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Football Field-Sized Kite Powers Latest Freighter
coondoggie writes to tell us that a new freighter set to launch in December will be receiving a hefty dose of power from a kite the size of a football field. The 460-foot ship, owned by the Beluga shipping company, hopes to see as much as a 50% drop in fuel consumption during optimal conditions. "The SkySails system consists of a towing kite with rope, a launch and recovery system and a control system for the whole operation. The control system acts like the autopitot systems on an aircraft, the company says. Autopilot software sends and receives data about the sail etc to make sure the sail is set at its optimal position. The company also says it provides an optional weather routing system so that ships can sail into optimal wind conditions.The kites typically fly at about 1,000 feet above sea level, thereby tapping winds that can be almost 50% stronger than at the surface. "
????B.C. - Random Dude "You know this wind would be pretty cool if it were used to run a ship"
*Investors throw money at random dude*
1769 - James Watt "You know this steam engine thing would be pretty cool if it were used to run a ship"
*Investors throw money at Watt*
1896 - Karl Benz "You know this gas powered combustion engine thing would be pretty cool if it were used to run a ship"
*Investors throw monoey at Benz*
2007 - SkySails "You know this wind thing would be pretty cool if it were used to run a ship"
*Beluga corp. throws money at SkySails*
Seems to me that SkySails is a few millenia back on their innovation.
...but in the end I don't think it'll fly. Too bad, as the failure of such an interesting idea will really knock the wind out of their sails. I hope they don't blow it.
This strikes me as a good example of the reusing old tech.
I think some of the article misses the point:
'What if fuel prices go down?' What if they don't? Prices will not go down in the long term and the companies using these will benefit the most.
'These can't be used in a head wind.' Well no sh*t Sherlock, thanks for that. It's to cut fuel use, not eliminate it. Any cut will be good for the company and the environment.
Certainly some bird is going to get hit by that kite! It will look ugly flying offshore hundreds of miles from where we can see it! The kite is made from polymers derived from fossil fuels! It somehow violates the second law of thermodynamics! It will sap energy from global winds leading to something bad! Won't somebody please think of the children [ of oil company executives]!
Seriously though... I can't think of any alternatives to fossil fuels that haven't run into enormous amount of flack.
Once the pirates learn that there's a tasty morsel attached to that giant kite on the horizon...
God: When you do things right, people won't be sure you've done anything at all.
All they need is to have a moderately strong, steady wind that is abaft the beam. Plus good enough weather that they don't risk the kite and its hardware. If you sail the traditional sail-era trade routes the wind is abaft the beam quite a bit more than 50% of the time, the wind is steady at 1000' in the open ocean pretty much always as long as the weather is good, and you can supply your own finagle factor for how often the weather is good.
Frankly, I think the major limitation on any kind of sail power has been crew cost. Big freighters run with tiny crews these days, and often not very well trained and not especially reliable, except for the top few officers. Getting a crew that can handle a big sail competently, without endangering the cost of the apparatus, sounds expensive. But maybe they've got a robotic, computerized control system that can eliminate that problem.
The original article is here:
http://hardware.slashdot.org/article.pl?sid=06/07/08/1735227
The original article claimed a 33% savings in fuel costs. This new article claims a 50% savings under optimal conditions. Interestingly, the greenhouse gas savings are only 10-20%. Where is the logic in that?
Motive power is only the largest fraction of consumption on a ship. On all ships, auxiliary equipment must be powered. This ranges from the small consumers, such as navigation equipment and lighting, to the large consumers, such as reefer containers and engineering subsystems. A 10,000 TEU Maersk liner might have 250 reefer slots, and that sucks a lot of power, as does the bunker fuel heater (though usually steam, but still energy from the engine).
Then consider that engine efficiency doesn't scale linearly with fuel consumption, and that propellers on large ships are fixed, not constant speed. This means that a ship moving at 17 knots HAS to make, say, 83 RPMs (for a big Sulzer). So, the kite might provide 50% of motive power, but the ship will only be able to cut the fuel pumps 20%-25%, and can't cut RPMs at all, else the prop starts dragging and cavitating.
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Football field is a potential field generated by a standard football ball resting in air with temperature 22C and pressure 1013.25 hPa
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But how many bowling balls does it weigh?
Really, we're all geeky adults here. Can't we use real units? And moreover, we're not all in the U.S. (I happen to be, but still).
When it docks in the U.S., it's 100 yards long by 160 feet wide. Apparently when the ship docks in a Canadian port the sail will expand to 100 meters long and 59.4 meters wide. When it docks anywhere in the rest of the world, it will expand to anywhere from 100 to 110 meters wide to 64 to 75 meters wide. I guess it'll fold out or something.
And when it docks in Australia, it will run about 165 meters long by 135 meters wide (and while it will be hard to figure out how it works or what it's doing, it will be brutally violent).
Can we find anything more ambiguous to compare it to? How many loaves of bread long is it?
It is pitch black. You are likely to be eaten by a grue.
I do kite sailing in the winter here in Norway, and the kite shown in the article is almost identical, except for size of course, with the kite I use. (I have also windsurfed since around 1990.)
My kite is a Peter Lynn Venom II http://www.peterlynnkiteboarding.com/, this is a twinskin kite which keeps its airfoil shape due to internal air pressure: A set of small mesh openings in the leading edge allows air into the opening between the front and back side.
This form of kite is an airfoil, not a spinnaker, the difference is huge:
A spinnaker is effectively a large bag to catch the wind, while a kite works best by having air moving faster on one side than the other. Among other things, this means that a kite allows you to sail much faster at an angle to the wind instead of straight downwind.
Another nice trick you can do with a kite, unlike a windsurfing rig, it to let the kite loop around in little figure-of-eights: This makes the airfoil move even faster through the air, increasing the lift particularly during a lull in the wind.
Terje
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