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Mass Migration out of CA Imminent

Re: Mass Migration out of CA Imminent

Unread postby Tanada » Sat 20 Jul 2019, 20:14:42

ozcad wrote:Newfie said:
Unless you know of some other technology.

Nope. I got nuffin else. Sorry.
My main thrust was about the doubtful wisdom of burning FF's followed by multiple energy transformations to get a bit of mechanical work done when you could directly harness the mechanical energy of waves, which, I hear, are often close to water. Near-zero GHG emissions to run.
The high water pressure is a worry, the head of water required to raise water over intermediate terrain to get it inland is directly added to the filter pressure differential.
We could use one pump for filtering, the LOW pressure output of which is fed into a secondary delivery pump. All wave-powered.
This would reduce the danger of having extremely high pressures throughout a large scale delivery network. All of the above is still required if FF's are used to power things anyway.
Suggestions invited.


There is a low tech energy solution not unlike your suggestion. Simply place a pipeline out to sea going down the continental slope until the bottom has the needed pressure gradient. Then place a reverse osmosis filter system on the deep intake end and flush the pipeline by pumping water out of the shore end and dumping the water into the sea. As the sea water in the pipe is removed you create a partial vacuum that will draw fresh water through the filters on the deep end. After a few days of pumping the water in the pipe will be pure fresh water. You then back flush the system for a half hour or so with fresh water to clear the filters on the deep end of accumulated gunk. After that you pump fresh water out at the shore and every week or so back flush to clear the filters. every few months you shut valves and replace the filters on the deep end being careful not to contaminate the fresh water already in the pipeline. For this system you don't need a super powerful pump, by removing water from the inside of the pipeline you create a pressure gradient that causes water to seep in through the filters at the deep end.
I should be able to change a diaper, plan an invasion, butcher a hog, design a building, write, balance accounts, build a wall, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, pitch manure, program a computer, cook, fight efficiently, die gallantly. Specialization is for insects.
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Re: Mass Migration out of CA Imminent

Unread postby Newfie » Sun 21 Jul 2019, 06:34:33

Tanada,

I’m having a hard time imagining that.

This process requires that a high pressure be exerted on the high-concentration side of the membrane, usually 2–17 bar (30–250 psi) for fresh and brackish water, and 40–82 bar (600–1200 psi) for seawater, which has around 27 bar (390 psi)[7] natural osmotic pressure that must be overcome. This process is best known for its use in desalination (removing the salt and other minerals from sea water to produce fresh water), but since the early 1970s, it has also been used to purify fresh water for medical, industrial and domestic applications.


Water pressure increases by about 0.5 PSI per foot. So for 1,000 PSI you need 2,000 feet of immersion. I get that if you had an unpressurized room l, vented to the surface, at 2,000 down you would not need a pump, just some real hefty plumbing to the membrane.

But how do you get that fresh water to the surface? If you run a pipe well then you need 1,000 PSI to over come the weight of the water column. where is the improvement?

I believe I heard of something along these lines proposed in in Hawaii many years ago but that was working with the thermocline somehow. That article was weak technically and didn’t really explains the process.
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Re: Mass Migration out of CA Imminent

Unread postby Tanada » Sun 21 Jul 2019, 10:51:44

Newfie wrote:Tanada,

I’m having a hard time imagining that.

This process requires that a high pressure be exerted on the high-concentration side of the membrane, usually 2–17 bar (30–250 psi) for fresh and brackish water, and 40–82 bar (600–1200 psi) for seawater, which has around 27 bar (390 psi)[7] natural osmotic pressure that must be overcome. This process is best known for its use in desalination (removing the salt and other minerals from sea water to produce fresh water), but since the early 1970s, it has also been used to purify fresh water for medical, industrial and domestic applications.


Water pressure increases by about 0.5 PSI per foot. So for 1,000 PSI you need 2,000 feet of immersion. I get that if you had an unpressurized room l, vented to the surface, at 2,000 down you would not need a pump, just some real hefty plumbing to the membrane.

But how do you get that fresh water to the surface? If you run a pipe well then you need 1,000 PSI to over come the weight of the water column. where is the improvement?

I believe I heard of something along these lines proposed in in Hawaii many years ago but that was working with the thermocline somehow. That article was weak technically and didn’t really explains the process.


Picture the top of the pipe being an open air well like the kind the ancestors used to use a rope and bucket to get water out of. As you pump water off the surface section of the water column the weight of the water inside the pipe drops lower the more water you pump out. As the differential between the water pressure on the inside and outside the pipe grows at the 2,000 foot deep end water flowing past the reverse osmosis membrane will donate some of its water molecules through the membrane to try and equalize the pressure on the inside of the pipe with the pressure on the outside.

The strength of the pressure gradient depends on how much of the water inside the pipe you pump out. Say you pump the pipe until the water inside the pipe is 300 feet deeper than the water outside the pipe. That same differential in pressure will exist at the 2000 foot deep level where the outside water column is 2,000 feet deep but the inside water column is 1,700 feet deep.

The osmosis membrane will pass water through at this pressure differential, just not at a high rate of speed. Speed requires more energy, at which point you might as well build a processing plant on the shore where it is easy to maintain. It is a function of the old truism, you can have it fast, you can have it cheap, or you can have it good quality. Pick any two of the three. The pipeline system gives you very pure water at a relatively low cost, but more slowly. A shore plant gives you very pure water, very quickly, but at high cost. The other choice (cheap and fast) gives you low purity water and nobody wants that lol.
I should be able to change a diaper, plan an invasion, butcher a hog, design a building, write, balance accounts, build a wall, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, pitch manure, program a computer, cook, fight efficiently, die gallantly. Specialization is for insects.
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Re: Mass Migration out of CA Imminent

Unread postby Newfie » Sun 21 Jul 2019, 12:56:29

Got all that, but you still gotta get the fresh water back up 2,000’ to use it.
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Re: Mass Migration out of CA Imminent

Unread postby Tanada » Sun 21 Jul 2019, 20:25:23

Newfie wrote:Got all that, but you still gotta get the fresh water back up 2,000’ to use it.

The fresh water entering the bottom of the pipe through the filter will keep filling the pipe until the pressure differential is too low to draw water through the membrane. The pressure to do that is around 300 feet, not 2,000 feet, so the pipe will fill up to around the 300 foot below sea level mark. You only have to pump the water up from that 300 foot mark, not from the bottom. As you pull water off the top of the water column more water will pass through the filter at the bottom refilling what you pulled out.
I should be able to change a diaper, plan an invasion, butcher a hog, design a building, write, balance accounts, build a wall, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, pitch manure, program a computer, cook, fight efficiently, die gallantly. Specialization is for insects.
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Re: Mass Migration out of CA Imminent

Unread postby tire » Mon 22 Jul 2019, 06:23:09

Tanada wrote:The fresh water entering the bottom of the pipe through the filter will keep filling the pipe until the pressure differential is too low to draw water through the membrane.


I assume if left alone long enough the pipe will fill completely, albeit at an ever slower rate as pressure difference approaches 0.

The pressure to do that is around 300 feet, not 2,000 feet, so the pipe will fill up to around the 300 foot below sea level mark. You only have to pump the water up from that 300 foot mark, not from the bottom. As you pull water off the top of the water column more water will pass through the filter at the bottom refilling what you pulled out.


If the pressure difference needed is 300ft, there's no reason to use a 2000 feet pipe. 300 will be sufficient. And the energy needed to constantly lift water from 300ft down you can as well have a pump push it through the filter at surface level.

Or am I missing somehting?
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Re: Mass Migration out of CA Imminent

Unread postby Newfie » Mon 22 Jul 2019, 06:52:09

@Tire

The speed at which water will flow through the membrane. The greater the differential the more flow.

You trade depth for flow rate and ease of pumping out.

BTW - Welcome aboard!

@Tanada

Are there any operational plants? Any specific name for this process?
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Re: Mass Migration out of CA Imminent

Unread postby shortonoil » Mon 22 Jul 2019, 08:27:48

by Oily Stuff » Fri Oct 24, 2014 6:58 am
Dear California:

If you folks need to flee your beautiful state please do not come to Texas. ........
May I suggest Kansas?


Classic; we used to say that about New Yorkers in Vermont. "Enjoy your stay, and don't forget to leave".

It didn't work! Don't let them in unless they show up in an RV. Hand them a map at the border with all the routes leading "OUT" of the state clearly marked. After the San Andreas Fault goes, and Southern Cal winds up 6 feet underwater, still don't let them in; send them fishing poles.
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Re: Mass Migration out of CA Imminent

Unread postby tire » Mon 22 Jul 2019, 10:53:38

Newfie wrote:@Tire

The speed at which water will flow through the membrane. The greater the differential the more flow.

You trade depth for flow rate and ease of pumping out.


Yes. But what's your point?
I claim this system doesn't save energy, the pressure needs to come from somewhere.
Also what's the purpose of 2000ft pipe if 300ft is sufficient.

Heck we can just build the 300 ft pipe straight into the air with the membrane at the bottom. Then we pump the water up into the pipe and let it drip through the membrane. No 2000ft pipe deep into the ocean needed.

cheers
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Re: Mass Migration out of CA Imminent

Unread postby Newfie » Mon 22 Jul 2019, 18:09:48

That was my point, that I don’t see how it saves energy.

300’ won’t work, or rather will work too slow to be useful.
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Re: Mass Migration out of CA Imminent

Unread postby diemos » Mon 22 Jul 2019, 21:49:50

http://www.ijesd.org/papers/243-B20001.pdf

2.5 kwh per cubic meter of fresh water

It's a known, in use, technology. I know you love arguing about things but you can just look it up.
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Re: Mass Migration out of CA Imminent

Unread postby Newfie » Tue 23 Jul 2019, 04:35:14

From your paper.

While in a typical seawater reverse osmosis plant, 3 to 10 kWh of electric energy is required to produce one cubic meter of freshwater, in the proposed approach, since only the product water needs to be pumped to the surface the specific energy consumption can be reduced to 2.46 kWh.


I can see a change from 3kwh to 2.46. Surely an improvement but hardly free. If I understand the paper correctly that difference does not include the wave energy device. It’s probably best to consider the two processes separately.

So I ask again:

1 - Is there any practical working example of this technology underwater technology?

2 - is there any practical working example of a save energy device? Every example I’ve heard of has not survived. I think there has been some limited success with submerged tidal turbines, but haven heard recent reports on longevity.
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Re: Mass Migration out of CA Imminent

Unread postby Tanada » Tue 23 Jul 2019, 09:00:53

Newfie wrote:From your paper.

While in a typical seawater reverse osmosis plant, 3 to 10 kWh of electric energy is required to produce one cubic meter of freshwater, in the proposed approach, since only the product water needs to be pumped to the surface the specific energy consumption can be reduced to 2.46 kWh.


I can see a change from 3kwh to 2.46. Surely an improvement but hardly free. If I understand the paper correctly that difference does not include the wave energy device. It’s probably best to consider the two processes separately.

So I ask again:

1 - Is there any practical working example of this technology underwater technology?

2 - is there any practical working example of a save energy device? Every example I’ve heard of has not survived. I think there has been some limited success with submerged tidal turbines, but haven heard recent reports on longevity.


IIRC I read about the pipe option I was discussing some years ago in the context of SPAR oil platforms that float anchored in deep water. The idea was they already have the platform anyhow and by sizing the filter surface area properly they could supply the platform with all its fresh water needs more cheaply than other options. You don't have to just put a filter over the end cap of the pipe, you can use a slotted pipe for the last say 50 feet of depth covered in the membrane giving you and arbitrarily large filter area compared to a typical shore plant.
I should be able to change a diaper, plan an invasion, butcher a hog, design a building, write, balance accounts, build a wall, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, pitch manure, program a computer, cook, fight efficiently, die gallantly. Specialization is for insects.
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Re: Mass Migration out of CA Imminent

Unread postby Newfie » Tue 23 Jul 2019, 09:49:58

Thanks Tanada. Makes a lot of sense in that application. Reuse of existing resources and very high energy costs and available specialized labor.
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