Water versus Energy

If polywell fusion is developed, in what ways will the world change for better or worse? Discuss.

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Professor Science
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Postby Professor Science » Fri Sep 04, 2009 4:19 pm

So things you can produce out on an ocean bound platform with infinite energy,

liquid Hydorgen, liquid oxygen, liquid Nitrogen, Amonia, Metalic Magnesium...

Fishing would be less of an infinite resource, I'd say, but I think you should be able to mine carbon out of the atmosphere and not a lot of people would mind. CO2 is somewhat soluble in water too... I wonder what happens to the nearby water if you extensively are mining ions out of water, difussion would kick in before too long, but you could potentially end up with a zone of practically fresh water near your little village. all depends on rates I suppose, bloody differential equations.
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KitemanSA
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Postby KitemanSA » Sat Sep 05, 2009 11:40 am

Wouldn't your activities make the near shore ocean brinier if anything? After all, what you are extracting MOST is the fresh water. Maybe some minor ions like boron, but how much salt do you want?

By the way, CO2 is much more concentrated in the ocean than the atmosphere which is why the NRL study is anticipating getting it from there.

Professor Science
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Postby Professor Science » Sat Sep 05, 2009 3:54 pm

I was starting with a facility out at sea, like on a refurbished oil tanker or something. anything you take out of the ocean's ion supply will mean a region of lower ion concentration, i'm just trying to figure out how fast diffusion would kick in.
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D Tibbets
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Postby D Tibbets » Sat Sep 05, 2009 5:12 pm

KitemanSA wrote:Wouldn't your activities make the near shore ocean brinier if anything? After all, what you are extracting MOST is the fresh water. Maybe some minor ions like boron, but how much salt do you want?

By the way, CO2 is much more concentrated in the ocean than the atmosphere which is why the NRL study is anticipating getting it from there.



It all depends on the amounts. If you eat 1000 gallons per minute and discharge 1000 gallons of now pure water into a mixing tank that is fed with 9,000 gallons of sea water per min (now at 90% of original ion content), then discharge that into one or more outlet pipes so that it mixes with ~ 90,000 gallons of sea water within a couple of minutes, you would be effectively discharging ~99% normal sea water into the local area. Alternatly, instead of expensive 100% efficient solute extraction, if the extraction efficiency was 10% you would decrease th local effects by another factor of 10 (at the same water volume intake).

Also, keep in mind that you are segragating the products, not removing them from the overall enviornment. Given enough time the balances will be restored - through erosion, rusting, runnoff, sewage , etc. You are expending energy to temperarily reverse entropy in a very small area. So long as you are carefull to not concentrate the effects to much and/ or avoid secondary effects (like cutting down forests leading to more erosion) any changes will be tolorable*.

* Tolorable being a political standard.


Dan Tibbets
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tombo
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Postby tombo » Sat Sep 05, 2009 9:29 pm

The EPA has a freeware program called Visual Plume that calculates the dispersal of a plume of any effluent, say brine, with inputs for currents, current gradients, temp, temp gradients, etc.
You can easily calculate the rate at which your plume of brine or fresh water, if you're mainly removing dissolved solids, disperses.
I've done it for environmental impact statements and it is really quite straightforward. Count on a little current and the ocean is really really big so I think you will get quicker dispersion than you think.
-Tom Boydston-
"If we knew what we were doing, it wouldn’t be called research, would it?" ~Albert Einstein

Professor Science
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Postby Professor Science » Sat Sep 05, 2009 9:47 pm

Alas, windows only operation...
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jsbiff
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Is human desalination more efficient than moving fresh water

Postby jsbiff » Mon Jun 07, 2010 9:13 pm

Whenever discussions of desalination come up, I always have to wonder if desalination, long term, would be cheaper/more efficient (even with cheap power from fusion), than simply moving surface water from places that have excess to places with shortages?

There's always fresh surface water somewhere. Much of it just ends up running out of rivers into the ocean. The Sun is constantly desalinating massive, massive quantities of ocean water into fresh water, then raining it down.

In the U.S., where I live, it seems like every year in the spring and fall you see in the news about some place that's experiencing some massive flood. Meanwhile, other places don't have enough water.

Mightn't it make sense to build more reservoirs, and try to catch more water in places that tend to have lots of precipitation, then use large canals or pipes to move the water to places with fresh water shortages?

I don't know much about Africa, but it seems to me there must be some countries in Africa that get way more water than they can consume, and could export their water to other countries? (I suppose the flip side of that is, if you are the importing country, it kind of sucks to be at the mercy of someone who can turn off your water whenever they want - so maybe for that reason alone, desalination plants are very necessary).

KitemanSA
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Re: Is human desalination more efficient than moving fresh w

Postby KitemanSA » Mon Jun 07, 2010 11:50 pm

jsbiff wrote:Whenever discussions of desalination come up, I always have to wonder if desalination, long term, would be cheaper/more efficient (even with cheap power from fusion), than simply moving surface water from places that have excess to places with shortages?

There's always fresh surface water somewhere. Much of it just ends up running out of rivers into the ocean.
Maybe it would be cheaper in the long run to convert that water running into the ocean into electricity via osmotic pressure powered turbines and ship the power to the other side of the country / world and run that process in reverse.

No, wait, it might just be easier to run that reverse osmosis with a polywell.

Hmm. Round in circles!

BenTC
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Re: Is human desalination more efficient than moving fresh w

Postby BenTC » Wed Jun 09, 2010 2:57 pm

jsbiff wrote:There's always fresh surface water somewhere. Much of it just ends up running out of rivers into the ocean.


The rivers may just need that water to stay healthy. There are big issues in eastern Australia with irrigation basically sucking the river dry and downstream river users suffering.
In theory there is no difference between theory and practice, but in practice there is.

jsbiff
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Re: Is human desalination more efficient than moving fresh w

Postby jsbiff » Thu Jun 10, 2010 7:29 pm

BenTC wrote:
jsbiff wrote:There's always fresh surface water somewhere. Much of it just ends up running out of rivers into the ocean.


The rivers may just need that water to stay healthy. There are big issues in eastern Australia with irrigation basically sucking the river dry and downstream river users suffering.


I guess I should clarify - I'm not suggesting we kill rivers by sucking 100% (or even close to that) of the water out of them. I guess I'm more suggesting that we could do a better job of trapping 'excess' water in reservoirs during times of 'flooding', and even during 'normal' weather, you could probably siphon something like 20-25% of the water out of most rivers without hurting things too much (there may be some particular rivers/streams which would be more sensitive to having any significant amount of water diverted, but those issues would have to be dealt with on a case-by-case basis).

I'm also not saying I don't think there's any place for desalination, I just wonder if we couldn't be doing more with diverting solar-desalinated (i.e. rain/snow) water resources from places of abundance to places of drought. It also seems to me that global warming should have the implication of more rainfall in the future than we have now (more energy in the atmosphere and ocean should mean more evaporation of water from the oceans).

You would have to build many, many, many fusion plants to generate the kind of power the Sun already puts towards desalination.


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