Tidal Hydrokinetic Energy
Brian PolagyeResearch Assistant Professor
University of Washington
SAMPE 2010SAMPE 2010May 17-20, 2010
NNMREC
Tidal EnergyTidal Energy
Northwest National Marine Renewable Energy Center
Materials Suitability Materials Suitability
NNMREC
Tidal Energy
Barrage Hydrokinetic
Comparable to hydroelectric
Very high cost and
Comparable to wind
Potentially lower cost andVery high cost and environmental footprint
Potentially lower cost and environmental footprint
NNMREC
Tidal Hydrokinetic Devices
NNMREC
“Typical” Sites and DevicesGearbox Generator Ch i hGearbox‐Generator Pile Chain Anchor
Direct Drive Generator
Drive TrainRotor 5 20 m
Tension LegGravity Base
2‐4 m/s
5‐20 m 10‐20 rpm
20‐60 m Foundation
NNMREC
Tidal Energy Projects in Puget Sound
100‐200 avg. MW practically recoverable
Race RocksDemonstration turbine
p y
Marrowstone IslandDemonstration array
Admiralty InletPilot project
Demonstration array
NNMREC
Local Drivers■ Initiative 937 obligations
– 15% renewable energy by 2020– 15% renewable energy by 2020
– Excludes conventional hydropower
■ Limited transmission capacity for new■ Limited transmission capacity for new wind energy
Tid l d t■ Tidal energy advantages– Predictable resource
N CO i i– No CO2 emissions
– No visual impact
– Close to load
NNMREC
Tidal Energy Challenges
Technology ReadinessReadiness
Societal Concerns
iEconomic Viability
Environmental Effects
NNMREC
Tidal EnergyTidal Energy
Northwest National Marine Renewable Energy Center
Materials Suitability Materials Suitability
NNMREC
Northwest National Marine Renewable Energy Center (NNMREC)
UW‐NNMRECTidal Energy
OSU‐NNMRECWave Energy
Resource and Site
Assessment
Device and Array
Optimization
Testing Facilities
Environmental Effects
Materials SuitabilityAssessment Optimization
8 Faculty members involved6 Graduate student researchers supported6 Graduate student researchers supported
NNMREC
Resource and Site Assessment ‐ Approach
Shipboard SurveyR/V Jack RobertsonR/V Jack Robertson
Land ObservationAIS Ship Tracks
Seabed InstrumentationMeasurement Tripod
AIS Ship Tracks
NNMREC
ROV Surveys
Seabed– Cobbles (10‐20cm)Cobbles (10 20cm)– Shell fragments– SpongesS ll l– Small slope
Less than 4m visibility (with lighting)
NNMREC
Sea Spider Instrumentation Tripod
CTDO (conductivity, temperature, depth,
Acoustic release (redundant recovery)
ADCP
dissolved oxygen –partnership with WA Dept of Ecology)
( y)
(Acoustic Doppler Current Profiler) Fish Tag Recorder
(partnership with NMFS)
Hydrophone (background noise) T‐Pod/C‐Pod
(porpoise clicks)
Lead Weight(650 lbs)Programmed for 3
month deployments
NNMREC
month deployments
Challenging Research Environment
NNMREC
Ferry Noise Study
Sea Spider
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Device and Array Optimization
Numerical Simulations:P ll l i l ti fParallel simulations of device and array performance
R/V Jack Robertson
Wave‐Current Flume:E i t l t diExperimental studies of device wakes
NNMREC
Understanding Environmental Effects
■ Near‐field Effects
– Pressure drop (model)– Sediment transport p(model)
– Noise (experiment)
■ Far‐field Effects
id l i ( d l)– Tidal regime (model)
NNMREC
Tidal EnergyTidal Energy
Northwest National Marine Renewable Energy Center
Materials Suitability Materials Suitability
NNMREC
Materials Suitability
■ Hydrodynamic performance
■ Structural performance– Metal corrosionMetal corrosion– Composite aging
i i l
Orme, Masters, Griffiths (2001)
■ Long maintenance intervals– 2‐4 years for power train– 20+ years for foundation
NNMREC
316 Stainless – 3 months immersion
Approaches to Minimize Biofouling
■ Biocides: “Anti‐fouling”– Effective– ToxicToxic
■ Low friction: “Foul‐release”– Cost– Long‐term effectiveness
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Shallow Water Biofouling
Clean Current turbine: 6 months deployment
Before After
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Deep Water Biofouling
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Damage: Composite Aging
■ Water absorption■ Water absorption, leading to loss of strength
I i i■ In‐situ screening tests
– 9 – 18 months exposure– Four composite material systems
NNMREC
Thank You!Thank You!
More about Tidal Energy:http://depts.washington.edu/nnmrec
More about Wave Energy:http://nnmrec.oregonstate.edu/
NNMREC