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Sun-Powered Desalination


Airbrush
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Posted (edited)

Is this a possible source of fresh water?  In theory this is the way it works.

There is a steady migration of unskilled labor thru the US southern border.  Let's put them to work.  That is the region where this idea can work.  You need coastal deserts and lots of unskilled labor.  There are coastal deserts on the Pacific side and the Gulf side of the US border, both in the USA and in Mexico.  The idea is to build hundreds, then thousands, of shallow concrete ponds.  The ponds are covered with glass made from abundant desert sand. Huge pipes deliver seawater from the Pacific and Gulf of Mexico into these coastal desert concrete ponds.  Unskilled laborers mix and pour concrete slabs and manufacture glass.  Inside the covered ponds the temperature gets very hot in the desert sun.  That rapidly evaporates seawater.  The condensation collects inside glass covers and flows by gravity to a central collector. 

After most of the seawater is converted into freshwater, the remaining brine in each pond is pumped out to a dumping area in the desert wastelands to create salt flats.  Some of that salt and minerals can also be used later. 

 

Edited by Airbrush
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Posted (edited)
19 hours ago, zapatos said:

I'm not sure about the part where we Mexica immigrants slaves, but it's an interesting idea.

There is no mention of slavery.  People are migrating north, searching for employment.  Here is a good job that pays better than expected.  First you need to build a small conventional water-desalination plant to supply water to the work force.  They pour thousands of concrete slabs, and manufacture thousands of square feet of glass.  As sections are completed, the passive, sun-powered, distillation system starts creating a freshwater oasis, that spreads outward.  Effort would be made to not ruin the desert for the scarce wildlife, there would be spaces between the ponds, for wildlife.  The oasis would cultivate it's own crops, and produce most of it's own food.  This would be small-scale terraforming.

Edited by Airbrush
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19 hours ago, Airbrush said:

deserts and lots of unskilled labor.  There are coastal deserts on the Pacific side and the Gulf side of the US border, both in the USA and in Mexico.  The idea is to build hundreds, then thousands, of shallow concrete ponds.  The ponds are covered with glass made from abundant desert sand. Huge pipes deliver seawater from the Pacific and Gulf of Mexico into these coastal desert concrete ponds.  Unskilled laborers mix and pour concrete slabs and manufacture glass.  Inside the covered ponds the temperature gets very hot in the desert sun.  That rapidly evaporates seawater.  The condensation collects inside glass covers and flows by gravity to a central collector. 

After most of the seawater is converted into freshwater, the remaining brine in each pond is pumped out to a dumping area in the desert wastelands to create salt flats.  Some of that salt and minerals can also be used later. 

 

Have you done an energy balance for the project or a cash flow plan ?

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Posted (edited)
20 hours ago, Airbrush said:

You need coastal deserts and lots of unskilled labor.  There are coastal deserts on the Pacific side and the Gulf side of the US border, both in the USA and in Mexico.  The idea is to build hundreds, then thousands, of shallow concrete ponds.  The ponds are covered with glass made from abundant desert sand. Huge pipes deliver seawater from the Pacific and Gulf of Mexico into these coastal desert concrete ponds.  Unskilled laborers mix and pour concrete slabs and manufacture glass.  Inside the covered ponds the temperature gets very hot in the desert sun.  That rapidly evaporates seawater.  The condensation collects inside glass covers and flows by gravity to a central collector. 

After most of the seawater is converted into freshwater, the remaining brine in each pond is pumped out to a dumping area in the desert wastelands to create salt flats.  Some of that salt and minerals can also be used later. 

Reality is different - skilled labor and existing technologies, construction techniques and supply streams for materials like glass already grows significant amounts of vegetable crops with desalinated water in Australia.

Sundrop Farms -

It is an example of concentrated solar thermal power being used cost effectively, providing on-site power as well as desalination. Without the climate controlled greenhouses it probably wouldn't work; the local climate would not support outdoor growing and they reduce overall water requirements. It has contracts with one of the largest (the largest?) supermarket chains in Australia. These chains are ruthless with keeping supplier costs low; if it weren't cost competitive with other growers that wouldn't happen. Even the "climate responsible" PR benefits wouldn't be enough.

"We use the sun’s energy to produce freshwater for irrigation. And we turn it into electricity to power our greenhouse to heat and cool our crops."

World's First Farm to Use Solar Power and Seawater Opens ...

 

Edited by Ken Fabian
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1 hour ago, Airbrush said:

There is no mention of slavery.  People are migrating north, searching for employment.  Here is a good job that pays better than expected. 

It was said in jest, but only partly so. Saying "...there is a steady migration. Let's put them to work..." sounds like forced labor. You've got women and children, people unskilled and illegal, with their own dreams and plans. What makes you think they want (or would be allowed) to stay in the desert, some of them in Mexico, under unknown conditions? Unless you've done some kind of manpower study of illegal immigrants and the legal ramifications, you are just daydreaming.

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PS - I do wonder if they'd have done it differently if they were planning that farm now - solar PV with battery storage instead of solar thermal and thermal storage, powering reverse osmosis rather than evaporative desalination. Most new solar desalination is PV + reverse osmosis. But unless your water needs are low or the demand is high value it won't be cost effective.

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Sydney's desalination plant is turned on — so what does that mean? - ABC  News

The Sydney Desalination Plant also known as the Kurnell Desalination Plant is a potable drinking water desalination plant that forms part of the water supply system of Greater Metropolitan Sydney. The plant is located in the Kurnell industrial estate, in Southern Sydney in the Australian state of New South Wales. The plant uses reverse osmosis filtration membranes to remove salt from seawater and is powered using renewable energy, supplied to the national power grid from the Infigen Energy–owned Capital Wind Farm located at Bungendore.

https://en.wikipedia.org/wiki/Sydney_Desalination_Plant

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53 minutes ago, Ken Fabian said:

PS - I do wonder if they'd have done it differently if they were planning that farm now - solar PV with battery storage instead of solar thermal and thermal storage, powering reverse osmosis rather than evaporative desalination. Most new solar desalination is PV + reverse osmosis. But unless your water needs are low or the demand is high value it won't be cost effective.

Where I live we get fresh water by reverse osmosis powered by wind turbines.

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