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UTK FWF Seminar – Sept 18, 2013
Dr. Mark Bevelhimer
Oak Ridge National Laboratory
Understanding the
Effects of Hydrokinetic
Devices on Aquatic
Organisms
Marine and Hydrokinetic Energy Devices Extract Energy from Water without Dams
www.bourneenergy.com www.atlantisresourcescorporation.com
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www.openhydro.com
www.newenergycorp.ca
Primary Stressors of Concern Noise
Electromagnetic Fields (EMF)
Physical Encounters (blade strike)
Effects of Concern Injury or death
Behavioral effects (feeding, spawning)
Impediment to movement and migration
Free Flow Power
ORPC
Noise: Field Measurements
Underwater sound emitted from a variety of natural and anthropogenic sources have been recorded and analyzed
Sound levels compared to fish hearing sensitivity
Measurement at operating devices has been a challenge
(AAMI sound analysis software by PNNL)
Noise: Field Measurements
Measured SPL from TidGen turbine at 20m
Relative power spectral densities: • work boat with 25 hp motor • tugboat and barge train • cabin cruiser with diesel engines • rain • ambient background
Noise as a fxn of distance: • passing vessels of various sizes on the Tennessee and Mississippi rivers • predicted levels of the ORPC TidGen turbine as recorded in Cobscook Bay, Maine.
Noise: Field Measurements
Sound fields of three vessels (small boat, cruiser, tug & barge) relative to a 4-turbine MHK array at proposed site on the Mississippi River near Memphis, TN.
Noise: Mesocosm Studies Behavioral responses to recorded HK
device sound evaluated in net pen studies.
Largemouth bass, paddlefish, and pallid sturgeon (7-10 at a time).
Volumes represented distances of 0-60 m from device.
Fish movement tracked by surgically implanted transmitters.
Location data used to evaluate attraction, avoidance, and change in activity.
RESULTS
No consistent trends of attraction or avoidance to the sound at any volume.
Level of activity varied among the 3 species, but no consistent changes in activity in response to sound at any volume.
Floating Net Pen (6m wide x 20m long x 1.5m deep)
Underwater Speaker
Arial view of sound levels in net pen at V=6 setting (SPL range 126-140 dB)
EMF: Laboratory Studies
SHORT-TERM EXPOSURE METHODS
1 fish per tank in both treatment and control aquaria
Treatment tanks with 1 of 2 magnet types on one side of tank
Half-pipe cover provided on each side
46-hr observation recorded on digital video imaging system
Location evaluated every 5 min
Location and activity levels compared between magnet exposure and control
EMF: Laboratory Studies
SHORT-TERM EXPOSURE RESULTS
Responses among species and magnets were inconsistent
Redear sunfish showed a significant but slight attraction to both magnets.
Fathead minnows increased activity with magnet exposure.
EMF: Laboratory Studies
IMMEDIATE EXPOSURE METHODS
Electromagnet with variable control
Circular tank and high-speed camera (250 frames/sec)
One fish tested at a time; 5 trials/fish/treatment
Various magnet strengths (100%, 50%, 25%, 5%, 4%, 1%, 0%)
Magnet and camera activated for 4 sec
Abnormal behaviors noted as fish encounter magnet
Magnet strength reduced until ‘no effect’ observed
Lake Sturgeon
Acipenser fulvescens Paddlefish Polyodon spathula
EMF: Laboratory Studies IMMEDIATE EXPOSURE RESULTS
Lake sturgeon consistently reacted to high levels of EMF (25-100% full strength).
Responses diminished at levels below about 5,000 µT and were normal at 700 µT.
Paddlefish showed no abnormal responses to EMF exposure.
(Bevelhimer et al. 2013 Transactions of the American Fisheries Society)
Lake Sturgeon response was frequent and obvious
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Magnet strength (mean μT across the face)
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Magnet strength (mean μT across the face)
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No magnet
1% 5% 25% 50% 100%
EMF: Mesocosm Studies
Pond studies with similar design as noise studies.
EMF provided with electric cable that runs under net pen
Pallid sturgeon and largemouth bass tests recently completed
Results not yet analyzed
Floating Net Pen (6m wide x 20m long x 1.5m deep)
Underwater Speaker
Onshore
power
source
Application of Results
EMF Example: Minimizing the amount of transmission cable that crosses migration pathways by aligning in parallel with migration direction or by burial will decrease impacts on sturgeon.
river deployed turbines
BAD! GOOD!
Probability of Encounter:
Avoidance, Attraction, or Random Encounter
Probability of Being Struck
if Encountered
Probability of Injury if Struck
by Blade
Blade Strike: Laboratory Experiments, Field Observations, and Modeling all play a part
Lab studies with Alden &
EPRI
Future field studies with
Verdant Power
Modeling studies at
ORNL
Blade Strike & Injury: Modeling
From Cada et al. 2009
Function of Many Variables
Fish Length
Ground speed (velocity)
Number of Turbine Blades
Which part of blade is encountered.
Species-specific habitat choice and movement behavior
Blade Strike & Injury: Alden Lab Study
METHODS
Three species: rainbow trout (2 sizes), white sturgeon, hybrid striped bass
Approach velocities: 5 to 6.5 fps
Survival Tests
Fish released immediately in front of turbine
Evaluated for injury and survival after forced passage
Behavioral Tests
Fish released 2-3m upstream of turbine
Dark and light conditions
Entrainment evaluated with video and acoustic cameras
Free Flow Power
Half scale, 1.5m diam
Blade Strike & Injury: Alden Lab Study
RESULTS
High survival rates for the species and size groups evaluated (typically 98 to 100%).
Injury/descaling ranged from 0-27% depending on size and species
Behavioral tests demonstrated a high degree of turbine avoidance (86 to 100%) for trout and sturgeon and moderate rates of avoidance for striped bass (32 to 65%).
Avoidance same during night conditions as day
When survival rates are combined with avoidance rates, total passage survival estimates were typically very high (99-100%).
Rainbow trout swimming in front of turbine
Upcoming Study: Field Observations of Turbine Encounter Tidal Array in the East River, New York City
Verdant Power’s RITE Project
Upcoming Study: Field Observations of Turbine Encounter
Multiple sonar units collected fish data near operating turbines
Data analysis objective: Determine fish densities and swimming
direction in the area relative to tidal flow and turbine locations.
Upcoming Study: Field Observations of Turbine Encounter
Multi-beam acoustic camera aimed at single turbine
Data analysis objective: Document behavioral
response of fish that encounter turbine including
incidence rate of turbine passage.
Preliminary Impressions
BLADE STRIKE
Probability of encounter for most fish is likely low
Likelihood of strike and minor injury is moderate
However, more studies needed, especially at deployed devices
NOISE
Probably little risk of impact on freshwater species in already noisy riverine and tidal environments
Might be a different story for marine species and under full deployment of an array of dozens of devices
EMF
Response among freshwater fishes is species-specific
Behavioral effects at high EMF levels or in close proximity to sources
More testing needed to understand if EMF might have significant effects or is just a nuisance
Acknowledgments
U.S. Dept. of Energy Office of Energy Efficiency and Renewable Energy, Wind and Water Power Technologies Program
Pacific Northwest National Laboratory
Alden Research Laboratory
Electric Power Research Institute
Tennessee Wildlife Resources Agency
For more information contact Mark Bevelhimer at [email protected]