Posted on 09/19/2006 8:50:52 AM PDT by Uncledave
MIT designs 'invisible,' floating wind turbines
An MIT researcher has a vision: Four hundred huge offshore wind turbines are providing onshore customers with enough electricity to power several hundred thousand homes, and nobody standing onshore can see them. The trick? The wind turbines are floating on platforms a hundred miles out to sea, where the winds are strong and steady.
Today's offshore wind turbines usually stand on towers driven deep into the ocean floor. But that arrangement works only in water depths of about 15 meters or less. Proposed installations are therefore typically close enough to shore to arouse strong public opposition.
Paul D. Sclavounos, a professor of mechanical engineering and naval architecture, has spent decades designing and analyzing large floating structures for deep-sea oil and gas exploration. Observing the wind-farm controversies, he thought, "Wait a minute. Why can't we simply take those windmills and put them on floaters and move them farther offshore, where there's plenty of space and lots of wind?"
In 2004, he and his MIT colleagues teamed up with wind-turbine experts from the National Renewable Energy Laboratory (NREL) to integrate a wind turbine with a floater. Their design calls for a tension leg platform (TLP), a system in which long steel cables, or "tethers," connect the corners of the platform to a concrete-block or other mooring system on the ocean floor. The platform and turbine are thus supported not by an expensive tower but by buoyancy. "And you don't pay anything to be buoyant," said Sclavounos.
According to their analyses, the floater-mounted turbines could work in water depths ranging from 30 to 200 meters. In the Northeast, for example, they could be 50 to 150 kilometers from shore. And the turbine atop each platform could be big--an economic advantage in the wind-farm business. The MIT-NREL design assumes a 5.0 megawatt (MW) experimental turbine now being developed by industry. (Onshore units are 1.5 MW, conventional offshore units, 3.6 MW.)
Ocean assembly of the floating turbines would be prohibitively expensive because of their size: the wind tower is fully 90 meters tall, the rotors about 140 meters in diameter. So the researchers designed them to be assembled onshore--probably at a shipyard--and towed out to sea by a tugboat. To keep each platform stable, cylinders inside it are ballasted with concrete and water. Once on site, the platform is hooked to previously installed tethers. Water is pumped out of the cylinders until the entire assembly lifts up in the water, pulling the tethers taut.
The tethers allow the floating platforms to move from side to side but not up and down--a remarkably stable arrangement. According to computer simulations, in hurricane conditions the floating platforms--each about 30 meters in diameter--would shift by one to two meters, and the bottom of the turbine blades would remain well above the peak of even the highest wave. The researchers are hoping to reduce the sideways motion still further by installing specially designed dampers similar to those used to steady the sway of skyscrapers during high winds and earthquakes.
Sclavounos estimates that building and installing his floating support system should cost a third as much as constructing the type of truss tower now planned for deep-water installations. Installing the tethers, the electrical system, and the cable to the shore is standard procedure. Because of the strong offshore winds, the floating turbines should produce up to twice as much electricity per year (per installed megawatt) as wind turbines now in operation. And because the wind turbines are not permanently attached to the ocean floor, they are a movable asset. If a company with 400 wind turbines serving the Boston area needs more power for New York City, it can unhook some of the floating turbines and tow them south.
Encouraged by positive responses from wind, electric power, and oil companies, Sclavounos hopes to install a half-scale prototype south of Cape Cod. "We'd have a little unit sitting out there andŠcould show that this thing can float and behave the way we're saying it will," he said. "That's clearly the way to get going."
This research was supported by the National Renewable Energy Laboratory.
Source: MIT, by Nancy Stauffer
Most of these big windmills are designed to automatically "feather" the blades under conditions of high wind, so the "lift profile" would be minimal. I think the answer "is" no.
Alternator generators with blade pitch governors ought to work.
Dear Wonder Warthog,
I thought that there might be some mechanism like that in play.
Thanks.
sitetest
Let Darwin deal with the hapless birds.
Building, sorry.
A very long extension cord.
You're joking, but enough of these things to generate a significant amount of power, when located in deep water, would be a serious hazard to navigation.
It seems to me that they could be much closer to shore without 'offending' sensitive eyeballs, such as Ted Kennedy's.
Back in the day that telegraphy guy strung a cable covered in gutta-percha all the way across the atlantic. Took him about three tries too -- it kept breaking and falling to the bottom. That was some high-voltage stuff too, that was the only way they could keep it charged across all those thousands of miles.
Dear jrp,
"It would take thousands of these things to equal the capacity of one nuclear power plant."
Well, the article says that the turbines being designed can generate 5MW each. I live in Maryland, not too far from the Calvert Cliffs nuclear power plants. Each of the two Calvert Cliffs units generates about 850MW, for a total of about 1.7GW.
I'm sure there are bigger nuclear plants, but I'm sure there are smaller, too.
To generate as much electricity as Calvert Cliffs, one would need about 340 of these turbines.
I read another article posted by UncleDave about a proposed off-shore wind turbine farm in New England. From that article, it seems that one places hundreds of these turbines together in a "farm," several hundred feet apart from one another. I guess you could get roughly a hundred of these turbines in a square mile.
So, to generate the electricity equivalent of the Calvert Cliffs nuclear facility, you'd need a few square miles of ocean. Since these facilities can be "planted" between about 30 to 100 miles off-shore, and since we have a pretty good amount of coastline off the East and West coasts of the US, we could plant a few hundred of these farms without using much of the available surface of the ocean.
That'd generate a substantial portion of the electricity used by the United States.
sitetest
It would probably remain DC all the way to the shore, then conversion from DC to AC is done with an inverter. While they're not as big as what they would use, you can buy DC-AC converters at any electronics shop, or at Wal-Mart where it plugs into your cigarette lighter.
--thanks--I go all the way back to Ward-Leonard systems on AC-DC--have been around a few windmill setups from the highway--was curious about the big outfits with three hundred foot blades and the high-voltage three-phase conversion---
By keeping it "50 to 150 kilometers from shore" old sport.
In the late 60's early 70's Offshore Power Systems, I believe a div of GE, was going to build floating Nuclear power plants off the coast of Jacksonville FL, but I think the Enviro Nutcases got it killed before it was ever off the ground (or on the water)...........
You think THATS bad, what about the birds?
It was Westinghouse, not GE..........see link for more info......
http://www.atomicinsights.com/aug96/Offshore.html
BTW nobody speaks of OTEC which solves multiple problems utilizing the energy in sea water!
I wonder if the electricity from these things would be cheap enough for Iran to end their nuclear power development?
Yes, but that's not what that idiot wants!
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