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Kite Powered Ships: Harnessing Abundant Energy
Craig Neilson, 24 Dec 07

There's no quicker way to show somebody that energy is abundant than taking them out to fly a really big kite. My favourite is a five metre, two-lined parafoil, and with lines only 20 metres high, ten knots of wind will throw you all around the park. Yet from a distance, the kite is merely a tiny speck on the horizon.

So imagine my delight when I learnt that the Beluga Shipping Company will use a massive SkySail to tow a 132 metre MV container ship across the Atlantic Ocean in January.

You might remember the beginning of this story from 2004, when we first reported on Skysails' project. The ship won't be entirely wind propelled, the kite will assist a standard diesel engine, but given the right wind conditions, the technique could save up to 50% of the ship's diesel requirements.

Ships are a great example of the difficulty in putting abundant energy to use. As the world's 50,000 merchant container ships cross the ocean they are constantly surrounded by energy: waves soar past, ocean currents channel massive volumes of water (and temperature) around the globe, winds swirl overhead, and of course, the sun bears down. Despite this, most ships carry and burn fossil fuels to reach their destination. Piggy-backing on the plentiful power from one of the abundant forces is an engineering dream, and constitutes an economic and environmental breakthrough.

The breakthrough is that despite being at the peak of oil extraction right now, it's already cheaper to move the 'My Beluga Skysail' vessel with wind power than it is to move it on diesel. To be precise, Beluga expects to save around $1600 on fuel every day - a saving that will have funded the system's deployment costs in three years.

So let's work with that figure - $1600 per day - from the perspective of the most conservative accountant we can imagine. Ships of this type usually serve for 20 to 30 years, so let's say it lasts for 20 (despite that hybridisation may reduce engine maintenance requirements). We'll say that the kite system cost $1m to set up (it cost around $725,000), and that it will need to be fully replaced once (so allow $2m). Most conservatively of all, we'll say that the price of oil remains stable at today's super-low prices for the ship's entire lifespan. What's the cash saving? Ten million dollars per vessel.

I'm not an accountant, but what I hear in that is that it's possible to save tonnes of oil from being wasted on transport - on every converted ship, every day. The opportunity here is profound - the 800 million tonnes of CO2 emmited each year from merchant ships is 5% of the world's total. If that doesn't excite you, or you're concerned that one ship is not enough, consider what competition, further research and another 20 years of rising feul prices could do. Thirty years from now, will all ships look like this? Maybe! Beluga plan to build two more kite ships in 2008 and then look to even bigger deployments. SkySails' target is 1500 vessels by 2015.

What's particularly beautiful about kite-powered ships is the remarkable level of energy converstion and efficiency. Unlike the challenges green electricity generation typically faces in capturing and storing electrical energy, the forces on a kite powered ship are delivered by a charmingly low tech solution: ropes. A kite is not a wind version of a hydro dam, the amount of air it actually stops from moving is mathematically negligable. Even once the energy (enough to move a container ship at speed) is removed, the source is still massively abundant and highly available to other ships.

Kite-powered ships are visible on the horizon and will be arriving in port sooner rather than later. I can't wait to see which way the wind blows for the shipping industry.

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Welcome to the new age of sail!

Posted by: Randolph Fritz on 24 Dec 07

Craig, thank you for a fine and interesting article. Please excuse one observation: we should be careful, especially with energy, not to confuse abundant with available. Hydrogen is the most abundant element in the universe, and can be burned as a fuel. Yet we have to go to great lengths to make hydrogen available, often at little energy returned for the energy invested. The use of kites in shipping is a different matter: this looks very promising, a good way to tap an abundant energy source. But I think it's vital that we not kid ourselves into thinking that any plentiful resource can just fall into our laps - it's a kind of thought trap to confuse the promise of abundance with the reality of availability.

Posted by: David Foley on 24 Dec 07

I love the idea, but the extra energy that is supplied by wind power can also be converted into extra speed, by running the diesel motor on full power while the wind blows (SkySails also recommends that option).

Posted by: Kris on 24 Dec 07

I love this technology. It's so elegantly simple and clever. New Scientist covered them in an interesting article a little while back if you're interested in reading a little more:

One idea that's been circulating through my mind this week is combining this kite technology with the Magenn Air Rotor System:

Harness that to an electric drive and use the thrust from the Skysail...? Naturally you'd need a diesel engine as well for when the wind's not blowing.

Posted by: Scatter on 26 Dec 07

There was an article on electric drives for ships in the Economist recently:

Posted by: Scatter on 26 Dec 07

So we are back to the galleon days :)

Posted by: Wai Yip Tung on 3 Jan 08

So we are back to the galleon days :)

Posted by: Wai Yip Tung on 3 Jan 08



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