A new look at seawater desalination

Discussion in 'Environmental Discussion' started by tochatihu, Nov 18, 2015.

Page 2 of 2
  1. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    9,510
    3,672
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    I have made more progress. Corresponding author of the best paper I cited above is now at a university where 'mine tailings cleanup' is the highest priority. So, s/he might get distracted. Abundant chemicals in seawater (=RO bypass) are right on the cusp of profitable extraction. Success will require chemists to commit themselves to working out the details.

    At stake here is RO for potable water supply becoming much more widely economically feasible, supported by chemical sales. Still looking for the right person to dump this thing on.
     
    #21 tochatihu, Nov 22, 2015
  2. austingreen

    austingreen Senior Member

    Joined:
    Nov 3, 2009
    13,635
    4,177
    0
    Location:
    Austin, TX, USA
    Vehicle:
    2018 Tesla Model 3
    Model:
    N/A
    I think it is probably not economic to get that many chemicals processed. Remember these will be located on beaches near highly populated areas. These are often the worst places for chemical processsing plants. Still sea water may be vital to get water to dry areas.

    It seems a bad idea in california that is dry because of drought and agriculture. No reason to spend the money, when you could curtail agricultural water use for much lower costs.
    Desalination plants aren't a good solution for California drought - LA Times

    Then there are cheaper new designs, where there is never enough water.
    Cheap Water from the World's Largest Modern Seawater Desalination Plant | MIT Technology Review
     
    #22 austingreen, Nov 22, 2015
    Last edited: Nov 22, 2015
  3. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    9,510
    3,672
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    You'd not convince a sea-level-riser like me to site any durable facility 'on a beach'. Hope that is not what Sorek has done.

    Nano materials are hinted to outdo current RO membranes, but that is a separate matter. Commodity (and transport) costs are what seawater chemical extractions slide against.

    Most everybody has heard of a mine-tailings release in Colorado (made EPA look not good). Much larger one just now reaching the sea in Brazil. Getting ions out of water, in the context of much more concentrated other ions, is a big deal. These are all applications of a particular type of chemistry.
     
    #23 tochatihu, Nov 22, 2015
  4. austingreen

    austingreen Senior Member

    Joined:
    Nov 3, 2009
    13,635
    4,177
    0
    Location:
    Austin, TX, USA
    Vehicle:
    2018 Tesla Model 3
    Model:
    N/A
    near the beach not on it. The higher and farther you place it, the more energy it takes. Think 30 year useful life and likely sea level rise, not 100 years worst case sea level.
    [​IMG]

    Yep. I don't think most of the need for this expensive water is where the salt and potash are needed. The cheaper isreali plant uses solar to help the process, and keeps it simple. The same company developed it and carlsbad (near san diago), CA. I have no idea why carlsbad is so much more expensive.

    I think its not as much of a problem in the dry areas, but in california its a major concern.
     
    #24 austingreen, Nov 22, 2015
    Last edited: Nov 22, 2015
  5. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    9,510
    3,672
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    Moving water around has energy costs. Sea level is 0 and the end user is some number of meters higher. Even in Prius chats we usta talk about E=mgh (the potential energy). Frictional pumping losses seem to be determined empirically from measured pressures.

    If your end user is (say) at 100 m elevation and 10 km from the ocean, it can all be calculated. I don't think it matters (much) whether the water treatment is at the 'beach' end of the pipe, or the other. I'll let the 'tsunami guys' tell me how high to go.

    The MIT link has a nice global 'water risk' map. Could be made better by overlaying the CIESIN global population density map, and how far (high) inland would the water need to go. Then you can make a global cost and benefit map for seawater RO. If the 'waste' chemicals have no (or below local market) value, that's the end of it. Where they have value after extraction, the cost and benefit map gets revised lower.

    We have heard here from the 'unconvinced', and I gave you some links to read. Personally I am more swayed by the latter.

    New water purification technologies will probably be driven by currently stored contaminated water, because that is the Shibboleth. But at least some of those technologies would have application for the Na, Cl, Mg, K and Br that RO currently tosses back.
     
    #25 tochatihu, Nov 22, 2015
  6. austingreen

    austingreen Senior Member

    Joined:
    Nov 3, 2009
    13,635
    4,177
    0
    Location:
    Austin, TX, USA
    Vehicle:
    2018 Tesla Model 3
    Model:
    N/A
    Sure, but much of the water is returned, as the concentrations get higher it takes more energy for reverse osmosis. I'm sure they are talking to the weather people to figure out how high they need to go to be safe for the life of the plant, but closer is better. At most only half the water is purified as it takes more energy the higher the concentration is of the remaining solution. Turbines can recover some of the energy of this solution when it is put back out to sea.

    IMHO its location location location. For instance in California they make the salt in the east bay (newerk) and baja (mexico) where land is cheaper and solar energy simply evaporates the water. In isreal the dead sea. In order to compete you either need cheap energy to process (nothing is cheaper than the free solar currently being used) and cheap land, while much of the fresh water need is geographically different.
     
    #26 austingreen, Nov 23, 2015
  7. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    9,510
    3,672
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    Most SWRO works with 5 or 6 fold more concentrated waste water. Evap ponds are primo way to make NaCl on the cheap, but I don't know yet of other minerals are ideally extracted from this very concentrated matrix.
     
    #27 tochatihu, Nov 23, 2015
  8. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    9,510
    3,672
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    #28 tochatihu, Dec 19, 2015
  9. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    9,510
    3,672
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    A new way to extract lithium from highly concentrated mixed salts

    https://www.sciencedaily.com/releases/2016/04/160413084312.htm

    There is local interest in lithium for secondary batteries. My other reason for bumping this is 'counter-current circulation'. The process shows up many times in unrelated biological systems. If we each made lists of the most amazing 100 things we ever learned, this would be on my list.
     
    #29 tochatihu, Apr 13, 2016
  10. tochatihu

    tochatihu Senior Member

    Joined:
    Apr 10, 2004
    9,510
    3,672
    0
    Location:
    Kunming Yunnan China
    Vehicle:
    2001 Prius
    I had not noticed before the rapid rise of lithium commodity prices in late 2015. Battery gigafactories and all that.
     
    #30 tochatihu, Apr 23, 2016
  11. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    112,163
    51,032
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    yes, there is another thread describing the potential for lithium shortages, and/or rapidly rising prices.
     
    #31 bisco, Apr 23, 2016
(You must log in or sign up to post here.)
Page 2 of 2