Kite Power on Ships Out Performs Sails Five Times Over
by Sami Grover, Carrboro, NC, USA on 08.18.08
Kite Power Beats Sails
The idea of reinventing wind-power for ocean going transport is certainly a seductive one. But usually when TreeHugger reports on the idea of kite powered boats, whether it’s Kite For Sale’s yachts or SkySail’s cargo ships, we inevitably get comments from folks asking “what’s wrong with traditional sail boats?” Now the folks at SkySail have set out to answer this very question (of course they have a certain vested interest in the outcome) by releasing the latest figures from their ongoing tests on one of their kite-powered freight ships. And if their numbers are anything to go by, kites come out ahead. Way ahead:
“ The latest measurements made aboard the cargo ship “Michael A.“ demonstrate how the SkySails-System delivers far more than five times the performance per square meter of sail than traditional wind propulsion systems. With the help of the wind, the 160 square meter kite generates up to 8 metric tons of tractive force – this approximately corresponds to the thrust of an Airbus A318 turbine engine. Depending on wind conditions, ships in the future shall be able to post fuel savings of between 10% and 35% using this auxiliary propulsion system. “Our own measurements show that we were able to temporarily save far more than half the fuel by deploying SkySails in favorable wind conditions,” reports Gerd Wessels (37), managing partner of the Wessels shipping company based in Haren/Ems, adding that “alternatively we were able to increase the ship’s cruising speed from 10 to 11.6 knots with the help of this towing kite propulsion.” The innovative and environmentally sound wind-propulsion system retrofitted aboard the 90 meter long multi-purpose cargo ship “Michael A.“ has been undergoing pilot testing in European waters since the end of 2007.”
::SkySails::via site visit::
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And easier to install by a big factor I suspect...
NICE!
HG
I can't imagine that would work well if you're trying to tack into the wind.
More powerful or not, most of the motive power still comes from fossil fuel, which is not renewable, and therefore not sustainable. And no, we can't simply switch to biofuel. Maybe these would be good in combination with sails...
5x more efficient! and reducing the petrol engine demand by up to half! I think the next X-Prize should go to wind powered transport. I wonder what kite sails could do with sailboating!?
I can imagine the rigging is more expensive. Everything has to be both lighter and stronger. Of course, you don't have to have a mast.
That doesn't mean its not a good idea.
Very nice news. Saving 10-35% fuel saves too much carbon.
I was wondering, if anybody of SHIP makers actualy thought of building the ship with less weight.
I know that ship is made up huge metal for the purpose of corrosion, holding cargo etc, but is it possible to build ship with less weight and thereby reducing more fuel?
Venu
Cool. More power per square meter is certainly a good thing, but it may not be the best comparison. Is the area of the sail a sailing ship might have comparable to the area of the kite such a ship could conceivable carry? These might be different. Probably not a five-fold difference, though.
Venu,
I'm sure you could make a ship that weighed half of a conventional ship but it would be cost prohibitive.
I think these sails provide the best bang for the buck. Maybe with the sails and that bubble hull technology (to reduce drag) shippers can cut 50% of their fuel consistently.
I guess the big difference in performance comes from the altitude. If you get 2 times more windspeed you get 8 times more power.
Also, with a kite you need far less modification on an existing ship.
Buts still, it would be cool to get a specially built for kite sailboat and have it race the conventional one. I wonder if they van outperform the high tech sail designs of modern yachts?
The benefit of kites over sails is that kites catch the wind at much higher altitudes where it's both more powerful and more consistent.
There are all sorts of problems putting masts on cargo freighters like they wouldn't be able to transverse certain bridges any longer, and the masts might interfere with the cargo container crane. I do remember a decade ago a cargo ship with two masts and solid sails. I think it was a Japanese ship.
As for making the ships lighter, I imagine that they're as light as they can be and still handle the stresses of an ocean journey. I've heard stories of cargo vessels that have their noses ripped off in heavy seas. When that happens the ship sinks in about 60 seconds.
I wonder what keeps them from using the sail as primary propulsion instead of just secondary.
I think it's a good idea, but I'm not sure it would be much use unless your sailing with the wind. Tacking into the wind would be impossible, from what I can tell since the kite will always be moving in the direction of the wind. So, while it might help a sail boat move more quickly with the wind I don't think you could use one to the exclusion of a traditionally rigged ship. I guess I don't see why this is anything more than just a fancier spinnaker. I suspect this is something that might be more useful on a traditionally powered ship - something of a hybrid wind / fuel - pop that thing up when your sailing with the wind and lower the speed at which your turning the prop.