Sea Power
Terra Up Close
Coastal Views
Four residents of Oregon's shore — a fisherman, a former mayor, a teacher and a doctor — weigh in on wave energy.
Surviving the Tempest
The notion of extracting energy from waves is not new. When von Jouanne and her colleague, OSU electrical engineering professor Alan Wallace, began exploring the potential of wave power, their search for prior scientific writings and inventions took them into records two centuries old. As they pored over thousands of patents for turning wave energy into electricity, they pinpointed the big flaw in those earlier designs: too many moving parts. In an environment as tempestuous as the sea, moving parts require frequent maintenance and are vulnerable to breakdowns.
"To capture energy from waves, the device must be survivable, reliable, and maintainable," says von Jouanne, a principal investigator in OSU's wave energy research project. "In the past, there have been some failures because of the survivability issue."
Prevailing technologies generate power by compression of a liquid (such as water) or a gas (such as air). Pumps and pistons, valves and filters, hoses and tubes, fittings and couplings and all sorts of switches, gauges, meters and sensors go into operating these systems. In contrast, with $270,000 from the National Science Foundation and a total of $60,000 in proof-of-concept grants from Oregon Sea Grant at OSU, von Jouanne and Wallace are developing technologies that work with just a handful of basic components, including an electric coil, a buoy and a magnetic shaft secured by a steel cable.
One of the OSU devices on the drawing board — which the engineers describe as a "permanent magnet linear generator" — works like this: A spiral of copper wire is secured inside a 12- by 15-foot long buoy made of an impervious composite of plastic and fiberglass. The coil surrounds a magnetic shaft, which is stationary and tethered to the ocean floor by a steel cable. As the buoy rises and falls on the waves, the coil moves up and down relative to the shaft, inducing voltage as it passes through the magnetic field. A power take-off cable carries the resulting electric current about 100 feet down to the seafloor where another cable takes the power generated by many buoys to an onshore substation.
“I can promise you one thing. Whatever we build out there for wave-action generation is gonna have to be one tough dude.”
Terry Thompson
Fisherman
One buoy is projected to generate 100 kilowatts of power, on average. A network of about 500 such buoys could power downtown Portland. Moreover, wave parks could address the state's energy imbalance. West of the Cascades, Oregon consumes about 1,000 megawatts more than it generates. By tapping about 5 percent of the coastline, wave energy could make up the difference, and no new transmission lines would be needed.
The engineers' goal is to produce a device that is lean and streamlined, designed to withstand gale-force winds, monster storms and the vagaries of sea life, from rafts of floating bull kelp to colonies of seals looking for a place to haul out. The engineers are now working on their fourth and fifth prototypes. They call their simplified approach to energy conversion "direct drive." The fishermen just call it common sense. As one lifelong Oregon fisherman, Terry Thompson, puts it, "There's a rule of working in the ocean that fishermen use that goes, 'Keep it simple, stupid.'"
Wallace and von Jouanne agree. "Simplicity is the essence of it," Wallace says. However, embedded in their design is a great deal of engineered precision. The magnetic shafts are made of a steel alloy that creates an exceptionally strong force field. The highly conductive "air-gap" coils are made of solid copper instead of the more common combination of copper and steel used in generator armatures. Thus, the conversion of mechanical motion (waves) into electrical energy can take place with great efficiency and efficacy.
The engineers develop their prototypes in OSU's Motor Systems Resource Facility, the highest-power motor and drives testing lab at any U.S. university, and test them across campus in the O.H. Hinsdale Wave Research Laboratory, which boasts a 342-foot flume. But it will be in Reedsport that the wave-energy buoys meet their real test: the Pacific Ocean.
Of all the waves washing across the planet, Oregon's are optimal for extracting energy, according to a study by the Palo Alto, California-based Electric Power Research Institute (EPRI). That's because on the West Coast, the trade winds blow strong and steady, and the seafloor is a long, gentle slope, a configuration that lends itself to good wave action. And then there's the old mill just north of Reedsport. In addition to its 50-megawatt electrical substation, it has an outflow pipe stretching 3,000 feet into the ocean — a ready-made conduit for the subsea power cable bringing electricity back to shore.
Von Jouanne and Wallace have been working closely with Justin Klure of the Oregon Department of Energy to promote the Reedsport/Gardiner area as an optimal location for the nation's first commercial wave park. Several developers have stepped forward with the first planned phases in the 20- to 30-megawatt range. Manufacturing and fabrication would be performed locally, meaning job opportunities for coastal Oregonians. At about one to three miles offshore, the park will be invisible from the beach, thus preserving views, but close enough to make anchoring and transmission feasible.
