Water from icebergs
is it some crazy pipe dream, or is it feasible?24th Mar 2020
Something like 70% of the world’s fresh water is frozen up in polar icebergs – and the idea of towing them to dry or drought-stricken areas like California, Saudi Arabia and the Canary Islands has long been a dream – an impossible dream.
But these places are all in the northern hemisphere, and 75% of the polar ice in the world is in Antarctica, where over 100,000 icebergs break away every year and slowly drift north – some of them more than two-thirds of the way to Cape Town. So, while harvesting icebergs is a futile fantasy in the northern hemisphere, it is definitely feasible in the southern hemisphere, said marine salvage expert Nick Sloane in an interview with Estate Living.
A frozen treasure-trove
Considering the resources humans put into the frenzied guano rushes of the 19th century, heading down into the deep Southern Ocean to hunt whales, and digging the great hole of Kimberley or tunnelling deep under the Witwatersrand, what do you think we would do if huge rafts of gold, platinum or diamonds were floating around in the ocean? Well, there is a greater treasure doing just that. It’s taken us a while, but we have finally realised that clean, fresh, potable water is infinitely more precious than diamonds, gold or platinum, never mind whale oil, baleen or guano. And, yes, there are vast treasure-troves of the stuff floating around, eventually evaporating and/or melting, and just disappearing. Perhaps we should get us some.
Would that really solve our water problem?
Since the terrifying Day Zero prospect of 2018, we’ve had some nice rain, and the dams are looking better, but we’re still a very water-stressed country, with numerous towns in the Western Cape, Northern Cape and Eastern Cape still suffering drought conditions – let alone the vast agricultural areas where labour forces have been drastically laid off, as crops fail and livestock farmers struggle to find sufficient feed to keep their herds alive.
We need to continue to exercise restraint on how we use water, and how much water we use, but our population is constantly growing, and agriculture and industry are growing apace, so we really do have to find alternative sources. We’ve stepped up our rainwater harvesting, and we’ve considered desalination, which is not without its problems, so are icebergs really the answer? Well, they are certainly an answer.
Here are some cool stats. An iceberg of 800 metres x 400 metres x 230 metres deep can supply about 47,000 megalitres, which translates to 130 megalitres per day for a year. That’s around 20% to 25% of Cape Town’s current needs – about the same amount of water as that in Steenbras Lower Dam.
So, hey, that means that if we could tow not just one, but four or five such icebergs to the city every year, we could divert all the water in our storage dams to agriculture – and perhaps even tanker some into the Karoo.
That’s worth thinking about. Five icebergs could supply all of Cape Town’s water needs, and there are hundreds of suitable icebergs floating around the Southern Ocean – tantalisingly close to the source of the Benguela Current near Gough Island.
Is it possible?
Do a search on harvesting icebergs, and you will find loads of reasons why it’s not possible – but almost all those studies refer to northern hemisphere icebergs. Now, you may think an iceberg is an iceberg, but northern icebergs are ungainly, unstable, pear-shaped whippersnappers (only a few thousand years old) that like to play fast and loose with oil rigs and ‘unsinkable’ ocean liners. Southern icebergs, on the other hand, are mature (over 200,000 years old), solid, staid, straight-sided, stable floating platforms. And there are lots of them – every year about 110,000 icebergs calve off Antarctica, about 90,000 of which are the big, flat, stable tabular ones described above. But, for the programme to be feasible, icebergs need to be not only the right shape, but also the right size and in the right place. Studies have shown that the ideal size is around 85 to 120 million tonnes – 800 to 1,000 metres in length by 400 to 500 metres wide by 220 to 230 metres high, with most of that being underwater. About 3,000 (3% to 4% of those 90,000 tabular icebergs) fall within the Goldilocks target size range. And while most of them are inconveniently positioned, a good few hundred drift far enough north to be captured near Gough Island.
But what about the carbon footprint?
The icebergs would be captured in a huge net that would initially be installed by tugs and then towed by a VLCC supertanker. But it’s not so much towing as guiding. The icebergs drift as far as Gough Island all by themselves, and the tow would guide them into the cold Benguela Current that flows up the west coast of South Africa and Namibia. Once in the Benguela, the icebergs would drift – just being steered, when necessary, to stay on track in the complex Southern Ocean currents.
But seriously …
It’s not only Cape Town, although it is the most perfectly positioned city. The project was presented at the UN International Symposium on the Use of Nonconventional Waters for Achieving Food Security, held in Madrid, Spain, from 14–15 November 2019, as being feasible for Cape Town, Namibia, Western Australia and Chile. But Cape Town is top of the list, both because of all the positive factors in its favour, with its natural geographic advantage in the south Atlantic Ocean and, Sloane admits, because it’s his home city.
And once it’s here?
Okay, don’t picture an iceberg floating off Clifton Beach. The plan is to take them to St Helena Bay, where they can be kept in cold waters after running aground some 25 to 30 kilometres offshore, and then to harvest – or mine – them from the top. The ‘mined’ slurry would be pumped into shuttle tankers, and then – through a mooring buoy – added in to the existing water reticulation infrastructure in Saldanha Bay and Cape Town.
But don’t worry – some of this delicious, purest water on earth will be bottled, so you can savour the experience of drinking 200,000-year-old water. And, yes, some of the ice will be harvested ‘as is’, too, so you can add the purest ice in the world to your G&T or single malt – at a price.
‘So,’ I asked Sloane eagerly, ‘when can we expect our first iceberg?’
‘Optimistically, about two to three years,’ he replied, ‘but, realistically, about three to four.’
I can’t wait!