Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

China Turns to the Sea for Fresh Water

bloomberg.com

Post reply on HN
Print view View original

21–30 of 53 posts

Re: China Turns to the Sea for Fresh Water

#21

Post by Mankhool »

derekp7 wrote: post #11
kiba wrote: 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).

There are other products that come out of the process with the salt. There is a good example of the Persian Gulf because of the number of installations and the ability to easily measure the increase in salinity and contaminants.

http://www.warponline.org/uploads/contents/103-content-9.-En...

Re: China Turns to the Sea for Fresh Water

#22

Post by jacquesm »

singlow wrote: post #15
ryannevius wrote: post #12

Earlier quoted context omitted.

No...Most ocean life is ridiculously dependent on perfect salinity levels. We wouldn't be doing any favors by increasing these levels, no matter how small our impact may be.

won't the new fresh water get back to the ocean too?

There will be a phase lag and a concentration effect.

Re: China Turns to the Sea for Fresh Water

#23

Post by CHY872 »

jessriedel wrote: post #20
ryannevius wrote: post #12

Earlier quoted context omitted.

No...Most ocean life is ridiculously dependent on perfect salinity levels. We wouldn't be doing any favors by increasing these levels, no matter how small our impact may be.

The change in salinity would obviously be negligible averaged over the ocean, and would be massively, massively dwarfed by other human factors. Your extreme use of the precautionary principle would prohibit essentially all new constructions, if applied widely. Much more interesting is the question of the impact to the nearby ecology in the immediate neighborhood of the discharge pipe. I'm not familiar with this, but…

http://www.ncbi.nlm.nih.gov/pubmed/20633919 suggests that they can be mitigated.

Re: China Turns to the Sea for Fresh Water

#24

Post by spiritplumber »

jarito wrote: post #18
allendoerfer wrote: post #16

Earlier quoted context omitted.

Many places with water shortage are sunny and hot. In my mind it is the perfect use case for solar thermal power plants. I just love how simple they are. If we build coal or nuclear power plants, we just ditch one problem for another. It is also a great way to smoothen the varying production of renewal energy.

That's an interesting idea as well. A molten salt reactor or something similar would have the same benefits as nuclear, you just trade reliability for cleanliness. I would imagine that a molten salt set up would be significantly cheaper to build as well, but I could be wrong on that.

A good thing is that you don't care about normalizing usage: if the plant happens to only work during the day, it's fine, you can make fresh water during the day and use your storage tanks at night. Unlike with batteries, there's basically no waste in storing water overnight.

Re: China Turns to the Sea for Fresh Water

#25

Post by lotsofmangos »

ryannevius wrote: post #12
jessriedel wrote: post #10

Earlier quoted context omitted.

Put it back in the ocean.

No...Most ocean life is ridiculously dependent on perfect salinity levels. We wouldn't be doing any favors by increasing these levels, no matter how small our impact may be.

Add it to a large tidal river mouth and you just shift the mix point upstream slightly.

Re: China Turns to the Sea for Fresh Water

#26

Post by adventured »

pmorici wrote: post #3

Maybe they can export their excess freshwater in giant tankers to CA to solve their drought problem. They already produce most of the electronics we consume.

China already imports a vast amount of California's water via produce (eg their consumption of California almonds), so to be accurate it would be more like them sending the water back.

Re: China Turns to the Sea for Fresh Water

#27

Post by hyperbovine »

mmoche wrote: post #6
jarito wrote: post #5

Why not look at something like nuclear? Since the need is both electricity and heat, a nuclear reactor seems ideal since you don't have to convert power back in to heat - you can just use it directly. With modern recycling techniques and reactor designs the chance of meltdown and wastes are limited, but that seems better than more coal. Not an expert on reactor design vs desal design by any means - would love an opin…

Agreed. Particularly for California which has heavy energy and water needs, nuclear desalination seems like the most future-proof approach, particularly considering the dramatic decrease in aquifer volume as groundwater is extracted to make up for drought-level rainfall.

This seems to be a common fallacy: desal, which is being considered by a few wealthy urban water districts on the coast, will do absolutely nothing to alleviate overpumping by farmers in the Central Valley.

Re: China Turns to the Sea for Fresh Water

#28

Post by LiweiZ »

jarito wrote: post #5

Why not look at something like nuclear? Since the need is both electricity and heat, a nuclear reactor seems ideal since you don't have to convert power back in to heat - you can just use it directly. With modern recycling techniques and reactor designs the chance of meltdown and wastes are limited, but that seems better than more coal. Not an expert on reactor design vs desal design by any means - would love an opin…

In my experience working with one of the major players among Chinese nuclear power groups, nuclear power plants have low acceptance rate among local residents, perhaps even local governments, especially after Fukushima Daiichi nuclear disaster. If I recall correctly, there was some big plan in government's 5 year master plan at that time. Well, there are more factors come to play. What I mentioned is just one of them.

Re: China Turns to the Sea for Fresh Water

#30

Post by [deleted] »

jarito wrote: post #5

Why not look at something like nuclear? Since the need is both electricity and heat, a nuclear reactor seems ideal since you don't have to convert power back in to heat - you can just use it directly. With modern recycling techniques and reactor designs the chance of meltdown and wastes are limited, but that seems better than more coal. Not an expert on reactor design vs desal design by any means - would love an opin…

[deleted]
Post reply on HN