It does sound like the volume is an advantage, but there are a lot of ifs. But I guess the assumption is starting the process of snaring a berg and getting it moving is much less costly than mining the ice. You could probably pick up a lot of loose ice at the edge of the shelf to inexpensively load in tankers, but then it you’d pick up a lot of saltwater and maybe penguin feathers too. So yeah, the amount risked to tow a berg is fairly low even if you end up with little ice at the destination. The overall transport costs in fuel for both tanker or towing wouldn’t be that different but certainly higher to load the tankers initially. Perhaps it would be different if you could tap into flowing water in the Antarctic which does exist but I have no idea if that’s at all feasible.
Another approach would be to send oil tankers on return trips with fresh water, essentially trading oil for water. It still seems like efficient desalination is a simpler approach in a region with lots of sunshine, but perhaps that just hasn’t worked out so far.
There’s a reason why you won’t see many icebergs in the Mediterranean Sea or even in the Atlantic near Spain or Miami - they melt.
If you’d haul that iceberg, it would get there faster and melts less, but then you have to drag that iceberg through the warm Mediterranean Sea.
Desalination seems to be far more cost effective, at least at the moment to provide drinking water.
The statement might just have meant that (let’s say napkin calculation) per ton original Iceberg only 0.1 ton arrives at the destination and got badly translated or misunderstood.
The article is inconsistent in describing what size of berg they are going after:
It doesn’t make any sense to me harvest growlers. Unless each ship towed a large number it wouldn’t be worth the cost. And I would think the growlers, with large surface-to-mass ratios, would melt long before they reached Dubai.
Towing a large berg would make a lot more sense. 20 billion gallons is about 75,708,235 cubic meters. Taking the cube root of the latter figure gives a diameter of is 423 m for a berg that would contain that much water.
ISTM that a berg with 240 times the mass of a tanker load would be of such width, height (above sea level) and depth (below sea level) as to be completely at the mercy of air and water currents.
There’s also the interesting problem of the prop wash from the tow vessel hitting the leading face of the berg, negating the tug’s towing capacity. You’d need at least two tugs and some sort of rigging to allow them a lateral separation greater than the width of the berg.
I think that’s a reasonable guess as to what the original sentiment was, although the quote in its present form is so meaningless that it’s hard to tell.
Even this explanation depends on knowing the size of the iceberg. The bigger the berg, the smaller fraction of it is lost to melt per unit time. And while a bigger berg is going to be slower to tow, it’s not going to be linearly slower with respect to its volume.
(Very) roughly, the cost to tow and loss due to melt are both going to be proportional to the surface area of the berg, while amount of water is proportional to the volume.
If you can haul a big enough iceberg, then this scheme could make sense.
Take a look at the article I linked earlier. There is reference to a Rand study that imagined exactly that–a train of small bergs, pulled by a nuclear tug. (There is also mention of some ships moving bergs out of the paths of oil rigs, where the nylon ropes would start off 8 inches thick at the beginning, and be stretched to 1 inch thick at the end.)
I’d think towing the berg through the water would streamline it’s shape. Could it be pushed instead of pulled? Could a heat engine be used once it’s out of the coldest region so no more fuel is consumed?
Fighting air and water currents does seem problematic. Turning against the water current will continually change the shape of the berg.
How far do icebergs float away without assistance before they melt away? Do they expect this berg to travel much faster than currents normally carry them?
I never said it was feasible–just that someone had suggested towing a train of them. (Personally, I’m still sticking on my primary understanding of “growler” as being a euphemism for feces.)
Anyone remember that Irish firm who had discovered the secret arcana of perpetual motion some years back and proposed to dispense free energy ? They too were elusive.
Apparently either they’ve never really looked at the ice in their drinks, or they gulp them. They seem to think what causes melting is light rather than heat exchange.
As to your first point, maybe but you can tow on a very long line (a km or two would not be unusual) by which time I don’t think the effect would be very noticeable.
As to your second point, I think rather more than two, if you want to get where you are going before you die of old age.
As you said tankers haul liquids.Why get ice you have to thaw to put in your tanker when you can go to the other end of the world and fill your tankers from rivers that flow into the Arctic Ocean. Very few are contaminated to the extent they’d need purifying. Only need to negotiate with a few nations to suck up the output of a few rivers instead of developing an entire infrastructure and technology to thaw ice in the Antarctic.
As to towing 'bergs wait until you get it home and the activist environmental groups realize you have icebergs sitting in a smallish salt water body thawing and changing the salinity of the area waters.
Once you get the berg anchored offshore Dubai or wherever the first thing you do is put a bag around it to keep the pure melt water you want separate from the Gulf salt water you don’t.
IOW, if you’re materially affecting the salinity of the local environment you’re doing it wrong.
Now the impact on local water *temps *is another matter. You’re relying on that high local water temp and solar flux on the above-surface part to provide the energy to melt the berg into drinking water.
Your activists can get excited about the environmental impact of all that artificial cooling.
