Posted on 04/23/2007 7:18:22 AM PDT by aculeus
Turbines are being submerged in the East River to generate electricity from rapid tidal currents.
Working from barges and tugboats off New York City's Roosevelt Island, engineers are battling northeasters and this month's heavy spring tides to install the first major tidal-power project in the United States. The project involves a set of six submerged turbines that are designed to capture energy from the East River's tidal currents. The three-bladed turbines, which are five meters in diameter and resemble wind turbines, are made by Verdant Power of Arlington, VA.
Thanks to lessons learned by wind turbine designers, tidal power is already economically competitive, producing electricity at prices similar to wind power, according to feasibility studies by the Electric Power Research Institute, an industry R&D consortium. And it offers a big advantage over wind and other renewables: a precisely predictable source of energy. As a result, developers in the United States have laid claim to the best sites up and down the Atlantic and Pacific coasts. In the past four years the Federal Energy Regulatory Commission in Washington, DC, has issued preliminary permits for tidal installations at 25 sites, and it is considering another 31 applications.
Current-harvesting turbines represent a sharp break from the first wave of tidal power, so-called "barrages" in which impoundments installed across estuaries or bays created hydroelectric reservoirs refilled twice daily by rising tides. The La Rance barrage in Normandy has produced up to 240 megawatts of power--as much as many natural-gas-fired power plants--since 1966. Halifax utility Nova Scotia Power has been generating up to 20 megawatts of power since 1984 at a tidal barrage in the Bay of Fundy, whose funnel-shaped inlet produces the world's largest tides--16 meters at its head.
But these constructions have fallen out of favor because of their outsize impact on ocean ecosystems. James Taylor, general manager of environmental planning and monitoring for Nova Scotia Power, notes that commercial-scale installations planned for the Bay of Fundy in the 1980s would have altered tides as far away as Boston. "It would be a pretty hard thing to get permitted today," says Taylor.
Hence the attraction of in-flow turbines such as Verdant's. "The whole point of doing kinetic hydro is to have a very small environmental footprint," says Dean Corren, Verdant's director of technology development, who designed the tidal turbines in the early 1980s while conducting energy research at New York University.
Corren's team installed its first two turbines in the East River in December. One has been delivering a maximum of 35 kilowatts of power to New York City, swiveling to generate power as the river swells with the high tides and empties with the low. The other turbine delivers performance data that Corren says will be crucial to refining the blades and gearbox, generator, and control system to optimize power generation.
This month Verdant added four more 35-kilowatt turbines. Corren says Verdant is now working on a next-generation design that will be cheaper to mass-produce, in anticipation of installing a farm of at least 100 turbines at the East River site.
Before the company proceeds, however, it must monitor the first six turbines for 18 months to assuage concerns of federal and state regulators that the turbines, whose tips cut through the water at up to nine meters per second, won't chew up the river's fish. Such qualms have already delayed the first-of-its-kind project by several years. Corren says monitoring to date has shown that few fish venture into the strong currents flowing past the turbines, but he says the extensive studies will provide a critical foundation for future developments.
Meanwhile, Canadian and European tidal-turbine producers are already scaling up their designs. Marine Current Turbines of Bristol, England, has operated an 11-meter, 300-kilowatt turbine off Devon for four years and plans to install a one-megawatt turbine in Northern Ireland's Strangford Lough this year. Marine Current's design resembles Verdant's but uses two rotors, each with two blades. Other competitors are scaling up so-called ducted turbines, which are surrounded by a power-boosting shroud to guide water flow. Nova Scotia Power recently signed up Dublin's OpenHydro to install a one-megawatt ducted turbine in the Bay of Fundy, while Vancouver-based Clean Current Power Systems is working on a two-megawatt version of the 65-kilowatt ducted turbine it installed off the coast of British Columbia in December.
Although scale will reduce costs, Clean Current president Glen Darou says the nascent industry will also have plenty of work ahead proving the reliability of its mechanical and electrical systems underwater. "Salt water is insidious," says Darou; try as you might to seal it out, corrosive seawater "will get in there eventually."
Copyright Technology Review 2007.
Got a ways to go.
As regular as the tides... :)
I’m surprised the Greenies aren’t howling that this will cause elevation of the water temperature, massive die-off of plankton or some other blibbering nonsense.
That watt I noticed also.
35 kW ain’t real big. The East River is low flow as well, wonder why they didn’t use the Hudson to start with?
Cheasapeake Bay, San Francisco Bay, Columbia River outlet could be reasonable places for larger scale units - at the threat of ship collision, but there are very, very few places in the US where (non-taxpayer-funded) power this way will be steadily profitable. Note that they compare the water source to wind power, not to conventional power sources = still cheaper.
Don’t forget the plexiglass covers that must be placed on the front of these devices to keep critters away from those turning blades.
U can only turn the lights on during tide, for no tide no power. Is this like one square of toilet paper?
No - you can use one square of toilet paper regardless of the tides...
But, what about all of the fishies that will be chopped to pieces by these murderous things?
You ever take a sailboat up the East River? You can't do it on the outgoing tide, and when you go with the flow, you're doing about 6-8 knots without any help. With engine, we were doing about 12 knots over the ground. I'm not sure what qualifies for "low flow", but in my book that qualifies for a pretty stiff current.
Where the Chesapeake Bay meets Hampton Roads, local sailors call it "The Monster", because you can't through it against the tide without some serious power behind you. I could see putting some turbines between the piers of the Hampton Roads Bridge Tunnel to catch the tidal flow.
The Hudson freezes over now and then. That might affect expensive machinery adversely.
What about using the Gulf Stream and Japan Current? I suspect they are very slow, but massive in volume.
“Before the company proceeds, however, it must monitor the first six turbines for 18 months to assuage concerns of federal and state regulators that the turbines” (US)
“Meanwhile, Canadian and European tidal-turbine producers are already scaling up their designs. Marine Current Turbines of Bristol, England, has operated an 11-meter, 300-kilowatt turbine off Devon for four years and plans to install a one-megawatt turbine in Northern Ireland’s Strangford Lough this year.” (Them)
This is why nothing ever gets done in this country. I don’t know if these things are worth the effort or not, but as usual as the rest of the world speeds forward with modern technology, we will be wading through reams of government paperwork and regulations.
Robert MacKay, director of the Society for the Preservation of Long Island Antiquities, points out that a prominent map of Long Island in the mid-1800s bothered to show only two types of buildings: mills and lighthouses -- ``both structures critical to the economic well-being of the region.''Long Island's grains were highly prized. ``We had probably the greatest concentration of tide mills on the eastern seaboard, and we have the greatest surviving concentration of windmills,'' MacKay said. ``This is due in part because we don't have a lot of rivers to provide the kind of falling water that powered the Industrial Revolution in New England.''
Or let some smaller company spend 15 years developing the technology. Then GE can come in and buy them.
Don’t worry, Al Gore sells TP offset credits. For each sheet you use, he pays some guy in Bangladesh to wipe with his left hand.
Carolyn
The La Rance barrage in Normandy has produced up to 240 megawatts of power--as much as many natural-gas-fired power plants--since 1966. Halifax utility Nova Scotia Power has been generating up to 20 megawatts of power since 1984 at a tidal barrage in the Bay of Fundy, whose funnel-shaped inlet produces the world's largest tides--16 meters at its head.
Watts (or megawats) measure the rate of energy flow. Watt-hours (or kilowatt-hours) measure energy. These sentences seem to be telling us the peak (actual) instantaneous power output of these two plants over the decades of their operation. Is this what we care about? How about average power output? Or capacity factor (the average power output expressed as a percentage of the maximum)? Or the total energy produced? Or the cost per unit of energy?
This seems totally dumb to me. What am I missing?
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