NNMREC November 4, 2010 Passive Acoustics New Environmental Technologies Renewable Ocean Energy and the Marine Environment Brian Polagye, Chris Bassett, and Jim Thomson University of Washington Northwest National Marine Renewable Energy Center

NNMREC  Need for New Environmental Technologies  Passive Acoustics —Introduction —Ambient Noise —Environmental Effects

NNMREC Marine Energy Development  Uncertainty around the potential environmental effects of marine energy poses a barrier to development  Consensus that well- monitored pilot projects are a first step in reducing environmental uncertainty Courtesy of Marine Current Turbines

NNMREC Pilot Monitoring: Wish List  Monitor the full range of potential stressor (e.g., noise) and receptor (e.g., marine mammal) interactions  Discriminate changes caused by marine energy pilot projects from large natural and anthropogenic variability  Robust, species specific identification  Provide information for decision making in real time  Monitor over a range of time scales (seconds to years) and length scales (cm to km)

NNMREC Pilot Monitoring: Reality  Resources are scarce and monitoring needs must be prioritized based on risk  Some interactions will not be measurable at the pilot scale  Conditions at marine energy sites preclude or complicate many conventional methods  Integrating multiple, rich data streams is a major software challenge

NNMREC  Need for New Environmental Technologies  Passive Acoustics —Introduction —Ambient Noise —Environmental Effects

NNMREC Passive Acoustics  Broadband noise —Existing, ambient noise —Noise from marine energy projects  Marine mammal echolocation —Species specific —Presence or absence Mature Technology, New Applications

NNMREC Recording Hydrophone  Deployments for three months at a time on seabed  Sample ambient noise —1% duty cycle —20 – 40,000 Hz Loggerhead DSG

NNMREC  Need for New Environmental Technologies  Passive Acoustics —Introduction —Ambient Noise —Environmental Effects

NNMREC Ambient Noise Sources

NNMREC Ambient Noise Characteristics

NNMREC Ambient Noise Variability What is the context for this variability?

NNMREC Establishing Context: Shipping Automatic Identification System (AIS) ffffffffffffss

NNMREC Acoustic Doppler Current Profiler (ADCP) Establishing Context: Currents

NNMREC Measuring Noise in Strong Currents  When currents exceed 1 m/s, elevated, broadband noise masks other sources  Two contributors to this increase —Propagating noise —Pseudo-noise and self-noise  When currents exceed 1 m/s, most hydrokinetic turbines begin to operate Bassett et al., Characteristics of underwater ambient noise at a proposed tidal energy site in Puget Sound, MTS/IEEE Oceans 2010, Seattle, WA, September

NNMREC  Need for New Environmental Technologies  Passive Acoustics —Introduction —Ambient Noise —Environmental Effects

NNMREC Source-specific Received Levels

NNMREC Evaluating Sound Transmission Loss RL = 179 – 18.4 log 10 (d) Source level at 1m Transmission loss coefficient Received level Distance from source

NNMREC Estimated Project Noise  Two turbines  Source level for each turbine = 160 dB re 1 µPa at 1 m  Sources are incoherent  Same transmission loss as noise from ferry 0.5 km 1.0 km

NNMREC Conclusions  Passive acoustics are a powerful tool for evaluating and monitoring acoustic effects of marine energy projects  Most effective when combined with additional tools to establish context

NNMREC Thank You More information available at: