View Online

Cape Construction take off 14 September 18
Bloembuild take off 27 July 2018
Interbuild take off 19 Aug 2018

Water from the Antarctic?

Online since 28.06.2018 • Filed under General • From Issue 24 page(s) 22-23
Water from the Antarctic?

By Gareth Griffiths

For over thirty years, people from South African and elsewhere in the world have reflected on the possibility of harvesting fresh water from icebergs that originate in Antarctica. In certain instances, countries in the Northern Hemisphere, including the UAE that have faced serious drought consequences, have seriously pondered the viability of such an endeavour over the long haul.

 

Some in a rather bemused way, have discussed it at dinner tables and dismissed the concept. Now a world renowned South African marine salvage expert, Nick Sloane, has presented a rather interesting solution: to tow an iceberg from Antarctica to off the Western Cape coast where it can be mined for water. According to a team of heavyweight experts, floating ice that has broken off mainland Antarctica could be trapped near Gough Island, 4 000km to the north of Antarctica and 2 600km south-west of Cape

Town.

 

Salvage experts involved

Salvage expert and director of the Resolve Marine Group, Nick Sloane, addressed delegates at the African Utility Week conference during a keynote session on solutions from nature to address increasing energy and water constraints. According to Sloane, in 2017, the UAE water supply was in trouble and an elaborate project was set up to tow an iceberg to the region. They planned to harvest icebergs off Heard Island, around 1000km off the coast of mainland Antarctica. However, the distance from Heard Island to Dubai is considerable at over 9 000km.

 

However, the Cape Town scenario is different. ‘It sounds like a crazy idea but if we break it down, it is not so crazy after all,’ Sloane says. According to Sloane, the answer may just be in “mother nature’s icebergs” – a total of 140 000 icebergs to be specific - drifting in the southern oceans and melting. Harvesting icebergs, he said, can help provide at least 20% of Cape Town’s water needs. He told delegates icebergs break off in Antarctica and hold some of the purest quality water that is between 15 000 and 20 000 years old.

 

‘About 2 000 million tons of ice are breaking off every year,’ he said. The idea is to use the ocean’s currents to guide these icebergs towards the Cape. Sloane said the iceberg can be captured in the area round Gough Island and will ultimately have to be guided and moored about 40km offshore from St Helena on the West Coast, to be harvested. According to Sloane, the ideal candidate iceberg would be a “table top” variety – one with sheer sides and a flat surface that could be mined. He said they will then have to ‘create a saucer (in the centre of the iceberg) to capture the melting water that can deliver up to 60 million litres per day’. With milling, this volume can increase to 160 million litres a day, that is then pumped into tankers and ferried to land where it will be treated before it goes into the water system. “So, with four to six of these tankers, 150 million litres can be harvested per day for one year.’

An iceberg of 850 x 450 x 220 metres deep could supply 85 000 Ml - at a 70% harvest rate, this means 160Ml/day - approximately 25% of Cape Town’s needs.Of the 140 000 icebergs that break away from the Antarctic mainland each year, approximately 7% of them are the right size and shape. The intention would be to let icebergs arising from the Antarctic’s Weddle Sea drift as far as the vicinity of Gough Island at 43.3° S (latitude) 9.9° W longitude. The passage of such icebergs would also be favourably assisted by currents moving in the direction of the Cape, including the Circumpolar Current, Coriolis effect and the Benguela Currents.

 

How would the iceberg be towed?

A geo-textile net “skirt” would be floated around the iceberg and closed off. This would tend to insulate the iceberg and prevent excessive water loss from melted ice. The mass would have to be towed by the world’s most powerful tugs, such the ALP Tugs with a bollard pull of 300 tonnes. Attached to a webbing tow bridle, the chain length would be 1-1.5 km, with the potential of an additional submerged hawser. However, said Sloane, it is recommended that a large tanker be used to tow the iceberg, with two tugs supporting alongside the iceberg to ensure correct alignment with the predetermined route.

 

Placement for mining operations

The initial placement of the iceberg would be in the St Helena Bay area where extraction operations could begin. The water would effectively be mined from the iceberg and then loaded on to chartered tankers with food quality coatings and a capacity of between 30 000 to 50 000m3. It is envisaged that a fleet of three to six of these tankers be used via a rotational scheme.


Purer and better

Purification of the water mined would be via chlorination. Water from icebergs has been tested and found to be exceptionally pure and low in deuterium due to its source in the Antarctic. Deuterium is a relatively rare form of hydrogen and can be formed into “heavy water”. This is significant from a public health perspective, since deuterium depleted water has been the subject of research in the reduction in morbidity of certain cancers of the human body (www.researchgate.net - see https://goo.gl/PXXVPz). For someone with the reputation of Nick Sloane, famously known for the 2013 lifting of the previously unsalvageable Costa Concordia wreck, to stake time, resources and reputation on such an endeavour shows that this is a serious prospect indeed.

 

[Source: Capt. Nick Sloane – PowerPoint presentation, African Utility week 2018, Cape Town International Convention Centre. Additional reporting by Alicestine October/AUW2018]

Power Purchase  Conference 2018 take off 23 Nov 18
CAPE INDUSTRIAL FLOORING take off Feb19
 Affiliated Members AAAMSA - The Association of Architectural Aluminium Manufacturers of South Africa | Tel: 011 805 5002 CifA Institute for Landscape Architecture in South Africa KSA - Kitchen Specialist Association | Tel: 0827878806 SAIA