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Race Rocks tidal current power project

As multiple agents in Western Washington begin the process of harnessing the tidal currents of the Salish Sea for generating electricity, it’s worth a close examination of what’s been learned by a pioneering tidal turbine project associated with the Race Rocks Ecological Reserve/Marine Protected Area. Through a partnership between Pearson College of the Pacific (288 students from 28 countries study International Baccelaureate) and Clean Current Power Systems (Vancouver, Canada), a project was initiated to provide renewable energy to the marine station and lighthouse.

Today, a tidal and solar power system has replaced the twin 15kW diesel generators that provided electrical power (and noise, air pollution, environmental risks) during most of the 20th century and much of the history of the Race Rocks reserve (established in 1980). I assume wind was judged inappropriate because so many sea birds nest and rest on the Rocks.  I’m still just learning about the details, but wanted to share some notes and frame-grabs I took while watching a nice overview video of the Race Rocks tidal power project.

My overall impression is the turbine is big.  Approximately 4m in diameter, the ~65kW turbine is designed to be scaled up to 1MW (presumably for future commercialization by CCPS). The forces exerted on the support column during the maximum 3.35 m/s tidal flows must be tremendous.  A cool innovation I didn’t anticipate is that the blades are designed to turn in current from opposite directions.  This means that the whole turbine assembly doesn’t have to rotate on the support column (like wind turbines do).

It’s hard to find measurements or engineering data on the blade rotation rate.  Quoting from generic references about tidal turbines on the EIA page, “The blades themselves rotate quite slowly relative to hydroelectric and wind turbines, namely a few revolutions per minute depending on current speed, blade curvature and size but always to maintain a blade tip speed of less than 7m/s (when cavitation is likely to occur)” and typical rotation rates are “10-20 rpm.”  For a blade radius of 2m, the tip velocity would be ~4m/s at 20rpm and ~2m/s at 10rpm.  Given the arrangement of guided vanes I certainly wouldn’t want to swim through it at those rotation rates… but maybe a fish would do alright?

Funding for the project has come from Encana (natural gas and oil company’s Environmental Innovation Fund) and Sustainable Development Technology Canada (non-profit foundation created by Canadian government; Vicky Sharpe).


  • Late 2005: preparatory (concrete) work on island for cable route and battery storage
  • Jul 2006: Drilling complete (after 3 weeks), piling installation continues
  • Sep 2006: Installation of turbine; hydraulic and electrical performance testing begins
  • Dec 2006: Testing complete; cables connected to shore storage; Summary Report on Environmental Monitoring final draft submitted
  • Apr 2007: Turbine raised to repair bearings
  • Oct 2008: New turbine with stainless steel bearings, lubrication system, and reinforced augmenter duct.
Artists depiction of installed turbine

Artists depiction of installed turbine

Technical details (these are surprisingly hard to find… values to be filled in are in italic):

  1. located ~100m from Island, ~15m depth, ~20m of water
  2. The top of the turbine is at a mean depth of 10m, or ~5m below MLLW; thus the whole assembly reaches about 10m off the seafloor.
  3. post diameter?
  4. turbine and funnel dimensions? (~3m diameter, but not sure if that’s augmenter or blades)
  5. power and voltage (what function of current speed?)
Diver guiding generator unit onto post

Diver guiding generator unit onto post

The generator sans cowling

The generator sans cowling

Clean Current Power Systems staff interviewed in video

  • Russel Stothers
  • Glen Darou
  • Virgil Young (aerospace)
  • Chris Gora

Pearson College staff interviewed in video

  • Gary Fletcher
  • Dave Skilling

Other projects to keep an eye on:

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No fish, no blackfish?

I’ve asked a lot of people why the southern resident killer whales spend so much of their time swimming up and down the west side of San Juan Island. Most folks suggest that they’re here because the fish are here. Ask long-time population surveyor Ken Balcomb of the Center for Whale Research what motivates the orcas to be resident and you’ll get the succinct synopsis he passes on from First Nations elders: “No fish; no blackfish.” Yet I’m amazed at how little is known about what fish are present at any particular time in this part of the San Juan Islands, not to mention the Salish Sea in general.

From April through October the three resident pods are most frequently found along this coastline, the eastern side of Haro Strait. Their most common dance is known as the “west side shuffle” in which the pod(s) travel back and forth from somewhere near Eagle Point in the south to Henry Island in the north, often pausing to forage, socialize, or mill, but rarely resting. I’ve yet to hear of the residents transiting the same body of water on the Canadian (west) side (though transients often do), and I doubt it’s because the Canadians don’t treat their sewage as much as we do.

The orcas often make intermittent excursions further afield. They loop out to visit Hein and Middle banks offshore. They zip west past Race Rocks for a listen along south Vancouver Island. Or they voyage northward to the Fraser River delta before circumnavigating the archipelago via Rosario Strait. But they always seem to return to the west side — the core of their summertime range.

There might be non-fishy reasons orcas might like the west side of San Juan Island. Perhaps they appreciate the great acoustics along the steep unsedimented submarine coastline. Maybe they have a rubbing “beach” like the Northern residents, but hidden deep off of False Bay. Or maybe the west side is just a cross-roads: a familiar pathway that you take whether you’re headed out to the Pacific and the Elwha, up to the Fraser or Nooksack, or down to the Skagit and Puget Sound.

How could we demonstrate that prey availability is the factor that focuses the southern residents attention on the west side of San Juan Island? What kind of fish are they eating? Why and when are which fish available; and implicitly, how do the killer whales navigate the complex distribution of salmon in the Salish Sea? More practically, which (endangered?) fish population segments should we be saving for our endangered whales?

Our primary approach to answering such questions is to discern what the southern residents eat and then observe the behavior of those prey items along the west side. Secondarily we gather basic information about distributions of potential prey in case the prey sampling studies have biases that lead us to overlook important food sources.

The growing body of information about what orcas eat is the best evidence we have of what prey they are after. The current scientific consensus — from analysis of scraps, underwater video, the rare stranded whale’s stomach contents, and poop — is that southern resident killer whales really like Chinook salmon. In the best synopses I’ve seen (of data predominantly from May-October) Ford et al (1998) and Ford and Ellis (2006) suggest that Chinook are preferred at all times except perhaps in the late fall when chum salmon return to many local rivers (and the residents, especially J pod, begin making southward forays into Puget Sound). There also hints that bottom fish such as halibut, lingcod, and dover sole are taken occasionally.

A big problem is that not many people are doing a good job of monitoring what fish are present in the Salish Sea (as opposed to Northwest rivers) generally, and in Haro Strait specifically. A major goal of the spring 2008 Beam Reach program was to test new acoustic tools that could help us fill the observational gap. I’ll post separate articles with detailed results this summer, but for now here is a synopsis of the two new tools we tested:

Example hydroacoustic surveyFirst, through a new partnership with Seattle-based Biosonics, we used a 200 kHz scientific echosounder to measure fish densities in Haro Strait.  Mounted on a pole and pointed straight downward, the echosounder projected sound in a 6-degree-wide beam and received the echoes from fish, plankton, and the sea floor. With real-time display and data logging, we were able to survey fish distributions in Haro Strait (and map bathymetry and bottom type) both in the presence of orcas and when they weren’t around. Thanks to the generous donation of equipment and software, we were able to observe remarkably complex distributions of fish along the west side and to quantify fish densities in a preliminary suite of foraging locations.

Another active acoustic technology we tested was an acoustic tag that can transmit a depth measurement from inside a fish. We purchased two tags from Vemco and guided by instructor Eric Eisenhardt, implanted them surgically in lingcod near Lime Kiln State Park. With the mobile tracking unit that Vemco kindly provided for free, we were able to monitor the two young fish for about a month and learned they make only occasional depth excursions while remaining in the area where they were caught and released. The fish stayed near 18 and 40 meters depth throughout our study, suggesting that when killer whales make deep dives (>100 meters) to the local bottom (Baird, 2003) are probably not related to foraging for young lingcod on the west side of San Juan Island in the spring.


Baird, Robin W., M. Bradley Hanson, Erin E. Ashe, Michael R. Heithaus, and Gregory J. Marshall (1993) STUDIES OF FORAGING IN “SOUTHERN RESIDENT” KILLER WHALES DURING JULY 2002: DIVE DEPTHS, BURSTS IN SPEED, AND THE USE OF A “CRITTERCAM” SYSTEM FOR EXAMINING SUB-SURFACE BEHAVIOR. Report to the National Marine Fisheries Service, National Marine Mammal Laboratory, 7600 Sand Point Way N.E., Building 4, Seattle, WA, 98250 USA.

Ford, John K. B., Graeme M. Ellis, Lance G. Barrett-Lennard, Alexandra B. Morton, Rod S. Palm, and Kenneth C. Balcomb III (1998) Dietary specialization in two sympatric populations of killer whales (Orcinus orca) in coastal British Columbia and adjacent waters. Can. J. Zool. 76(8): 1456–1471 | doi:10.1139/cjz-76-8-1456.

Ford, John K. B., Graeme M. Ellis (2006) Selective foraging by fish-eating killer whales Orcinus orca in British Columbia. Marine Ecological Progress Series, 316:185-199.

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Snug Harbor to Snug Harbor

We left Snug with a series of science goals for the day. We headed south on the ebb tide towards Lime Kiln. On the way there and back we deployed the Biosonics 200 kHz echosounder for the first time. This marks our first forays into using active acoustics. We got so excited that we even lowered a video camera under water to see if the objects we were interpreting as fish and eel grass really were fish and eel grass. We did see a few fish, but for sure the eel grass we saw on the echosounder was real eel grass. We also figured out how we would deploy the hydrophone array along with a high frequency hydrophone. Because some of the student projects involve high frequency clicks, we needed to add a hydrophone with a high frequency response. We figured out a new configuration that would allow us to do that with the regular linear array on the port stern and the single high frequency hydrophone on the starboard stern. After dinner we had our journal club discussion about an article on prey species of Northern and Southern Resident killer whales. All in all a productive science day.

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Students set sail

On Monday of this week the Spring 08 Beam Reach program set sail on the Gato Verde. They’ve been all over the west side of the San Juan Islands including False Bay and Snug Harbor. I’ve gotten several emails and as of Tuesday they hadn’t seen the whales. I hope they are getting to use the tools from Biosonics to check out the salmon. I’m sure they are seeing plenty of other interesting sea life. I’ll post an update once I get more details.

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Fish Tools and a Pilot Project

We now have another state of the art tool for our students. In a pilot project with Biosonics — a fisheries research equipment manufacturer in Seattle — Beam Reach students will be using a 200kHz hydroacoustic instrument to track salmon (the food of choice for the killer whales).

This will allow students to investigate the whale’s food when the whales aren’t around, which could lead to some answers about where the whales go, when they go, and why. It really opens up a whole new dimension through which the students can investigate why the whale population is declining and what we can do about it.

I’ll continue to post updates, but I also recommend following Dr. Scott Veirs’s entries to see how this unfolds. It will also be interesting to see how the students utilize this new tool.

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