UW scientists work to harness the power of tides

As large swaths of the Middle East erupt in violence, the price of oil goes sky high, which in turn drives the price of gas and food even higher just about everywhere. But in some ways, Washington state is lucky, since hydroelectric power supplies approximately 66 percent of the state’s energy.

When people think about water and power, they usually think about dams like Hoover or Washington’s own Grand Coulee Dam. But there is another kind of water power—tidal power—that holds tremendous potential, especially here in the Evergreen State, because of the sheer volume of water moving in and out of Puget Sound each day. Tidal energy has a leg up on wind energy or solar power because it’s more predictable. Steve Klein, ’77, CEO of the Snohomish County Public Utility, is leading the state’s second-largest public utility into new energy frontiers by exploring this form of energy. This is so important and timely because by the year 2020, state law requires that 15 percent of energy sources in the state of Washington must be renewable.

Not surprisingly, two clean-energy projects on the utility’s front burner depend on partnerships with UW scientists. In one project, UW scientists and engineers are collaborating with OpenHydro, an Irish company that is making underwater turbines to capture tidal energy. The UW’s job is to investigate the effects of tidal power on marine life. In May, the Federal Energy Regulatory Commission gave the Snohomish County agency a 10-year pilot license to install, operate and monitor two tidal-energy turbines in Admiralty Inlet, which is located between Whidbey Island and the northeastern part of the Olympic Peninsula. UW scientists recommended Admiralty Inlet as the best available test site based on its flat sea bed and the fact that the tidal currents peak at about 7 to 8 knots per hour, fast enough to power tidal turbines.

The utility also has the green light to convert energy from Puget Sound tides into power. In this innovative effort, turbines weighing 414 tons are set 200 feet below the ocean surface, and are connected to the region’s electrical grid via undersea cables.

Three hundred kilowatts of electrical energy are expected to be generated during periods of peak tidal currents with an average energy output annually of 216,000 kilowatt-hours, enough to serve about 20 homes. Admittedly, this is a small number but only because project managers need to learn about the effects of tidal power on marine life before they consider expanding the effort.

With endangered species—such as the Southern Resident Killer Whale —making their home in Admiralty Inlet, investigating the effect on marine life is critical. And the UW’s scientific monitoring will give the answer whether tidal energy could play a larger role in meeting the state’s energy needs.

If the technology continues to develop and becomes cheaper, it will completely change the way the electricity-supply system works.

The tidal turbines don’t look like the wind turbines that can be seen in some of Eastern Washington’s counties. Tidal turbines don’t have long open blades. Instead, tidal turbines have plating that looks like slightly tilted baffles. The small blades are contained in a kind of “shroud,” or cover. The tidal turbines are also tiny compared to wind turbines. Wind turbines are 120 meters in diameter while the largest tidal turbine is only 16 meters.

People who picture a wind turbine underwater could imagine an open blade swinging and hurting a marine species. But that’s not the way tidal turbines work. With the protective shroud, tidal turbines don’t have blades like those on wind turbines that sometimes kill birds. Leading whale experts, who conducted studies before tidal turbines were in place, concluded that a whale could not force its head into the apparatus. Even if a whale tried, there is no surface edge that could strike the whale.

It’s no surprise that UW scientists are playing a key role in this innovative project. The UW is the home of the Northwest National Marine Renewable Energy Center, a collaborative venture with Oregon State University. OSU is focusing on wave energy while UW is leading the way in tidal energy. (Wave power is not the same as tidal power. Waves are driven by the wind blowing across the surface of the water while the moon’s rotation around the earth drives the tides.) The center has the largest concentration of marine renewable energy researchers anywhere in the world.

“Snohomish County’s PUD gets the leading edge of scientific thought and we get to see if what we develop really works. The outcome will affect everything from turbine design to international standards for tidal energy performance,” says Brian Polagye, the center’s co-director. “We get a whole other set of lessons learned.” What will happen to marine life after the current is reduced from taking energy from the tides?

It took years for the Snohomish County utility to receive the permit to start the pilot project. UW scientists developed models to find the best locations for the turbines, managing deployment of a remote monitoring device called “the Sea Spider” to measure sounds, tidal velocity, water quality and the sounds of marine mammals.

We cannot overstate the importance of collaborating with the UW, ... They aren’t just idea people; they are get-out-there-and-get-it-done people.

Craig Collar, Snohomish County PUD assistant general manager

“Brian helped us file our preliminary permits. He’s been with us every step of the way ever since. It would be difficult to overstate the role of the UW in this project. They have been absolutely essential to the progress that we’ve made,” says Craig Collar, the Snohomish County PUD’s assistant general manager. UW scientists and engineers have also worked with OpenHydro on the specifications for the turbines. It’s an illustration of how the state’s powerhouse research university is asking and answering the questions that will change the world for the better.

Scientists and engineers from oceanography, applied physics and engineering are inventing a monitoring instrument that looks a little like a chubby, four-armed robot. In a bit of whimsy, they named the underwater vehicle that deploys their monitoring package “Millennium Falcon,” which Star Wars fans will recognize as the name of a spacecraft.
For the rest of the year and into 2015, UW scientists will continue testing instruments in the field. These instruments must be launched and connected to a docking station, no easy task in an open sea.

Over the course of the project’s life—five years—the instruments will be modified if necessary. There are multiple instruments incorporated into a single package that is launched and connected to a docking station. The individual instruments aren’t launched by themselves. The major instruments are: optical cameras, acoustic cameras (using sound to “see” underwater) and underwater microphones (hydrophones) to listen to marine mammal calls.

“We cannot overstate the importance of collaborating with the UW,” Collar says. “These guys have consistently found ways to get work done is a cost-efficient way. They aren’t just idea people; they are get-out-there-and-get-it-done people.”

The Snohomish County PUD is also collaborating with the UW and Seattle-based 1Energy Systems on a project to test battery-energy storage. When energy sources like solar, wind, wave and tides produce energy when none is needed, that energy can be stored in a technologically advanced battery. Daniel Kirschen, the Donald W. and Ruth Mary Close Chair in Electrical Engineering, will study the technical and economic value of the battery that will be installed in Snohomish County PUD’s Hardeson substation during the winter of 2014-15.

“Essentially, we will be evaluating the value of the batteries. We want to know how much money the utility could save by using these batteries,” says Kirschen. “These batteries are very expensive but the expectation is that the price will come down. If the technology continues to develop and becomes cheaper, it will completely change the way the electricity-supply system works. But that will only happen if it makes sense from an economic perspective.”

This project involves developing electrical and communication connections so that batteries, power converters and software work as a modular energy-storage system. To understand what this project will do, think about how children’s Legos fit together to build a structure. Right now, the ‘Lego pieces’ don’t fit together because they are not standardized across industry. Key technologies in this project ultimately will be available in the public domain so that everyone can benefit.

Although these projects are relatively small now, they have big implications. If the environmental concerns are satisfied, tidal power may provide an economically feasible, sustainable source of clean energy. If it can be determined that batteries can smooth out erratic energy generated by wind and the sun, it would be a huge win for everyone.