desalination plants

Discussion in 'The big picture' started by lezstar, Nov 19, 2007.

  1. lezstar

    lezstar Junior Member

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    one of the biggest arguments against desalination plants is the amount of energy to run the things is considered too high, thats not the problem we have wave, tidal ,solaretc as ways of supplying the energy requirements.The main problem not fully solved is the waste disposal of the brine left over from the process.One proposal is mini desal plants dotted along the coastline to minimise the amount of brine waste left over from the process. Look ,I am a politician ,(greens,of course),not a scientist I am sure there are ways around this problem,we just need a shift in community support and some more reseach funding,its not just do-able its necessary and 'necessity is the mother of invention ',any thoughts out there on the topic?
     
  2. Ojo

    Ojo Junior Member

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    yup, necessity will prolly make for more thoughts on the topic. I hear dumping the hyper-saline brine back into the ocean (in dynamic areas to avoid plumes and resulting harm to marine life) is one strategy and I hear the western coast of Australia is pretty dynamic.

    OR you could dig a big hole and dump the brine in it and create solar salterns and get a grant for the study of salt bioremediation. Maybe yeast and halophile bioreactors

    (pdf)
    https://nsdl.org/resource/2200/20061002133831329T

    The Saudis have been doing it for awhile, maybe they can give you some tips on "ancillary power generation equipment,"
    https://www.water-technology.net/projects/shuaiba/

    Desalination plants also generate electricity. In 2000, the Kingdom's desalination plants generated a total of 28 million Megawatt Hours.
    excerpt
    https://saudinf.com/main/a541.htm
     
  3. lezstar

    lezstar Junior Member

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    desalination plants

    I noticed the saudis have been at this desal thing for a while,the area I wasn't aware of was the (if it is in fact feasible), actual possibilty of converting this' waste brine' by-product into a viable energy source, the beauty and symmetry of this potential water AND energy alternative, as part of the wider, indeed well termed 'perma-culture is 'much more sustainable than the mess we have gotten into with our present way of living on the planet, ESPECIALLY given water and energy are two of the biggest factors in this whole climate change 'elephant in the room' of global governance ,the UN and the whole danged shooting match that is called civilisation. One more thing, I would like to see is a bit more australia wide cohesion when it comes to the various scientists and organisations working TOGETHER as opposed to COMPETITEVLY in the whole desal industry and how indeed we best deal with the waste issue .We seem to have a myriad ways of RUNNING these DESAL plants via clean energy sources such as solar wind wave tidal etc. (which is an area my colleagues and I will have to get on board about a bit more ,cohesively) anyway all I can suggest is all you local Australian Desal scientists , need to get together,and really nut out the project in a spirit of COOPERATION rather than in an environment of that overated term COMPETITION.[We will be in touch ,lez and hopefully with some real political 'CLOUT' in the not too distant future.In the meantime maybe you blokes can get together and really 'join the dots' on this thing.]
     
  4. ppp

    ppp Junior Member

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    I'm sorry to burst the bubble, but there is NO WAY to generate electricity from the brine or any of the byproducts.

    Ojo, and lezstar, please read the saudi website you supplied properly.

    The reality is, that becasue the saudi desalination plants require so much electricity, they have their own power plants. I could not find what they are powered by (coal?, oil?, gas?) but I would assume oil or gas since they have huge quantities of the stuff.

    The organisiations which run the desalination plants, also therefore produce electricity, not by some magical process, but, simply, by burning more oil.
     
  5. 9anda1f

    9anda1f Administrator Staff Member

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    just a thought that popped into my head....

    if you flashed the brine in a focusing solar collector, couldn't you get clean water and power from the steam?

    9anda1f
     
  6. lezstar

    lezstar Junior Member

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    desalination plants

    regarding desalination ,what about that Max Whisson feller? He seems to have some pretty good ideas,in response to the bloke who said I need to really look more closely at the saudi system and its flaws ,I will mate, after this bloody election, its kinda time consuming but will be worth it if we get our bloke across the line DR Richard Nitale (greens). Its a shame we are having these preliminary debates into the issues of water and energy use NOW instead of 10 years ago but... thats what you get in a short term economic growth political environment.As I said in my last post I am NOT a scientist ,just a concerned for our future ,australian trying to come up with some solutions to the impending disasters attached to climate change. Now the main argument against these DESAL plants seem to be the prohibitive energy requirements I ask again what about solar , wind ,wave etc as an energy source for these desal things and is the waste disposal problem the main hurdle environment wise to these things being viable? ,any referrals to other sites would be appreciated,speaking of hurdles to overcome, gotta go, there is an election on and a change of govt is the first hurdle in an I hope, not too long race to get these industrys ecologically viable before its too late[ re-IPCC,s latest report],cya lez
     
  7. lezstar

    lezstar Junior Member

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    greens candidate

    just a small point in my last message I got the green candidates name a bit wrong, its richard DI natale thanks
     
  8. ppp

    ppp Junior Member

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    9anda1f: I'm not sure what this would acheive, the brine is a waste product, because of the high amount of salt in it. Extracting even more water out of the brine, will simply make it more salty, cause salt build up, and make the subsequent more concentrated brine, more difficult to dilute back into the sea.

    I think the idea is to not extract too much water, so that the waste water is more easily diluted back into the ocean.
     
  9. 9anda1f

    9anda1f Administrator Staff Member

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    :) It was a spurious thought in reference to the power needed for desalination plants (or potentially provided by them). Upon more careful reading, it appears that lezstar's question is about how to utilize the brine byproduct of the desalination process. In all I've read so far, that byproduct is referred to as a "waste". Permaculture teaches that there is no waste, only an unrealized potential from the asset.

    So, what's in that salty brine? Sea salt. Probably every trace mineral known to humans. How much factory "byproduct" (i.e., pollutants)? What is the potential to "mine" the brine? In some of the desalination plants in the middle east, the brine is further "processed" by evaporation to yield a dry "product" (dehydrated). Could this mixture be separated into various useful components? (Edit: some interesting information on the chemical makeup of seasalts https://www.curezone.com/foods/saltcure.asp)

    On a deeper note, is active desalination of our ocean water a viable option to providing fresh drinking water to masses of humanity???

    9anda1f
     
  10. Ojo

    Ojo Junior Member

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    The Saudi desal plants are integrated with their power stations so they can use wasted heat from power generation to power the desal process. (I read the links,)
    Yes, extracting the minerals from the brine is a possibility and it's being done in some places. But salt and epsom salts are pretty cheap, so not much profit incentive there. All animals need salt and if you ever bought salt licks for cattle, you would think someone is making some money there. Yes, there is a potential asset there, if you could remove the sodium, your plants would probably love it. "Culture" is as permanent as the ecosystem which supports it. I don't see it growing fast enough to make that "window of opportunity". Maybe offering free courses to gov't agencies involved in the agriculture, forestry and environmental fields and offering the course through more colleges and even grade schools would help. (are there permaculture texts suitable for all levels of education? Teaching them while they are younger and less commited to destructive habits might help) Maybe reducing the price of books on the topic and placing more permaculture books in the public domain would help. No one person or plan will will fix everything for every one everywhere. Only alot of co-operation will help now, the 'cost effective' approach means more extinctions, even our own.
    _________________________________________________-_


    Various tree species can grow in areas affected by salt and can play an important role in reducing the effects of salinity. Forests NSW' nurseries have identified a range of species that are suitable for planting in such areas and can recommend establishment techniques that will improve the chances of these trees surviving. For more information please contact one of our nurseries.
    (excerpt)
    https://www.forest.nsw.gov.au/env_servic ... efault.asp
    free book
    https://www.dnr.nsw.gov.au/salinity/solu ... book04.htm
     
  11. gnoll110

    gnoll110 Junior Member

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    Yes and No. I'm not aware of any system the CONSUMES salt to produce electricity. I am aware of two ways to use salt in the production of energy (electricity or other forms like process heat).

    Salt can be used in 'molten salt' thermal battery systems. These are the type of batteries that are needed to make solar dish and heliostat systems in to base load systems.

    https://en.wikipedia.org/wiki/Molten_salt_battery
    https://en.wikipedia.org/wiki/Heliostat
    https://en.wikipedia.org/wiki/Stirling_e ... generation

    Salt can also be used in 'saline gradient' solar ponds. From memory it takes 4000 tonne of salt to 'salt' a 20 Megalitre pond.

    https://en.wikipedia.org/wiki/Solar_pond

    So if you're prepare to foot the capital costs, you can generate desalinated water using salted water and sun light.

    RMIT research

    With all the stuff, viability depends on the price of energy generated from the fossils fuel systems you're competing against.


    Gnoll110
     
  12. ColinJEly

    ColinJEly Junior Member

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    desalination plants

    hello lezstar

    What is the problem? They are talking about building a desalination plant down at Wonthaggi. Just down the coast at Cape Schank we have a big pipe that pours megalitres of fresh water into Bass Straight.
    No Problem :D

    Cheers

    Col
     
  13. Ichsani

    Ichsani Junior Member

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    Hi lezstar,

    I'm not a politician, but I am a scientist. In short I agree with what Col says....... so on the in between......

    What is generally termed 'desalination' can refer to several processes for extracting 'pure' water from water with higher levels of dissolved salts than appropriate for drinking. The most efficient of these methods is called 'reverse osmosis' and is the type of plant that has been built and will be built in Australia.

    The Saudis have been at it for longer and also have older systems such as flash distillation (which takes far more energy than reverse osmosis (RO)) as well as the RO plants. They use both sea based disposal as well as evaporative and land based methods (including unlined ponds = straight to groundwater........ eek!).

    The amount of energy that an RO plant uses is related to the pressure gradients that must be generated in order to 'push' water molecules through the membranes and leave the salty stuff on the other side (hence reverse osmosis). The pressures needed to push the water through is related to the amount of salt in the water (as well as the level of fresh water 'recovery' per volume aimed at).

    So seawater is ~34 000 ppm dissolved salts needing between 54 and 80 bar depending on the 'recovery efficiency'.

    Below are some figures from the 2006 environmental assessment of the Kurnell plant.

    Table 1: Desalination outlet and intake volumes (EA, Appendix 2, 2006)
    Capacity (ML/day)*_____Intake (ML/day)___Discharge (ML/day)
    _________50___________141______________91
    _________200_________ 562_____________362
    _________500_________1405_____________905

    * 1 ML = 1 000 000 litres (.....silly lines are meant to make the table more readable)

    There are some very fancy 'dense jet' design outlet structures for dispersal of brine and the estimates for the near field impact zone was modelled at about 0.5 ha (5 000 m2) where salinities are expected to range between 65 000 and 45 000 ppm, falling to background levels about 75 m from the structures.

    The ocean dispersal of seawater concentrate from RO desalination and its effect upon local ecological communities is an area containing little scientific literature. As far as I know, there isn't too much risk from the anti scalents and the like and free chlorine and acidic detergents are meant to be neutralised before disposal.

    Whilst brine disposal is an issue that needs careful consideration, I think that as a whole, it is the developmental ATTITUDE (ie the super desal plant is a 'drought proof solution at the ready' for Sydney) that is a worry. Its not the technology that worries me so much as the style of its application.

    We waste so much water in this city.

    For instance, there is ALOT of stormwater just flowing out the drains of Sydney, far more than we consume. And with much much less dissolved salts than seawater, meaning far less energy for RO process. Yes there are logistical issues, timing of flows and storage and such, but its not exactly an insurmountable challenge. It just needs creative vision mixed with a good dose of common sense. Plus, RO is definitely not the only way to treat stormwater. There are other, far more appealing methods too.

    Ditto for tertiary treated wastewater. Thats a far more constant supply of water, far less salty than seawater to. And a waste stream that really should be cleaned up big time. It makes my skin crawl how much we pollute our waters.

    I think what I'm trying to say lezstar, is that flexibility and creative thinking are sorely needed in terms of planning for water security and its continuous management. A big mix of demand reduction, stormwater harvesting, waste water recycling, greywater recycling, rainwater tanks, aquifer treatment, aquifer storage, small RO plants etc etc. Where one is and what the resources available are should determine the appropriate mix, not a 'one fix wonder' approach.

    More thinking like a permie, more integration, more willingness to challenge 'business as usual' with better solutions.

    ......one day, when I take over the world........ :lol:


    Cheers
    Ichsani


    PS

    Heres some stuff on the generation of CO2 from the same EA for those who are interested.

    Table 2: Operational emissions of proposed desalination plant (EA, 2006)
    Desalination Plant Capacity__________________125ML/day___500ML/day
    Electricity demand (megawatts)__________________30_______110
    Electricity consumption (gigawatt hours/annum)*_____225_____906
    CO2 emissions (tonnes/annum)_________________240 000____950 000
    CO2 emissions to water production (tonnes/megalitre)__5.3_____5.3

    *Emission factor of 1.054 tonnes/CO2 per megawatt hour from current grid electricity

    I think that there are some plans to change some or all of the power source to greener options but I don't know the particulars.
     
  14. milifestyle

    milifestyle New Member

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    Obviously from the discussion the key is to find a use for the brine, not a way of "getting rid of it".

    I can see it bottled to spot on Hawkbit & Cats Ear in lawns - among other uses.
     
  15. Ichsani

    Ichsani Junior Member

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    Reuse instead of disposal is great, but logistically, in 600ml bottles that works out at around 377 a day of double salty sea water for each person in Sydney. We simply don't have that much lawn!

    The packaging industry would love it though :)
     
  16. milifestyle

    milifestyle New Member

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    For sure, but its one of many potential uses for the product.
     
  17. Ichsani

    Ichsani Junior Member

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    I'm going to have to side with ocean disposal on this one. Whilst some reuse is possible, the logistics make even a small proportion of reuse a substantial amount of salt. The scales involved are substantial.

    Smaller RO plants would disperse impacts if these were of particular concern.

    Or, even more adventurous, run stormwater or tertiary treated waste water through RO plants, collect the concentrate and then process that. Alot more valuable than salt, and the second bird hit with this stone is the greatly reduced pollution loads put on waterways.

    Now that would be a more permie way to do it 8)
     
  18. ppp

    ppp Junior Member

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    I did work on a small solar powered, portable reverse osmosis set up for remote communities whilst at uni. My understanding of the reverse osmosis (desalinisation) process, is that two main things increase the cost in energy and new filters
    1) the amount of salt
    2) the turbidity (amount of suspended solids)

    I have always thought that it isn't that bad, that all of these desal plants are springing up all around Australia.. as long as once they are built, they use stormwater instead.
     
  19. Michaelangelica

    Michaelangelica Junior Member

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    Re: desalination plants

    Climate change and water from the sea
    Tuesday, 16 December 2008
    By Brian Sadler


    Forty years ago a change in atmospheric circulation occurred, un-noticed. Rain-bearing systems of the south-west of Western Australia moved pole-wards. This change would delay the start of winter rains, reduce the incidence of wet winters, increase the incidence of low-rainfall winters and reduce rainfall intensities.
    , , ,.

    Twenty years ago, the drought persisted. A good wet year to rejuvenate water systems had not occurred for two decades. Internationally, climate scientists gave the first warning of human-induced climate change and in 1987 national scientists forecast a rainfall decrease as likely for the region.

    Controversially, water engineers responded by amending plans for the water systems of Perth and its hinterland. They assumed rainfall had undergone a small permanent decrease from global warming and that rainfall and water resources would follow a further slow decline amounting to 20 per cent and, by 2040, 40 per cent of historic averages.

    Despite the controversy, these risk-management responses were far from extreme.


    . . .
    Is some of this explained by natural variability? Are the models underestimating change? What is the next surprise?

    Not just the drying, but the uncertainty


    As a consequence of this history there has been a regional loss of confidence in the future reliability of surface water resources. Uncertainty, not just drying, has become a water issue in its own right. Water planners seek solutions that eliminate the climatic risk. They cannot allow serious, sustained failure in a major regional water system.

    Diversity and declining robust options

    In living with these problems, the Perth region has some advantages enjoyed by few other regions of Australia. The coastal plain has deep, unconfined and accessible aquifers, which are a source of mid-term security and have helped manage through a severe climatic crisis. These aquifers extend under the Perth metropolis. They create opportunities for water harvesting, at domestic and community level, which no other Australian city enjoys. The aquifers also enhance the future opportunity for wastewater re-use.

    Water managers make use of this diversity to pursue a full range of supply, re-use and use-efficiency measures with a community that has a relatively long history of awareness and commitment. This is a great strength of the Perth circumstance.

    Nonetheless, some measures are decidedly ‘softer’ than others.

    To be secure, the diverse system also needs growth in a robust supply core.
    . . .

    Water stress in natural water systems is growing insidiously, initiating automatic environmental change that no one likes to accept as the new reality. Such change has increased the conflict surrounding environmental water. Its mixture of inevitability and uncertainty is a public policy time-bomb.

    In these circumstances the community has widening distaste for remaining terrestrial options, particularly from their own backyard.

    Water from the sea

    Water planning of the 1990s and earlier looked at the seawater source as a post-2020 benchmark. However, events of the past decade, and loss of confidence in terrestrial water sources, have seen the 2020 options largely utilised or, in some instances, marginalised.

    The sea, by contrast, is an unlimited source, unaffected by the regional climate uncertainties.

    For major public water supplies, security is a more critical criterion than cost. The recent commissioning of a major seawater desalination unit for the Perth regional integrated water system was a development whose time had come.
    . . .

    The hydrological cycle is a natural solar-driven process that takes water from the sea, leaving its salt behind to be re-joined later. Seawater desalination might be simply viewed as a small human ‘bolt-on’ to this cycle, also taking water from the sea and leaving salt, but powered instead by engineered sources of energy. If such energy sources were truly carbon-emission-free, the seawater solution would be truly ‘climate independent’.

    In the recent Perth development the desalination project has funded an equivalent component of renewable (wind) energy in the power system. Future planning anticipates trialling a wider set of renewable energy options, including wave power.

    . . .


    What are the lessons?


    * Uncertainty, in its own right, as well as attributable climate change, creates a demand for risk-avoiding options, which are independent of climate.
    * Seawater use taps an unlimited resource that is not climate-dependent. Because of its plenitude and reliability, seawater is likely to be used increasingly as a source of security in vulnerable water systems. However, its energy use could have unwanted feedback to global warming.
    * If seawater use can occur with a neutral impact on carbon emissions it is an excellent option for many vulnerable systems.
    This is a challenge.



    Brian Sadler PSM FTSE is an engineer hydrologist with interests in water resources management, planning, public participation and the role of water in society. He has been active on issues of adaptation to climate change since the late 1980s and was independent Chair of the Indian Ocean Climate Initiative from 1998 until 2006. After 40 years with the State of Western Australia, he is now an independent consultant.

    Editor's Note: This article was first published in Australian Academy of Technological Sciences and Engineering's (ATSE) Focus Magazine issue 153 (River Health and Water). This article is under copyright; permission must be sought from ATSE to reproduce it.
    Comments. . .[/quote]
    For comments and the full article see:-
    https://www.sciencealert.com.au/opinions ... 586-2.html

    Florida USA, alone, has 130 de-sal plants and is now building another,-the biggest in the USA.
     
  20. inahd

    inahd Junior Member

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    Re: desalination plants

    wouldn't growing certain plants lower the salt levels, while making that sodium available to you?
     

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