Tuesday, April 9, 2013

Low Cost Fresh Water From Icebergs?

Even though plans to extract from one dates back to the 1950s, can Antarctic icebergs ever be a viable source of low cost fresh water? 

By: Ringo Bones 

Young Turks these days may have only heard of the scheme from a 2012 Dassault Systèmes advert often aired on the BBC but believe it or not, the idea of obtaining low cost fresh water from icebergs dates as far back as the 1950s. After complex logistical issues are taken into account do icebergs – as in Antarctic icebergs – really provide low cost drinking water for our increasingly thirsty civilization? 

During the 1950s, the US state of California’s number one community problem – and still probably is today – is where to get a low cost supply of fresh water fit for both domestic and industrial use. Back then, an oceanographer from the Scripps Institution of Oceanography named John Isaacs has suggested that icebergs be fetched up from the Antarctic to ease the state of California’s local water shortage. Even though the idea seems too fantastic at the time (and even for this day and age) – Isaacs’ colleagues from the Scripps Institution says not at all when they made the requisite mathematical calculations and found, somewhat to their astonishment, that it is the one dreamboat that might really float. 

Being formed from glaciers, icebergs are completely salt-free and unlike their smaller North Atlantic variety, Antarctic icebergs are big enough to make the idea worthwhile – as in economically viable. A good sized Antarctic iceberg is typically 10 miles long, half a mile wide and 600 feet thick can even be considered “small” when talking about Antarctic icebergs. 

Using 1950s era slide rules to crunch the numbers, the scientists of the Scripps Institution of Oceanography together with John Isaacs calculated that in two months time, three ocean-going tugboats could work a 10 mile long, half a mile wide iceberg drifting in the Antarctic into the Humboldt Current running up the west coast of South America. Where the Humboldt Current slows down off Peru and Ecuador, the tugboats would steer the icebergs into other favorable ocean currents that would lead it in a long, lateral loop almost to Hawaii and eventually to Los Angeles. 

Given that these favorable currents move at around 2 to 3 knots, the whole trip would take about a year and along the way the iceberg might lose as much as half of its vast bulk. But it would still represent about 300 billion gallons of fresh water. Authorities could ground the iceberg on an offshore shoal and surround it with a floating dam extending about 20 feet or so below the surface. This would keep the fresh water penned in around the iceberg as the ice melted. 

Because it is lighter, the fresh water would stay on top of the surrounding salt water and the city of Los Angeles could just pump it out as needed through pipes leading to the mainland. One iceberg that was originally 10 miles long when it was toed back from the Antarctic would be enough to supply the city’s then normal needs of fresh water for about a month – using 1950s water consumption figures. 

Back in the 1950s, the total cost of the water so delivered – mainly the then rate of one million US dollars for a year’s hire of the three ocean going tugboats – works out to be something like one-third of a US cent per thousand gallons, a minute fraction in comparison to what the city of Los Angeles pays back in the 1950s for its regular source of drinking water. Calculated to be financially feasible for California using 1950s prevailing costs, this method of “outsourcing” fresh water might still be appropriate for the water needy arid regions of the Southern Hemisphere – like South Africa, Australia and the Peruvian desert communities. 

1 comment:

May Anne said...

Basing on that now famous Dassault Systèmes advert that you mentioned where the firm helped Georges Mougin and his team to prove that it is economically viable to tow / harvest icebergs from the Antarctic as an economically viable source of fresh water using Dassault's really advanced computer 3D modeling package, it isn't only Georges Mougin and John D. Isaacs who have tried such grand scheme. Though Georges Mougin's plan might become a reality given that it is projected that our current fresh water sources will be depleted by one-third based on current consumption, the scheme of harvesting low cost fresh water from icebergs dates as far back to 1825 when a group of British scientists proposed of towing Antarctic icebergs back to their South Sea -i.e. South Atlantic - island territories. Not as a source of cheap fresh water but to make the tropical hot climate cooler and more temperate like that of "Merry Old England".