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The Viability of Wave Energy. Applicability for the Pacific Northwest?. Visual Impact Comparison. Relative Strength of Wave Energy. Best sites are a) North Atlantic b) Gulf of Alaska – units are KW/meter. More Continuous Data. Wave Resource Map. Conceptual Difficulties. - PowerPoint PPT Presentation
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The Viability of Wave EnergyThe Viability of Wave Energy
Applicability for the Pacific Applicability for the Pacific Northwest?Northwest?
Visual Impact ComparisonVisual Impact Comparison
Relative Strength of Wave Energy
Best sites are a) North Atlantic b) Gulf of Alaska – units are KW/meter
More Continuous Data
Wave Resource MapWave Resource Map
Conceptual DifficultiesConceptual Difficulties
In a wave, the energy content is In a wave, the energy content is distributed throughout the wavedistributed throughout the wave
Therefore, one needs to build a device to Therefore, one needs to build a device to focus or collimate that distributed energyfocus or collimate that distributed energy
Design challenge then becomes a) how big Design challenge then becomes a) how big of device is needed and b) what is the of device is needed and b) what is the efficiency of converting wave mechanical efficiency of converting wave mechanical energy into electricity?energy into electricity?
Wave energy is variable hourly and Wave energy is variable hourly and seasonaly but is continous over 24 hoursseasonaly but is continous over 24 hours
Three Basic Kinds of SystemsThree Basic Kinds of Systems
Offshore (so your dealing with swell energy Offshore (so your dealing with swell energy not breaking waves)not breaking waves)
Near Shore (maximum wave amplitude)Near Shore (maximum wave amplitude) Embedded devices (built into shoreline to Embedded devices (built into shoreline to
receive breaking wave – but energy loss is receive breaking wave – but energy loss is occurring while the wave is breaking) occurring while the wave is breaking)
Some PhysicsSome Physics
Ocean waves are irregular and are not Ocean waves are irregular and are not easily characterized by an average heighteasily characterized by an average height
Relevant parameter is A, or amplitude of Relevant parameter is A, or amplitude of the wave (above mean sea level)the wave (above mean sea level)
More PhysicsMore Physics
Power per meter is the product of the energy density and Power per meter is the product of the energy density and the wave front velocity (inverse of period)the wave front velocity (inverse of period)
On the PNW coast, values for average wave amplitude and for wave period are such that wave power is in the 30-50 kw/m area.
So potential yield along the Oregon Coast, assuming 10% efficiency is:
40 kw/m x 1000 m/km x 600 km = 24000 MW equivalent to PNW Hydro
Devices 1: The Air Devices 1: The Air PistonPiston
Incoming wave pushes water level up to basically compress air in a piston to turn the crank on a generator. When water recedes, air comes back into the chamber.
This device is known as the oscillating water column (OSC).
OSC ContinuedOSC Continued
In principle, one could modify extant coastal headline topography to build these devices.
Note: Red Line is average sea level – front wall must be located below that line to make a seal so that the air doesn’t rush out – tidal variations are therefore important
Difficulties with OWC Difficulties with OWC approachapproach
• Initial cost of barrier wall is high – Initial cost of barrier wall is high – due to lack of access to the site (not due to lack of access to the site (not easy to build anything on a coastal easy to build anything on a coastal headland)headland)
• Zoning regulations protect most Zoning regulations protect most coastal headlandscoastal headlands
• Rich marine life is often found thereRich marine life is often found there• Device must withstand potentially big Device must withstand potentially big
stormsstorms
Unit Capacity of OWCUnit Capacity of OWC
• Physics is similar to that of a wind turbine but Physics is similar to that of a wind turbine but wave power is more dense wave power is more dense
• Yield depends on total square meters of rotor Yield depends on total square meters of rotor area but efficiencies are very difficult to area but efficiencies are very difficult to calculatecalculate
• Near Shore anchored devices capture highest Near Shore anchored devices capture highest amount of wave energy but sensitive to local amount of wave energy but sensitive to local mean sea levelmean sea level
• Reliability of waves is about 2 times higher Reliability of waves is about 2 times higher than windthan wind
Unit Capacity/FootprintUnit Capacity/Footprint
• Based on existing ON shore facility in Based on existing ON shore facility in India (operational around 1993)India (operational around 1993)
• 50 KW plant requires50 KW plant requires• 100 square meter footprint and 3000 100 square meter footprint and 3000
tons of concretetons of concrete• Scaling up to 100 MW implies 2000 Scaling up to 100 MW implies 2000
individual 100 square meter individual 100 square meter installations or roughly 5 per mile installations or roughly 5 per mile along Oregon coastline and this is just along Oregon coastline and this is just for 100 MWfor 100 MW
Conclusions about OWCConclusions about OWC
Shoreline installations probably don’t Shoreline installations probably don’t make sense – even if previous make sense – even if previous calculation is wrong by a factor of 10 calculation is wrong by a factor of 10 (which is unlikely)(which is unlikely)
Therefore, look towards large Therefore, look towards large installations in near shore installations in near shore but that but that could be expensivecould be expensive
Ocean Power Technologies Ocean Power Technologies ClaimClaim
• The footprint of a 100MW conventional The footprint of a 100MW conventional power plant, including surrounding power plant, including surrounding grounds, fuel unloading areas, waste grounds, fuel unloading areas, waste settling ponds, and additional facilities settling ponds, and additional facilities can be up to 2 sq miles (not true on can be up to 2 sq miles (not true on average). A comparable OPT power average). A comparable OPT power plant would occupy less than 1 square plant would occupy less than 1 square mile of unused ocean surface out for mile of unused ocean surface out for sight from the shore (sight from the shore (okay?)?)
The Tapered Channel The Tapered Channel DeviceDevice
• Works like a hydroelectric damWorks like a hydroelectric dam
Waves rush in to fill reservoir which then drains through a turbine system back into the ocean. Simple idea really. Power depends on total volume of water.
Pros and Cons of TAPCHANPros and Cons of TAPCHAN
• Could incorporate this into new kinds of seawall/jetty/harbor protection projects
• Average wave energy must be high in order to push all the water into the reservoir
• Reservoir needs to stay full and can’t drain at low tides
• Significant capital cost and large coastal footprint per MW because the depth of the reservoir is shallow
• Likely not practical in most locations
Power Buoy ContinuedPower Buoy Continued Unit capacities are small (20KW) so Unit capacities are small (20KW) so
you need a large network – possibly you need a large network – possibly subject to catastrophic failure in subject to catastrophic failure in severe weathersevere weather
An Offshore Buoy Farm
Initial prototype was 50 Watts: Scaled capacity for a 12 x15 foot cylinder is 250 KW (on paper) 4000 for 1000 MW farm
Principle Advantage: Can Withstand severe Weather
Power Buoy FootprintPower Buoy Footprint
80 MW per square KM this is good
Don’t need to be anchored to sea floor
But Material Footprint is But Material Footprint is largelarge
• Hard to find real technical data from Hard to find real technical data from the vendorthe vendor
• Can scale a couple of known casesCan scale a couple of known cases
• OPT 20KW buy weighs 17 tonsOPT 20KW buy weighs 17 tons
• That’s 850 tons of material per MW That’s 850 tons of material per MW much more material intensive much more material intensive than wind turbinesthan wind turbines
The Overtopping DeviceThe Overtopping Device
Similar to TAPCHAN idea but can easily be installed near short instead of on shore. Power basically depends on incoming wave amplitude (height above mean sea level)
Focus MechanismFocus Mechanism
The The Wave Dragon Project Project
Ambitious project to harvest up to 10 Ambitious project to harvest up to 10 Gigawatts of Power in the North AtlanticGigawatts of Power in the North Atlantic
Floating sea monstersFloating sea monsters
Pros and Cons of Wave DragonPros and Cons of Wave Dragon
In principle this could actually workIn principle this could actually work Unit capacity appears to be 16 Unit capacity appears to be 16
Turbine 4 MW individual dragonTurbine 4 MW individual dragon 25,000 then gives you 10 GW of 25,000 then gives you 10 GW of
powerpower Principle challenge is then “grid Principle challenge is then “grid
connection” but scale of project does connection” but scale of project does not seem formidablenot seem formidable
Hinged DevicesHinged Devices A large Sea Snake A large Sea Snake length is important length is important
to generate high unit capacitiesto generate high unit capacities Material/production scheme similar to wind Material/production scheme similar to wind
turbine main shaftsturbine main shafts
UK Pelamis ProjectUK Pelamis Project
Unit Capacity is 750 KW; Power is generated at each of the hinged locations essentially through a device that converts pressure wave energy into electrical current.
Each tube is 150 meters long and 3.5 meters wide
UK project employs 7 tubes to generate 5.25 MW
Biggest potential problem (besides grid connection) is durability
The Pelamis ProjectThe Pelamis Project
To set the scale of the devices
The Future The Future Sea Snake Farm ? ?
Footprint argument is favorable: 30MW Footprint argument is favorable: 30MW facility would occupy 1 sq km of ocean.facility would occupy 1 sq km of ocean.
Look to the UK to seriously develop this Look to the UK to seriously develop this resource if initial prototypes prove succesfulresource if initial prototypes prove succesful
New Idea New Idea Use Bottom Waves Use Bottom Waves
Wave Roller device Wave Roller device anchored to the sea anchored to the sea floor (obviously near the cost)floor (obviously near the cost)
Easiest to build electricit export Easiest to build electricit export infrastructureinfrastructure
But energy density is lower; still But energy density is lower; still prototypes are being developedare being developed
SummarySummary
There is much potential in worldwide wave There is much potential in worldwide wave energy; 1000 TerraWatts availableenergy; 1000 TerraWatts available
Capturing wave energy and converting that Capturing wave energy and converting that into electricity is difficult into electricity is difficult but this allows for but this allows for innovate devices to be designedinnovate devices to be designed
Large scale projects very capital intensiveLarge scale projects very capital intensive Optimum technology not yet discovered so Optimum technology not yet discovered so
best to experimentbest to experiment Surface sea snakes may be best optionSurface sea snakes may be best option
Potential Local ProjectsPotential Local Projects
OPT facility at off shore from ReedsportOPT facility at off shore from Reedsport Oregon State wave energy research facility Oregon State wave energy research facility
at newportat newport Tidal power project in Tacoma NarrowsTidal power project in Tacoma Narrows
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