11 ms·

Can Desalination Counter the Drought?

51 points by cwal37 11y ago

sageabilly 11y ago
Drought caused by global warming countered by using desalinated water which is produced using energy from fossil fuels which contributes to more global warming. Although in CA looks like the majority of their electricity comes from natural gas and renewable resources[1] which is a start, I suppose. [1]http://energyalmanac.ca.gov/electricity/total_system_power.html http://energyalmanac.ca.gov/electricity/total_system_power.h...
- logfromblammo 11y ago
  I have wondered for a long time whether pairing a desalinator with a generation III+ or later fission reactor could be made more efficient than having both built separately and linked via transmission lines. It seems like there ought to be some opportunity for synergy there, but there are now so many reactor designs that include light water that I have no idea how that might work for any of them.
  - ivankirigin 11y ago
    This is an already popular idea called cogeneration https://en.wikipedia.org/wiki/Desalination#Cogeneration https://en.wikipedia.org/wiki/Desalination#Cogeneration
  - mrfusion 11y ago
    And potentially the same plumbing for incoming water could be used to cool the reactor. In fact now that I think about it, all of the waste heat of the reactor could go toward evaporating the water.
    - sliverstorm 11y ago
      Waste heat? Evaporating the water? Nuclear power plants are steam engines. All their heat goes to evaporating water. Come to think of it, I wonder if you could harvest the steam from a nuclear plant, run it through a condenser or distiller, and in that way produce electricity and purify water at the same time.
      - cpeterso 11y ago
        Harvesting the steam is a clever idea, but I don't know if the average consumer is ready for what would be spun as "radioactive Franken-water".
      - logfromblammo 11y ago
        Not all fission reactors use the same cycles to turn heat from the nuclear reaction into usable power. Most existing reactors in the US use the reactor core as the heat source, a convection cooling tower as the heat sink, and water/steam as the working fluid. Using salt water as the working fluid in a BWR or SCWR would probably be dangerous, as it circulates around the reactor core. In a PWR, the working fluid and the fluid circulating past the reactor core are separated via heat exchangers in the steam generator, so that's probably the only widely used reactor type that could do distillation-based desalination without heavy modification. But probably the most useful way to go about doing it is to keep the rest of the reactor as it is, and just attach the reverse osmosis desalinator pumps to the same driveshaft as the electricity generator. Even though boiling and condensing water is an integral part of steam engine operation, it really works best when that water has been completely demineralized already. Otherwise, your boiler fills with salt sludge, and your condenser gets clogged with mineral scale. You're saving efficiency by taking out the two conversions between electrical and mechanical work and the transmission loss between generator and pump motor. The purified water and waste brine could also carry heat away from the steam engine's heat sink if it can go out hotter than the ocean water that comes in. I'm thinking that you'd heat the waste brine as hot as possible before dumping it in a solar evaporation pond. The infrastructure required to pump pre-heated water to the nearest community along with cold is probably not going to pay off unless you're supplying high-rises or a university campus.
- hukep 11y ago
  It is a difficult task. SA needs plenty of water for the nearest decades. What are the options to get it? How much will it cost? Many difficult questions to answer. Many approaches to choose. If the ideal is to built a great dam, then everything else burden the environment more. Creating of the desalvation factory take a lot of earth resources as well as the energy which also comes mostly out of non-renewable sources. If you produce electric energy you have a great impact on the environment too.
- mentat 11y ago
  How exactly does one draw the connection between the drought and global warming? Both are warm?
- tsotha 11y ago
  There's no actual evidence the drought has anything to do with global warming.
kondor6c 11y ago
I've thought about solar desalination a lot lately, pumps + glass + desert = water. Then you can sell the salt by product during the cold weather to the north east.
- cwal37 11y ago
  That's the sort of thing that sounds like you're closing the loop, but has some serious flaws the deeper you go. First off, where is that water coming from? You mention desert, so is it an incredibly saline salt lake or briny fossil aquifers? If you're pumping out mass quantities of fossil water, be prepared for an eventual end, and localized subsidence, depending on the depth/structure of the formation. Then there's the salt. Salt's actually kind of on the downslope in terms of its use in de-icing. You're literally salting the earth around roadways. Places that see a lot of snow and have a lot of waterways (from personal experience, like Northern Wisconsin and the UP), actually use sand instead. You expect there to be snow on the roads for a number of months regardless, so you're just offering some traction. Certain places in the Northeast are the same as far as I'm aware. Here's a resource on road salt from New Hampshire[1]. Pickle brine[2] and beet juice[3] are also beginning to get some play. Not to say the rock salt market couldn't absorb some additional supply, but I don't know where the limit is if we're talking mass desalinization. [1] http://des.nh.gov/organization/divisions/water/wmb/was/salt-reduction-initiative/impacts.htm http://des.nh.gov/organization/divisions/water/wmb/was/salt-... [2] http://news.nationalgeographic.com/news/2014/02/140204-melt-snow-ice-salt-beet-juice-pickle-brine/ http://news.nationalgeographic.com/news/2014/02/140204-melt-... [3] http://time.com/5761/salt-shortage-triggers-beet-juice-cheese-brine-alternatives/ http://time.com/5761/salt-shortage-triggers-beet-juice-chees...
  - logfromblammo 11y ago
    The Salton Sea is below ocean level. If you dug a canal out to Laguna Salada and into the Gulf of California, the ocean water would flow, by gravity, into the depression. If nothing else, you could probably truck the salt to Coyote Dry Lake and just dump it on the existing salt flats there.
    - 11y ago
scythe 11y ago
The conclusion of the debate here is boring: yes, but only by extreme effort, i.e. redirection of 1-10% of economic and energy resources towards water acquisition. We're not all gonna die, but that's as comforting as it gets. Desalination is great for supplying coastal cities, bonkers everywhere else. The economic consequence is a drastic rise in the price of conventional agricultural products (especially land meats) and a corresponding relative fall in the price of unconventional products (nuts, seeds, beans, aquaculture) which drives investment in the latter to hopefully yield a less water-hungry agricultural system... but a very different palate. The general outcome of capitalist systems are heterodox (one of capitalism's advantages); we expect to see some compensation from desalination, tertiary sewage treatment, and more water-efficient farming practices. It would be less painful if we didn't fight reality with agricultural subsidies and water grants.
alwaysdoit 11y ago
> All told, it takes about 3460 kilowatts per acre-foot to pump water from Northern California to San Diego; Carlsbad will use about thirty per cent more energy, five thousand kilowatts per acre-foot, to desalinate ocean water and deliver it to households, according to Poseidon’s report to the Department of Water Resources These units are abominations. Couldn't just say 2.8 Watts per liter vs 4.0 Watts per liter? Or even 10.6 and 15.3 Watts per gallon? I'm not a metric purist, but the only advantage to using imperial units is that they are more familiar to the average American, but when does the average person deal with acre-feet?
- msandford 11y ago
  It doesn't even make sense! The units don't match up. Kilowatts are a measure of power, energy over time, and an acre-foot is a measure of volume, not flow (volume over time). It's like saying how many horsepower it takes to drive from SF to LA. Makes no sense.
  - oaktowner 11y ago
    Yes, they must have meant kilowatt hours. Was there no editor?
    - istorical 11y ago
      Scientific mistakes in a paper like the new yorker is like poor grammar in a startup CEO's writing. It just happens.
  - benkuykendall 11y ago
    Huh. So they are really talking about a pressure. 1 kWh/(acre ft) = 2919 Pa It makes a great deal of intuitive sense that the quantity that describes how hard it is to move water over a path is a pressure.
  - seanflyon 11y ago
    It's sad that they mistook kilowatts for kilowatt-hours, but I think acre-foot is a good unit for measuring volumes of water. It helps communicate the scale of water use.
function_seven 11y ago
> All told, it takes about 3460 kilowatts per acre-foot to pump water from Northern California to San Diego; Does the author mean 3,460 kilowatt-hours? > Lambert showed me a series of pumps at the Carlsbad plant that collectively exert seven thousand horsepower of energy (eleven hundred pounds per square inch of pressure) Holy hell, how am I supposed to reason about any of these numbers? The mix of units and ignorance of power/energy differences makes the numbers completely useless to the reader. Near the beginning of the article, the daily volumes are discussed in terms of millions of gallons, but later on, acre-feet is used. Sorry if this comment is too ranty...
- mikeash 11y ago
  Not nearly ranty enough, IMO. Units are not that hard, and anyone who wants to write about this stuff for public consumption must put in the effort to get them right.
- deleted 11y ago
  [deleted]
markbnj 11y ago
> Add to that the fact that almost all of the freshwater consumed by the twenty-two million people of Southern California is imported, much of it pumped long distances, over mountains, from Northern California The author's conclusion may very well be correct for all I know, but I think it is somewhat misleading to say that the water is "pumped long distances." There are points where it is pumped, but one of the things that makes the system so fascinating from an engineering standpoint is how much of it relies on gravity, including massive siphons that literally pull the water over mountain ranges.
- function_seven 11y ago
  > including massive siphons that literally pull the water over mountain ranges. I don't think that is physically possible. Water won't siphon more than 33ish vertical feet. It will just draw a vacuum in the pipe. EDIT: Found a good link. The word "siphon" is quoted on every use in this link, suggesting that they're not actual gravity-powered siphons. See #10. http://www.kcet.org/news/redefine/revisit/commentary/concrete-and-chaparral/a-self-guided-tour-of-the-los-angeles-aqueduct.html http://www.kcet.org/news/redefine/revisit/commentary/concret... EDIT2: Ok, they are gravity-powered, but not by the "pulling" action of the water on the downslope side of the siphon, as much as by the pushing action of the previous downward slope feeding into the siphon. Technically, it's still a siphon i guess, just operating at higher than atmospheric pressure.
  - stcredzero 11y ago
    Siphons that are an inverted U have this limit. However, siphons that are a U shape have been in use in aqueducts since Roman times. (There is even an old Scientific American article specifically about them.) Of course, these aren't relevant for getting over mountains, though they are very relevant in mountain ranges for crossing gorges and steep valleys.
    - function_seven 11y ago
      Yeah, I just went on an edit frenzy after you replied. Thanks.
KaiserPro 11y ago
No. its not the answer. The answer is keeping that water where it is for longer. this means that it'll evaporate where it lays. Which means more rain. It also mean that the water table is higher for plants and animals. a brilliant example are johads: http://www.ecotippingpoints.org/our-stories/indepth/india-rajasthan-rainwater-harvest-restoration-groundwater-johad.html http://www.ecotippingpoints.org/our-stories/indepth/india-ra... cheap, easy, quick and simple.
- mindcrime 11y ago
  > this means that it'll evaporate where it lays. Which means more rain. I'm no meteorologist or anything, so I honestly don't have any idea about this, but I can't help but wonder if that matters? I mean, if there's "more rain" overall, but it all happens somewhere else, that doesn't necessarily help California. Is there any connection between where water evaporates and where it ultimately falls as rain? That is, is it actually possible to cause more rain in a certain spot, but doing what you're talking about?
  - mentat 11y ago
    There are these things called winds generated by pressure systems that tend to move evaporated water around, so yes, you are right.
- laurencerowe 11y ago
  The southwest US is naturally semi-desert, water has to be brought in or people couldn't live and grow crops here.
mindcrime 11y ago
I've often felt a twinge of guilt that I don't spend my time working on something with a more direct path to making people's lives better... by doing something like creating freshwater, for example. I sometimes wish I'd chosen to major in materials science (or whatever) and was working on, say, creating a newer better desalination technology or something. Oh well, too late to go back now, but at least it warms the heart a bit to see this happening. I've always thought desalination was an amazingly powerful technology, and I'm glad to see it getting some use on a large scale. Of course, that's not to ignore the side effects, like what to do with the leftover salt, but almost everything has some side effect.
- jtjt2323 11y ago
  If you want to make a difference one option is to consume less meat and dairy (or none). Interesting statistics on CA's water use: https://www.thedodo.com/drought-1085519358.html https://www.thedodo.com/drought-1085519358.html Basically personal use accounts for 4% of the total. Meat and dairy production takes 47% of California's water.
- ZenoArrow 11y ago
  "Oh well, too late to go back now" I understand the regret, but it's only too late when you're dead. If you want to do it you can find a way.
  - mindcrime 11y ago
    Strictly speaking, yes. On a more practical level, not really. As old as I am, if I started over now trying to learn a new field like that, I'd probably be ready to retire before I learned enough to be useful. Anyway, it's not that I dislike the path I'm on, it's just the occasional twinge of that feeling that I wish the stuff I was doing had a more direct impact on the world. OTOH, given the path I'm on, I still hope to help make the world a better place, and if we'e successful I think we'll have a chance at doing that, albeit in a different way.
    - ZenoArrow 11y ago
hinkley 11y ago
The only time these designs seem to work is when there's never any water (islands) or they have a complex cogeneration strategy. For instance, ship the brine to someone who needs chill water, and then ship the warm brine off for salt extraction (apparently it's hard to profit off of sea salt if you can't get free BTU's from somebody, like a neighbor or the sun)
vondur 11y ago
I've often wondered why solar power are not used with the desalination plants? Perhaps that would help bring the power usage down to the same level as pumping the water in from the north of the state.
- dredmorbius 11y ago
  Solar power isn't free. you've got the costs of plant capital and maintenance. That said, desalination is the type of readily added or shed load which can tolerate surplus / deficit variable energy supply.
xigency 11y ago
Considering the environmental impact of desalination and the power requirements, it doesn't seem like a proper way to end the drought. The answer is always going to be adequate planning and conservation, as well as improved infrastructure with higher-level planning. And legislators need to consider the true cost and benefit of catering to either the interests of farms and corporations or the people. Living by the great lakes, I'm sure the people of California would lay a pipe across 1700 miles of the country if they could, but irresponsible usage of water is always going to drain whatever freshwater source is available. I do hope projects like these can help in some small way, though. This also isn't the first time there has been a drought in any part of this country, obviously, and looking at weather in Texas recently, for example, you can see how quickly rain will come and go. There are large numbers of people in California. I'm sure that some of them must be smart enough to figure this out. Otherwise, we're looking at the beginning of another dustbowl. The future of climate change is only going to make these problems more severe, and this obviously isn't a conservative solution going forward. It's also interesting that the Santa Barbara desalination plant is mentioned. I lived in Santa Barabara recently (12 months ago) and I was unaware that there was a desalination plant there at the time during the drought. Recently I had heard that it was going to start up again, after never having ran more than 1 month in its lifespan. I would be surprised that that project is still behind its timeline, but then again, I wouldn't really be surprised. (Edit: After 1 year, the city council voted to restart the plant last Tuesday.)
- cwp 11y ago
  Considering the environmental impact of diverting whole watersheds to Southern California and the the power requirements of pumping it over mountain ranges, this seems like a great way to end the drought. The only reason it hasn't been done before is that SoCal has successfully externalized the cost of water. So, yes, it costs more to the residents of San Diego, but it's not a bad option when you consider all the people and wildlife that could be using the Colorado river. And by the way, the "irresponsible usage of water" by the people of California is largely growing food for the rest of the continent. You may live near the great lakes, but you undoubtedly consume water from California. It's just packaged inside fruit and vegetables.
lucaspiller 11y ago
I've posted about this before, but the UAE has an interesting solution to water and electricity generation. One of the by products of oil production is natural gas that accumulates as pockets in the wells. Compared to crude oil this is a lot harder to store and transport, so in most cases is just burned off (if you ever fly over The Gulf at night, you can see the flames from the wells doing this). This by product is what is used to generate water and electricity. Sea water is heated with the natural gas, and turned into steam which runs turbines to generate electricity. The steam is then cooled, which provides desalinated water. The water is stored in tanks for a few days where limestone rocks are added (from other parts of the country) to provide minerals, then fed into the public water system. The newest "M" plant produces 2,000 MW of electricity and 140 million gallons of water a day, with an overall efficiency of 85%. It cost around $3 billion to build. http://www.power-technology.com/projects/jebel-ali-m-station/ http://www.power-technology.com/projects/jebel-ali-m-station...
- tertius 11y ago
  How much natural gas does this cost?
  - deegles 11y ago
    Presumably very little since the natural gas is a by-product of oil drilling.
    - tertius 11y ago
      I was asking how much natural gas, not how much money. And I'm assuming it's not very little since the energy required to desalinate is the #1 cost.

51 points by cwal37 11y ago

Drought caused by global warming countered by using desalinated water which is produced using energy from fossil fuels which contributes to more global warming. Although in CA looks like the majority of their electricity comes from natural gas and renewable resources[1] which is a start, I suppose. [1]http://energyalmanac.ca.gov/electricity/total_system_power.html http://energyalmanac.ca.gov/electricity/total_system_power.h...

logfromblammo 11y ago
I have wondered for a long time whether pairing a desalinator with a generation III+ or later fission reactor could be made more efficient than having both built separately and linked via transmission lines. It seems like there ought to be some opportunity for synergy there, but there are now so many reactor designs that include light water that I have no idea how that might work for any of them.
- ivankirigin 11y ago
  This is an already popular idea called cogeneration https://en.wikipedia.org/wiki/Desalination#Cogeneration https://en.wikipedia.org/wiki/Desalination#Cogeneration
- mrfusion 11y ago
  And potentially the same plumbing for incoming water could be used to cool the reactor. In fact now that I think about it, all of the waste heat of the reactor could go toward evaporating the water.
  - sliverstorm 11y ago
    Waste heat? Evaporating the water? Nuclear power plants are steam engines. All their heat goes to evaporating water. Come to think of it, I wonder if you could harvest the steam from a nuclear plant, run it through a condenser or distiller, and in that way produce electricity and purify water at the same time.
    - cpeterso 11y ago
      Harvesting the steam is a clever idea, but I don't know if the average consumer is ready for what would be spun as "radioactive Franken-water".
    - logfromblammo 11y ago
      Not all fission reactors use the same cycles to turn heat from the nuclear reaction into usable power. Most existing reactors in the US use the reactor core as the heat source, a convection cooling tower as the heat sink, and water/steam as the working fluid. Using salt water as the working fluid in a BWR or SCWR would probably be dangerous, as it circulates around the reactor core. In a PWR, the working fluid and the fluid circulating past the reactor core are separated via heat exchangers in the steam generator, so that's probably the only widely used reactor type that could do distillation-based desalination without heavy modification. But probably the most useful way to go about doing it is to keep the rest of the reactor as it is, and just attach the reverse osmosis desalinator pumps to the same driveshaft as the electricity generator. Even though boiling and condensing water is an integral part of steam engine operation, it really works best when that water has been completely demineralized already. Otherwise, your boiler fills with salt sludge, and your condenser gets clogged with mineral scale. You're saving efficiency by taking out the two conversions between electrical and mechanical work and the transmission loss between generator and pump motor. The purified water and waste brine could also carry heat away from the steam engine's heat sink if it can go out hotter than the ocean water that comes in. I'm thinking that you'd heat the waste brine as hot as possible before dumping it in a solar evaporation pond. The infrastructure required to pump pre-heated water to the nearest community along with cold is probably not going to pay off unless you're supplying high-rises or a university campus.
hukep 11y ago
It is a difficult task. SA needs plenty of water for the nearest decades. What are the options to get it? How much will it cost? Many difficult questions to answer. Many approaches to choose. If the ideal is to built a great dam, then everything else burden the environment more. Creating of the desalvation factory take a lot of earth resources as well as the energy which also comes mostly out of non-renewable sources. If you produce electric energy you have a great impact on the environment too.
mentat 11y ago
How exactly does one draw the connection between the drought and global warming? Both are warm?
tsotha 11y ago
There's no actual evidence the drought has anything to do with global warming.

kondor6c 11y ago

I've thought about solar desalination a lot lately, pumps + glass + desert = water. Then you can sell the salt by product during the cold weather to the north east.

cwal37 11y ago
That's the sort of thing that sounds like you're closing the loop, but has some serious flaws the deeper you go. First off, where is that water coming from? You mention desert, so is it an incredibly saline salt lake or briny fossil aquifers? If you're pumping out mass quantities of fossil water, be prepared for an eventual end, and localized subsidence, depending on the depth/structure of the formation. Then there's the salt. Salt's actually kind of on the downslope in terms of its use in de-icing. You're literally salting the earth around roadways. Places that see a lot of snow and have a lot of waterways (from personal experience, like Northern Wisconsin and the UP), actually use sand instead. You expect there to be snow on the roads for a number of months regardless, so you're just offering some traction. Certain places in the Northeast are the same as far as I'm aware. Here's a resource on road salt from New Hampshire[1]. Pickle brine[2] and beet juice[3] are also beginning to get some play. Not to say the rock salt market couldn't absorb some additional supply, but I don't know where the limit is if we're talking mass desalinization. [1] http://des.nh.gov/organization/divisions/water/wmb/was/salt-reduction-initiative/impacts.htm http://des.nh.gov/organization/divisions/water/wmb/was/salt-... [2] http://news.nationalgeographic.com/news/2014/02/140204-melt-snow-ice-salt-beet-juice-pickle-brine/ http://news.nationalgeographic.com/news/2014/02/140204-melt-... [3] http://time.com/5761/salt-shortage-triggers-beet-juice-cheese-brine-alternatives/ http://time.com/5761/salt-shortage-triggers-beet-juice-chees...
- logfromblammo 11y ago
  The Salton Sea is below ocean level. If you dug a canal out to Laguna Salada and into the Gulf of California, the ocean water would flow, by gravity, into the depression. If nothing else, you could probably truck the salt to Coyote Dry Lake and just dump it on the existing salt flats there.
  - 11y ago

scythe 11y ago

The conclusion of the debate here is boring: yes, but only by extreme effort, i.e. redirection of 1-10% of economic and energy resources towards water acquisition. We're not all gonna die, but that's as comforting as it gets. Desalination is great for supplying coastal cities, bonkers everywhere else. The economic consequence is a drastic rise in the price of conventional agricultural products (especially land meats) and a corresponding relative fall in the price of unconventional products (nuts, seeds, beans, aquaculture) which drives investment in the latter to hopefully yield a less water-hungry agricultural system... but a very different palate. The general outcome of capitalist systems are heterodox (one of capitalism's advantages); we expect to see some compensation from desalination, tertiary sewage treatment, and more water-efficient farming practices. It would be less painful if we didn't fight reality with agricultural subsidies and water grants.

alwaysdoit 11y ago

> All told, it takes about 3460 kilowatts per acre-foot to pump water from Northern California to San Diego; Carlsbad will use about thirty per cent more energy, five thousand kilowatts per acre-foot, to desalinate ocean water and deliver it to households, according to Poseidon’s report to the Department of Water Resources These units are abominations. Couldn't just say 2.8 Watts per liter vs 4.0 Watts per liter? Or even 10.6 and 15.3 Watts per gallon? I'm not a metric purist, but the only advantage to using imperial units is that they are more familiar to the average American, but when does the average person deal with acre-feet?

msandford 11y ago
It doesn't even make sense! The units don't match up. Kilowatts are a measure of power, energy over time, and an acre-foot is a measure of volume, not flow (volume over time). It's like saying how many horsepower it takes to drive from SF to LA. Makes no sense.
- oaktowner 11y ago
  Yes, they must have meant kilowatt hours. Was there no editor?
  - istorical 11y ago
    Scientific mistakes in a paper like the new yorker is like poor grammar in a startup CEO's writing. It just happens.
- benkuykendall 11y ago
  Huh. So they are really talking about a pressure. 1 kWh/(acre ft) = 2919 Pa It makes a great deal of intuitive sense that the quantity that describes how hard it is to move water over a path is a pressure.
- seanflyon 11y ago
  It's sad that they mistook kilowatts for kilowatt-hours, but I think acre-foot is a good unit for measuring volumes of water. It helps communicate the scale of water use.

function_seven 11y ago

> All told, it takes about 3460 kilowatts per acre-foot to pump water from Northern California to San Diego; Does the author mean 3,460 kilowatt-hours? > Lambert showed me a series of pumps at the Carlsbad plant that collectively exert seven thousand horsepower of energy (eleven hundred pounds per square inch of pressure) Holy hell, how am I supposed to reason about any of these numbers? The mix of units and ignorance of power/energy differences makes the numbers completely useless to the reader. Near the beginning of the article, the daily volumes are discussed in terms of millions of gallons, but later on, acre-feet is used. Sorry if this comment is too ranty...

mikeash 11y ago
Not nearly ranty enough, IMO. Units are not that hard, and anyone who wants to write about this stuff for public consumption must put in the effort to get them right.
deleted 11y ago
[deleted]

markbnj 11y ago

> Add to that the fact that almost all of the freshwater consumed by the twenty-two million people of Southern California is imported, much of it pumped long distances, over mountains, from Northern California The author's conclusion may very well be correct for all I know, but I think it is somewhat misleading to say that the water is "pumped long distances." There are points where it is pumped, but one of the things that makes the system so fascinating from an engineering standpoint is how much of it relies on gravity, including massive siphons that literally pull the water over mountain ranges.

function_seven 11y ago
> including massive siphons that literally pull the water over mountain ranges. I don't think that is physically possible. Water won't siphon more than 33ish vertical feet. It will just draw a vacuum in the pipe. EDIT: Found a good link. The word "siphon" is quoted on every use in this link, suggesting that they're not actual gravity-powered siphons. See #10. http://www.kcet.org/news/redefine/revisit/commentary/concrete-and-chaparral/a-self-guided-tour-of-the-los-angeles-aqueduct.html http://www.kcet.org/news/redefine/revisit/commentary/concret... EDIT2: Ok, they are gravity-powered, but not by the "pulling" action of the water on the downslope side of the siphon, as much as by the pushing action of the previous downward slope feeding into the siphon. Technically, it's still a siphon i guess, just operating at higher than atmospheric pressure.
- stcredzero 11y ago
  Siphons that are an inverted U have this limit. However, siphons that are a U shape have been in use in aqueducts since Roman times. (There is even an old Scientific American article specifically about them.) Of course, these aren't relevant for getting over mountains, though they are very relevant in mountain ranges for crossing gorges and steep valleys.
  - function_seven 11y ago
    Yeah, I just went on an edit frenzy after you replied. Thanks.

KaiserPro 11y ago

No. its not the answer. The answer is keeping that water where it is for longer. this means that it'll evaporate where it lays. Which means more rain. It also mean that the water table is higher for plants and animals. a brilliant example are johads: http://www.ecotippingpoints.org/our-stories/indepth/india-rajasthan-rainwater-harvest-restoration-groundwater-johad.html http://www.ecotippingpoints.org/our-stories/indepth/india-ra... cheap, easy, quick and simple.

mindcrime 11y ago
> this means that it'll evaporate where it lays. Which means more rain. I'm no meteorologist or anything, so I honestly don't have any idea about this, but I can't help but wonder if that matters? I mean, if there's "more rain" overall, but it all happens somewhere else, that doesn't necessarily help California. Is there any connection between where water evaporates and where it ultimately falls as rain? That is, is it actually possible to cause more rain in a certain spot, but doing what you're talking about?
- mentat 11y ago
  There are these things called winds generated by pressure systems that tend to move evaporated water around, so yes, you are right.
laurencerowe 11y ago
The southwest US is naturally semi-desert, water has to be brought in or people couldn't live and grow crops here.

mindcrime 11y ago

I've often felt a twinge of guilt that I don't spend my time working on something with a more direct path to making people's lives better... by doing something like creating freshwater, for example. I sometimes wish I'd chosen to major in materials science (or whatever) and was working on, say, creating a newer better desalination technology or something. Oh well, too late to go back now, but at least it warms the heart a bit to see this happening. I've always thought desalination was an amazingly powerful technology, and I'm glad to see it getting some use on a large scale. Of course, that's not to ignore the side effects, like what to do with the leftover salt, but almost everything has some side effect.

jtjt2323 11y ago
If you want to make a difference one option is to consume less meat and dairy (or none). Interesting statistics on CA's water use: https://www.thedodo.com/drought-1085519358.html https://www.thedodo.com/drought-1085519358.html Basically personal use accounts for 4% of the total. Meat and dairy production takes 47% of California's water.
ZenoArrow 11y ago
"Oh well, too late to go back now" I understand the regret, but it's only too late when you're dead. If you want to do it you can find a way.
- mindcrime 11y ago
  Strictly speaking, yes. On a more practical level, not really. As old as I am, if I started over now trying to learn a new field like that, I'd probably be ready to retire before I learned enough to be useful. Anyway, it's not that I dislike the path I'm on, it's just the occasional twinge of that feeling that I wish the stuff I was doing had a more direct impact on the world. OTOH, given the path I'm on, I still hope to help make the world a better place, and if we'e successful I think we'll have a chance at doing that, albeit in a different way.
  - ZenoArrow 11y ago

hinkley 11y ago

The only time these designs seem to work is when there's never any water (islands) or they have a complex cogeneration strategy. For instance, ship the brine to someone who needs chill water, and then ship the warm brine off for salt extraction (apparently it's hard to profit off of sea salt if you can't get free BTU's from somebody, like a neighbor or the sun)

vondur 11y ago

I've often wondered why solar power are not used with the desalination plants? Perhaps that would help bring the power usage down to the same level as pumping the water in from the north of the state.

dredmorbius 11y ago
Solar power isn't free. you've got the costs of plant capital and maintenance. That said, desalination is the type of readily added or shed load which can tolerate surplus / deficit variable energy supply.

xigency 11y ago

Considering the environmental impact of desalination and the power requirements, it doesn't seem like a proper way to end the drought. The answer is always going to be adequate planning and conservation, as well as improved infrastructure with higher-level planning. And legislators need to consider the true cost and benefit of catering to either the interests of farms and corporations or the people. Living by the great lakes, I'm sure the people of California would lay a pipe across 1700 miles of the country if they could, but irresponsible usage of water is always going to drain whatever freshwater source is available. I do hope projects like these can help in some small way, though. This also isn't the first time there has been a drought in any part of this country, obviously, and looking at weather in Texas recently, for example, you can see how quickly rain will come and go. There are large numbers of people in California. I'm sure that some of them must be smart enough to figure this out. Otherwise, we're looking at the beginning of another dustbowl. The future of climate change is only going to make these problems more severe, and this obviously isn't a conservative solution going forward. It's also interesting that the Santa Barbara desalination plant is mentioned. I lived in Santa Barabara recently (12 months ago) and I was unaware that there was a desalination plant there at the time during the drought. Recently I had heard that it was going to start up again, after never having ran more than 1 month in its lifespan. I would be surprised that that project is still behind its timeline, but then again, I wouldn't really be surprised. (Edit: After 1 year, the city council voted to restart the plant last Tuesday.)

cwp 11y ago
Considering the environmental impact of diverting whole watersheds to Southern California and the the power requirements of pumping it over mountain ranges, this seems like a great way to end the drought. The only reason it hasn't been done before is that SoCal has successfully externalized the cost of water. So, yes, it costs more to the residents of San Diego, but it's not a bad option when you consider all the people and wildlife that could be using the Colorado river. And by the way, the "irresponsible usage of water" by the people of California is largely growing food for the rest of the continent. You may live near the great lakes, but you undoubtedly consume water from California. It's just packaged inside fruit and vegetables.

lucaspiller 11y ago

I've posted about this before, but the UAE has an interesting solution to water and electricity generation. One of the by products of oil production is natural gas that accumulates as pockets in the wells. Compared to crude oil this is a lot harder to store and transport, so in most cases is just burned off (if you ever fly over The Gulf at night, you can see the flames from the wells doing this). This by product is what is used to generate water and electricity. Sea water is heated with the natural gas, and turned into steam which runs turbines to generate electricity. The steam is then cooled, which provides desalinated water. The water is stored in tanks for a few days where limestone rocks are added (from other parts of the country) to provide minerals, then fed into the public water system. The newest "M" plant produces 2,000 MW of electricity and 140 million gallons of water a day, with an overall efficiency of 85%. It cost around $3 billion to build. http://www.power-technology.com/projects/jebel-ali-m-station/ http://www.power-technology.com/projects/jebel-ali-m-station...

tertius 11y ago
How much natural gas does this cost?
- deegles 11y ago
  Presumably very little since the natural gas is a by-product of oil drilling.
  - tertius 11y ago
    I was asking how much natural gas, not how much money. And I'm assuming it's not very little since the energy required to desalinate is the #1 cost.