Tidal power supply coming to Puget Sound

A multi-million-dollar tidal energy project in Admiralty Inlet, north of the Kitsap Peninsula, has been approved by the Federal Energy Regulatory Commission.

Tidal turbines for Admiralty Inlet are to be provided by OpenHydro. Graphic courtesy of OpenHydro
Tidal turbines for Admiralty Inlet are to be provided by OpenHydro.
Graphic courtesy of OpenHydro

The Snohomish County Public Utility District, which was granted a license for the double-tidal-turbine pilot project, says it will be the first “grid-connected array of large-scale tidal energy turbines in the world.” The twin turbines are designed to produce 600 kilowatts of electricity, enough to power several hundred homes.

“Anyone who has spent time on the waters of Puget Sound understands the power inherent in the tides,” PUD General Manager Steve Klein said in a news release. “In granting this license, the FERC acknowledges the vigilant efforts of the PUD and its partners to test the viability of a new reliable source of clean energy while at the same time ensuring the protection of the environment and existing uses.”

The federal commission acknowledged concerns for fish and wildlife brought forth by area tribes, whale-watch operators and environmental groups. But the pilot project has precautionary measures built in, according to the commission’s order (PDF 503 kb) issued yesterday:

“For these new technologies, where the environmental effects are not well understood, the risks of adverse environmental impacts can be minimized through monitoring and safeguard plans that ensure the protection of the public and the environment.

“The goal of the pilot project approach is to allow developers to test new hydrokinetic technologies, determine appropriate sites for these technologies, and study a technology’s environmental and other effects without compromising the commission’s oversight of a project or limiting agency and stakeholder input…

“A pilot project should be: (1) small; (2) short term; (3) located in non-sensitive areas based on the commission’s review of the record; (4) removable and able to be shut down on short notice; (5) removed, with the site restored, before the end of the license term (unless a new license is granted); and (6) initiated by a draft application in a form sufficient to support environmental analysis.”

Among tribes that fish in the area, the Suquamish Tribe raised concerns about the likelihood of underwater turbines violating tribal treaty rights to fish. The turbines have the potential for killing or injuring fish, according to the tribes, and they could become a point of entanglement for fishing nets and anchor lines.

Tidal turbine location in Admiralty Inlet
Tidal turbine location in Admiralty Inlet

“Though we respect the tribes’ perspective and concerns, we disagree that licensing this project will adversely affect their treaty rights,” the commission stated in its order. The license contains no restrictions on fishing, and it requires measures to protect the fish.

Suquamish Tribal Chairman Leonard Forsman said tribal officials have not had time to review the license conditions in detail but will do so over the coming days. He said he would consult with legal and technical advisers before laying out possible actions for consideration by the tribal council.

Michael Harris, executive director of the Pacific Whale Watch Association and a board member for Orca Conservancy, said he was disappointed that more people have not recognized the problems that can be created by these turbines — especially in Admiralty Inlet, a primary route for killer whales and many other species.

The turbines will create unusually loud and potentially painful underwater noise, Harris said. This installation is being developed at a time when researchers are coming to understand that noise can disrupt the behavior of killer whales and other marine mammals.

The turbines themselves have open blades that can injure any curious animal getting too close, he noted. And if the turbines become a serious threat, someone must swim down and mechanically stop the blades from turning, something that could take four days.

“I’m not against green energy,” Harris said when I talked to him this morning. “But let’s not put blinders on. I would like to see these turbines located in another spot. Why not Deception Pass?”

Harris said it is critical for people to pay close attention to the pilot project if it goes forward. Everyone should be prepared to stop the experiment if it proves costly to sea life.

The order by the Federal Energy Regulatory Commission maintains that conditions of approval will protect killer whales and other marine mammals:

“The Near Turbine Monitoring and Mitigation Plan requires detection of fish and should provide observation of nearby killer whales. Those observations combined with the hydrophone monitoring required under the Marine Mammal Protection and Mitigation Plan will allow detection and observation of killer whales if they come near the turbines.

“The adaptive management provisions of the Marine Mammal Protection and Mitigation Plan will also allow adjustments to project operation if potential harm to killer whales is detected or, in the very unlikely event, a whale is injured….

“This license also contains noise-related requirements that will ensure the project does not have detrimental effects on killer whale behavior. The Acoustic Monitoring and Mitigation Plan of this license requires that if the sound level from turbine operation exceeds 120 dB at a distance greater than 750 meters from the turbine … the licensee shall engage the turbine brake until modifications to turbine operations or configuration can be made to reduce the sound level.”

According to several Internet sources, 120 dB is what someone might hear standing near a chainsaw or jack hammer. That level is considered close to the human threshold for pain.

In the Admiralty Inlet area, at least 13 local species are listed as threatened or endangered under the Endangered Species Act.

  • One plant: golden paintbrush, threatened
  • One bird: marbled murrelet, threatened
  • Two marine mammals: Southern Resident killer whales, endangered, and North Pacific humpback whale, endangered
  • Nine fish: Puget Sound Chinook salmon, threatened; Hood Canal summer chum, threatened; Puget Sound steelhead, threatened; bull trout, threatened; green sturgeon, threatened; bocaccio rockfish, endangered; canary rockfish, threatened; yelloweye rockfish, threatened; and Pacific eulachon, threatened.

U.S. Fish and Wildlife Service and National Marine Fisheries Service have concluded that none of the species would be in jeopardy of extinction because of the pilot project.

Experts have concluded that marine mammals, including killer whales, could be subjected to Level B harassment (behavioral shifts) as a result of noise from the turbines. That would be in violation of the Marine Mammal Protection Act without incidental take authorization. That means the Snohomish PUD must undergo consultations with the National Marine Fisheries Service and possibly change its plans before moving forward.

The PUD chose Admiralty Inlet for its swift currents, easy access and rocky seabed with little sediment or vegetation. A cable-control building for connecting to the power grid will be located on Whidbey Island near Fort Casey State Park. The turbines will be located in about 150 feet of water about a half-mile from shore.

The turbines are manufactured by OpenHydro of Dublin, Ireland. Each turbine measures about 18 feet in diameter, with a 414-ton total weight.

According to the PUD, these turbines have been used in ecologically sensitive areas in other parts of the world. One location is Scotland’s Orkney Islands, which features a diverse and productive ecosystem that is home to numerous species of fish, dolphins, seals, porpoises, whales and migrating turtles.

The pilot project has been supported with about $13 million in grants from the U.S. Department of Energy and Bonneville Power Administration along with federal appropriations.

Partners in various aspects of the project include the University of Washington, Pacific Northwest National Laboratory, Sound & Sea Technology and the National Renewable Energy Laboratory.

2 thoughts on “Tidal power supply coming to Puget Sound

  1. If these two tidal turbines are placed in Admiralty Inlet they will create noise and an obstruction to travel. Both should be avoided if possible, so from the point of view of the orcas and other marine life it would be better if they were not put there. If the project is built out and dozens of turbines are placed in Admiralty Inlet the noises and obstructions could become significant, and other effects could become serious, including reducing tidal currents and therefore reducing the flushing of Puget Sound, which could increase pollution levels.

    These are issues to worry about, and the project is without precedent so these are predicted estimates, but these two turbines are not expected to generate more noise that the average, every day background ambient noise levels at that location. The turbines are expected to generate about 120 dB, which will dissipate and be masked by ambient noises beyond a few hundred meters.

    The only mention of 180 dB in the FERC license is: “The terms and conditions require Snohomish PUD to: (1) cease operating and obtain NMFS approval to resume operations if sound levels exceed 180 dB any distance from the turbines or if sound levels of 120 dB propogate to a distance of 750 meters or more from the turbines; ”

    Quoting the FERC license:

    p. 43 –
    In regard to turbine noise, the EA concluded that the nature of the noise coming from the relatively slow turbines and passive mechanics was not likely to harm or displace whales or fish.[1] Staff determined that outside of a few hundred meters from the operating turbines, the chance of marine mammals, including killer whales, from distinguishing the turbines from background noise was less than 25 percent.

    p. 44 –
    If the maximum allowable area of 750 meters around the turbines was affected by noise emanating from the project, that affected area would occupy less than 15 percent of the cross section of Admiralty Inlet, leaving the remainder of the inlet available for whale passage or foraging. If killer whales were to respond negatively to noise levels, a behavioral change of this degree will not have a detrimental energy cost to a highly mobile killer whale.

    Northwest National Marine Renewable Energy Center
    University of Washington, Seattle, WA 98195
    Estimated Received Noise Levels for Marine Mammals from
    OpenHydro Turbines in Admiralty Inlet, Washington
    Technical Report: UW-2011-01
    January 2011
    Mean ambient noise levels in the project area are 117 ± 3 dB re 1 Pa. Broadband noise levels rarely (< 2.5% of the time) fall below 100 dB re 1 Pa and rarely (1/2 mile away from the turbines) would mask the turbine noise most of the time. Orca calls are also typically louder than the noise the turbines will generate. Holt et al. (2007) studied noise effects on the call amplitude of southern resident killer whales and found that with increasing background noise,source level increased, ranging from 130-160 dB re1 Pa.

    Howard Garrett

  2. This article acknowledged concern from tribal fishers but does not address at all any adverse impacts upon other waterway users such as recreational boaters and fishers. Will there be total exclusionary zones? Will there be no fishing zones as 15 pound downrigger weights might not be compatible with turbine blades (despite the 150 installation depth the size of the turbine and mounting base could put the top at 100-120 feet which is clearly within trolling depth)? And is there a risk to fishers if their gear were to become entangled in the turbines?

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