Slashdot Mirror
UAE To Drag Iceberg From Antarctica To Solve Water Shortage Set To Last 25 Years (express.co.uk)
schwit1 quotes a report from Daily Express: The UAE, which is among the top 10 water-scarce countries in the world, hopes to help ease the stress of a drinking water shortage by towing an iceberg from the freezing Antarctica in order to create more drinking water. The National Advisor Bureau Limited's (NABL) managing Director Abdullah Mohammad Sulaiman Al Shehi says an average iceberg contains "more than 20 billion gallons of water" which would be enough for one million people over five years. Up to four-fifths of an iceberg's mass is underwater, and due to their vast density, they would theoretically not melt in the boiling climate of the Middle Eastern coastal line. Mr Al Shehi says it could take up to a year to drag the huge body of ice up to the UAE, and the project is set to begin in 2018.
They mean the mass to surface ratio.
I did some math. Previously, I've considered similar absurd ideas, and the cost just didn't fall in their favor.
I feel I should start with a disclaimer: It's currently a very late (or early, depending on one's perspective) hour of the evening, and my physics skill isn't what it used to be. I invite and encourage you all to review my work, and if I'm wrong, please tell me how.
Based on the figures provided, we can work out the magnitude of the problem. The first computation is simple: Our speed will be .3m/s, to travel the (roughly) 10000 kilometers between Antarctica and the UAE in one year.
20 billion gallons of water corresponds to roughly 80 million cubic meters of ice. Cut into a sphere for ease of transport and calculation, it would have a radius of about 300 meters, with a cross-sectional area of about 200,000 square meters. We'll ignore the air resistance of the 10% above water, which falls within the error of my rough calculations. Calculation for the force of drag is ugly*, but works out roughly to C*9*10^6 newtons. That "C" is a coefficient simplifying the effect of the iceberg's shape, ranging from 0.5 for a sphere to 2 for more troublesome shapes.
Considering that range, the water's drag is between 4 and 20 meganewtons. A power source (tugboat, added motors, etc) will need to supply that much force just to maintain speed. If I remember my physics correctly, at 0.3m/s, that's between 2000 and 7000 horsepower.
There are tugboats with that much power. I haven't found much information on the annual cost to operate such a beast, but one tugboat operator gives price estimates per hour. For the purposes of this discussion, we can assume that the quoted price covers the operator's expenses well enough to also cover the overhead of running such a large operation, and the benefits of scale will cover the higher costs of an ocean-going expedition. Those are some very large assumptions, but I don't have information to clarify it further.
With those assumptions, the cost to pull an iceberg for a year is only about $20 to $100 million. That's surprisingly cheap, putting the cost of mostly-fresh water at under $0.001 per liter ($0.005 per gallon). In comparison, a desalination plant supplies water at about $0.0005 to $0.003 per liter ($0.001 to $0.01 per gallon).
In short, it's expensive, but it's in the same ballpark as regular desalination for that much water, and if the losses due to melting and evaporation can be controlled, it might just be feasible. As noted in TFA and elsewhere, it would also be quite the spectacle, promoting yet more tourism to the area.
* The formula I ended up with is F[drag] = C*.5*1g/cm^3*(.9*pi*(80000000 m^3/(4*pi/3))^(2/3))*(0.3m/s)^2.
You do not have a moral or legal right to do absolutely anything you want.