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China Turns to the Sea for Fresh Water

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41–50 of 53 posts

Re: China Turns to the Sea for Fresh Water

#41
This has been mentioned elsewhere, but I wonder if we could use the super large tankers that are currently being built for transporting oil and gas for transporting water instead? There is tons of fresh water in the great lakes and the polar ice caps.

These ships don't need all the advanced machinery that they currently have for making sure there is no leaks: if there are minor leaks, its water anyways. So its likely to be much cheaper.

I'm concerned about the amount of fossil fuels they would consume though.

Re: China Turns to the Sea for Fresh Water

#42
post #41

This has been mentioned elsewhere, but I wonder if we could use the super large tankers that are currently being built for transporting oil and gas for transporting water instead? There is tons of fresh water in the great lakes and the polar ice caps. These ships don't need all the advanced machinery that they currently have for making sure there is no leaks: if there are minor leaks, its water anyways. So its likely…

Is it enough? I'd imagine the amount of water used (industrial, residential, agricultural) is far greater than oil. For example -- ~3k gallons water / lb of beef. That means growing a cow uses A LOT more than the cost of transporting that beef once it's slaughtered.

Re: China Turns to the Sea for Fresh Water

#43
post #11
post #8

Earlier quoted context omitted.

What will you do with the salts and various impurities?

Dump it on the roads in the North during the winter. Or, more seriously, if it is salt that was extracted from the sea, there shouldn't be much harm in putting it back. The fresh water that was extracted will end up back in the sea also, so overall there should be no increase in salinity (except locally where the salt is dumped).

Why can't we just eat the salt?

Re: China Turns to the Sea for Fresh Water

#44
post #11

Earlier quoted context omitted.

Dump it on the roads in the North during the winter. Or, more seriously, if it is salt that was extracted from the sea, there shouldn't be much harm in putting it back. The fresh water that was extracted will end up back in the sea also, so overall there should be no increase in salinity (except locally where the salt is dumped).

Why can't we just eat the salt?

A liter of seawater has 35 grams of salts in it (I looked it up: http://en.wikipedia.org/wiki/Seawater ). Compare that to the recommended daily intake of several grams of salt.

It's also the case that most of the desalination methods produce concentrated brine instead of dry, clean salt (so extracting the salt would require further energy), but not needing that much of it is the bigger reason.

Re: China Turns to the Sea for Fresh Water

#45
post #41

This has been mentioned elsewhere, but I wonder if we could use the super large tankers that are currently being built for transporting oil and gas for transporting water instead? There is tons of fresh water in the great lakes and the polar ice caps. These ships don't need all the advanced machinery that they currently have for making sure there is no leaks: if there are minor leaks, its water anyways. So its likely…

Wouldn't be worth it.

The largest super tankers have a deadweight tonnage of approximately half a million tons, which is worth ~$500MM of crude oil.

But water is super cheap by comparison. Assuming $0.0015/L (which is what I pay for my tap water in California), half a million tons of water is worth only $750k.

Another way to see it: the transport cost per super tanker is about $0.02 per gallon [1] but tap water is ~$0.006 per gallon (again, my tap water cost). So you would be tripling its cost to transport it by sea...

[1] http://en.wikipedia.org/wiki/Oil_tanker

Re: China Turns to the Sea for Fresh Water

#46
post #35

"the facility will remove salt from 120,000 tons of seawater each day. The result will be 50,000 tons of potable water" Huh? What happens to the other 70,000 tons of water? Or do they mean it will take in 120,000 tons, use something (e.g. distillation, filtering) to move almost all the salt in it to about half of it, and get 50,000 tons of potable water and 70,000 tons of about twice as salty as the input water?

You are correct. The energy cost to desalinate increases as the salt content increases, eventually you have to let it go.

Re: China Turns to the Sea for Fresh Water

#47
post #32

Earlier quoted context omitted.

There's serious and then there's serious. Fiji exports water to the US. I've heard of a bagel company in London which imports its water from New York City. People buy ice that comes from Alaskan glaciers. (Minor note: If you use under 20 tons/year of tidewater glacier ice then you don't need a permit.) So people are willing to pay a lot of money for provenance. Fiji Water is a good comparison. According to its Wikipe…

There certainly isn't a serious existing proposal, there is a series of agreements making sure it isn't done. I was just saying that someone had thought about doing it, enough so that they went ahead and got a permit. I wonder what the prices for shipping and desal were in 1997...

Oh, I agree. I was just saying that there's "serious" and there's "serious"

http://www.greatlakeswaterwars.com/chapter11.htm says that it was a for-profit "humanitarian effort on behalf of the world’s poor that was also designed to make money".

I can't figure out how it was supposed to work. It looks like it comes down to person who wanted to do it was in Sault Ste. Marie, Ontario, and thought of the tons of water in the backyard [paraphrasing]. So he and his partners could have been serious about, but there's no real chance it would work out.

It doesn't really matter what the prices were in 1997. Alaska water is closer to Asia than the Great Lakes. If it made sense for Lake Superior, it would make even more sense for water from the Sitka.

http://www.heatisonline.org/contentserver/objecthandlers/ind... says that around the same time :

> A company called Global Water Corp. has announced plans to ship up to 5 billion gallons a year of glacier water by tanker from Alaska, near the port city of Sitka, to the Middle East. The company said on its Internet web site that it has reached agreements with buyers in China, and that it plans to negotiate with interested parties in the southwest U.S.

There's a lot of people who talk, in the hopes that someone else will front the money. It's not really a con, because it might actually work. But if things are borderline, it can help to sound serious and express no doubts.

Re: China Turns to the Sea for Fresh Water

#48
post #8

Earlier quoted context omitted.

What will you do with the salts and various impurities?

Many desalination plants mix it back into the ocean, you pump more water than you are desalinating and the 'waste water' is a mixed brine at an acceptable salinity level. That said with global warming melting a bunch of fresh water glaciers into the ocean, one of the side effects is lowering the salinity level. This suggests to me that boosting it slightly by desal efforts will be negligible at worst, and remediation…

> That said with global warming melting a bunch of fresh water glaciers into the ocean

That's a very good point! Potentially desalination could help fixing problems of rising see levels too. There are many deserts that could become huge lakes (in Sahara, Persia, China) and eventually it should be possible to move enough water from sea to compensate for some of polar ice melt.

Re: China Turns to the Sea for Fresh Water

#49
post #37

Earlier quoted context omitted.

> The salinated impurities that are a byproduct of this process That's a very inaccurate way of saying that. You are implying that that desalination creates new byproducts. It does not. Any byproducts were already in the ocean. You just run your outflow pipe far into the ocean, and mix it with ordinary seawater and it's sufficiently diluted.

That's misleading. It's not technically a byproduct, but taking literally tons of salt that was spread evenly throughout the ocean and dumping it out at high concentration at the end of a pipe has significant (and bad) ramifications for the ecosystem at the end of the pipe.

Nobody said to dump it out a pipe at one single point. Spread it out leaky pipe style over a large volume of ocean so that the average salt concentration does not significantly rise.

Re: China Turns to the Sea for Fresh Water

#50
post #8
post #2

Israel (obv a different scale than china) has recently also experienced a big push toward desal. What's interesting is there's a moore's law type of effect at play here, desal keeps getting cheaper and cheaper to the point where it's actually a practical alternative to ground water, filtering etc. I think water will be another great Malthusian disappointment, ocean water is basically unlimited (correct me if I'm mist…

What will you do with the salts and various impurities?

Less mining.
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