1. Locate iceberg
2. Tow sheet of impermeable fabric below iceberg
3. Join four corners of sheet with ropes to sky sail
4. Pull sheet above ocean surface around iceberg using wind energy
5. Release salt water from base valve.
6. Close base valve
7. Tow Iceberg away from pole to melt
8. Release dirty water from base valve
9. Tow sphere of melted glacier water to shallow water
10. Kite tows bag up sheltered coastal sea floor slope on rising tide.
11. Use tidal energy to pump water from bag to land reservoir

What are the min/max Iceberg sizes?
What is the optimal ratio of the size of the sail to the size of the iceberg?
What tension will each rope sustain?
How do you avoid having so many ropes that the sail becomes closed?
What wind velocity is necessary? optimal, min/max.
How will you steer this?

SkySails GmbH & Co. KG is a Hamburg-based company that sells equipment to propel cargo ships, large yachts and fishing vessels by the use of wind energy. The company was founded in 2001 by engineers Stephan Wrage and Thomas Meyer. A test facility was set up in Wismar. The SkySails propulsion system consists of a large foil kite, an electronic control system for the kite and an automatic system to retract the kite. The system bears similarities to kitesurfing. The system was first tested on the Baltic Sea, before commercial implementation. The kites, which have an area of around 320 square metres (3,400 sq ft), can be flown at altitudes of 100–300 metres (330–980 ft). Because of the stronger winds at these heights, they receive a substantially higher thrust per unit area than conventional mast-mounted sails. A ship equipped with the current SkySails could consume from 10 to 35% less fuel. The SkySail-system is implementable on many large vessels. A conventional ship with a SkySail-system has two propulsion methods, making it a type of hybrid vehicle. MS Beluga Skysails is the world's first commercial container cargo ship which is partially powered by a 160-square-metre (1,700 sq ft), computer-controlled kite. The kite could reduce fuel consumption by 20%. It was launched 17 December 2007 and departed the northern German port of Bremerhaven to Guanta, Venezuela in January 2008. Stephan Wrage, managing director of SkySails GmbH announced: "During the next few months we will finally be able to prove that our technology works in practice and significantly reduces fuel consumption and emissions." The ship completed its journey on 13 March 2008 after sailing from Germany to Venezuela, then to the United States, and ultimately arriving in Norway. While the kite was in use, the ship saved an estimated 10-15% fuel, $1,000 to $1,500 per day.

Thanks Stahrwe, these are excellent questions.

As I see it, this method is like fishing, and needs to develop through trial and error. Minimum and maximum size of icebergs for water supply is a practical and economic question.

http://en.wikipedia.org/wiki/Iceberg#Size gives iceberg size classifications. Growlers have about one metre above water, for ice volume up to about one megalitre = one acre foot. The aim is to start by hunting growlers and gradually scale up.

The size and shape of sail is shown at http://www.skysails.info/english/
See also http://en.wikipedia.org/wiki/SkySailsOptimal ratio depends on the economics. As I envisage it, there could be four sails, one for each corner of the sheet. These would fly at height of several hundred metres, with the four ropes joined together above the iceberg.

The winds around Antarctica are steady westerlies, known as the Roaring Forties, the Furious Fifties and the Shrieking Sixties. The aim would be to find icebergs at the northernmost point to reduce towing distance. Steering uses the electronic control system in the kite.

The map at http://publishing.cdlib.org/ucpresseboo ... fig167.gif shows that icebergs are found north of 40 degrees latitude in the Indian and Atlantic Oceans. The tuna fishery in Port Lincoln South Australia could be a base to hunt bergs due south of Australia and bring them in to provide water at much lower price than desalination.

This is all very interesting. I would love to see pictures of one in operation. How likely do you suppose it is it will ever happen?

FAQ
Here are 20 questions that we asked Georges Mougin and François Mauviel:
1. Who do icebergs belong to? Can anyone exploit them freely?
Within territorial waters they are under the state juridiction.
In high seas they are « rex nullius » and could become like a wreck, property of the entity which get control of it.
2. Can your project work only with tabular icebergs? Or would it work with icebergs of another shape?
Tabular icebergs present a uniform draft, shape is regular and ratio of total area to the volume is optimum, for all these reasons iceberg transfer and exploitation is feasible pratically only with tabular icebergs.
3. How easy and where can we find tabular icebergs?
In the arctic tabular icebergs are yielded by north Greenland inlands they drift between Greenland and Labrador down to the East of Newfoundland. In the antarctic pratically all icebergs are tabular being fragments of iceshelf, they are concentrated near the Mer de Weddell, in the south of the Atlantic océan.
4. What about the possible ecological risks related to exploiting icebergs: water see level rise? Calving of the inlandsis?
It is the calving of the inlandsis through icebergs which could raise water level (if the balance of snow accumulation on it is less). Melting of floating icebergs cannot change water level. Ice-floe (or banquise) is sea-ice not related to icebergs.
5. What about the possible risk of overexploitation of icebergs?
The amount of iceberg released is such (300 to 500 billions tonnes yearly) that there is no risk of overexploitation. Transfer of a few thousandth only could be foreseen.
6. What if a herd of seals or a white bear lives on the iceberg selected as the best candidate?
Freeboard of an iceberg, 10 to 20 meters does not allow seals to stay on it, white bears feed themself on the ice-floe.
7. Why don’t you exploit the icebergs on-site and build a dedicated floating factory to that effect, rather than towing them?
1st reason: there is no energy available on iceberg natural sites for their melting.
2nd reason: iceberg transfer is far cheaper that shipping by tankers, a small arctic iceberg of 10 millions tonns would require the capacity of 50 to 100 large tankers!
8. What are the possible destinations where we can imagine towing icebergs to?
According to prevailing winds and currents, earth rotation, practical destinations of iceberg transfert are the west coasts of the continents like for instance Maroco, Namibia for Africa, western and south Australia, Chili, Perou California.
9. Are there any risks to see the iceberg break off during the transfer? How to avoid such a thing?
Risk of fracture is minimal, airborn radiosounding for iceberg selection eliminate those prone to fracturation.
10. Are there any risks for the seine of the skirt to tear off during the transfer? How to avoid such a thing?
Risk of net or skirt tearing is minimal, there is no vibration or chock and these materials and the towing line have a natural elasticity.
11. The iceberg convoy will sail across many miscellaneous ecosystems along its route. What are the impacts on the local plankton and other fish species that might be sensitive to thermal variation?
Size of iceberg is very small relatively to the sea around it and a related ecosystem, impact will be negligible.
12. What if the convoy sails across an oil slick?
Oil remain on the surface, encounter with some will only pollute the protective belt on the floating line whitout sequel to the berg.
13. What if a damaged ship blocks the route initially selected for the convoy?
Obstacles will be dedected by radar ten of miles in advance, the very slow speed of the transfer leave plenty of time to slightly alter the route for avoiding them.
14. Do you plan to anchor the iceberg on the exploitation site, or to use moorings?
Mooring or anchoring of iceberg will use the belt and carried out like for an oil offshore platform.
15. Do you need a specific authorization to bring an iceberg into areas such as the Canary Islands?
Before beginning a transfer the precise destination will have been agreed upon, and mooring facities being prepared.
16. What are the consequences of bringing an iceberg in an geographical area where you usually don’t see icebergs? On the wildlife and flora? On the local climate? Will it not generate a fog above the iceberg?
Size of the iceberg relatively to the sea around it makes alteration to the fauna and the climate negligible, fog if so, limited to the top of the iceberg will be quickly dissipated outside.
17. By which process do you plan exploiting the iceberg at the arrival site?
Exploitation procedures depends of the use of the iceberg: complete use would be energy production, cooling for airconditioning and finally soft water for consumption. Latent heat being an essential value of iceberg’ ice. For energy production a slurry of crushed ice is produced in a pond created on top by insulated edges , ice latent heat is absorbed in the condenser of the thermal process (same that an OTEC plant), water at low temperature feed then the exchanger of an airconditionning system, the released water being piped to the consumption. Without power plant direct production of water is achieved by the natural melting of iceberg slices wrapped in watertight bag, melting being provided by the surrounded sea water.
18. How can you be sure about the purity of iceberg water?
Water purity results of the ice made of snow accumulated since thousand of years. Contemporary pollution, if so would be limited to the surface and eliminated by the melting.
19. What yearly water consumption would represent a 7-million ton iceberg?
7 millions tonnes of ice or water could represent the yearly domestic consumption of 35000 persons.
20. Don’t you think that towing icebergs is a bit like playing God?
Naturally all icebergs melt; Their transfer change only the site of this melting where the fresh water produced is used before to be ultimately rejected to the sea.

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