Harnessing Tides In The Northwest

Aug. 23, 2011 | KUOW
Ashley Ahearn


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  • Chris Bassett (center) and Brian Polagye make some final adjustments before the sea spider deploys. credit: Ashley Ahearn
  • OpenHydro, the company developing the turbines for Admiralty Inlet, put the same turbine technology into the Bay of Fundy. The donut shape is thought to provide some protection to marine life from the spinning blades. credit: National Oceanic and Atmospheric Association
  • Jim Thomson oversees the deployment of one of the sea spiders. credit: Ashley Ahearn
  • Brian Polagye holds a hydrophone, used to record underwater marine life at the site. credit: Ashley Ahearn
Chris Bassett (center) and Brian Polagye make some final adjustments before the sea spider deploys. | credit: Ashley Ahearn | rollover image for more

PORT TOWNSEND, Wash. — The sun is setting as the Jack Robertson, a 65-foot research vessel, leaves the harbor. Two spidery-looking orange pieces of machinery, each one weighing about 1,000 pounds, crouch on the back deck. These sea spiders, as they’re called, are for measuring tidal currents and more.

They’re part of an extensive research project, lead by researchers at the University of Washington, to try to better understand the environmental impacts of putting turbines on the sea floor.

Jim Thomson, an oceanographer at the University of Washington Applied Physics Lab, explains what they’re after.

“We’ll have a three-year data record from the site that has all the parameters that are relevant: tidal currents, ambient noise, water quality, fish passage, marine mammal activity in the area, all these quantities of interest,” he says.

The information Thomson and his team gather will be used to maximize potential power from this bottleneck of water at the mouth of Puget Sound and minimize the impacts on the critters that hang out here.

Moonlight bounces off black water as the research vessel heads out to the site of the proposed turbine installation. In the distance a ferry goes by. It can’t be heard above the noise of the Robertson’s engines, but Chris Bassett, a PhD student in the Applied Physics Lab at the University of Washington, says that if you’re a fish or a whale hanging out in Admiralty Inlet right now, you’re hearing that ferry.

“It’s the difference between someone talking and someone screaming as loud as they can,” he says.

Bassett says tidal turbines will add to the general underwater noise in the area, measuring somewhere between the “talking” and “screaming” levels, but on the quieter end of the spectrum.

As the boat nears the middle of Admiralty Inlet, it slows down and starts to position itself over the turbine site. It’s not an easy task. Water flows through here at upwards of 9 miles per hour and the Robertson’s engine strains to hold it in place.

On the back deck the researchers prepare to lower the first of the two sea spiders into the water to collect more data. Two position themselves on either side of an enormous hydraulic winch, straining against the ropes that guide the devices out over the black water.

Thomson holds what looks like the remote control for the whole operation and calls to the captain.

“Alright, everybody ready? Coming up. Frame out slow.”

Researchers submerge a ‘sea spider’ to monitor the environmental impact of energy-generating turbines on the floor of Puget Sound’s Admiralty Inlet. (video by Ashley Ahearn)

The sea spider disappears below the surface. It will be there, 200 feet below, gathering three months worth of data. That depth places the research equipment well below any tanker ship that might pass through here, but it’s not outside the range of Southern Resident orcas, which regularly pass through these waters.

“That is within their diving capability,” says Alison Agness, the lead fisheries biologist overseeing the approval process for the National Oceanic and Atmospheric Administration. “It is uncertain how much time they’d spend at that depth or what they’d be doing.”

Agnes says she’s less concerned about the noise generated by turbines than she is about the potential for sea life to come into contact with their spinning blades.

Marine mammals are known to be at times drawn by their curiosity to the unfamiliar, and at times to avoid the unknown at all costs, she says. “So there’s just a range of potential behavioral responses and it’s unknown if attraction or avoidance will be the mode.”

Agness says that NOAA will require the Snohomish County Public Utility District –- which is funding the Admiralty Inlet project – to put in underwater monitoring systems that would automatically shut the turbines down if whales come too close.

These turbines are a pilot project, which means they’ll have to come out within the next ten years and the maximum amount of power they’ll generate would be enough to power about 200 homes. But that doesn’t mean there’s not the potential for a lot more power to come out of this spot in the future.

According to a report by Electric Power Research Institute, Admiralty Inlet is listed as one of the best tidal sites in the US with an estimated energy potential of 1.7 terawatt hours per year.

Peter Asmus, a renewable energy analyst with Pike Research, says the Pacific Northwest is one of the best regions in the country for tidal power. But with the economic downturn and the absence of a mandatory limit on carbon emissions, Asmus says tidal power probably won’t take off any time soon.

“Realistically looking over the next five years, if I had to guess. I would say there’s going to be less than 100 megawatts of tidal power coming online in the U.S. and probably much less than that.”

The Snohomish County Public Utility District is funding the Admiralty Inlet tidal project, with help from the Department of Energy, but Craig Collar, the district’s senior manager for energy resource development, says it isn’t putting all its eggs in the tidal basket.

“The truth is we’re really not zealots for tidal energy,” he says. “We just think it’s interesting and we think it deserves responsible rigorous scrutiny.”

Even if tidal power doesn’t have a strong foothold in the renewable market today, it could be a steady source of renewable power for this region in the future, Collar adds.

“When wind was first developed and starting to be installed it was very expensive. It wasn’t very reliable,” he says. “It was difficult to permit. But look where it is today and what an important resource it has become. Tidal energy has the potential to follow the same kind of path.”

Within the next ten years all the utilities in Washington will be required to get 15 percent of their power from renewable sources.

There are no tidal facilities contributing power to the grid in this country yet. The Admiralty Inlet turbines will be installed in 2013 if the project makes it through the permitting process.

The University of Washington researchers will continue monitoring noise and marine life interactions after the turbines go in, but until there are actually turbines spinning under water, the full environmental impacts of tidal power will remain impossible to assess.

© 2011 KUOW
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