Deep geothermal energy

Renewable energies except solar electric or thermal (seeforums dedicated below): wind turbines, energy from the sea, hydraulic and hydroelectricity, biomass, biogas, deep geothermal energy ...
lilian07
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Re: Deep geothermal energy




by lilian07 » 09/06/16, 11:22

usages_geothermie2.jpg


The price of drilling as a function of depth is exponential and at this depth the investment is very heavy. In addition, as we are in particular areas of the earth's crust, we must prospect and therefore drill (the radar survey is not enough, it is a risk-taking aid ...).
Profitability is therefore uncertain even when a hot deposit is found.
However, the BGRM is increasing its studies because it has grasped the importance of this resource (the soil).
Drilling remains the black point of the problem.
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Re: Deep geothermal energy




by Christophe » 09/06/16, 11:26

Yes it was drilling that had posed the most concerns at Soultz ... according to my vague memories of this visit (it's been 13 years anyway)

Several years were required to drill and line the borehole in a sustainable manner
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Re: Deep geothermal energy




by Did67 » 09/06/16, 11:46

This had raised the question of the risk of earthquakes (as soon as we do something, there are those who are against it!). Alsace is a seismic region. We are on a fault ...

And then it is one of the most important water tables in Europe. So the risk of drilling through and not mastering the seal also existed ...

A "certain" concern was legitimate!
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Re: Deep geothermal energy




by Christophe » 09/06/16, 12:46

Yes there had been one (of ??) small earthquake attributable to a Swiss geothermal project (it seems to me) in Sundgau a few years ago ... the risk remains low because the earthquakes really not very important (and still you have to prove that it is linked ...)

For the tablecloths it is a much more complex problem to solve in the event of problems ...
Oilers know very well how to pierce ... repair a leak, generally, much less ... see the BP Deepwater disaster horizon ...

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Re: Deep geothermal energy




by Did67 » 09/06/16, 15:38

Well let's say that if we are "honest", it is difficult to be so that we break through in the case of geothermal energy (because it is green) and not when it is for gas or oil ... [Although there are lots of people whose arguments vary depending on whether it's them or the others, whether it's the naughty capitalists or the nice green-bob ... etc ... etc ...]

I can no longer find where it was, but a few years ago, a German village suffered major damage following a geothermal drilling which had inadvertently "pierced" a water table ...

Ah, there you go : http://www.spiegel.de/wissenschaft/natu ... 89944.html

http://www.spiegel.de/wissenschaft/natu ... 89944.html

Image

Image

They had fallen on a veneer of gypsum (plaster): that the rising water had "dissolved":

Image

So the breakthrough of the water table was automatic, in the Rhine basin (the entire Rhine plain is occupied by a water table and the border does not even stop it!). It was the gypsum lens that had not been planned!

Fortunately, for large projects, preliminary studies are more serious than for geothermal drilling!
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Re: Deep geothermal energy




by Christophe » 09/06/16, 16:21

Ah yes "pretty" damage!

Funny the radiator completely flared while the wall behind has nothing at all? Or then everything has been redone and the radiator has been kept as a "souvenir" ???

When you say geothermal drilling, was it for a heat pump? I read German but not all visitors here ...
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Re: Deep geothermal energy




by Did67 » 09/06/16, 17:54

Yes, it is geothermal energy (PAC). It is the town hall which should thus be heated. The boreholes were made at 140 m. By doing this, we crossed a layer of calcium sulphate called "anhydrite", then reached a layer where the pressurized water was. The water rose, the anhydrite turned into gypsum and swelled ... The village rose up! So that's a summary.

According to Wikipedia:


Calcium sulfate is an anhydrous, solid mineral chemical compound with an ionic structure, simply formed by a sulfate anion and a calcium cation, with the chemical formula CaSO4 and a molar mass of 136,14 g / mol1.

It actually corresponds most often to a natural mineral body, called anhydrite, typical of evaporites, fairly abundant, although hidden because it degrades by swelling with water, most often generating on the surface a dihydrate compound, CaSO4 · 2H2O , an emblematic mineral of evaporite rocks, even more abundant, known by mineralogists or geologists under the name of "gypsum"
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lilian07
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Re: Deep geothermal energy




by lilian07 » 09/06/16, 19:36

Impressive work on the structure of the building. For a simple drilling for a heat pump it is incredible.
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Re: Deep geothermal energy




by Obamot » 09/06/16, 20:10

Did67 wrote:Well let's say that if we are "honest", it is difficult to be so that we break through in the case of geothermal energy (because it is green) and not when it is for gas or oil ... [Although there are lots of people whose arguments vary depending on whether it's them or the others, whether it's the naughty capitalists or the nice green-bob ... etc ... etc ...]

I can no longer find where it was, but a few years ago, a German village suffered major damage following a geothermal drilling which had inadvertently "pierced" a water table ...

Ah, there you go : http://www.spiegel.de/wissenschaft/natu ... 89944.html

http://www.spiegel.de/wissenschaft/natu ... 89944.html

Image

Image

They had fallen on a veneer of gypsum (plaster): that the rising water had "dissolved":

Image

So the breakthrough of the water table was automatic, in the Rhine basin (the entire Rhine plain is occupied by a water table and the border does not even stop it!). It was the gypsum lens that had not been planned!

Fortunately, for large projects, preliminary studies are more serious than for geothermal drilling!

The guys who drilled that well were a little pissed off, or? The precautions also apply to "small" boreholes!
- the village is in the Rhine basin. Until then no problem, everyone knows that we will probably fall into the water table ...
- whoever does the job knows very well (in principle) that drilling even at medium depth is not without danger, so always there, nothing special, it's routine ... he must take all his precautions.
- but when the guy does his drilling, the resistance he meets must give him indications on the nature of the basement, which as everyone knows is composed of layers (this is the b_a ba in public works)
- thus arriving in a softer layer, he must stop, then put up a carrot to find out what he came across (sand, molasse, old buried alluvium or what do I know). And when he brought up calcium sulphate, it should have twisted in the brains of the guys from the design office, and they should have stopped drilling (amha).

It's still astonishing! Because if he drilled with pressurized water, nothing but the rising water could have given him a first clue, even without coring! If in doubt, maybe it was just a matter of having the well water analyzed? Anyway, it's always easy to give advice "after the fact" of course, but it would be interesting to know what was the result of the investigation and if responsibilities were released (or not) and if so, why ?
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Re: Deep geothermal energy




by Christophe » 11/06/16, 16:11

lilian07 wrote:Impressive work on the structure of the building. For a simple drilling for a heat pump it is incredible.


It is not really the drilling which distorted but as the diagram posted clearly shows (obviously exaggerated in the proportions) by did67: the water which caused the gypsum pocket to swell which therefore raised the surface
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