The concept of using icebergs as a water source has been around for a long time and commonly is seen to lie in the realm almost of science fiction but not quite; it has always been seen as something that is vaguely possible one day in the not too far distant future. Even though icebergs are floating in saltwater, the ice has no salt. It's compressed snow. If you melted an iceberg you would get drinkable fresh water after you killed any germs. Icebergs have never been used as a major source of drinking water because of the costs and risks associated with moving them.
It has been discussed at some length in the past in the popular press and has even been the subject of the odd humorous hoaxes. The idea may be traditional and ongoing but appears not to have been reviewed recently. It is relatively commonly conceived of as being a Southern Hemisphere issue, that is, using Antarctic ice, but there are companies in existence in the Northern Hemisphere to explore the concept seriously. So, how realistic is it to foresee a time when Antarctic ice will be exploited as a resource?
Iceberg water already is a small-scale resource in the Northern Hemisphere in some drinks alcoholic and otherwise. Iceberg utilization has begun. The first major international conference addressing the issue was held in 1977 (Balaban 1979: Husseiny 1978). Schwerdtfeger (1981) provided a very useful review of the status of the concept, and advances in relevant science to that time, and Schwerdtfeger (1982) expanded a little on the topic. His studies were based on the assumption of towing icebergs and he found that it was not likely to be viable because of the high cost of fuel. Since then, another possibility has emerged and the relative cost of fuel has fallen. In this paper, I wish to explore the idea a little further 'flying a kite' as it were.
The world's human population of six billion uses approximately 3,240 km3 of water each year from a total annual renewable resource of some 41,000 km3. Antarctica with about 30 million km3 contains 90% of Earth's ice and 70% of its freshwater, and yields about 1,250 km3 in the form of icebergs each year (about three to four times Australia's annual renewable water supply). With the world population expected to double to about 10-12 billion in 50 years, and with uncertainty about the impact of global change, pressure on the global water inventory must grow greatly (Australian water use has grown 65% since the early 1980s). Included in that pressured inventory will be the resource represented by icebergs. It has been stated quite often that the next war will be fought over access to water.
Small-scale experiments have been conducted using the German Antarctic RV Polarstern and included allowing ice-water to remain in this plastic for several months at sea (in the cold Antarctic) to check whether or not water quality would deteriorate. Apparently, it did not. No port of destination was offered as a preferable site. The report considered an influx of up to 2.5% seawater allowable while still providing useful water. I suspect 2.5% is too high and would prefer a figure of 1% or less. The concept is basically simple and has been applied to wrapping ice floes of 3,000 tonnes and conceptually icebergs of approximately one million tonnes. The plastic was in rolls 2m wide. Adjacent rolls are unrolled and welded at the same time. As the sheet is welded, it is folded into accordion format on a floating platform or barge which is brought to the upstream side of the iceberg.
The plastic is then allowed to sink under its own weight and to be carried under the iceberg by currents if strong enough, or to be drawn by cables if current activity is too weak. Once the underside of the berg is covered, air sacs or tubes in the plastic are inflated to make the plastic rise, excluding most seawater in the process. Covering the top of the ice mass is more difficult but has been overcome. Simply pulling the plastic across the top of the iceberg is hampered by friction. Cables from the platform to a tug are pulled across the top of the iceberg but require air-filled rollers to overcome friction. Once the iceberg is covered, the plastic is welded to seal the entire mass which can now be towed or carried by surface current activity.
It is clear that the economics are not viable for this scenario on the basis of wrapping a single iceberg. That would be appropriate only for experimental and developmental studies. If the economics ever becomes viable, it will only be so on the basis of wrapping several icebergs, but this also gives the opportunity for providing water for several destinations. Any proposal to utilize an Antarctic resource will have to pass scrutiny under the provisions of the Protocol on Environmental Protection to the Antarctic Treaty while such activity is contemplated south of 60S latitude and would come under national jurisdiction when in territorial waters. During the negotiation of the non-ratified Convention on the Regulation of Antarctic Mineral Resource Activities (CRAMRA), ice was excluded from consideration because it was seen as a renewable resource. The advantage to accrue from using icebergs as a water source lies in the minimal impact on any environment in the Antarctic, and potentially alleviation of environmental problems at or near the destination.