Water, Sewage & Effluent November December 2018 | Page 38

A Russian icebreaker has successfully towed an iceberg weighing approximately one million tonnes. The tow was part of a test
to see whether an icebreaker could influence the trajectory of a large iceberg to protect offshore installations in the Arctic.
at a ‘water mix’ for urban water. This
brings us to the icebergs. Certainly
not a new idea, but the looming of ‘day
zero’ in Cape Town has brought that old
dream to life once again.
Why is this an attractive option?
Every year, the Antarctic sheds 2 000
billion tonnes of ice that contains
more fresh water than the total
global freshwater consumption. The
iceberg idea has been seriously
considered for the desert cities in
the Middle East, and Prince Faisal of
Saudi Arabia has pumped substantial
amounts of oil funds into some proper
scientific research.
Professor Peter Wadhams, a
former director of the Scott Polar
Research Institute at the University
of Cambridge, was a leader in
this research. Two Saudi-funded
conferences later — at Ames, Iowa,
and the Scott Polar Research Institute,
featuring plans by Wadhams, Mougin,
and Orheim — convinced a lot of
people that it could be done. But not
to the Middle East as it is too far, and
the tow in tropical waters would melt
most of the ice. The conclusion of this
research? The tow needed to be done
within reasonably narrow latitude and
in relatively cold waters.
Whilst the Saudi project failed
on both counts, Cape Town is far
more attractive, and some additional
favourable conditions were pointed out
by the researchers: icebergs drift two-
thirds of the way up to the southern tip
of Africa and only need a tow for the
remaining third. The cold Benguela
current flows north from the Antarctic
and can drive an iceberg along. As one
proposal stated, all that is needed is to
36
South African towns
and metropolitan areas such
as Cape Town and Nelson
Mandela Bay (Port Elizabeth)
are historically dependent
on one single water source
type, namely surface dams
fed by run-off.
‘nudge’ the iceberg into the current,
and then nature will do the rest. Lastly,
developments in the past decade have
made a geo-textile ‘skirt’ available to
ease towing and lessen melting.
Earlier this year, scientists joined a
crew led by Captain Nick Sloane of
Cape Town-based marine engineering
company Resolve Marine. Sloane is
world renowned in the field of marine
salvage, having led the team who re-
floated the Italian Costa Concordia
wreck in 2014. Towing large unwieldy
objects in rough seas is what Sloane
does. And he is convinced that he
can tow an iceberg to the Cape.
“We have spent two months satellite
tracking icebergs around our target
area,” he told Tim Smedley of BBC
Future. The ‘target’ is penguin-
covered Gough Island in the South
Atlantic, 2 700km south-west of Cape
Town. There they hope to pick up an
85–100-million-tonne iceberg. Sloane
reckons that “Antarctic icebergs are
all tabular, they are as flat as a dining
room table; they are much more solid
Water Sewage & Effluent November/December 2018
and their core temperature is much
colder as compared to their unstable
Arctic relatives.”
The tow to Cape Town, says Sloane
— who would captain the mission —
would take 80–90 days, at 0.8–1.2 knots,
using a super tanker (with over 20 000
horsepower), plus three tugs. Central
to the plan are the natural currents
that converge around Gough Island:
the Circumpolar Current, which runs
like a ring road of icebergs around the
Antarctic, and the Benguela Current,
which runs in an arc from Gough Island
to the Cape and up the west coast of
Africa. Sloane describes the challenge
as simply ‘changing train tracks at an
intersection’, whilst currents would do
most of the delivery job for them. Even
the destination point near the Cape,
where the iceberg would be pinned
into place using oil rig anchors 40km
offshore, remains in a cold current,
reducing the melt-rate. The water
would be harvested using opencast
mining techniques carving into the top
of the iceberg, with shuttle tankers or
an underwater pipeline carrying the
water to the shore.
But the water needs a buyer. Cape
Town authorities reckoned it to be
too expensive. Apparently, the team
also made a presentation to the
Water Research Commission (WRC),
who seemed to stall an opinion and
conveniently asked for more details
on ‘the scientific, environmental, and
economic feasibility’. So, the response
has not been positive.
In the offshore industry, wrangling
icebergs, aka iceberg management,
is actually nothing new. There are
companies and vessels in the world
www.waterafrica.co.za