HARNESSING THE TIDE: The U.S. has begun an effort to capture the energy in the oceans' tides to power homes and businesses miles from the smell of salt air.
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SEATTLE – For eons, powerful tides have raged through Puget Sound, ripping along at 11 feet per second at their peak, predictable as the phases of the moon.
Three years from now, a local utility hopes to begin converting a portion of that raw energy to electricity, part of a growing effort to harness the tides to power homes and businesses miles from the smell of salt air.
The Snohomish County Public Utility District's pilot project is small – two turbines with 500 kilowatts of total capacity and an average output of 50 kilowatts – hardly a panacea for all that ails the United States' energy portfolio. But tidal power is garnering increasing attention as a niche supplier of renewable alternative energy in Washington, Maine and Alaska. The tides, some say, have the potential to light five percent of the nation's homes – nearly nine gigawatts of generating power.
And with wind and solar increasingly seen as viable commercial energy alternatives in the United States, investors and public utilities also seem more willing to literally test tidal energy's waters.
"There is a realization that a diversified suite of renewable energy resources will displace fossil fuel," said Monty Worthington, who is directing a tidal energy project in Alaska for the Maine-based Ocean Renewable Power Co. "To establish a place in the emerging marine renewable market, the time for [U.S.] investment is now."
To that end, earlier this fall, the Snohomish County utility, which serves 320,000 customers north of Seattle, won a Department of Energy grant covering half the costs of its $20 million tidal energy pilot project. Two 30-foot tall turbines will operate 200 feet beneath the surface in the narrow tidal passage of Admiralty Inlet, between the Olympic Peninsula and Whidbey Island, Wash. When fully developed, the Puget Sound project could power tens of thousands of homes, the utility says.
Tidal power remains a nascent technology, still very much being developed. But for the Snohomish public utility district, it offers several advantages over relatively more advanced renewable energy sources such as wind and solar, said Craig Collar, the utility's senior energy resource development manager.
"Solar is not yet economically competitive in the Northwest," he said. "And given wind's transmission and integration challenges, we would prefer to add more predictable – and potentially more local – resources such as tidal and geothermal."
Climate change and energy security concerns are tidal energy's primary drivers, Collar said. A desire to hedge against possible future carbon taxes makes it even more attractive.
The Puget Sound initiative is the first to be launched by a public utility in the Pacific Northwest. Tidal energy has made headway in recent years in Europe and Canada, and it is attracting growing interest inside the United States. Ocean Renewable Power is testing a turbine in Maine and has plans for a project in Alaska's Cook Inlet, which boasts the second-highest tidal range in the world.
Technology hurdles remain a huge issue. Solar and wind have seen considerable advancement in technology the past decade. But tidal energy – at least in the United States – has arguably been taken seriously only in the last five years. And while it will likely never be as ubiquitous as wind and solar, it is more predictable – a highly desirable trait for utilities looking for carbon-free baseload generating power.
At a basic level, a tidal turbine works fundamentally like a wind turbine. Instead of wind, tidal flows turn the turbine, converting the kinetic energy of moving seawater into electrical energy. Despite its promise, however, today there are less than a dozen tidal turbine projects operating worldwide, and few look alike.
"That's very unlike the wind turbine situation, where a non-expert at any distance can't tell one company's turbine from another," said Paul Jacobson, the ocean energy leader at the Electric Power Research Institute.
Tidal energy technology is also changing so quickly that it doesn't make sense to build a full tidal turbine farm at the outset, but rather adapt to technology innovations on a short term basis, said Collar.
"As the industry matures," added Brian Polagye, a mechanical engineer at the University of Washington in Seattle, "it should be possible to design turbines that are both highly efficient and robust, but we're still in the learning stages."
The U.S. lags Europe in all renewable energies, said Collar, and tidal energy is no exception. That's changing.
In addition to public utilities, startup companies like Ocean Renewable Power Co. are now getting involved with the tacit understanding that even if tidal energy's potential is limited, it can still be profitable.
This year Ocean Renewable started testing a tidal system in Cobscook Bay and West Passage, Maine. The company claims that within a decade, tidal energy could become a billion dollar industry in Maine alone, generating both electricity and hundreds of jobs.
The company is also planning a 2012 pilot project for Cook Inlet, Alaska, with a follow-on commercial project that could potentially provide ten percent of the energy needs for a majority of the state’s electrical grid.
Domestic interest is such that, experts say, the U.S. tidal energy market may overtake Europe in a few years.
"This technology could develop much faster in North America than Europe, where we are notoriously risk-averse and slow," said Peter Fraenkel, technical director of the U.K.'s Marine Current Turbines Ltd.
Indeed, last month the British government withdrew support for a $24 billion tidal energy project across the Severn Estuary that could have generated five percent of the United Kingdom's electricity.
The project is one of the world's most ambitious renewable energy projects, but a recent assessment pegged the project's true cost at closer to $54 billion. Environmentalists have also attacked it for destroying marsh and mud flats used by thousands of birds. The British government said it couldn't justify such a high-risk, high-cost project, though private backers have vowed to continue without government support.
Environmental harm remains a big concern as the tidal industry develops, and U.S. regulators require testing to insure that such turbines don't pose a threat to marine life. But whether the underwater acoustics of the turbines harm marine life and how fish and marine mammals might interact with the turbines' rotors remain open questions.
"Some data [are] starting to trickle in," said Collar, "and none of those efforts have revealed any detrimental effects on marine habitats or mammals."
Turbines designed for Puget Sound have no exposed blade tips, run at low speed, require no mechanical lubrication or seabed drilling, and are designed to leave the seabed undisturbed, according to the Snohomish County utility.
Still, Admiralty Inlet is the crossroads for several endangered species, including three types of rockfish, Stellar sea lions and orcas.
"There are no published studies," said Keith Kirkendall, a NOAA fisheries biologist, "so we just don't know what the impact to marine life will be."
But interest is there. The Energy Department is drafting its first nationwide assessment of the tidal energy resource. Just how much potential energy is out there is still debated.
Despite the uncertainties, it's worth pursuing, said the U.K.'s Fraenkel.
"No one really has reliable knowledge of tidal energy's global potential," he said.
"It's big enough to justify developing technology, but it's not a silver bullet in replacing fossil fuels."
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8 Comments
Add CommentYet another great idea. I wish them well and hope that in the next couple of decades while they work out the details, the scientifically advanced people will be creating clean, safe and efficient nuclear energy generators to actually do something practical and to scale so that we can maintain our scientific/technical and industrial capacity while effectively reducing our dependence on petro-fuels (much of which is imported) and which, no arguement from me, creates real pollution beyond the speculative impacts, exaggerated as many suspect that they are, of CO2. I'm eager to see soot, heavy metals and toxic organic pollutants addressed as soon as possible. CO2 on the other hand...not so much.
Reply | Report Abuse | Link to thisI do wonder what sort of impacts these tidal generators would have on our intertidal regions which are in fact the most pivotal and productive zone in the oceans systems, and which are already under assault from irresponsible unsustainable resource practices like fish farms and mangrove destruction, allowing more and more silt to settle onto near shore coral reefs. We don't know very much as to how so called acidification or warming will effect coral reefs but it's a sure bet that nitrogen rich run-off from eco-resorts on oceanic islands where divers go to enjoy the beauty of the reefs cause exactly the kind of degredation that we hear so much about in concern over warming and acid. So, keep up the great work but lets keep in mind that the solution or our energy in the near term can be nuclear, and probably will be for China, India, France and other advancing progressive nations that see beyond the hype and paranoia of the journalist science writers with their degrees in English, which they probably got because they suck at math. Cheers.
It amazes me that with wind energy, someone is worried about the turbines killing bats; with solar, people are worried about lizards in the desert; with geothermal power, people are worried about a possible earthquake that will probably never happen unless the geothermal is built over a fault; with tidal energy, people are worried about fish getting caught in the turbines; with hydro energy, people are worried about draining lake and river water that's been there for thousands of years.
Reply | Report Abuse | Link to thisWith oil drilling, there is no worry about spills - the killing of fish - the killing of all kind of animals and birds and humans; with coal extraction by MTR there is no worry about the total devastation of animal, bird, and fish habitats, no worry about chronic disease in humans, or the worry about the pollution of our air, water, and land and the killing of our children by carbon monoxide; with natural gas extraction - there is no worry about it causing earthquakes, which natural gas fracking causes 2.5 and above earthquakes on a regular bases, the poisoning of our water and land, and the killing of our children with poison water and foods; with nuclear there is no worry about an accident and wiping out whole communities with radiation, and the polluting of our water and land caused by the radiation storage.
Why is there such concern about clean energy destroying the environment and there is no concern about fossil fuels destroying the environment?
While I can generally empathize with your sentiments, I think that tidal energy extraction may have the potential to disrupt entire tidal ecosystems, affecting a wide variety of species over a substantial area...
Reply | Report Abuse | Link to thisIf some technology could replace our dependence on fossil fuels and their impact on the planetary ecosystem while unfortunately eliminating some tree slug: goodbye little slug!
Might have been a mention of the tidal power plant at Annapolis Royal, Nova Scotia, that has been in operation for decades. This harnesses the well known tides in the Ammapolis Basin, flowing from the Bay of Fundy. A trip here to find out how to do it, or not do it, would certainly be worth it.
Reply | Report Abuse | Link to thisThis project seems like worth to do it.
Reply | Report Abuse | Link to thisBut at least one thing should be proven - this tide technology doesn't produce any detremental effects on sea life forms. If not, the way to go. If it does, then get ride of it. We already have hideous coal plants, oil drilling ext. Don't create new dangerous sources for accelerating of Earth's elemination.
The power output of tidal energy is too low for commercial use bec. the amplitude of oceanic tide is only about 2 ft. You need a very large water reservior to convert 2 ft. of potential energy difference into electric power.
Reply | Report Abuse | Link to thisA reservior as large as the Panama Canal 80 km long, 35 m wide can impound 1.7 million cu.m. of water. This converts into 10 million kJ of energy every 12 hrs. at two high tides per day, producing 0.2 MW of electric power.
0.2 MW is very small for a commercial power plant. The Hoover Dam, which required less engineering work than the Panama Canal, produces 2,000 MW. Tidal energy is small compared to hydroelectric power.
@JamesDavis: You wrote: "Why is there such concern about clean energy destroying the environment and there is no concern about fossil fuels destroying the environment?"
Reply | Report Abuse | Link to thisIt would seem that you have been missing much of the information over the past few decades regarding the pollution and illness caused by fossil fuels. Perhaps you're not aware of the Exxon Valdez 20 years ago, or the BP spill in the Gulf of Mexico earlier this year, or the multitude of oil spills over the years, or the amount of human and animal illness caused by petroleum products, or the acid rain that ruins water & forests. And the list goes on (& on).
These few examples (of very many problems environmentally with fossil fuels) would be some of the concerns taking place, but if you haven't been paying attention, I can understand your confusion. To suggest that there is 'no concern' about the effects of fossil fuels destroying the environment is just plain...well, wrong.
In France , city of Saint Malo (48.62 N, 2.00 W) since 1967 a tidal dam produces electricity equivalent to the needs of a 200 000 people city. 250MW max power. The average tides are 10 meters amplitude here. In fact the electricity company uses this dam to produce electricity mainly during the peak demand hours, like the company manages the hydroelectric dams in the mountains. The reason is that nuclear plants which produce 80% of the national electricity, are not flexible at all to adjust rapidly to the demand. Disturbance on the marine life is relatively limited : fish can go through the large low pressure turbines with no damage. A lock give access to sailing yachts, every hours, and recently an iPhone WebApp gives you the daily tidal table.
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