Will Oceans Be Our Best Source of Clean Power?
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The resource is clean, renewable and vast. In fact, it covers 70 percent of the planet. That would be the ocean, with endless waves and ceaseless tides that can be harnessed to create electricity with zero carbon or particulate emissions. If logistical, environmental and efficiency challenges can be overcome -- a big "if" -- this could be a major clean energy source for the half of the world's population who live within 50 miles of coasts.
So far wave and tidal power have not been tapped on a commercial scale, but a number of pilot projects are underway worldwide and so far the prospects seem relatively promising.
This summer the world's first commercial offshore wave power project was launched off the coast of Portugal. The Agucadora Wave Park consists of three 142-meter-long hinged steel tubes called Pelamis machines. As waves move along the tubes, they move up and down and hydraulic devices at the joints generate electricity. The project plans call for 25 Pelamis machines generating up to 21 megawatts of power, which would save 60,000 tons of carbon emissions per year compared to a fossil fuel plant making the same amount of energy.
Meanwhile a commercial shore-based wave energy project was also launched in Islay, Scotland. The LIMPET, or Land Installed Marine Powered Energy Transformer, is attached to the shore and uses the waves' momentum to funnel air into turbines to produce electricity. Plans are also in the works for a 40-turbine, four megawatt wave project in Scotland's Siadar Bay which could provide electricity for a fifth of Scotland's population.
Australia, England and Israel are among other countries where the government and private companies are actively pursuing wave power.
As with other renewable energy methods the US is lagging behind Europe, but there are a number of wave power projects in the works off the west coast. In September Oregon State University's Hatfield Center and the University of Washington secured a $6.25 million, five-year grant from the Department of Energy for wave energy development including an experimental project involving large energy-generating buoys about 12 miles off Newport, Ore.
"It's very much an emerging technology," said Roger Bedard, head of ocean power for the Electric Power Research Institute, the research and development arm of the utility industry. "I am not ready to say whether the US or the world should add wave power to the portfolio of energy options. What are the effects on sedimentation, fish, marine mammals, whales migrating from Alaska to Baja? First we need to do pilot testing and get hardware in the water to answer these questions."
Bedard said there are currently about 40 device developers in various stages of development. About six are doing full scale prototype testing, he said, and about 25 more have done subscale testing in the ocean. Others are still testing devices in wave tanks.
In December 2007 the Federal Energy Regulatory Committee (FERC) issued its first permit for a hydrokinetic wave energy project in the U.S., the Makah Bay Offshore Wave Pilot Project which calls for four floating buoys and an underwater transmission cable two miles off the coast of Washington state. It is being developed by the company Finavera Renewables Ocean Energy and expected to power 150 homes. But Bedard said it still needs permits from multiple government agencies, a lengthy and costly process, to proceed.
"Unfortunately in this country the regulators want to know what the environmental effects are before we put it in the water, but we need to do pilot tests in the water to know," he said. "It's a catch 22." In 2008, FERC permit applications for wave energy projects were filed by Pacific Gas & Electric in Mendocino and Humboldt County, Calif.; and by other private companies in California and Oregon. "PG&E has all the coast of California with good strong waves as their territory," said Bedard. "They're the one utility that can really capitalize in a big way in the future in wave energy."
The company Ocean Power Technologies (OPT) is developing a wave project off Reedsport, Ore. involving 10 buoys similar to the ones being tested by Oregon State, which could generate enough power for 1,500 homes. They are still seeking permits but hope to launch a pilot buoy next summer. These buoys need waves at least four feet high and can work in waves up to 22 feet high, according to the company. The motion of the waves essentially moves a piston up and down inside the buoy, which generates electricity magnetically. OPT, founded by an Australian surfer, is a publicly traded company that launched its first test buoy in New Jersey in 1997. An OPT buoy that produces 40 kilowatts is about 52 feet long and 12 feet in diameter, with about 13 feet rising above the ocean surface.
An Irish company called Wavebob with headquarters in Annapolis is also hoping to develop wave projects on the US west coast. The Pacific has much stronger waves than the Atlantic, since winds blow west to east across the globe and hence gain power all across the Pacific before hitting the coasts of California, Oregon and Washington. Wave power is also about 10 times stronger in winter than summer.
George Boehlert, director of the Hatfield Center and a professor of fisheries and wildlife at Oregon State, noted that the Pacific Northwest is conducive to wave power because it not only has steady, powerful waves but also electricity transmission infrastructure near the coast.
"There are an awful lot of places where you have very good wave energy, but you don't necessarily have a mechanism to transport it where the power is needed." he said.
"In Oregon we had a lot of industries related to timber and mills at the coast. So we have a lot of substations essentially right near the beach."
The Oregon governor's office has instituted a program to fast track wave power projects, and state officials hope wave power could help them meet a goal of getting 20 percent of the state's power from renewable sources by 2025. A government grant helped form the Oregon Wave Energy Trust, a public-private partnership to study the development of "responsible wave energy."
Wave power has been explored more than tidal power, partly because tidal power is more limited geographically. The power of the tides can generally only be harnessed in a narrow passageway between large bodies of water, for example between a bay or estuary and the open ocean. A major tidal power plant is operating in the Bay of Fundy between New Brunswick and Nova Scotia, known for having the world's largest low tide-high tide gap at up to 50 feet. But this project and other proposed tide power schemes involving dams or turbines in the Bay of Fundy have raised serious environmental concerns, including shoreline erosion, contamination and whales stuck behind the generating apparatus.
In the U.S., many tidal areas only vary by about three feet between high and low tide, meaning much less potential energy. But Bedard said places like under the Golden Gate Bridge could still be attractive for tidal power, since they are close to populations which need electricity. "San Francisco is right there, you just plug it into the city," he said. "In Puget Sound, the Admiralty Inlet is just 20 miles from downtown Seattle. Whereas in Alaska, you have a huge tidal resource, but no people and no transmission wires."
There are a number of wave power technologies being tested worldwide, including the Pelamis tubes and the buoys being used off the Pacific Northwest. Boehlert said Oregon State also has experimented with a different prototype he describes as "basically an electromagnetic system like shakeup flashlights."
"Where wave energy is today is similar to where wind was 15 or 20 years ago," said Justin Klure, former director of the Oregon Wave Energy Trust and a consultant with the company Pacific Energy Ventures. "You had four blades, five blades, vertical, horizontal, towers of all heights. Now a 100-meter tower with three blades is the technology of choice. It will be a while before we can make a determination on what technology is most efficient in extracting the linear motion of waves into electricity. It might not be one single device like wind -- there might be multiple devices that make sense."
Researchers at the University of Southampton are developing huge rubber "snakes" known as Anacondas which they hope can generate power more cheaply than most wave technologies, to the tune of six cents per kilowatt hour. The 200-meter-long, seven-meter-diameter Anacondas are rubber tubes sealed, filled with water and placed in the sea facing oncoming waves. The motion of rolling waves passing over them moves the water inside in a "bulge" towardÂ a turbine at one end of the tube to generate electricity.
A technology is being tested off Australia which involves a piston pump attached to the sea floor moved by a float rising and falling on the waves above. Another device developed by the company Energen Wave Power involves floating pontoons and multiple "pivot arms" that capture wave energy. One of Bedard's favorites is an "artificial muscle" being developed by SRI International in Menlo Park, Calif. in partnership with the Japanese company Hyper Drive Corp which he says, "is very much like a rubber band. You stretch it, and it makes energy." He noted simple devices like this are key, since the off shore location makes maintenance difficult and costly.
"Since the ocean concentrates energy from wind into waves, it's a much higher density resource than wind or solar," he said. "That means the machine to extract it can be smaller, which means less capital. But the kicker is the deployment and maintenance cost. The ocean is a remote and hostile place. Unless developers make something highly highly reliable (that doesn't need much maintenance) it won't be economically successful."
Energy from wave projects is transmitted to the grid through undersea electrical cables, which are commonly used for various purposes including offshore wind farms that are prevalent off several European countries and in development in the U.S.
While land-based and offshore wind farms -most notably the proposed Cape Wind project in the Nantucket Sound -- have provoked significant opposition because of their effects on views, wave energy buoys would be virtually unnoticeable to people onshore.
However wave energy does raise serious environmental concerns, especially in places like the federal Olympic Coast National Marine Sanctuary, where the Makah project would be located. Oregon State is beginning to investigate whether their buoys could alter gray whale migration routes, ocean currents or sand dispersal patterns. Environmentalists also worry about the electromagnetism from undersea transmission cables. And some worry wave power operations could impede the commercial fishing and crabbing industries which are economically crucial to the Pacific Northwest.
"If there are egregious environmental effects, we should not add wave power to our portfolio," said Bedard. "If there are negative effects but they are outweighed greatly by the negative effects of other supplies like coal, maybe we should consider it. (Wave power) should be adaptively managed as part of the national energy supply portfolio."
"It's clear there's a lot of energy in the ocean yet to be tapped," added Klure. "There's no free lunch, there are risks. It's a risk worth taking but we need to do it in a very logical, sequential manner to explore what the real long-term potential is."