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Tidal Project overview

Starting in 2007, the PUD began pursuing a pilot tidal energy plant in Admiralty Inlet. The purpose of the pilot plant project was to learn more about the performance and potential for environmental impacts from tidal energy generation in the Puget Sound.

View tidal project overview by Sound Waters >

Pilot plant overview

The turbines were to be sited approximately 1 km west/southwest of Admiralty Head near latitude 48.15 longitude -122.69 in water depth of 58 m. The plant was to consist of two horizontal-axis tidal turbines designed and manufactured by OpenHydro Group Ltd. and connected to the grid near Admiralty Head on Whidbey Island via two subsea cables. The turbines were planned to be removed at the end of the FERC license period, following three to five years of operation.

The PUD submitted a Final License Application (FLA) for a Pilot License to FERC on March 1, 2012, and FERC released an “Order Issuing Pilot License” on March 20, 2014. The PUD continued to pursue other required federal, state, and local permits.

Plans called for preliminary preparation work on shore and installation of underground transmission cables beginning in Spring/Summer 2015, and deployment of the turbines into the water in Summer 2016.

Post-installation monitoring

The PUD partnered with the Northwest National Marine Renewable Energy Center (NNMREC) and Applied Physics Lab (APL) at the University of Washington to develop methods for post-installation environmental monitoring of a variety of parameters:

  • Marine mammals and other aquatic species
  • Benthic habitat changes
  • Acoustic effects
  • Derelict fishing gear
  • Water quality effects

Monitoring plans for the above parameters were submitted with the PUD’s FLA, and implementation of the plans is a requirement of the Pilot License. The PUD’s partners at NNMREC procured equipment to construct monitoring instrumentation packages, which were to be mounted on each turbine and retrieved several times per year during the turbine deployment period. Such environmental monitoring provides valuable information essential to assessing the viability of tidal energy generation.

Study sites

During its early research, the PUD focused on Admiralty Inlet and Deception Pass.

Click to view tidal project map >

  • Deception Pass, North Whidbey Island – 3 average-megawatts; FERC Project # P-12687
  • Admiralty Inlet, East of Port Townsend – 29.3 to 75.3 average-megawatts; FERC Project # P-12690