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Geothermal hot water 3000m under Larne

  • 20-10-2007 9:36pm
    #1
    probe
    Closed Accounts Posts: 2,055 ✭✭✭


    The Irish Examiner had an item recently on the finding of geothermally heated water at -3000 m under Larne which is close to 100C in temperature. Ideal for a CHP type heating system for the area. One wonders what other parts of Ireland have hot water under ground if one digs deep enough? Old spa towns are prime candidates. The water at the Mallow spa source is about 20C as it emerges at ground level. One wonders how hot it is deep down in the ground?

    90% of houses in Iceland are heated by geothermal energy.

    http://www.os.is/page/english/

    Iceland is planning to install an electric grid connection to export electricity generated by geothermal and hydro power to mainland Europe. One suspects they will have it up and running long before Ireland gets similar grid connections going!

    .probe


Comments

  • #2
    SeanW
    Registered Users, Registered Users 2 Posts: 9,167 ✭✭✭SeanW


    Iceland is also sitting on a hell of a lot of volcano activity, which Ireland - thankfully - is not.


  • #3
    probe
    Closed Accounts Posts: 2,055 ✭✭✭probe


    SeanW wrote: »
    Iceland is also sitting on a hell of a lot of volcano activity, which Ireland - thankfully - is not.

    The absence of seismic activity does not mean that there is no geothermal energy available if you dig deep enough. The area around Baden (NW of Zurich) has geothermal springs – but no signs of earthquake activity - http://www.earthquake.ethz.ch/research/Swiss_Hazard

    The same goes for many other spa areas around Europe.

    .probe


  • #4
    Gurgle
    Closed Accounts Posts: 5,064 ✭✭✭Gurgle


    probe wrote: »
    The Irish Examiner had an item recently on the finding of geothermally heated water at -3000 m under Larne which is close to 100C in temperature. Ideal for a CHP type heating system for the area.
    You wouldn't need a CHP heating system, just circulate the water through your radiators.

    Unfortunately, a column of water can only be drawn up to about 10m before a vacuum is formed by the weight of the column. So to pump up from 3000m would require a 30-stage pumping system.

    With a pressurised closed loop system, this can be increased. I'm not sure by how much but if its linear you could circulate it in one stage at 30 bar or so. A bit much for a central heating system though.


  • #5
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 93,588 Mod ✭✭✭✭Capt'n Midnight


    Gurgle wrote: »
    Unfortunately, a column of water can only be drawn up to about 10m before a vacuum is formed by the weight of the column. So to pump up from 3000m would require a 30-stage pumping system.

    With a pressurised closed loop system, this can be increased. I'm not sure by how much but if its linear you could circulate it in one stage at 30 bar or so. A bit much for a central heating system though.
    not too sure but wouldn't the water down there be under pressure anyway so you wouldn't need to pump all the way. You would not send the water directly to the radiators because of corrosion and pollution. A simple heat exchanger should do. Steam from a power station is clean, water from 3000m downmay have enough dissolved minerals to make it worth your while to try to recover them, or maybe not.


  • #6
    maniac101
    Registered Users, Registered Users 2 Posts: 233 ✭✭maniac101


    True geothermal resources are very limited in Ireland and are not in any way comparable to Iceland's. As someone mentioned earlier, this is related to the levels of seismic activity in both countries. Larne is the only high-enthalpy geothermal potential on this island. In the 80's an attempt was made to drill 3km down at Larne but the yields were poor and the hole clogged up. I believe there were vague plans to provide a district heating system to Belfast at the time.

    There is some low-enthalpy geothermal potential in the republic. This involves exploiting either geothermal heat in warm springs (as is the case in Mallow) or "geosolar" heat captured in buried valleys and aquifers. This is low-grade heat and is unsuited to electricity generation, but it can be used for heating and cooling of buildings, for small district heating systems, or for heating of swimming pools and greenhouses.

    "Geosolar" is a renewable energy resource whereas true geothermal is not.


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  • #7
    ircoha
    Closed Accounts Posts: 2,290 ✭✭✭ircoha


    maniac101 wrote: »
    "Geosolar" is a renewable energy resource whereas true geothermal is not.

    How come?


  • #8
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 93,588 Mod ✭✭✭✭Capt'n Midnight


    ircoha wrote: »
    How come?
    Estimates of the core-mantle boundary heat flux are between 8 and 10 TW - so that's the upper limit on continued heat extraction after we have cooled down all the stored heat.

    Potassium-40, has a radioactive half-life of about 1.2 billion years
    The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years.


  • #9
    ircoha
    Closed Accounts Posts: 2,290 ✭✭✭ircoha


    Capt'n Midnight wrote: »
    Estimates of the core-mantle boundary heat flux are between 8 and 10 TW - so that's the upper limit on continued heat extraction after we have cooled down all the stored heat.

    Potassium-40, has a radioactive half-life of about 1.2 billion years
    The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years.

    What effects would this have on the position of the magnetic north pole MNP, from a navigational perspective, or will we be extinct as a species well before the shift in MNP is material?


  • #10
    BendiBus
    Closed Accounts Posts: 2,074 ✭✭✭BendiBus


    ircoha wrote: »
    What effects would this have on the position of the magnetic north pole MNP, from a navigational perspective, or will we be extinct as a species well before the shift in MNP is material?

    I think magnetic north is due to flip any day now. It should turn up somewhere in Antarctica. Happened several times before apparently and it's overdue!


  • #11
    bowsie casey
    Closed Accounts Posts: 332 ✭✭bowsie casey


    probe wrote: »
    The Irish Examiner had an item recently on the finding of geothermally heated water at -3000 m under Larne which is close to 100C in temperature.

    AFAIR from my oil days, 100C would be a very typical reservoir temperature at this depth (standard temperature gradient of 3C/100m). Therefore, not so sure what is special about Larne...maybe its the presence of a suitable aquifer ?


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  • #12
    probe
    Closed Accounts Posts: 2,055 ✭✭✭probe


    bowsie casey wrote: »
    AFAIR from my oil days, 100C would be a very typical reservoir temperature at this depth (standard temperature gradient of 3C/100m). Therefore, not so sure what is special about Larne...maybe its the presence of a suitable aquifer ?

    Probably not a lot special about Larne - other than someone dug deeply enough! (They were digging for minerals and came across the hot water AFAIR). There was a news item over the last ten days about a company prospecting for deep hot water along a fault line which runs from memory between North Co Dublin into Co Louth, near the Irish Sea coastline.


  • #13
    maniac101
    Registered Users, Registered Users 2 Posts: 233 ✭✭maniac101


    probe wrote: »
    Probably not a lot special about Larne - other than someone dug deeply enough!

    No, the north-east of the island simply has a steeper temperature gradient than elsewhere. It's due to the younger sedimentary rock there. This is why the deep geothermal potential there is greater than in the republic.


  • #14
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 93,588 Mod ✭✭✭✭Capt'n Midnight


    ircoha wrote: »
    What effects would this have on the position of the magnetic north pole MNP, from a navigational perspective, or will we be extinct as a species well before the shift in MNP is material?
    We'll be stuck withjust GPS / Galileo / Glonass / Loran / Beacons / GPS masts / Astronavigation

    Magnetic north isn't used much as it wanders around. Airport runways get renamed when they move relative to magnet north though.


  • #15
    probe
    Closed Accounts Posts: 2,055 ✭✭✭probe


    maniac101 wrote: »
    No, the north-east of the island simply has a steeper temperature gradient than elsewhere. It's due to the younger sedimentary rock there. This is why the deep geothermal potential there is greater than in the republic.

    While that may well be the case, someone is planning to spend €22 million on geothermal energy (digging up to 6,000 m) as far south as the Newcastle-Rathcoole area.

    http://www.ireland.com/newspaper/ireland/2007/1025

    .probe


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