5 ms·

Feels like cheap desalination breakthrough every year. I know some middle east petro-states are building out the infrastructure, but it doesn't seem like there'

Feels like cheap desalination breakthrough every year. I know some middle east petro-states are building out the infrastructure, but it doesn't seem like there's broad adoption. Is it because cheap is still not cheap enough? Granted I don't follow developments closely. I just want better non flush/composting toilets.

oxfordmale 6y ago
I had an uncle who worked in the Middle East. One of the major problems with desalination plants is corrosion of all the pipe work, due to the high salt content. Better membranes will make a difference, but will not solve the corrosion issue that reduces the life time of a desalination plant.
- achow 6y ago
  Aren't plastics or polymer inert to salt water?
  - InvaderFizz 6y ago
    Yes, but I would guess that at the volumes these pipes will be pushing, the abrasive qualities of a high salt concentrate makes such soft piping material susceptible to being eaten through rather quickly.
    - ianai 6y ago
      So use lower volume across more pipes in parallel? Seems like something to engineer around.
    - sudosysgen 6y ago
      Seems like something where ceramic-like coatings would help.
- CyberDildonics 6y ago
  What about cross linked polyethylene (PEX) ? Why use metal pipes at all?
  - LinuxBender 6y ago
    Just guessing, but probably pressure? PEX has much lower pressure ratings than metal. I plan to use PEX for a water purification system, but it will be sub 100 PSI. Most PEX-A are rated to 200 PSI at room temp and 120-150 PSI at 180 degrees F. They will rupture at 400 to 800 PSI of water depending on the brand. Metal pipes can handle thousands of PSI, required for pushing water through membranes.
    - CyberDildonics 6y ago
      If that is the case it still seems like you would just need metal for a section that reduces the size of the pipe down to something smaller to give you the pressure. A larger diameter pex should be able carry the water around with a reducer only where the pressure is needed.
      - rhodozelia 6y ago
        Is Pex used in industry? I’ve only seen it in newish residential construction. Is there such a thing as a 6” diameter pex pipe? And fittings? 12”? 24”? Where corrosion is a problem i’ve Seen metal pipes coated with epoxies. I’ve seen big HDPE pipe used for low pressure sections to save cost over metal.
        CyberDildonics 6y ago
        What do you mean by 'in industry'. In what industry? I don't know about anything larger than 3", but the general point was more than it doesn't seem right that corrosion of metal pipes would be a huge barrier to desalination since there are options for non metal pipes. There is also PVC which can be huge in diameter and CPVC which is used in some situations that need pipe that is more inert, but it is very brittle.
chrisco255 6y ago
Israel has led the way here: https://www.scientificamerican.com/article/israel-proves-the-desalination-era-is-here/ https://www.scientificamerican.com/article/israel-proves-the... They've had efficient desalination tech for several years now deployed in the country. My understanding is they use lava stone to make the membranes more efficient. 55 percent of their fresh water now comes from desalinated salt water.
manfredo 6y ago
Human civilizations have built population centers close to sources for fresh water for millennia. Cities like Los Angeles that require moving vast amounts of fresh water long distances to be viable are a recent phenomenon - appearing only in the last century or so. So a big reason for the lack of desalination is a lack of demand. Yes, some places are experiencing a lack of water but those are the exception to the norm. And even if a population center does need more fresh water, desalination is competing against traditional options: digging wells, building aqueducts, and expanding reservoirs. And have lots of experience - again, literally millennia of experience - implementing these pieces of infrastructure. So in summary, desalination isn't seeing widespread adoption because it's not necessary for most places and we have much more experience with the alternatives. That said, it's great we're still improving desalination and it puts the world in a better place if water scarcity gets to the point that traditional water infrastructure is not sufficient.
- jcranmer 6y ago
  > Cities like Los Angeles that require moving vast amounts of fresh water long distances to be viable are a recent phenomenon - appearing only in the last century or so. That's not exactly true. The Hohokam started building canals in the Sonoran Desert maybe 1500 years ago (some of which form the basis for the modern water supply system of Phoenix!). Somewhat earlier than the Hohokam, the Romans were infamous for their aqueducts, the longest of which stretched over 250 miles. That's longer than the aqueducts that supply New York City or even Los Angeles!
  - manfredo 6y ago
    The California aqueduct system has a total length of 444 miles and the main branch is 300 miles [1]. More important is the demographic impact of water management: Rome's largest population center was ~1 million people, the Hohokam ~80,000 as compared to the Los Angeles metro's 18 million. Preindustrial populations had very little capacity to built large infrastructure projects like these. Huge population centers consuming substantially more water than is brought to them naturally is a very recent phenomenon, Roman aqueducts and Hohokam irrigation notwithstanding. In most years Los Angeles imports 80-90% of its water. Situations like these are not possible without industrialized water infrastructure. Los Angeles used to be primarily supplied by the Los Angeles river and its population was correspondingly lower. Human need water daily to survive, and without pumped plumbing building a population center that isn't near a lake, river, or with access to groundwater is effectively impossible. The Hohokam were no exception. Their aqueduct system did not exist to deliver water to the city center, but to their agricultural settlements. Their main population center was along the Gila river. Preindustrial irrigation systems are impressive when considering they were built without machines, and moreso in hostile terrain like the Sonoran desert or Afghanistan [2] - but it pales in comparison to the demographic impact of water management systems built over the last century. 1. https://en.wikipedia.org/wiki/California_Aqueduct https://en.wikipedia.org/wiki/California_Aqueduct 2. https://en.wikipedia.org/wiki/Qanat https://en.wikipedia.org/wiki/Qanat
golemiprague 6y ago
There is broad adoption in places where you don't have other alternatives. It is unlikely that manufacturing water will be cheaper than just collecting it if there is enough sweet water in the area. The thing is, many places in the world just don't have the water so they use desalination whether it is cheap or not.
pjc50 6y ago
There's a physical minimum energy required, but I don't know close things are to this limit.
- Gibbon1 6y ago
  Found this. http://www.desware.net/Energy-Requirements-Desalination-Processes.aspx http://www.desware.net/Energy-Requirements-Desalination-Proc... Seems like reverse osmosis takes 3.5-5.5 kwh/m3. Vs 0.86 theoretical. So 15 to 25% of theoretical efficiency.
ghshephard 6y ago
Desalination has been inexpensive for 10+ years - ~$0.45/1000 liters (m^3) if you are willing to enter a long term (10+ year) contract. Down in Cabo, Hotels build their own desalination plants. The reason why you don't see broad adoption is that the competition is free, and often comes with gravity assist. The challenge with desalination isn't so much the cost of the product, but (A) its competition and (B) The ocean (almost) always has to be pumped up to get to its destination, which can be expensive (C) Pollution - you end up with a lot of byproducts that you need to dilute out into the ocean (and you still end up with pretty devastated areas of the ocean floor where it goes out). Cutting the price of desalination only helps with (A) - Even if desalination were completely free, you would still need to deal with geographic/pumping issues and the pollution.
EricE 6y ago
It's not just used in the middle east. https://en.wikipedia.org/wiki/Claude_%22Bud%22_Lewis_Carlsbad_Desalination_Plant https://en.wikipedia.org/wiki/Claude_%22Bud%22_Lewis_Carlsba... Finally you could build them and then just not run them: https://azcapitoltimes.com/news/2018/05/04/yuma-desalination-plant-unused-could-cost-millions-to-update/ https://azcapitoltimes.com/news/2018/05/04/yuma-desalination...

oxfordmale 6y ago

I had an uncle who worked in the Middle East. One of the major problems with desalination plants is corrosion of all the pipe work, due to the high salt content. Better membranes will make a difference, but will not solve the corrosion issue that reduces the life time of a desalination plant.

achow 6y ago
Aren't plastics or polymer inert to salt water?
- InvaderFizz 6y ago
  Yes, but I would guess that at the volumes these pipes will be pushing, the abrasive qualities of a high salt concentrate makes such soft piping material susceptible to being eaten through rather quickly.
  - ianai 6y ago
    So use lower volume across more pipes in parallel? Seems like something to engineer around.
  - sudosysgen 6y ago
    Seems like something where ceramic-like coatings would help.
CyberDildonics 6y ago
What about cross linked polyethylene (PEX) ? Why use metal pipes at all?
- LinuxBender 6y ago
  Just guessing, but probably pressure? PEX has much lower pressure ratings than metal. I plan to use PEX for a water purification system, but it will be sub 100 PSI. Most PEX-A are rated to 200 PSI at room temp and 120-150 PSI at 180 degrees F. They will rupture at 400 to 800 PSI of water depending on the brand. Metal pipes can handle thousands of PSI, required for pushing water through membranes.
  - CyberDildonics 6y ago
    If that is the case it still seems like you would just need metal for a section that reduces the size of the pipe down to something smaller to give you the pressure. A larger diameter pex should be able carry the water around with a reducer only where the pressure is needed.
    - rhodozelia 6y ago
      Is Pex used in industry? I’ve only seen it in newish residential construction. Is there such a thing as a 6” diameter pex pipe? And fittings? 12”? 24”? Where corrosion is a problem i’ve Seen metal pipes coated with epoxies. I’ve seen big HDPE pipe used for low pressure sections to save cost over metal.
      - CyberDildonics 6y ago
        What do you mean by 'in industry'. In what industry? I don't know about anything larger than 3", but the general point was more than it doesn't seem right that corrosion of metal pipes would be a huge barrier to desalination since there are options for non metal pipes. There is also PVC which can be huge in diameter and CPVC which is used in some situations that need pipe that is more inert, but it is very brittle.

chrisco255 6y ago

Israel has led the way here: https://www.scientificamerican.com/article/israel-proves-the-desalination-era-is-here/ https://www.scientificamerican.com/article/israel-proves-the... They've had efficient desalination tech for several years now deployed in the country. My understanding is they use lava stone to make the membranes more efficient. 55 percent of their fresh water now comes from desalinated salt water.

manfredo 6y ago

Human civilizations have built population centers close to sources for fresh water for millennia. Cities like Los Angeles that require moving vast amounts of fresh water long distances to be viable are a recent phenomenon - appearing only in the last century or so. So a big reason for the lack of desalination is a lack of demand. Yes, some places are experiencing a lack of water but those are the exception to the norm. And even if a population center does need more fresh water, desalination is competing against traditional options: digging wells, building aqueducts, and expanding reservoirs. And have lots of experience - again, literally millennia of experience - implementing these pieces of infrastructure. So in summary, desalination isn't seeing widespread adoption because it's not necessary for most places and we have much more experience with the alternatives. That said, it's great we're still improving desalination and it puts the world in a better place if water scarcity gets to the point that traditional water infrastructure is not sufficient.

jcranmer 6y ago
> Cities like Los Angeles that require moving vast amounts of fresh water long distances to be viable are a recent phenomenon - appearing only in the last century or so. That's not exactly true. The Hohokam started building canals in the Sonoran Desert maybe 1500 years ago (some of which form the basis for the modern water supply system of Phoenix!). Somewhat earlier than the Hohokam, the Romans were infamous for their aqueducts, the longest of which stretched over 250 miles. That's longer than the aqueducts that supply New York City or even Los Angeles!
- manfredo 6y ago
  The California aqueduct system has a total length of 444 miles and the main branch is 300 miles [1]. More important is the demographic impact of water management: Rome's largest population center was ~1 million people, the Hohokam ~80,000 as compared to the Los Angeles metro's 18 million. Preindustrial populations had very little capacity to built large infrastructure projects like these. Huge population centers consuming substantially more water than is brought to them naturally is a very recent phenomenon, Roman aqueducts and Hohokam irrigation notwithstanding. In most years Los Angeles imports 80-90% of its water. Situations like these are not possible without industrialized water infrastructure. Los Angeles used to be primarily supplied by the Los Angeles river and its population was correspondingly lower. Human need water daily to survive, and without pumped plumbing building a population center that isn't near a lake, river, or with access to groundwater is effectively impossible. The Hohokam were no exception. Their aqueduct system did not exist to deliver water to the city center, but to their agricultural settlements. Their main population center was along the Gila river. Preindustrial irrigation systems are impressive when considering they were built without machines, and moreso in hostile terrain like the Sonoran desert or Afghanistan [2] - but it pales in comparison to the demographic impact of water management systems built over the last century. 1. https://en.wikipedia.org/wiki/California_Aqueduct https://en.wikipedia.org/wiki/California_Aqueduct 2. https://en.wikipedia.org/wiki/Qanat https://en.wikipedia.org/wiki/Qanat

golemiprague 6y ago

There is broad adoption in places where you don't have other alternatives. It is unlikely that manufacturing water will be cheaper than just collecting it if there is enough sweet water in the area. The thing is, many places in the world just don't have the water so they use desalination whether it is cheap or not.

pjc50 6y ago

There's a physical minimum energy required, but I don't know close things are to this limit.

Gibbon1 6y ago
Found this. http://www.desware.net/Energy-Requirements-Desalination-Processes.aspx http://www.desware.net/Energy-Requirements-Desalination-Proc... Seems like reverse osmosis takes 3.5-5.5 kwh/m3. Vs 0.86 theoretical. So 15 to 25% of theoretical efficiency.

ghshephard 6y ago

Desalination has been inexpensive for 10+ years - ~$0.45/1000 liters (m^3) if you are willing to enter a long term (10+ year) contract. Down in Cabo, Hotels build their own desalination plants. The reason why you don't see broad adoption is that the competition is free, and often comes with gravity assist. The challenge with desalination isn't so much the cost of the product, but (A) its competition and (B) The ocean (almost) always has to be pumped up to get to its destination, which can be expensive (C) Pollution - you end up with a lot of byproducts that you need to dilute out into the ocean (and you still end up with pretty devastated areas of the ocean floor where it goes out). Cutting the price of desalination only helps with (A) - Even if desalination were completely free, you would still need to deal with geographic/pumping issues and the pollution.

EricE 6y ago

It's not just used in the middle east. https://en.wikipedia.org/wiki/Claude_%22Bud%22_Lewis_Carlsbad_Desalination_Plant https://en.wikipedia.org/wiki/Claude_%22Bud%22_Lewis_Carlsba... Finally you could build them and then just not run them: https://azcapitoltimes.com/news/2018/05/04/yuma-desalination-plant-unused-could-cost-millions-to-update/ https://azcapitoltimes.com/news/2018/05/04/yuma-desalination...