9 ms·

This drought seems pretty awful, and water resources in a lot of places in the US seem threatened by issues (either natural or man-made), which makes me wonder:

by rtpg 12y ago

This drought seems pretty awful, and water resources in a lot of places in the US seem threatened by issues (either natural or man-made), which makes me wonder: What if we were to build a bunch of desalination plants and just start pumping water into aquifers or something of the sort? Are there major issues with desalination on a large scale?

schiffern 12y ago
>What if we were to build a bunch of desalination plants and just start pumping water into aquifers or something of the sort? If you're talking about conventional fossil fuel desalination, I invite you to do the energy audit on that activity. If you're talking about solar desalination in industrially-manufactured greenhouses, I invite you to do the energy audit on that activity. Don't forget to account for the energy-opportunity cost of land use. I know there's a lot of hype surrounding desalination here, but a centralized energy-sucking plant (owned by the ultra rich naturally) is a counterproductive business-as-usual non-solution. We can get a net-positive energy audit by redesigning our agricultural and storm water management. Right now they're designed with exactly the wrong goal in mind — shunt rainwater to the ocean in big straight hardware as fast as possible. This maximizes runoff instead of infiltration, so we're simultaneously preventing aquifer recharge and necessitating aquifer pumping by drying out the soil. "Keyline" design—a method of cheaply altering landform to soak water—is probably a good start for these new infiltration maximizing strategies, but this is by no means a solved problem. In California, like any desert, the name of the game is minimizing evaporation. This means all of the above, plus shading (e.g. date palms), sunken beds, buried drip irrigation, and dew/rain harvesting strategies like land imprinting. Proper rainwater management is the lazy hacker's desalination. :D
- jaekwon 12y ago
  Yeah I was wondering if our storm-water sewage system is sucking the water out of our lands. But how much does this really matter? There would have to be some analysis of these systems vs land with no such system vs where they are to rain sources etc.
  - schiffern 12y ago
    http://www.usgs.gov/water/ http://www.usgs.gov/water/ The storm system drains all the "hardware" in an urban or suburban area — roofs, roads, parking lots, and sometimes even constantly mowed grass (which can form subterranean hardpan). Higher runoff rates lead to flow bottlenecks, flooding, and untreated sewage discharge. Still, agricultural land has more catchment.
  - mason240 12y ago
    The city live in (Maplewood MN) recently built rain gardens in our neighborhood for catching rainwater. They are basically deep pits filled in with gravel with slightly sunken garden on top. The water runoff from the street is diverted into them where most of it is absorbed into the ground. http://www.bwsr.state.mn.us/images/ww-box.jpg http://www.bwsr.state.mn.us/images/ww-box.jpg http://1.bp.blogspot.com/-31kb5tVYmJU/Ub9T22Hgy_I/AAAAAAAAAvI/_TMboIzREK0/s1600/merge1.jpg http://1.bp.blogspot.com/-31kb5tVYmJU/Ub9T22Hgy_I/AAAAAAAAAv... http://1.bp.blogspot.com/-VLZpvg9e-H8/UbY86YdLjzI/AAAAAAAAAn0/gUv7kV1HjCA/s1600/2466+East+7th+St..jpg http://1.bp.blogspot.com/-VLZpvg9e-H8/UbY86YdLjzI/AAAAAAAAAn...
- badsock 12y ago
  What do you think of Western Australia's desalination efforts? http://en.wikipedia.org/wiki/Perth_Seawater_Desalination_Plant http://en.wikipedia.org/wiki/Perth_Seawater_Desalination_Pla...
  - gilgoomesh 12y ago
    Desalination can handle drinking water but 90% of water usage is usually for irrigation. It is not cost effective to do that with desalination. As for Australia's 6 or 7 built/planned desalination plants: they are for backup and supplemental purposes only. They can't supply more than about 10% of the largest Australian cities' typical water usage. They would provide emergency water in a catastrophic drought and in low rainfall years can lessen the burden but they are not a replacement for good water catchment management.
- rtpg 12y ago
  If this can work and we can get the gov't behind this sort of solution, this seems good. Wouldn't this create a bit of water shortages downhill though? Like when you build a dam? Or is the quantity captured not on the same scale. I guess the desalination plant is something that a single rich person can do, whereas going around drilling holes all over California is a bit more complicated. Sometimes we come up with solutions that work well in Sim City, but reality proves a bit more complicated.
  - schiffern 12y ago
    >Wouldn't this create a bit of water shortages downhill though? Like when you build a dam? Great question! Dams themselves don't causes water shortages. It's the pumping of water from the dam to a separate watershed, or into highly evaporative irrigation systems (e.g. the Aral Sea and cotton). Keyline design actually proposes building dams, but on a smaller scale than is typically seen and with no pumping between watersheds. Picture multiple redundant dams for every farm, each a few megalitre in size and a few thousand dollars to construct. Many small dams wet up the entire landscape by slowing water down. Maybe this sounds obvious, but if water takes 10 times as long to reach the ocean then you have 10 times as much water to work with in the landscape. Infiltration does the same. Subterranean water continues to flow downhill, but thousands of times more slowly. You can even recharge old spring lines in this way, benefiting the downhill hydrology directly. >Sometimes we come up with solutions that work well in Sim City, but reality proves a bit more complicated. On a wildly off-topic tangent, I just saw a fascinating talk in which Naomi Klein refers to this as "astronaut-eye environmentalism". https://www.youtube.com/watch?v=Jdaxehd0cF0#t=6m29s https://www.youtube.com/watch?v=Jdaxehd0cF0#t=6m29s
    - lotsofmangos 12y ago
      They are looking into something similar in the UK to manage floodwaters, so that instead of funneling water fast and out, which massively increases erosion and sometimes overwhelms bridges down stream, you work out where you can let the water hang around in times of flood and make agreements with farmers to have flash flood basins.
- ElectronCharge 12y ago
  The way to go is nuclear desalination. The nuclear industry needs to be incentivized, and is badly in need of a SpaceX type company.
  - glomph 12y ago
    That will not happen because current nuclear power just isn't economical without government guarrantees.
    - ElectronCharge 12y ago
      The reason it's less economical than it could be is because of excessive regulation. We've come a long way with automation and safety engineering. Next-gen nuclear plants could produce energy far less expensively than coal if handled properly - with zero air pollution. Then there's the promise of thorium power: http://energyfromthorium.com http://energyfromthorium.com
      - dragonwriter 12y ago
        No, unless by "excessive regulation" you mean the fact that the industry is exposed to the same liability for unconsented harms done to third parties that every other industry is; because exemption from that liability is what the industry keeps lobbying for as the thing necessary to make it worthwhile to invest in new plants. But usually, this kind of liability is wHat libertarians promote in place of regulation, not something anyone calls excessi regulation.
        guscost 12y ago
        The argument that US nuclear power projects face the same regulatory challenges as "every other industry" is completely untenable. There is an entire regulatory body (the NRC) charged with managing regulations for that one particular method of power generation. This fact alone is enough to refute it. There is also an argument that the "regulatory ratcheting" from the NRC is due to political pressure rather than engineering principles[0]. Finally it is hard to read former chairman Gregory Jaczko's recent comments about Fukushima and not conclude that the NRC was, and quite possibly still is, actively opposing the nuclear industry with an ultimate goal of shutting it down[1]. [0] http://www.phyast.pitt.edu/~blc/book/chapter9.html http://www.phyast.pitt.edu/~blc/book/chapter9.html [1] http://bigstory.ap.org/article/us-ex-nuclear-chief-fukushima-lesson-phase-out http://bigstory.ap.org/article/us-ex-nuclear-chief-fukushima...
mixmastamyk 12y ago
It's just very expensive.
- toomuchtodo 12y ago
  Use excess wind power generation.
  - PhasmaFelis 12y ago
    We'll have to get some excess wind power first.
    - toomuchtodo 12y ago
      That's actually the biggest problem with wind power; when you have excess power, you can't do anything with it except curtail your production and lock your turbines so they can't spin. http://www.renewableenergyworld.com/rea/news/article/2013/01/belgium-plans-to-build-island-to-store-excess-wind-energy http://www.renewableenergyworld.com/rea/news/article/2013/01... To be able to put that power to a good use, while also still realizing revenue (even at a lower per kwh rate) is win-win. Wind power, without subsidies, is already as low as 3-4 cents/kwh. If the rate of install continues, price will continue to decline, and we'll have even more cheap wind available in the US for large-scale projects such as this.
      - uptown 12y ago
        "That's actually the biggest problem with wind power; when you have excess power, you can't do anything with it except curtail your production and lock your turbines so they can't spin." There seems like countless ways a society could use "excess energy". What this article talks about is more like time-shifting the energy it's captured. But if excess energy were a problem, wouldn't you be able to store it in batteries, or apply it towards desalinization or other net positive activities rather than just locking the turbines?
        12y ago
declan 12y ago
This is a serious drought, but remember 80% of California's water goes to agriculture. More water is used to grow almonds than for all of residential irrigation. There are more non-farmers than farmers in the state; if the drought continues I expect the next step will be to cut back more on agricultural uses. In terms of desalination, my recollection is that it's a reasonably mature technology now, it's used in many parts of the world that are freshwater-constrained, and San Diego is building a 50M gallon/day desalination plant that will go online in a year or two. But the per-gallon price is largely determined by the price of electricity, and California is rather hostile to new power plants going in. (I don't know enough about the state's aquifers; perhaps others do.) Meanwhile in a few generations we may look back and wonder why we were flooding fields in California half a foot deep with increasingly scarce water to grow rice in an extremely dry climate. Especially when rice grows perfectly well in areas of the world that actually, you know, get rain all year round.
- jqm 12y ago
  Almonds are one thing... we actually need those. The sad part is, most of the agricultural water goes to alfalfa. http://www.nytimes.com/2014/03/08/opinion/meat-makes-the-planet-thirsty.html?_r=0 http://www.nytimes.com/2014/03/08/opinion/meat-makes-the-pla...
  - mark_l_watson 12y ago
    A predominately meat diet uses about 10 times the water and energy to produce. Stop the free water subsidies to big agro businesses, and let the free market price of water affect meat prices.
    - masterleep 12y ago
      That's a fantastic idea, but it's far too practical and sensible for California. It doesn't include any feel-good meddling or opportunities for kickbacks for the powerful and connected.
  - lkbm 12y ago
    > Almonds are one thing... we actually need those. Unless I'm missing something major, we "need" almonds for exactly one reason: they're tasty. That exact same "need" exists for meat. Personally, I'm quite happy eating neither, since I'm not a fan of nuts in general. I recognize some people love almonds, and I'm not running around trying to get them banned, but I definitely think, just as with meat, we need to think of these things as choices, not just plain needs.
rdtsc 12y ago
> Are there major issues with desalination on a large scale? Maybe not too major but what to do with the salt?
- D_Alex 12y ago
  Desalination plants produce fresh water and salty brine, the brine is put back into the ocean. The effect on water salinity are negligible - in the sense that it will be less than the natural variance of the seawater salinity - beyond a few hundred meters from the brine discharge, even for city-scale desalination plants.
kabdib 12y ago
I read that aquifers, at least the ones in the Midwest (as in Colorado) are essentially "fossil water", and that when you pump it out the rock collapses somewhat, making it impossible to pump replacement water back in.
- toomuchtodo 12y ago
  Depends on the aquifers. Some are fossil, some are replenishable: https://www.classzone.com/books/earth_science/terc/content/investigations/es1406/es1406page10.cfm https://www.classzone.com/books/earth_science/terc/content/i...
- flavor8 12y ago
  In the central valley, some areas have sunk 30+ft over the past century due to aquifers collapsing. http://www.watercalifornia.org/projects/projects_img/enid/fables_large.jpg http://www.watercalifornia.org/projects/projects_img/enid/fa... http://www.capradio.org/articles/2013/11/22/usgs-study-1200-square-miles-of-central-valley-land-is-sinking/ http://www.capradio.org/articles/2013/11/22/usgs-study-1200-...
sliverstorm 12y ago
The issue with desalination is the tremendous energy input, normally provided by the sun. At least right now, that would probably have to come from coal.
- blisterpeanuts 12y ago
  True, but the Carlsbad desal plant in San Diego is going to build a bunch of solar collectors to offset much of its electricity demand. It's not clear they'll be able to offset all of it, but some is better than nothing, anyway.
abootstrapper 12y ago
Fixing our water shortage with energy consuming desalination plants will just continue the global warming negative feedback loop. Better would be to simply change what farmers are growing to conserve water. * Edit: Why the downvotes? Look, solving water shortages with desalination plants, is like trying to fix air pollution with air filtration systems. Unless you're powering the plant with 100% clean energy, you're just further contributing to the core problem. And even if you're powering the plant with 100% clean energy, that clean energy could instead be used to displace fossil fuels elsewhere if water was conserved instead of desalinated to continue business as usual. Am I wrong?
- Decade 12y ago
  Maybe you're getting downvoted because you misused the term "negative feedback loop." As any beginning engineering student knows, a negative feedback loop is a system that tends to return to an equilibrium state when perturbed. A positive feedback loop is a system that magnifies any disturbance until the conditions change, because it's inherently unstable. When you engineer a dynamic system, you typically want it to have a negative feedback loop, so it doesn't blow up or something. In other words, the term "negative feedback" does not have anything to do with the social consequences. Using it this way is painfully stupid.
  - deleted 12y ago
    [deleted]
Dylan16807 12y ago
Desalination works great for residential water use. It doesn't help the farmers that want massive amounts of ultra-cheap water. Better farming techniques could help. What would help most of all is if water was properly bought and sold at market rates, so people with major water rights would sell instead of wasting.
- ghshephard 12y ago
  There are policy reasons why we don't want water to go to the highest bidder - Food Security is one of the key reasons we give agriculture so much priority on water, even when economically it doesn't seem to make sense.
  - Dylan16807 12y ago
    Would it really affect the amount going toward farming very much? Taking away a few percent of farming use could give other uses huge amounts of water. I could see a scenario where instead of some farmers getting underpriced water, there are more farmers competing to produce food at marginally higher prices, leading more of them to use better irrigation techniques and solving the problem. Subsidies can be applied to the food prices after this point if desired, without the side effects of water shortages.
    - ghshephard 12y ago
      The issue is farming, though. There is more than enough water supply in California for residential use, which makes up less than 20% of water consumption in California.
      - Dylan16807 12y ago
        The issue is farming. They waste massive amounts of water because it's cheap. We don't need to give them water priority.
mhartl 12y ago
This question was tackled a while back by, of all people, John McCarthy (AI pioneer and creator of Lisp). You can find his analysis here: http://www-formal.stanford.edu/jmc/progress/arithmetic.html http://www-formal.stanford.edu/jmc/progress/arithmetic.html

by rtpg 12y ago

schiffern 12y ago

>What if we were to build a bunch of desalination plants and just start pumping water into aquifers or something of the sort? If you're talking about conventional fossil fuel desalination, I invite you to do the energy audit on that activity. If you're talking about solar desalination in industrially-manufactured greenhouses, I invite you to do the energy audit on that activity. Don't forget to account for the energy-opportunity cost of land use. I know there's a lot of hype surrounding desalination here, but a centralized energy-sucking plant (owned by the ultra rich naturally) is a counterproductive business-as-usual non-solution. We can get a net-positive energy audit by redesigning our agricultural and storm water management. Right now they're designed with exactly the wrong goal in mind — shunt rainwater to the ocean in big straight hardware as fast as possible. This maximizes runoff instead of infiltration, so we're simultaneously preventing aquifer recharge and necessitating aquifer pumping by drying out the soil. "Keyline" design—a method of cheaply altering landform to soak water—is probably a good start for these new infiltration maximizing strategies, but this is by no means a solved problem. In California, like any desert, the name of the game is minimizing evaporation. This means all of the above, plus shading (e.g. date palms), sunken beds, buried drip irrigation, and dew/rain harvesting strategies like land imprinting. Proper rainwater management is the lazy hacker's desalination. :D

jaekwon 12y ago
Yeah I was wondering if our storm-water sewage system is sucking the water out of our lands. But how much does this really matter? There would have to be some analysis of these systems vs land with no such system vs where they are to rain sources etc.
- schiffern 12y ago
  http://www.usgs.gov/water/ http://www.usgs.gov/water/ The storm system drains all the "hardware" in an urban or suburban area — roofs, roads, parking lots, and sometimes even constantly mowed grass (which can form subterranean hardpan). Higher runoff rates lead to flow bottlenecks, flooding, and untreated sewage discharge. Still, agricultural land has more catchment.
- mason240 12y ago
  The city live in (Maplewood MN) recently built rain gardens in our neighborhood for catching rainwater. They are basically deep pits filled in with gravel with slightly sunken garden on top. The water runoff from the street is diverted into them where most of it is absorbed into the ground. http://www.bwsr.state.mn.us/images/ww-box.jpg http://www.bwsr.state.mn.us/images/ww-box.jpg http://1.bp.blogspot.com/-31kb5tVYmJU/Ub9T22Hgy_I/AAAAAAAAAvI/_TMboIzREK0/s1600/merge1.jpg http://1.bp.blogspot.com/-31kb5tVYmJU/Ub9T22Hgy_I/AAAAAAAAAv... http://1.bp.blogspot.com/-VLZpvg9e-H8/UbY86YdLjzI/AAAAAAAAAn0/gUv7kV1HjCA/s1600/2466+East+7th+St..jpg http://1.bp.blogspot.com/-VLZpvg9e-H8/UbY86YdLjzI/AAAAAAAAAn...
badsock 12y ago
What do you think of Western Australia's desalination efforts? http://en.wikipedia.org/wiki/Perth_Seawater_Desalination_Plant http://en.wikipedia.org/wiki/Perth_Seawater_Desalination_Pla...
- gilgoomesh 12y ago
  Desalination can handle drinking water but 90% of water usage is usually for irrigation. It is not cost effective to do that with desalination. As for Australia's 6 or 7 built/planned desalination plants: they are for backup and supplemental purposes only. They can't supply more than about 10% of the largest Australian cities' typical water usage. They would provide emergency water in a catastrophic drought and in low rainfall years can lessen the burden but they are not a replacement for good water catchment management.
rtpg 12y ago
If this can work and we can get the gov't behind this sort of solution, this seems good. Wouldn't this create a bit of water shortages downhill though? Like when you build a dam? Or is the quantity captured not on the same scale. I guess the desalination plant is something that a single rich person can do, whereas going around drilling holes all over California is a bit more complicated. Sometimes we come up with solutions that work well in Sim City, but reality proves a bit more complicated.
- schiffern 12y ago
  >Wouldn't this create a bit of water shortages downhill though? Like when you build a dam? Great question! Dams themselves don't causes water shortages. It's the pumping of water from the dam to a separate watershed, or into highly evaporative irrigation systems (e.g. the Aral Sea and cotton). Keyline design actually proposes building dams, but on a smaller scale than is typically seen and with no pumping between watersheds. Picture multiple redundant dams for every farm, each a few megalitre in size and a few thousand dollars to construct. Many small dams wet up the entire landscape by slowing water down. Maybe this sounds obvious, but if water takes 10 times as long to reach the ocean then you have 10 times as much water to work with in the landscape. Infiltration does the same. Subterranean water continues to flow downhill, but thousands of times more slowly. You can even recharge old spring lines in this way, benefiting the downhill hydrology directly. >Sometimes we come up with solutions that work well in Sim City, but reality proves a bit more complicated. On a wildly off-topic tangent, I just saw a fascinating talk in which Naomi Klein refers to this as "astronaut-eye environmentalism". https://www.youtube.com/watch?v=Jdaxehd0cF0#t=6m29s https://www.youtube.com/watch?v=Jdaxehd0cF0#t=6m29s
  - lotsofmangos 12y ago
    They are looking into something similar in the UK to manage floodwaters, so that instead of funneling water fast and out, which massively increases erosion and sometimes overwhelms bridges down stream, you work out where you can let the water hang around in times of flood and make agreements with farmers to have flash flood basins.
ElectronCharge 12y ago
The way to go is nuclear desalination. The nuclear industry needs to be incentivized, and is badly in need of a SpaceX type company.
- glomph 12y ago
  That will not happen because current nuclear power just isn't economical without government guarrantees.
  - ElectronCharge 12y ago
    The reason it's less economical than it could be is because of excessive regulation. We've come a long way with automation and safety engineering. Next-gen nuclear plants could produce energy far less expensively than coal if handled properly - with zero air pollution. Then there's the promise of thorium power: http://energyfromthorium.com http://energyfromthorium.com
    - dragonwriter 12y ago
      No, unless by "excessive regulation" you mean the fact that the industry is exposed to the same liability for unconsented harms done to third parties that every other industry is; because exemption from that liability is what the industry keeps lobbying for as the thing necessary to make it worthwhile to invest in new plants. But usually, this kind of liability is wHat libertarians promote in place of regulation, not something anyone calls excessi regulation.
      - guscost 12y ago
        The argument that US nuclear power projects face the same regulatory challenges as "every other industry" is completely untenable. There is an entire regulatory body (the NRC) charged with managing regulations for that one particular method of power generation. This fact alone is enough to refute it. There is also an argument that the "regulatory ratcheting" from the NRC is due to political pressure rather than engineering principles[0]. Finally it is hard to read former chairman Gregory Jaczko's recent comments about Fukushima and not conclude that the NRC was, and quite possibly still is, actively opposing the nuclear industry with an ultimate goal of shutting it down[1]. [0] http://www.phyast.pitt.edu/~blc/book/chapter9.html http://www.phyast.pitt.edu/~blc/book/chapter9.html [1] http://bigstory.ap.org/article/us-ex-nuclear-chief-fukushima-lesson-phase-out http://bigstory.ap.org/article/us-ex-nuclear-chief-fukushima...

mixmastamyk 12y ago

It's just very expensive.

toomuchtodo 12y ago
Use excess wind power generation.
- PhasmaFelis 12y ago
  We'll have to get some excess wind power first.
  - toomuchtodo 12y ago
    That's actually the biggest problem with wind power; when you have excess power, you can't do anything with it except curtail your production and lock your turbines so they can't spin. http://www.renewableenergyworld.com/rea/news/article/2013/01/belgium-plans-to-build-island-to-store-excess-wind-energy http://www.renewableenergyworld.com/rea/news/article/2013/01... To be able to put that power to a good use, while also still realizing revenue (even at a lower per kwh rate) is win-win. Wind power, without subsidies, is already as low as 3-4 cents/kwh. If the rate of install continues, price will continue to decline, and we'll have even more cheap wind available in the US for large-scale projects such as this.
    - uptown 12y ago
      "That's actually the biggest problem with wind power; when you have excess power, you can't do anything with it except curtail your production and lock your turbines so they can't spin." There seems like countless ways a society could use "excess energy". What this article talks about is more like time-shifting the energy it's captured. But if excess energy were a problem, wouldn't you be able to store it in batteries, or apply it towards desalinization or other net positive activities rather than just locking the turbines?
      - 12y ago

declan 12y ago

This is a serious drought, but remember 80% of California's water goes to agriculture. More water is used to grow almonds than for all of residential irrigation. There are more non-farmers than farmers in the state; if the drought continues I expect the next step will be to cut back more on agricultural uses. In terms of desalination, my recollection is that it's a reasonably mature technology now, it's used in many parts of the world that are freshwater-constrained, and San Diego is building a 50M gallon/day desalination plant that will go online in a year or two. But the per-gallon price is largely determined by the price of electricity, and California is rather hostile to new power plants going in. (I don't know enough about the state's aquifers; perhaps others do.) Meanwhile in a few generations we may look back and wonder why we were flooding fields in California half a foot deep with increasingly scarce water to grow rice in an extremely dry climate. Especially when rice grows perfectly well in areas of the world that actually, you know, get rain all year round.

jqm 12y ago
Almonds are one thing... we actually need those. The sad part is, most of the agricultural water goes to alfalfa. http://www.nytimes.com/2014/03/08/opinion/meat-makes-the-planet-thirsty.html?_r=0 http://www.nytimes.com/2014/03/08/opinion/meat-makes-the-pla...
- mark_l_watson 12y ago
  A predominately meat diet uses about 10 times the water and energy to produce. Stop the free water subsidies to big agro businesses, and let the free market price of water affect meat prices.
  - masterleep 12y ago
    That's a fantastic idea, but it's far too practical and sensible for California. It doesn't include any feel-good meddling or opportunities for kickbacks for the powerful and connected.
- lkbm 12y ago
  > Almonds are one thing... we actually need those. Unless I'm missing something major, we "need" almonds for exactly one reason: they're tasty. That exact same "need" exists for meat. Personally, I'm quite happy eating neither, since I'm not a fan of nuts in general. I recognize some people love almonds, and I'm not running around trying to get them banned, but I definitely think, just as with meat, we need to think of these things as choices, not just plain needs.

rdtsc 12y ago

> Are there major issues with desalination on a large scale? Maybe not too major but what to do with the salt?

D_Alex 12y ago
Desalination plants produce fresh water and salty brine, the brine is put back into the ocean. The effect on water salinity are negligible - in the sense that it will be less than the natural variance of the seawater salinity - beyond a few hundred meters from the brine discharge, even for city-scale desalination plants.

kabdib 12y ago

I read that aquifers, at least the ones in the Midwest (as in Colorado) are essentially "fossil water", and that when you pump it out the rock collapses somewhat, making it impossible to pump replacement water back in.

toomuchtodo 12y ago
Depends on the aquifers. Some are fossil, some are replenishable: https://www.classzone.com/books/earth_science/terc/content/investigations/es1406/es1406page10.cfm https://www.classzone.com/books/earth_science/terc/content/i...
flavor8 12y ago
In the central valley, some areas have sunk 30+ft over the past century due to aquifers collapsing. http://www.watercalifornia.org/projects/projects_img/enid/fables_large.jpg http://www.watercalifornia.org/projects/projects_img/enid/fa... http://www.capradio.org/articles/2013/11/22/usgs-study-1200-square-miles-of-central-valley-land-is-sinking/ http://www.capradio.org/articles/2013/11/22/usgs-study-1200-...

sliverstorm 12y ago

The issue with desalination is the tremendous energy input, normally provided by the sun. At least right now, that would probably have to come from coal.

blisterpeanuts 12y ago
True, but the Carlsbad desal plant in San Diego is going to build a bunch of solar collectors to offset much of its electricity demand. It's not clear they'll be able to offset all of it, but some is better than nothing, anyway.

abootstrapper 12y ago

Fixing our water shortage with energy consuming desalination plants will just continue the global warming negative feedback loop. Better would be to simply change what farmers are growing to conserve water. * Edit: Why the downvotes? Look, solving water shortages with desalination plants, is like trying to fix air pollution with air filtration systems. Unless you're powering the plant with 100% clean energy, you're just further contributing to the core problem. And even if you're powering the plant with 100% clean energy, that clean energy could instead be used to displace fossil fuels elsewhere if water was conserved instead of desalinated to continue business as usual. Am I wrong?

Decade 12y ago
Maybe you're getting downvoted because you misused the term "negative feedback loop." As any beginning engineering student knows, a negative feedback loop is a system that tends to return to an equilibrium state when perturbed. A positive feedback loop is a system that magnifies any disturbance until the conditions change, because it's inherently unstable. When you engineer a dynamic system, you typically want it to have a negative feedback loop, so it doesn't blow up or something. In other words, the term "negative feedback" does not have anything to do with the social consequences. Using it this way is painfully stupid.
- deleted 12y ago
  [deleted]

Dylan16807 12y ago

Desalination works great for residential water use. It doesn't help the farmers that want massive amounts of ultra-cheap water. Better farming techniques could help. What would help most of all is if water was properly bought and sold at market rates, so people with major water rights would sell instead of wasting.

ghshephard 12y ago
There are policy reasons why we don't want water to go to the highest bidder - Food Security is one of the key reasons we give agriculture so much priority on water, even when economically it doesn't seem to make sense.
- Dylan16807 12y ago
  Would it really affect the amount going toward farming very much? Taking away a few percent of farming use could give other uses huge amounts of water. I could see a scenario where instead of some farmers getting underpriced water, there are more farmers competing to produce food at marginally higher prices, leading more of them to use better irrigation techniques and solving the problem. Subsidies can be applied to the food prices after this point if desired, without the side effects of water shortages.
  - ghshephard 12y ago
    The issue is farming, though. There is more than enough water supply in California for residential use, which makes up less than 20% of water consumption in California.
    - Dylan16807 12y ago
      The issue is farming. They waste massive amounts of water because it's cheap. We don't need to give them water priority.

mhartl 12y ago

This question was tackled a while back by, of all people, John McCarthy (AI pioneer and creator of Lisp). You can find his analysis here: http://www-formal.stanford.edu/jmc/progress/arithmetic.html http://www-formal.stanford.edu/jmc/progress/arithmetic.html