Environmental Monitoring Technologies for Marine Energy

Acoustics

Project: DAISY

 

Marine renewable energy devices create sound that we need to quantify, but it is challenging to distinguish background noise from that produced by the devices. For example, a stationary listening technology—one that’s located on or near an energy device—will also capture natural noises from water flow. In order to separate the background from the sound produced by the device, the University of Washington developed the Drifting Acoustic Instrumentation SYstem, or DAISY.

 

Background

The light-weight, drifting spar buoys have a GPS, marker light, and data collection electronics. Underneath the floating portion is the listening device, or hydrophone, connected by one of several attachment methods aimed to further improve the accuracy of characterizing the sound of a marine energy device.

 

In multiple tests, three DAISY systems were deployed in the Sequim Bay channel simultaneously and left to drift past the pier where a sound source played known sounds. In other tests, observations of the hydrodynamics of the DAISY have been made to assess how the flow shields—protective, acoustically-transparent covers that protect the device from pseudo-noise—affect the speed and trajectory. Most recently, UW researchers have successfully reduced noise associated with waves contacting the floating portion of the DAISY as well as water flow around the hydrophone. By reducing these sources of noise, pinpointing the frequencies and intensity of marine energy device noise will be more accurate and aid the MRE industry.
 

Triton’s contributions:

 

  • Vessel – R/V Desdemona
  • Platform – moored at Sequim Bay permitted site
  • Wireless data transmission to shore, but through their own system
  • Personnel help to deploy/set up
  • Onshore escort/assistance
  • Sound simulations
  • An acoustic Doppler current profiler (ADCP)
  • Data backup storage
Project: Integral NoiseSpotter

 

 

An obstacle to monitoring acoustic sounds in marine environments is locating the source of sound traveling through the water. Integral Consulting, Inc. is tackling this challenge with the NoiseSpotter project, which involves a sensor system that classifies and provides accurate location information about sounds related to marine energy installations.

 

Background

In addition to using typical hydrophones that measure sound pressure and strength, researchers are measuring particle velocity, which is a vector quantity that can provide information about direction. The NoiseSpotter contains an acoustic vector sensor array that triangulates these particle velocity vectors to determine the location and identity of a sound.

 

Researchers tested the vector sensors in July 2017 using acoustic sources in a quiet part of Sequim Bay and then in a more energetic environment in the Sequim Bay channel in January 2018.

 

The next goal is to develop and implement a location estimation algorithm on board the NoiseSpotter for real-time processing of the vector data, making the output from the technology accessible to end-users. Once these steps are accomplished, the system will be tested in various locations around a marine energy device to collect measurements of MRE-associated noise.

 

Triton’s contributions:

 

  • R/V Desdemona
  • Boat crew
  • Permitted Sequim Bay site
  • Simulated sound
  • Personnel help to set up and deploy
  • Onshore assistance
  • An acoustic Doppler current profiler (ADCP)
  • Data backup storage