1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Home made desale plant

  1. Jun 6, 2010 #1
    i was thinking about how desalination plants work, i havent heard of one producing powered energy as like an electric company. I was thinking making one on a miniture scale, like in the Armed forces if a trooper doesn't have any iodine tablets he/ she could urinate in a hole then put a saram wrap cover over the top of the hole and put a rock in the center, as the heat evaporates the urine and takes up the water, it then purifies the water. the evaporated water could then go thru a turbine generator and that generator could then produce electricity. possibly first go in a transformer with industrial sized capacitors then be distributed to the public. Now i know this theory isnt like what i have posted in the past here lately. I know for a fact that this theory isnt impossible, just need enough salty water and some heat. the salt would not goto waste as it could be distributed to public stores for sale. As for the money needed for the elctricity, more of its income would come from the salt sales thus the electricity could be cheaper and hardly maybe 5% waste which could be the iron and other impurities that lay afloat in the sea water.
     
  2. jcsd
  3. Jun 6, 2010 #2

    the

    User Avatar

    Any industrial process that requires heat already uses a huge amount of energy. there are also factories and refineries that already implement ways to recycle energy leakage in the process of creating the heat, not in terms of the light it produces, but in terms of lost heat, in the form of smoke (smoke turns turbines to collect energy). also they have also implemented turbines to collect energy from the movement of the water in the refineries too. these processes do produce energy which can be converted to electricity, but not in a large enough scale to produce like an electricity company. these recycled electricity is used only to re power the refining process, just a small way to cut cost by the companies. it is in no way a large enough process to run a power plant.


    "About Energy Recovery Inc.
    Energy Recovery Inc. (NASDAQ:ERII) designs and develops energy recovery devices that help make desalination affordable by significantly reducing energy consumption. Energy Recovery's PX Pressure Exchanger™ (PX™) device is a rotary positive displacement pump that recovers energy from the high pressure reject stream of seawater reverse osmosis systems at up to 98 percent efficiency. The company is headquartered in the San Francisco Bay Area with offices in key desalination centers worldwide, including Madrid, Shanghai, Florida and the United Arab Emirates. For more information about Energy Recovery Inc. and the PX technology, please visit www.energyrecovery.com."

    this is an example http://www.waterworld.com/index/display/article-display/5257610665/articles/waterworld/world-regions/australia-oceania/2010/02/Australia-desalination-plant-expansion-to-incorporate-energy-efficiency-devices.html" [Broken]

    sorry for pouring cold water on your project
     
    Last edited by a moderator: May 4, 2017
  4. Jun 6, 2010 #3
    the website is great and all, but im talking about a small scale for a house. breaking the water up and using that steam for pure water and that steam would go thru a turbine generator for power.
     
  5. Jun 6, 2010 #4
    that info that i read from you and that site did help on my theory, but not upon a desal for a house, like a purifier with salt rocks that sit on the side of some homes.
     
  6. Jun 6, 2010 #5

    the

    User Avatar

    hm.. i would still question the energy efficiency of having a purifier of that sort in a house (you need to heat the process) but ive never done this project before so i don't have solid prove.

    would just advice you on looking at the ratio of energy used to power the process to energy received from the process. compare this to the cost of getting bottled water or the cost of using the services of your public utilities etc.





    side note about the salt:
    also about the salt.. not a physics idea but would you use salt you got from your urine?
    (it would be your main salt water source in a home unless you live near the sea)

    but for the desalination project, you could try =)
    good luck

    btw, don't let me discourage your project. any idea is worth working on.
    if it succeeds, excellent, if it doesn't, build on it!
     
    Last edited: Jun 6, 2010
  7. Jun 7, 2010 #6
    i think salt is salt on a technical scale, the heating ratio would be what temp does water boil at? and to having a water proof ducted fan. thinking a capacitor and transformer would be coming from the generator so if it does work you dont throw a breaker and your lights shut off or blowing your light bulbs and frying your electrical system of your house would be a good note lol.

    bottle water here cost about $1.69 for a 12oz
     
  8. Jun 7, 2010 #7

    russ_watters

    User Avatar

    Staff: Mentor

    I hesitate to post this link because I consider the project to be a boondoggle, but the concept is sound, so have a look at this site: http://www.enviromission.com.au/EVM/content/home.html

    In short, they are attempting to capture and funnel an updraft through a tower and use the resulting wind to create energy. A side effect of this process is condensation on the inside of the tower (the process is the same as what causes thunderstorms, just captured to produce energy), which fits your description fairly well.
     
  9. Jun 7, 2010 #8
    Yeah, well, peeing in a hole to generate electricity through evaporative measures to influence any substantive turbine activity is just ridiculous.
     
  10. Jun 7, 2010 #9

    alxm

    User Avatar
    Science Advisor

    Desalination by evaporation is very inefficient, and always will be, because
    1) Heat transfer creates entropy
    2) The amount of heat required for evaporation is huge compared to the amount of energy required for the actual desalination. (To get the idea, consider that the boiling point of sea water is only about 3 degrees higher than for pure water)

    Of course, and if you were to use evaporation for desalination, you wouldn't have any surplus heat. Any sane design would have a counterflow heat-exchanger to use the output stream to preheat the input stream.
     
  11. Jun 7, 2010 #10
    Very intresting, i read the descriptions of this project in austrailia and sounds like something thats state of the art in producing green power with out any kind of green house gases. infact i like that idea and i think i could possibly use part of that in my project as everyone knows Heat flows up along with any gases lighter than air.
     
  12. Jun 7, 2010 #11
    this was only an example of how to clean your urine to be drinkable, yea it may not be the best idea or water, but if your parched for thurst then you will do it if theres no other area that holds drinking water. I have actually did this in high school in JROTC though we did have iodine tablets our 1st sergent just wanted us to have a hands on test of actually knowing how to make drinkable water. Then after that and alot of PT we did the iodine tablets.

    As hot as it gets in Florida it didnt take very long for the urine to evaporate to be drinkable, i will admit the taste was alittle tangy but it was clean water. Also i seen the same thing on Bear Gyles survivor show on the Discovery channel, which i do watch alot of aswell with NatGeo, and the history channel.
     
  13. Jun 7, 2010 #12
    how would desalination by evaporation be inefficient? aslike in power plants they use i want to say coal to boil water and as we all know heat rises and along with that rise would be the evaporated water which both turns the turbine generator thus creating electrical power.

    well if i understand this correctly, just like a aircondition unit, water inside the condensor is heated then cooled and a fan blows the air into the living space thru a filter. with a project of what im thinking could use the concept of the A/C as the water is boiled and evaporated the water is broken down to a friendly gas and rises with the heat then when it reaches the normal temp it would then be funneled to a "cooling tube" and be distrubuted. If the water is in large amount in the open space, its preheated by maybe just a couple degrees, depending on the outside temprature and water temprature (lol maybe on how the sun feels that day) the water would be varied in its temprature on different days
     
    Last edited: Jun 7, 2010
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook