ICEBERG - A SOURCE OF FRESH WATER

Icebergs towed from Antarctica to the Red Sea could provide an economic source of fresh water for Saudi Arabia. There are no technical problems, to which we cannot find a solution.

In France a detailed plan for towing the icebergs, each weigh­ing 100 Mt, across the Indian Ocean, and through the Gulf of Aden to the mouth of the Red Sea was developed. There they would be chopped into manageable pieces (about 1 Mt each), us­ing heated cables and towed through the shallow Bab el Mandeb Straits to the Saudi coast.

Even in tropical temperatures, natural thawing of the icebergs would not be quick enough to match demand for fresh water and the problem is of working out ways of speeding up formation of the fresh-water pools by induced melting. That is the last of the problems to be solved, and it should not be a difficult one.

The giant icebergs must be wrapped in an insulating jacket to cut down melting losses on their 8,000 km journey. At an esti­mated towing speed of 1 knot, it will take 6-8 months for five tugs to pull the icebergs along a computer plotted route, taking advan­tage of prevailing currents and winds and dodging high ways.

Without protection, over half of the ice would melt en route, but there is a way of cutting this to 20% or less by using a huge iceberg "coddler", made from a 50 mm-thick sheet of plastic-coated felt, which will be drawn under the base of each 250 m-deep berg. A massive skirt of the same material will then be un­rolled around the 3-4 km perimeter, with weights holding its base 100 m or more below the water line.

No top protection will be needed. The pool forming naturally on top of the iceberg will itself limit melting. Similarly, water lay­ers inside the skirt and bottom protection will provide their own insulation against progressive thawing.

Once the bergs reach the Gulf of Aden, the jackets will be re­moved and heated cables will slice them into about 100 individual pieces, each no thicker than 15 m. These slices will then be floated through the Bab el Mandeb Straits. Inside the Red Sea, another skirt will be fixed to each berg, to separate the fresh water from the salt-water sea, and a pipeline will connect the offshore reser­voirs to the mainland.

French scientists have now developed all the technology needed to wrap an iceberg in its protective jacket, tow it halfway across the world, and deposit it in sections in the Red Sea.

The idea of using icebergs as a source of fresh water is not new. After all, 99% of the fresh water in the world is in the form of ice, and 90% of it is in the Antarctic. It seems natural that we should look at ways of using it.

The source has another important advantage — it is infinitely renewable. About 1,000 km³ of ice forms every year in Antarc­tica — and it is all free for the taking.

On the basis of this conception other plans have been drawn up for towing icebergs to Western Australia. Though the unit cost of water from these proposals is highly favourable, the authorities have so far not come to fruition because of the very high initial in­vestment needed to develop and build the size of tug needed and the risk of failure. A scheme to tow giant icebergs to California to provide water for Los Angeles also seems to have been aban­doned.

But all these schemes relied on the huge initial size of the ice­berg to overcome melting losses. Losses of 50% or more were considered acceptable, because the remaining ice would still con­stitute a massive reservoir. The French plan to insulate the ice­bergs before their journey makes the idea economic for much smaller bergs. Existing tugs can be used for towing and the finance becomes possible.

For Saudi Arabia the cost of the iceberg water is well below the cost of desalination. A side benefit for the Saudi Arabia is that a line of melting icebergs 1.5 km offshore would be a giant air-conditioning system, dropping local temperatures by as much as 5°C.

Answer the questions:

1. What can serve as an economic source of fresh water for Saudi Arabia?

2. What route will the icebergs follow to reach Saudi Arabia?

3. How long will it take the icebergs to reach the coast?

4. How will the icebergs be protected from thawing?

5. What part of the iceberg should be protected: underwater or overwater?

6. How will the icebergs be cut into pieces?

7. What part of the world's fresh water does the Antarctic contain?

8. What factors prevent the transportation of icebergs to Australia?

9. What made the plan economic for smaller icebergs?

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Date: 2016-01-03; view: 1719