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Wave Energy

TechnologyKa Hana ‘Imi Na‘auao – A Science Careers Curriculum Resource Go to: www.cds.hawaii.edu/kahana

Why explore wave powerin Hawai‘i?

Wave Energy Levels (kW/m of Wave Front)Formula used to calculate this Power (in kW/m) = k H² T ~ 0.5 H² T

k = constant, H = wave height (crest to trough) in meters, andT = wave period (crest to crest) in seconds

OverviewWhat is wave power?Wave energy

conversion systems(WECS)

Types of energy Physics of water power Benefits & ChallengesWave Energy

Technology (WET) inHawai‘i

PowerBuoy™

What is Wave Power?Wave power is the ________ of ocean surface

waves and the capture of that energy to douseful _______ - including electricitygeneration, desalination and the pumping ofwater.

Wave power is a form of __________ energy.Tidal power and ocean currents are othersources of ocean hydro-electric power.

energy

work

renewable

Wave Energy ConversionSystems (WECS)

1. Oscillating WaterColumns (OWC)

- generate electricityfrom the wave-drivenrise and fall of waterin a cylindrical shaft.The rising and fallingwater column drivesair into and out of thetop of the shaft,powering an air-driven turbine.

Wave Energy ConversionSystems (WECS)

2. Wave Surge orFocusing Devices

- These shoreline devices,also called "taperedchannel" or "TAPCHAN"systems, rely on a shore-mounted structure tochannel and concentratethe waves, driving theminto an elevated reservoir.Water flow out of thisreservoir is used togenerate electricity, usingstandard hydropowertechnologies.

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Wave Energy ConversionSystems (WECS)

3. Floats or PitchingDevices - Thesedevices generateelectricity from thebobbing or pitchingaction of a floatingobject. The objectcan be mounted toa floating raft or toa device fixed onthe ocean floor.

Archimedes Wave Swing

Which is it?1.Oscillating Water column?

2.Wave Surge/Focuser?3. Float/Pitch Device?

Which is it?1.Oscillating Water column?

2.Wave Surge/Focuser?3. Float/Pitch Device?

Wavegen™ created the“Limpet” … the world’s1st wave power station.It is in Islay, Scotland.

Which system arethese devices?

WaveRoller

Pelamis

Salter Duck

WaveDragonNone of the above! The Physics ofHydro-Electric Power

Key physics concepts: energy, power & work

What is Bernoulli’s Principle? (hint: think about conservation of energy)

How might engineers apply it to wave energy?

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Types of energy in a fixedwave power generator

Where in this diagram do each of the followingenergy types occur?

wave energy mechanical energy pneumatic energy electrical energy

Wave Power:Benefit or Challenge?

Portable, modulardesign

Noise

Pollution

Cost-savingpotential

Maintenance Site specifications

Abundance ofresource

Appearance ofdevice

Marine life effects Fishing & recreation Installation &

development cost Coastal erosion Sustainability

Hawaii’s PowerBuoy™Cylindrical, Steel Buoy

Diameter - 4.5 to 5 meters.Length – 12 to 20 meters.Mass – 35 to 55 tons.

Operates 1.0 - 4.0 metersbelow surface.

Average System Output:20 kW

Peak Output: 45-50 kWMooring:

Rigid spar buoy with universaljoint at base.

Deadweight anchor rock boltedinto the substrate providesup to 100-ton holding force.

Kane‘ohe Marine CorpsBase WET Project

The PowerBuoy™ islow-cost, efficient,and readily deployableelectric power thatcan reduce costs atKane‘ohe MarineCorps Base & similarnaval sites

Subsea cable installation

Issues KMCB had to address Shoreline ConditionsOceanographic Conditions Infrastructure Impacts Recreation Impacts Public Safety Cultural considerations

Subsea Cable Installation

Possible Environmental Issues

Alien Invasive Species Entanglement Entrapment Electromagnetic Radiation

(EMR) Electrical leakageHeat generation and

releaseNoise

Diver Working on Plate

Installation for Biological

Monitoring

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Hawaiian Blessing of Site Cable and Vault Located Above Ground

Historic Preservationstructure eligible for listing in National Register of Historic Places

Cultural ConsiderationAncient Hawaiian Burial Ground

Researchers foundEnvironmental Advantages

No fuel Absence of CO2 emissions, radiation, and particulate

matterNo waste or disposal requirementsNo danger of spillage or other environmental damage

No negative impact on marine life can encourage growth

Live coral areas avoided

Minimal aesthetic impact

No noise pollution

No visual pollutionAnchor Box

Goals of WET in Hawai‘i Develop and

ValidateTechnology

Demonstratereliability and costeffectiveness

Demonstratefeasibility ofcombining powerfrom a multi-buoyarrayAnchor Installation