November 23, 2009
Wave of Discovery: Harnessing the Ocean's Power
Wave energy research swells
Capturing the power of ocean waves could become an important part of the world's renewable energy portfolio. But capturing that clean energy is not just the vision of 21st century scientists.
"There are patents going back to 1799," says Annette von Jouanne, professor of electrical engineering and computer science at Oregon State University, and a world leader in wave energy research.
Interest and support of this technology has not been consistent. There was enthusiasm after the 1970s oil embargo, but it dropped when oil prices stabilized.
"There have been ebbs and swells of interest," says Ted Brekken, assistant professor of energy systems at Oregon State, "but a lot of people would agree that we have passed a turning point, and I think the interest level now is here to stay."
The cavernous Wallace Energy Systems and Renewables Facility (WESRF) in Corvallis, Ore., is where von Jouanne and Brekken work on wave energy systems. There is support now from federal and state governments, as well as some power companies, but that has not always been the case.
"In 1998 when I was writing these proposals, people were saying 'she's crazy--we're not going to be able to harness energy from the ocean, it's just too harsh of an environment,' and so it took a lot of persistence," says von Jouanne. "Some of my first proposals awarded were through the National Science Foundation (NSF). And that really was the seed money that helped this wave energy program grow."
The same constant motion of waves that provides the energy is also continuously battering the hardware that is capturing it. So the engineering challenge is making that hardware strong and simple.
"When you look at reliability and maintainability, you want devices out there that won't need regular maintenance, which would require people to go out there in vessels," adds von Jouanne, "because that factors into the cost."
In September 2008, Oregon State, working with Columbia Power Technologies and the U.S. Navy, deployed its eleventh wave energy prototype--a permanent magnet linear generator that creates power with few moving parts.
"A float heaves up and down with the waves. Underneath the float is a magnet assembly, and as that magnet assembly heaves up and down, it creates a changing magnetic field," explains von Jouanne. "The coils in the spar experience that changing magnetic field and that induces voltage, and creates electricity."
The concept for a wave energy installation would be an array of these buoys. They would have a power takeoff cable going down to the sea floor, coming together at a central junction box. From that central junction box would be a subsea cable back to shore and onto the electrical grid.
While there is great promise with this technology, there is also concern for the wildlife that will share the ocean with these energy devices. So the teams putting together the wave energy plans at OSU asked marine mammal specialists to be involved from the very beginning.
About 18,000 North Pacific gray whales migrate yearly between Alaska and Mexico, and often travel very close to shore. Their journey will take them near wave energy devices, which are expected to be anchored about two and a half miles off the Oregon coast.
"We're trying to be ready if issues develop. What we're looking at now is some testing of a potential mitigation measure, an acoustic deterrent, if it becomes necessary to keep whales away from the early test units," says Bruce Mate, fisheries and wildlife professor and director of the Marine Mammal Institute at Oregon State.
The cabling that will bring the energy from the buoys to the grid has to be designed to prevent entanglements. Thousands of whales, dolphins, turtles and other sea creatures are killed each year because they are caught in fishing gear.
"These animals weigh about 30 tons, and they're traveling at three to four knots," (up to 4.6 miles per hour), "so hitting something solid could constitute a problem," notes Mate.
Testing and deployment
So how close is wave energy to actually putting electricity onto the grid? Worldwide, the western sides of large land masses are optimal for capturing wave energy, because of the prevailing west to east winds. For that reason, the United Kingdom (UK) are leaders in wave research in Europe, with deployments planned off of Portugal. In the United States, Reedsport, Ore., is going to be a wave energy test and demonstration facility starting next year.
"We do have some companies like Ocean Power Technologies in the United States, and their timeline for deploying buoys off the Oregon coast is the summer of 2010 when they plan to deploy one 150 kilowatt buoy (enough to power between 60-150 homes), and in 2011, they plan to deploy nine more," says von Jouanne.
The Electric Power Research Institute (EPRI), along with the Bonneville Power Administration (BPA), determined that Reedsport would be an ideal site for a wave energy test site, because of its good wave action, existing marine access and terrestrial electric transmission lines.
While research in wave energy is 15-20 years behind renewables such as wind power, waves are far more reliable as an energy source. While solar power is only available about 50 percent of the time; and winds are not constant, waves are, and experts say wave energy might one day provide up to six percent of the electricity needs of the United States.
"One of the beauties of wave energy is that it is highly forecastable, up to 48 hours in advance," says Chris Haller, an OSU engineering graduate student. The National Oceanic and Atmospheric Administration (NOAA) maintains a huge network of data collecting buoys, so power companies would know with great accuracy how much energy the waves would be putting onto the grid.
Making an impact
Both von Jouanne and Brekken say many of their students are drawn to renewable energy research both by the engineering challenges and the desire to help solve the world's energy problems. They also say it can be a lot of fun.
"Something I try to stress to my students is there are a lot of creative opportunities for engineers and mathematicians. I often will sit at home, or on my bike ride to work, and think, oh, that would be cool, let's try that," says Brekken.
"I love helping students develop those skills to help them springboard into industry, and be successful in an area like renewable energy. They're making a significant impact on the energy future of their region of the country, and the world. And it's very exciting to be part of that process," adds von Jouanne.
Any opinions, findings, conclusions or recommendations presented in this material are only those of the presenter grantee/researcher, author, or agency employee; and do not necessarily reflect the views of the National Science Foundation.