Thursday, 16 June 2011

Towing Arctic icebergs for fresh water

Three-decade-old plan revived

Georges Mougin is no stranger to the idea of towing freshwater icebergs across the world with the intention to bring drinking water to millions; thirty odd years ago, the French engineer was to tow a freshwater iceberg from the Arctic to Saudi Arabia, where water from the melted berg would be used to plug the huge freshwater shortage in the desert nation. That plan did not take off owing to feasibility and cost, but recent 3D technology and simulation seem to have revived Moughin’s old plans.

More than a billion people across the world do not get drinking water, while billions of gallons of freshwater melt away from Arctic icebergs. Mougin says he has a new method, using recently declassified satellite data and oceanic forecasting, to tow icebergs for long distances using a "skirt" and a tugboat.  The plan involves harvesting table shaped icebergs in ‘season’- the shape facilitates towing “and is known by glaciologists as the family of icebergs which presents the minimum risk of fracture," according to one expert. A tugboat then deploys a floating geotextile belt- using a series of poles to make it rigid, much like a lasso. A geotextile “skirt” is used to stop the iceberg from melting away as it reaches warmer water; this is deployed up to 7 metres below the water surface, and traps cold water around the iceberg, reducing or stopping its rate of melt.

 The tugboat then tows the iceberg away to wherever it is needed. However, this is not as simple as it sounds, because no tug yet built has the power to tow gigantic icebergs anywhere. However, Moughin and Cedric Simrad- project director of Dassault systems, a French firm collaborating with Moughin – say that the sea’s natural forces are used with oceanic forecasting to guide the iceberg in the intended direction. "Though it doesn't look like this when on a boat, from a satellite's perspective, [the ocean] looks like a big map of bumps and holes," says Simard. The tug then navigates these ‘pockets’ like a giant ski slope.
A simulated launch did not work initially, but by adjusting the dates by a couple of weeks using advanced forecasting, the team found that even a single tugboat could theoretically haul an iceberg. They say it is like a nutshell towing a mountain--and yet it is possible. Mougin has now launched a new company to promote his plan, with an actual trial to haul an iceberg set tentatively for the year 2012 or 2013.
So, is this the solution to the global water shortage? Not so, say some experts, pointing out to the incredible dynamic properties of icebergs, 9/10ths of which are below the water surface. Some point to the very limited success the largest tugs have had with towing icebergs clear of oil platforms in the North Atlantic- these attempts end up usually with the iceberg pulling the tug backwards instead. Critics also point out that it is an incredibly difficult exercise to tow a massive iceberg even with ocean forecasting. Then there is the ‘rollover’ problem: as an iceberg melts, which it inevitably will as it reaches southern, warmer, waters, it tends to become top heavy and roll over. This phenomenon is seen around Newfoundland every summer.
In short, some analysts say that no amount of netting will prevent this natural rebalancing of an iceberg, which, in any case, will go wherever it wants to. No amount of human engineering will change that, they add, pointing out that fancy 3D programs cannot predict what nature is going to do.

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