4 ms·

> The team also continues to look at the possibility of extracting other, lower-concentration materials from the brine stream, he says, including various metals

> The team also continues to look at the possibility of extracting other, lower-concentration materials from the brine stream, he says, including various metals and other chemicals Lithium from desalination brines seems to be one potential (and promising) such [0], environmentally better in more than one way than the current methods of lithium mining [1]. [0] https://www.researchgate.net/publication/313372304_Towards_lithium_recovery_from_desalination_brines_via_an_integrated_scheme https://www.researchgate.net/publication/313372304_Towards_l... [1] https://www.wired.co.uk/article/lithium-batteries-environment-impact https://www.wired.co.uk/article/lithium-batteries-environmen...

philwelch 6y ago
You can also extract uranium from seawater, and use it to fuel nuclear reactors, and use the nuclear reactors to power your desalination.
- enkid 6y ago
  Do you get enough volume for this to work? My intuition would be the levels of Uranium would be low enough that it would not be energy positive. Do you have more information about this process?
  - jbay808 6y ago
    I remember some projects going on at MIT on this topic. https://dspace.mit.edu/handle/1721.1/111821 https://dspace.mit.edu/handle/1721.1/111821
  - 08-15 6y ago
    Energy consumption of reverse osmosis is about 4kWh/t. The byproduct is a ton of brine. Sea water contains about 3ppb Uranium, so our brine contains 6mg of U per ton of fresh water produced. A 1GW nuclear power station consumes about 1t of U per year and produces about 8000GWh of electricity in that time. So we need about 1mg/8kWh. We got 12 times that much. So, it sort of works out. Of course, this assumes a breeder reactor and I pretended that brine is purified uranium. If breeders are commercialized, it might be worth looking into this. Right now, it isn't.
    - enkid 6y ago
      Awesome, thanks!
    - credit_guy 6y ago
      Nice analysis. But the premise of the discussion here is that people do the desalination for its own sake, not in order to harvest Uranium. This [1] article from 2012. It presents a Uranium extraction method from seawater that would put the extraction cost at $300/kg. Nowadays the market price is about $70/kg. However, if method were to be applied to brine instead of regular seawater, maybe the cost would go down. Hard to see it going down by a factor of 5 though. [1] http://large.stanford.edu/courses/2012/ph241/ferguson2/ http://large.stanford.edu/courses/2012/ph241/ferguson2/
    - vilhelm_s 6y ago
      I think you overestimate the energy in uranium. 8000GWh per tonne and year would be 28.8 TJ/kg, while the numbers I have seen is more like 0.7 TJ/kg (http://www.plux.co.uk/energy-density-of-uranium/ http://www.plux.co.uk/energy-density-of-uranium/).
      - 08-15 6y ago
        What part of "this assumes a breeder reactor" did you not understand?
        vilhelm_s 6y ago
        Oh I missed that!
    - wolfhumble 6y ago
      So 4kWh/t is used to desalinate 2 tons of seawater that turn into 1 ton of freshwater and 1 ton of brine?
  - vilhelm_s 6y ago
    Googling a bit: it takes about 13 MJ to desalinate 1 m^3 of water by reverse osmosis. Seawater contains 3mg uranium per m^3, which gives 2 MJ, So it's not energy positive.
    - lxmorj 6y ago
      2/3rds power rebate on your desalination ain’t bad!
HarryHirsch 6y ago
For a long time, bromine was an important product made from brine. But that market has fallen away, since the lions share used to be made into lead scavengers for leaded petrol. The bromine works at Amlwch on Anglesey closed in 2004: https://www.octelamlwch.co.uk/ https://www.octelamlwch.co.uk/ The other obvious product would be magnesium, but they didn't isolate magnesium chloride at the bromine plant. The Wylfa nuclear power station was nearby, and Rio Tinto had an aluminium smelter nearby to provide a base load. Since magnesium is oftentimes produced through electrolysis a magnesium plant would have made sense, but somehow they didn't build one, likely for economic reasons.

philwelch 6y ago

You can also extract uranium from seawater, and use it to fuel nuclear reactors, and use the nuclear reactors to power your desalination.

enkid 6y ago
Do you get enough volume for this to work? My intuition would be the levels of Uranium would be low enough that it would not be energy positive. Do you have more information about this process?
- jbay808 6y ago
  I remember some projects going on at MIT on this topic. https://dspace.mit.edu/handle/1721.1/111821 https://dspace.mit.edu/handle/1721.1/111821
- 08-15 6y ago
  Energy consumption of reverse osmosis is about 4kWh/t. The byproduct is a ton of brine. Sea water contains about 3ppb Uranium, so our brine contains 6mg of U per ton of fresh water produced. A 1GW nuclear power station consumes about 1t of U per year and produces about 8000GWh of electricity in that time. So we need about 1mg/8kWh. We got 12 times that much. So, it sort of works out. Of course, this assumes a breeder reactor and I pretended that brine is purified uranium. If breeders are commercialized, it might be worth looking into this. Right now, it isn't.
  - enkid 6y ago
    Awesome, thanks!
  - credit_guy 6y ago
    Nice analysis. But the premise of the discussion here is that people do the desalination for its own sake, not in order to harvest Uranium. This [1] article from 2012. It presents a Uranium extraction method from seawater that would put the extraction cost at $300/kg. Nowadays the market price is about $70/kg. However, if method were to be applied to brine instead of regular seawater, maybe the cost would go down. Hard to see it going down by a factor of 5 though. [1] http://large.stanford.edu/courses/2012/ph241/ferguson2/ http://large.stanford.edu/courses/2012/ph241/ferguson2/
  - vilhelm_s 6y ago
    I think you overestimate the energy in uranium. 8000GWh per tonne and year would be 28.8 TJ/kg, while the numbers I have seen is more like 0.7 TJ/kg (http://www.plux.co.uk/energy-density-of-uranium/ http://www.plux.co.uk/energy-density-of-uranium/).
    - 08-15 6y ago
      What part of "this assumes a breeder reactor" did you not understand?
      - vilhelm_s 6y ago
        Oh I missed that!
  - wolfhumble 6y ago
    So 4kWh/t is used to desalinate 2 tons of seawater that turn into 1 ton of freshwater and 1 ton of brine?
- vilhelm_s 6y ago
  Googling a bit: it takes about 13 MJ to desalinate 1 m^3 of water by reverse osmosis. Seawater contains 3mg uranium per m^3, which gives 2 MJ, So it's not energy positive.
  - lxmorj 6y ago
    2/3rds power rebate on your desalination ain’t bad!

HarryHirsch 6y ago

For a long time, bromine was an important product made from brine. But that market has fallen away, since the lions share used to be made into lead scavengers for leaded petrol. The bromine works at Amlwch on Anglesey closed in 2004: https://www.octelamlwch.co.uk/ https://www.octelamlwch.co.uk/ The other obvious product would be magnesium, but they didn't isolate magnesium chloride at the bromine plant. The Wylfa nuclear power station was nearby, and Rio Tinto had an aluminium smelter nearby to provide a base load. Since magnesium is oftentimes produced through electrolysis a magnesium plant would have made sense, but somehow they didn't build one, likely for economic reasons.