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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. "
Still, good to see that people are trying different ideas.
Engineering is the art of compromise.
So a kite that provides most of the ship's power can only afford a 50% reduction in fuel consumption? Hmmm...
But No.6/Bunker-C is all the residual shit that can't be used for anything else. It'll get burnt somewhere, somehow. Refiners will find a way to sell it.
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?
Why put them on the sail. What are the odds that the sail will be pointing at the sun... Why put them on the sail/kite at all instead of the ship? Why risk them getting lost if the sail goes into the water or the cable fails? Why try to make the as flexable as the sail so it is easy to store in case of storm or headwinds? The electrical load of a freighter is actually pretty small compaired to the propulsion load. So are you going to carry a big honking electric motor to use make in to an hybrid? If so why care the extra weight and drag on the screw shaft for something you could only use for a few hours each day?
Why not? Because it wouldn't really help in any way and would cost a lot of money.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
What happens when the kite falls into water and the wind is not enough to lift it up wet? Or worse, what if it falls on top of the ship and hurts sailors, breaks things or rips? It seems we are too hasty to discard centuries of experience in designing sails, masts and lines. Even a spinnaker is at least tied to the top of the mast to keep it from falling and main sails are still useful in head and side winds.
I don't think it's so important how long it takes for a cargo to get somewhere so much as it's important that it get there when it's scheduled to do so, not earlier and not later. Modern manufacturing, to say nothing of port operations, rail schedules, et cetera, are pretty reliant on things being delivered at a certain hour on a certain day. If a boat happens to come in a day late or something, everything is flung out of synchrony -- you have to pay workers who are doing nothing, because the boat isn't there yet, and you have to hire other guys at overtime rates when the boat does come in, and meanwhile you've missed your rail connection and your factory has run out of raw materials or your showroom has run out of the popular new model of widget...
TCO is often overlooked.
Take a look at private boats -- sail VS diesel. Sure, sail power is free, right? No. The cost of the sail which wears out, the cost of the lines & riggings. Add it all up and get TCO. Depending on what you are doing, diesel may be cheaper. Especially in commercial applications.
The cost savings in fuel is offset by the cost in the kite, riggings, and management of the kite. The TCO will be interesting to see. I would be surprised if it was any better than a wash in savings.
Unless they put a lot of [heavy] steel stiffening in, the ship will flex at the attachment point rather than lift the bow. Ships aren't rigid.
On top of which, even if the kite were attached at the eyes - you don't want upward force. Upward force doesn't contribute as much to propulsion as lateral force.
The real question isn't necessarily the efficiency gain in percentage terms, but whether the fuel savings can offset the cost the kite system. No. 6 fuel (which most ships use) is relatively cheap, because it is one refining step above tar. Seriously, it is really nasty stuff, and doesn't burn cleanly at all. A big cargo ship will go through thousands of gallons of it a day, maybe in just hours. If you can use 25% less fuel in a year, that starts to look like hundreds of thousands of gallons of fuel saved per year, which in turn could mean hundreds of thousands of dollars a year in savings.
Makani power are planning to generate electricity using high altitude kites - at a cost competitive with coal power.
There's very little information about them for now but they did get a $10M investment from Google. Here is what Cringely dug up about them from old Usenet posts of one of the team members.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
Obviously, conditions aren't always optimal.