by forcing the water throughenergy into electricity by forcing the water throughturbines, activating a generator. Gates and turbinesturbines, activating a generator. Gates and turbinesare installed along the dam. When the tides produceare installed along the dam. When the tides producean adequate difference in the level of the water onan adequate difference in the level of the water onopposite sides of the dam, the gates are opened. Theopposite sides of the dam, the gates are opened. Thewater then flows through the turbines. The turbineswater then flows through the turbines. The turbinesturn an electric generator to produce electricity.turn an electric generator to produce electricity.


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Annual Average Electricity Generation inAnnual Average Electricity Generation inkWhr [E] is equal tokWhr [E] is equal to

Where: COP is coefficient of performance[typically 0.2 to 0.35]

R is dam head in Meters and A is the

area of water impoundment in KM2


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Tidal fenceTidal fenceTidal fences look like giant turnstiles. They can reachTidal fences look like giant turnstiles. They can reach

across channels between small islands or acrossacross channels between small islands or acrossstraits between the mainland and an island. Thestraits between the mainland and an island. Theturnstiles spin via tidal currents typical of coastalturnstiles spin via tidal currents typical of coastalwaters. Some of these currents run at 5waters. Some of these currents run at 58 knots8 knots(5.6(5.69 miles per hour) and generate as much energy9 miles per hour) and generate as much energy

as winds of much higher velocity. Because seawateras winds of much higher velocity. Because seawaterhas a much higher density than air, ocean currentshas a much higher density than air, ocean currentscarry significantly more energy than air currentscarry significantly more energy than air currents(wind).(wind).


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Tidal turbineTidal turbineTidal turbines look like wind turbines. They areTidal turbines look like wind turbines. They are

arrayed underwater in rows, as in some windarrayed underwater in rows, as in some windfarms. The turbines function best where coastalfarms. The turbines function best where coastalcurrents run at between 3.6 and 4.9 knots (4currents run at between 3.6 and 4.9 knots (4and 5.5 mph). In currents of that speed, a 15and 5.5 mph). In currents of that speed, a 15--meter (49.2meter (49.2--feet) diameter tidal turbine canfeet) diameter tidal turbine cangenerate as much energy as a 60generate as much energy as a 60--meter (197meter (197--feet) diameter wind turbine. Ideal locations forfeet) diameter wind turbine. Ideal locations fortidal turbine farms are close to shore in watertidal turbine farms are close to shore in water

depths of 20depths of 2030 meters (65.530 meters (65.598.5 feet).98.5 feet).


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Tidal Energy [EnvironmentalTidal Energy [Environmental

Impacts]Impacts] Tidal power plants that dam estuaries canTidal power plants that dam estuaries canimpede sea life migration, and silt buildimpede sea life migration, and silt build--ups behind such facilities can impact localups behind such facilities can impact localecosystems.ecosystems.

Tidal fences may also disturb sea lifeTidal fences may also disturb sea lifemigration.migration.

Newly developed tidal turbines may proveNewly developed tidal turbines may proveultimately to be the least environmentallyultimately to be the least environmentallydamaging of the tidal power technologiesdamaging of the tidal power technologies

because they don't block migratory paths.because they don't block migratory paths.


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http://www.tidalelectric.com/OFGEM%20Exec%20Summary.pdf


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http://www.tidalelectric.com/OFGEM%20Exec%20Summary.pdf


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Wave Energy [Technologies]Wave Energy [Technologies]

Oscillating water columnOscillating water column

The oscillating water column consists of a partiallyThe oscillating water column consists of a partiallysubmerged concrete or steel structure that has ansubmerged concrete or steel structure that has anopening to the sea below the waterline. It encloses aopening to the sea below the waterline. It encloses acolumn of air above a column of water. As wavescolumn of air above a column of water. As wavesenter the air column, they cause the water column toenter the air column, they cause the water column torise and fall. This alternately compresses andrise and fall. This alternately compresses anddepressurizes the air column. As the wave retreats,depressurizes the air column. As the wave retreats,the air is drawn back through the turbine as a resultthe air is drawn back through the turbine as a resultof the reduced air pressure on the ocean side of theof the reduced air pressure on the ocean side of the

turbine.turbine.


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Wave Energy [water column]Wave Energy [water column]

http://www.energyquest.ca.gov/story/chapter14.html

Higher waveheight andfasterwaves

create moreelectricity


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P=1.96h2T

Where

Pis power in kw/m

his wave height in m

Tis wave period, time forsuccessive crests to pass a fixed

observer (e.g. 4 seconds)


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Wave Energy ResourcesWave Energy Resources


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TapchanTapchan

The tapchan, or tapered channel system,The tapchan, or tapered channel system,

consists of a tapered channel, which feedsconsists of a tapered channel, which feedsinto a reservoir constructed on cliffs above seainto a reservoir constructed on cliffs above sealevel. The narrowing of the channel causeslevel. The narrowing of the channel causesthe waves to increase in height as they movethe waves to increase in height as they move

toward the cliff face. The waves spill over thetoward the cliff face. The waves spill over thewalls of the channel into the reservoir and thewalls of the channel into the reservoir and thestored water is then fed through a turbine.stored water is then fed through a turbine.


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Pendulor devicePendulor device

The pendulor waveThe pendulor wave--power device consists of apower device consists of a

rectangular box, which is open to the sea atrectangular box, which is open to the sea atone end. A flap is hinged over the openingone end. A flap is hinged over the openingand the action of the waves causes the flap toand the action of the waves causes the flap toswing back and forth. The motion powers aswing back and forth. The motion powers a

hydraulic pump and a generator.hydraulic pump and a generator.


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Wave Energy [EnvironmentalWave Energy [Environmental

Impacts]Impacts] Careful site selection is the key to keeping theCareful site selection is the key to keeping theenvironmental impacts of wave powerenvironmental impacts of wave powersystems to a minimum.systems to a minimum.

Wave energy system planners can choose sitesWave energy system planners can choose sitesthat preserve scenic shorefronts.that preserve scenic shorefronts.

They also can avoid areas where wave energyThey also can avoid areas where wave energy

systems can significantly alter flow patterns ofsystems can significantly alter flow patterns ofsediment on the ocean floor.sediment on the ocean floor.

More info on wave energy is atMore info on wave energy is athttp://www.worldenergy.org/wechttp://www.worldenergy.org/wec--

geis/publications/reports/ser/wave/wave.aspgeis/publications/reports/ser/wave/wave.asp


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Ocean Thermal Energy ConversionOcean Thermal Energy Conversion

[OTEC][OTEC]

A difference of at least 38 degreesA difference of at least 38 degrees

Fahrenheit (about 20 C) is neededFahrenheit (about 20 C) is neededbetween the warmer surface waterbetween the warmer surface waterand the colder deep ocean water toand the colder deep ocean water to

generate OTEC electricity.generate OTEC electricity.


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[OTEC][OTEC]

http://www.worldenergy.org/wec-geis/publications/reports/ser/ocean/ocean.asp


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[OTEC]: Global Resource Availability[OTEC]: Global Resource Availability


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[OTEC]: Global Resource Availability[OTEC]: Global Resource Availability


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OTEC TechnologyOTEC Technology


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OTEC Power Plant featuresOTEC Power Plant features


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OTEC Power Plant ExperimentOTEC Power Plant Experiment

http://www.worldenergy.org/wec-geis/publications/reports/ser/ocean/ocean.asp


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Typical Problems with OceanTypical Problems with OceanEnergy or ARE THESE REALLYEnergy or ARE THESE REALLY

PROBLEMS?PROBLEMS? Capital Intensive?Capital Intensive? Storm Resiliency?Storm Resiliency?

Scarcity of shoreline sites (competition withScarcity of shoreline sites (competition withresidential, recreational and industrial uses)?residential, recreational and industrial uses)?

Environmental impacts are only local (estuariesEnvironmental impacts are only local (estuariesdamaged, migratory fish and waterfowls mightdamaged, migratory fish and waterfowls mightsuffer, sediment transportation)?suffer, sediment transportation)?

Navigation hazards, aesthetics?Navigation hazards, aesthetics?

oceanic energy - presentation

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