- ‹ previous
- 1326 of 2041
- next ›
*Vortices
VORTICES....Via Mark Kleiman, researchers at the University of Michigan have created a wave-based system for generating electricity called VIVACE, or "vortex-induced vibrations for aquatic clean energy":
The new device, which has been inspired by the way fish swim, consists of a system of cylinders positioned horizontal to the water flow and attached to springs. As water flows past, the cylinder creates vortices, which push and pull the cylinder up and down. The mechanical energy in the vibrations is then converted into electricity.....A "field" of cylinders built on the sea bed over a 1km by 1.5km area, and the height of a two-storey house, with a flow of just three knots, could generate enough power for around 100,000 homes....The scientists behind the technology, which has been developed in research funded by the US government, say that generating power in this way would potentially cost only around 3.5p per kilowatt hour, compared to about 4.5p for wind energy and between 10p and 31p for solar power. They say the technology would require up to 50 times less ocean acreage than wave power generation.
...."If we could harness 0.1 per cent of the energy in the ocean, we could support the energy needs of 15 billion people. In the English Channel, for example, there is a very strong current, so you produce a lot of power."
Well, why not? Vortex-induced vibrations generated enough power to destroy the Tacoma Narrows Bridge in 1940, so why not get something useful out of it?
Of course, claims like these pop up constantly, and there's no telling how well VIVACE will work until there's been a real-world test. That will happen next year, when the boffins plan to set up a small prototype in the Detroit River designed to generate 3 kilowatts of power. No word yet on an ocean floor test.
Digg
Reddit
Twitter
Facebook
Buzz Up!
StumbleUpon
MySpace
LinkedIn
Delicious
Furl
Google
Yahoo
kudos for using the word 'boffin'.
And when are we going to get serious about alternative energy, and start harnessing the power of jumping 4-year-olds?
The VIVACE stuff, which seems like a great idea, was the first place I heard a claim the Tacoma bridge's resonance was started by vortex shedding.
I don't think that's a requirement for resonance in that bridge.
And it was the resonance that brought the bridge down, not any vortex shedding.
Their video and claims on how and why fish swim and school and how their shape and motion exploit vortex shedding were pretty interesting.
Environmentalists don't want the Navy to use sonar and you think this is going to fly?
Coyote: The VIVACE people claim their technology is pretty wildlife friendly. No telling if that's true until it's tested, of course, but apparently green groups are fairly happy with it.
It's true that there are still loads and loads of regs you have to deal with if you want to put stuff in rivers or ocean floors, but that's a whole separate issue.
How much energy does this system extract from the sea? Would it be a way to make the sea calmer?
I disagree, craigie. "Boffin", while showing Kevin's vocabulary skills and pleasing Anglophiles, is suggestive of polarization toward applied scientists and engineers, as in "those guys" - those somewhat obsessive and mildly strange geeky types who constantly mumble techno-jargon and who have no other personality traits whatsoever - those (almost uniformly white males) who never quite outgrew the need for ever bigger Erector sets.
Sorry, and it's likely I'm being too sensitive, but there's a quality to "boffin" - it is a slang word - that conjures up all those above stereotypes (which do, as all strong stereotypes do, contain a kernel of truth, but leave out an awful lot.)
Also of course, if you did a Jay Leno "Jaywalking" exercise and asked people to define or give an example of a "boffin", you're likely to get everything from metal-polisher to arctic bird to exotic fish served in high-priced sushi.
Environmentalists don't want the Navy to use sonar and you think this is going to fly?
This can turn the Navy green(er). The article states a small portable "ladder" could power an anchored boat -- no need to run diesels or turbines.
3 kts is awfully fast for ocean current. This is the peak speed for portions of the Gulf stream; most currents are far slower, less than a knot.
Of course, for some "boffin" is boffo, while for others, it's buffo. And if Kevin ever gets to be a columnist for the New York Times, he can write entire columns in Latin and still get paid.
Hmmm. About a square mile to power 100k homes. Ausra says 100 square miles of solar thermal collectors can produce *all* of the country's electricity. Seems like solar is a simpler, better solution. (Oh, and there are ways to store the heat for when the sun isn't shining.)
Won't they just get filled up with barnacles and seaweed and become quickly useless?
What happened to the Clean Coal we were promised?
"Vortex-induced vibrations generated enough power to destroy the Tacoma Narrows Bridge in 1940"
Umm, yes and no. What it really took was a freak resonance. The bridge pretty much destroyed itself by oscillating at its resonant frequency. But the rhythmic shedding of vortices certainly helped it along. The good news is that we engineers learned from it. We check the resonant frequency of structures now. But without the special resonance, that bridge would still be there.
This system works on a similar concept of vortex shedding, but there is no resonance if you're taking the energy out. We're not really talking about the kind of forces that would take a bridge down.
Great, governments the world over are broke and unable to sink vast sums into this. Privates firms will step in and develop the technlogy. Then Exxon, BP and Conoco eventualy own all the oceans.
There's hundreds of startup companies floating around (if you'll pardon the pun) with alternative energy technologies. There's everything from tapping the jetstream with flying windmills to making hot-tub sized nuclear reactors to making diesel out of algae.
Trying to pick which of these hundreds will actually end up with a salable product is something even VC's don't get right very often.
What happened to the Clean Coal we were promised?
Posted by: jimbo on 11/30/08
People are still washing it!
Which large-scale energy source will come first, clean coal, useful solar, useful tidal, useful wind or something else new?
The real claim to fame, is his claim to be able to significantly reduce the lower limit of current velocity that power could be economically harvested from. Assuming it proves to be practical, i.e. it can demonstrate a combination of low cost, reliability, and or lower environmental impact, than the alternitives, then it will be important. But, its importance is not is doing something (generating power from current) we can't currently do, but doing it better.
So, if this thing works, it should be less damaging environmentally than turbines, or dams for extracting energy from water flow. I doubt it can supply the world with huge amounts, like the article hypes, but it might be a useful addition.
he word comes from a name of a restaurant in East Anglia. From 1938 and during World War II the British scientists developing radar frequented an eatery called 'Boffin's'.
I dont find the word boffin to be demeaning...=)
And boffin' the boffins is boffo, if they're both consenting adults.
As "lampwick" stated above regarding barnicles that would certainly colonize those tubes, along with muscles and any other sea floor dwelling creatures that need something to attach to.
Even if those attached creatures don't disable the system, it would certainly lower the productivity.
the cost of monthly cleaning trips down to the ocean floor will certainly increase the cost of the energy. It's one thing to run those tests in bleached water without any organisms interfering; it's another to let nature have its way.
Anyone see Southland Tales? Fluid Karma!
New York has had a pilot project for while now. Some turbines were installed in the East River and they produce power for a supermarket and a parking facility. The manufacturer is Verdant Power.
There are many players and many technologies in this field. This WSJ article gives a good overview.
Not to mention zebra mussels, a type of freshwater clam known to jam water intake systems.
Most forms of generating electric power have bad consequences, some of which are not obvious at the time.
Harnessing ocean currents is something of an improvement on solar power since solar is cyclical. There's no power generated when it's dark. Ocean currents are pretty steady.
I was concerned that 3 knots is an unrealistically high current to expect. But the Kuroshio Current in the western Pacific is 3.5 knots, so maybe there are places we can tap into three+ knot currents.
The catch is that the current is lower close to the bottom. Think of how wind speed is lower close to the ground. And the sweet spots where ocean currents are as high as three knots are often way out in the ocean. So the power would have to be transmitted over a long distance. And repairs to the system would be difficult.
That said, the English Channel seems like quite a promising spot for this technology. The Bay of Fundy in Canada also comes to mind.
Most forms of generating electric power have bad environmental consequences, some of which are not obvious at the time.
Like solar power ocean currents are cyclical (annually instead of daily) and ocean currents move around.
I was concerned that 3 knots is an unrealistically high current to expect. But the Kuroshio Current in the western Pacific is 3.5 knots at its strongest.
One catch is that the current is lower close to the bottom. Think of how wind speed is lower close to the ground. And the sweet spots where ocean currents are as high as three knots are often way out in the ocean. So the power would have to be transmitted over a long distance. And repairs to the system would be difficult. It would both be far from shore and in some cases deep in the water.
That said, the English Channel seems like quite a promising spot for this technology. The Bay of Fundy in Canada also comes to mind.
My guess is that meandering currents and difficulties constructing and maintaining the system in deep water will limit this technology to bays and choke points.
http://www.youtube.com/watch?v=HxTZ446tbzE
Newsreel (complete with voice over and cheesy music) showing the collapse of Galloping Gertie (Tacoma Narrows) 2:34
http://www.youtube.com/watch?v=j-zczJXSxnw&feature=related
Color footage with no narration 5:56
Always amazing to watch
Neither vortex shredding nor 'resonance' can be solely assigned the blame for the tacoma bridge collapse.
It's the interaction of the two. Read any book on aeroelasticity if you want to understand what happens. http://books.google.com/books?hl=en&id=jtqDQ2nTvvcC&dq=holt+ashley+Aeroe... by Bisplingoff and Ashley is a classic in the field.
Three things I see right off is that:
1) if you are harvesting a diffuse energy source, you have a diffuse physical plant...with lots and lots of hardware and connections...which means lots of expense, maintenance, vulnerability, etc, etc.
2) The problem will all alternative energy harvesting I can think of is
that you are out there with Mother Nature...and that means enormous
low-level daily mechanical degradation challenges interspersed with the
times that Mother Nature is *pissed* and she'll trash you and your
little Tupperware projects........
3) things that go jerkety-jerk also go wearity-wear. A water turbine that just spins is a LOT less wear-prone than something that oscillates
Once upon a time in the late 70's, I tried doing solar domestic hot water. Anything that could go wrong, did, even with the best equipment...and the more safeguards you build into the system, the more it costs and the more unreliable it is.
Basic fact of statistics: the more parts you have, the more likely something will fail (think about it). They have found that 2 engine jet planes crossing the atlantic actually have fewer engine failures than 4 engine jets...needless to say, the 2 engine jets are designed to fly on one engine
Stewart,
Yeah, I was thinking exactly the same thing. This 'in theory' stuff is fine but the practical problems can be immense. Also it seems that everybody with an idea and a website has his/her hand out for money, and the line for money already includes the entire financial sector and Detroit.
Sigh.
Tripp: it seems that everybody with an idea and a website has his/her hand out for money, and the line for money already includes the entire financial sector and Detroit.
The difference is that the financial sector people screwed up a well known "technology" by ignoring the lessons of history. CDS's for example are just a repeat of the "bucket shops" that played a big role in the Panic of 1907 (thanks to the poster who first pointed this out, but who's name I can't remember).
It's as though 21st bridge designers ignored the lessons of the Tacoma Narrows Bridge disaster. Of course with engineers heads would roll, as well they should. With financial geniuses though, the problem is dismissed as "unforeseeable consequences". And since we know that these people are so bright, they have to be given a second (third, fourth ...) chance.
By contrast the alternate energy people are actually making improvements. Windmills work a hell of a lot better than they used to, and solar cells are a lot cheaper and less energy intensive to produce.
Of course alternate energy ideas are over-hyped by their proponents - you don't get visibility and funding by being overly realistic with your headlines. And sure many ideas just don't pan out. But overall there are important, even dramatic, improvements. Definitely a better investment than Wall St. BS.