Watts from the sea
Off the western coast of Scotland, on the Isle of Islay, science teacher Ray Husthwaite turns on the light in his classroom.
The electricity comes from a power cable that runs to the mainland.
But it also comes from the ocean.
A few miles from the school, wave action compresses and decompresses air in a chamber. The moving air powers a turbine, which generates electricity.
“It is pleasant, on a choppy but sunny day, to sit beside the gray, concrete structure and listen to the rising and falling of the waves, driving air through the turbines like the breath of a great sea monster,” Husthwaite said. “It seems insane to me to be investing in nuclear power stations and gas turbines when there are endless, free energy resources in the rivers, oceans and the wind.”
In a world addicted to fossil fuel, turning waves into watts might seem far-fetched. But as the U.S. and other countries look for alternatives to oil, natural gas and coal and try to curb global warming, ocean power gradually is joining the ranks of wind and solar power as a source of renewable energy.
Pacific Gas & Electric Co. caught the wave last month when it became the first California utility to file for permits to study the promise of sea power, a non-polluting but expensive and mostly untested way to take energy from the ocean.
PG&E;’s proposed projects could provide electricity for tens of thousands of homes, said Keely Wachs, spokesman for the San Francisco-based utility. “More importantly, it’s clean and totally renewable.”
PG&E; joins a global list of organizations experimenting with harnessing ocean power. In less than three years, U.S. energy regulators have received nearly five dozen applications for water-related energy projects from South Florida to Washington state.
Islay’s wave-power converter, the Limpet 500, has been operating since 2000. In Hawaii, the Navy has been churning up electrons with the help of a floating buoy. And in Portugal, engineers are installing snakelike tubes designed to convert the sea’s motion into electricity.
“We’re going to decide one way or another to displace the use of fossil fuel by clean fuel,” said Roger Bedard, ocean energy leader at the Electric Power Research Institute, a utility industry think tank in Palo Alto. “And our grandchildren are going to understand the consequences of that decision.”
Anyone who has ever been slammed to the sand by a wave can attest that the ocean packs tremendous power. Technology can harness that energy in several ways. Some designs, like the Limpet, use waves to push air through a column. Others convert the sea’s up-and-down motion into mechanical energy.
While U.S. regulators categorize wave power as hydropower, it differs from other methods of generating energy from water. Tidal power, for instance, relies on the gravitational force of the sun and the moon to provide energy. Wave power is less predictable than tidal power, but experts consider it more potent.
The California Energy Commission estimates that the state’s 1,100-mile coastline could generate seven to 17 megawatts a mile, enough power per mile to serve as many as 13,000 average homes. One wave-power company executive told a congressional committee last year that several hundred square miles off the California coast could supply the electrical needs of all of the homes in the state.
The allure of wave power is so strong that the number of organizations filing for permits has surged, causing the Federal Energy Regulatory Commission to get tough on applicants.
“We label it as a stricter-scrutiny approach,” commission spokeswoman Celeste Miller said. That means more frequent progress reports and greater consultation with federal, state and local agencies are required.
In California, interest in ocean power is so new that some state regulators aren’t exactly sure who has permitting authority over projects in state waters. Regulators are considering putting together a multiagency working group, probably led by the California Energy Commission, on how to deal with ocean power projects, said Alison Dettmer, manager of the energy and ocean resources unit of the California Coastal Commission.
Although wave power doesn’t create pollution, that doesn’t mean environmentalists and others don’t have concerns. Questions have been raised about potential harm to marine life, the coastline, fishing and boating operations and ocean views.
“At this point it’s all pretty preliminary,” said Vicki Frey, environmental scientist at the California Department of Fish and Game. “We will comment as we would on any project regarding potential impacts to marine resources.”
PG&E; will be studying all aspects of how the projects affect the environment, said Kevin Butler, director of new resource procurement at PG&E;’s energy supply department.
“There’s a variety of stakeholders,” Butler said. “We’re going to be in touch with communities to make sure we have a satisfactory solution.”
If it passes regulatory muster, PG&E; must still deal with wave power’s other challenges, including cost and a short history of commercial use. Bedard estimated that generating power from waves costs about seven times more than using natural gas and about six times more than using wind.
“Wave is a brand-new technology,” Bedard said, “and there’s a market barrier that new technologies have to overcome. How does a new technology compete with something that’s been around for a long, long time?”
One way, he said, is through incentives like the ones California gives homeowners who install solar panels. If the government doesn’t subsidize wave power, the utility could be risking an initial loss on the expense of installing such new technology.
“We’re trying to increase the supply of renewable energy at this point,” Butler said, “and we’ll let the supply dynamic lower prices.”
The plan could be feasible. In some parts of Texas, for example, the cost of generating electricity from wind is cheaper than using natural gas, Bedard said.
PG&E;, a subsidiary of PG&E; Corp., is asking regulators for the right to study wave-power projects at two Northern California sites. One, off Humboldt County, would be spread across 136 square miles. The second, off Mendocino County’s coast, would be 68 square miles. The final locations, known as “wave farms,” would be as close as half a mile from the coast or as far as 10 miles offshore.
The utility plans to spend $3 million studying the sites. The permits it is seeking from the Federal Energy Regulatory Commission would prevent other entities from developing the areas for three years. To move from research to development, the utility would file for a license.
The wave-power projects would fit the utility’s renewable energy strategy. About 55% of the energy PG&E; delivers to its customers is generated without producing carbon dioxide, and more than 12% is certified as renewable under California guidelines. If installed as planned, the wave-power projects would add 80 megawatts to the grid, equal to 7% of the company’s current renewable energy output. “We don’t think that’s insignificant,” Wachs said.
Still, the utility must prove to regulators -- and shareholders -- that a young technology can be effective in commercial use. During its study, it must also decide which of several wave-power technology companies has the design to suit California’s coast.
Islay’s Limpet system may not fly in California because it’s embedded in a cliff -- a no-no with environmentalists. Portugal’s slinky Pelamis isn’t exactly eye candy, making it a possible weak spot with oceanfront property owners. And the PowerBuoy system, in use at a Navy base in Hawaii, has yet to supply significant amounts of power.
“Many of these wave-power companies have limited at-sea experience,” said Andrea Gill, an energy conservation analyst at the Hawaii Department of Business, Economic Development and Tourism. “We still don’t have long-term data on how much electricity is coming out of these guys.”
PG&E; declined to comment on which technologies it was considering. But Gill said that, judging by the growing number of contenders, the utility may opt for something other than the Limpet, PowerBuoy or Pelamis. She cited examples such as a Danish device with parabolic arms and a Scottish machine that swings back and forth with each wave.
Regardless of the technology it chooses, Gill said, the utility was taking a leadership role by considering wave power.
“There’s just a growing acceptance that renewable energy’s time has come, and actually, it came some time ago. But people just weren’t acting as fast.”
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Harnessing wave power
Pelamis
What it looks like: a huge, red snake
How it works: Semi-submerged steel ballast tubes are linked with shorter power modules that contain generators. The pieces are connected by long rams that push and pull in the wave action, pumping hydraulic fluid through a device in the power module that drives a generator, producing electricity, which is sent to the shore via a cable.
Locations: Portugal, England and Scotland*
Made by: Ocean Power Delivery, Scotland
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PowerBuoy
What it looks like: a big, bobbing metallic cork
How it works: A buoy moored loosely to the ocean floor supports a cyclinder containing a generator. The up-and-down wave motion creates a mechanical stroking within the cylinder, which drives the generator. The electricity is sent shoreward via a cable.
Locations: Hawaii, New Jersey, Oregon, England, Scotland, Spain and France*
Made by: Ocean Power Technologies, New Jersey
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Limpet
What it looks like: a bunker
How it works: A concrete air collector is embedded along a rocky shoreline where there is an abundance of wave activity. As seawater rushes into the collector, air is forced up through its chamber into two turbo-generators. The force of the air through the generators spins turbines, creating electricity, which is sent to the power grid.
Locations: Scotland and Denmark*
Made by: Wavegen, Scotland, a unit of Voith Siemens Hydro Power Generation, Germany
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Note: Illustrations are schematic.
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*Includes some units in operation, being tested or proposed.
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Sources: The companies
