Geothermal energy in Ireland

GT Energy has applied for permission for a deep geothermal power plant in South Dublin. This has attracted some media attention (here, here, here) and Paul Cunningham cast me in my standard naysayer/party-pooper role.

The media attention is overblown. The project is small. It is only an application for planning permission. The legal framework for exploiting these resources has yet to be designed. Subsidies for geothermal power are zero at present.

The cost of geothermal energy depends, to a large extent, on the depth of the hole that needs to be drilled to get to the heat below our feet. In Iceland, Mother Nature nicely brings the hot water to the surface. GT Energy plans to drill 4 kilometers deep in South Dublin.

Unfortunately, Ireland is at a geological disadvantage in this regard (although mercifully free of volcanoes by the same token). As shown on this map (peer-reviewed version here, but in B&W and behind a pay wall), you’d need to drill deeper in Ireland than elsewhere in Europe to get to the hot stuff.

Therefore, if GT Energy can get this to work at a profit in Ireland, they’d be best advised to apply the technology elsewhere and make buckets of money. I will not invest in their company, but others are free to try their luck.

34 replies on “Geothermal energy in Ireland”

A number of years ago I saw a map that showed a few isolated locations in Ireland where geothermal was much closer to the surface. Not as close as in Iceland, but enough to make it worth a look.

Perhaps someone else will know more. The publication may have come through SEI.

i didn’t realise you had a standard naysayer/party pooper role! i wonder who this paul cunningham guy is. as you say, this project sounds very early stage, but the media attention shows the hunger for new ideas i think.

We might not have great geo thermal heat, but,
We are a great country for providing funds and subsidies.
We might even agree to a ten or fifteen year plan.
Might even raise electricity prices again to help…..

@ Richard,

All well and good if it can be made work, provide constant heat, low contaminants, low maintenance etc etc etc.

However 30m is a lot for 4Mw. Is that 4Mw electrical or 4Mw thermal?

What I don’t understand is that the plant will be mainly used for research and development.

What does this mean? If geothermal has been around for 100 years in some other countries then what research and development is going to be carried out in south Dublin that has not already been carried out elsewhere?

I’m surprised that geothermal doesn’t get at least equivalent help to wind – not least since it should be more predictable. Back in the glory days a handout to a unit at the Giant’s Causeway (most likely the best location on the island) would have been grabbed with both hands by the deep thinkers at Foreign Affairs (like how we subsidised flights between Dublin and Derry and paid for roads in NI).

I took one look at the geothermal map that Richard linked and thought “isostatic rebound”. Anyone here know enough geology to confirm or reject that?

After lots of discussion on this site about governments lack of ability to pick winners it now seems that you dont like the private sector trying it either. I’d say that PC is probably right to portray you in thay way. But dont feel bad as you are Sarah Carey’s go to guy 😉

So Paul Cunningham makes RTol’s enemies list. Not really surprising, given that he unearthed that incinerator get-out clause…

@Richard. I would share your concerns Richard but good luck to them all the same. Maybe down the line it will add up financially.
This is nothing new though. It was discovered way back in the 80’s and has been looked at since then.

I would have thought that a straight district heating system would require much less expensive infrastructure than electricity generation, espeically when they have to rely on the ESB.
You could use it to heat large scale buildings in South Dublin (too expensive to go residential) such as Vincent’s Hospital, UCD, ORTE etc. I’m not going to get into the costs in detail here but from what I read on the subject a few years ago this kind of application seemed the most viable.

Thanks for the maps.
Edenderry in the RoI; Dungannon and Coleraine in NI.

Why would GT Energy want to develop a pilot project in South Dublin where the geothermal energy is much deeper? Why not in the Edenderry/Tullamore area? Or in Coleraine?

What am I missing? There has to be more to this story.

Are they really testing a new technology for drilling 4km holes and the geothermal is a smokescreen or a way to get significant funding?

Maybe the question should be, what IS in South Dublin that might be of interest to GT Energy?

Ireland needs a miracle, so drilling into the ground may provide some interesting discoveries. Anyone who says they know what is underground is a charlatan. Always worthwhile especially if the results are made public, which seems fair in exchange for these tax credits. Once public money is paid, the results should belong to the public.

The location may provide viable marketing due to the density of customers.

Here’s hoping!

@ OAC,

Something does not add up with this one. It would be good if somebody from GT energy came on here and explained the issues. Perhaps a short paragraph or two would explain everything.

Drilling a 4Km bore is expensive, but I believe there are newer cheaper methods available now, so it is not as expensive as in the past.

If it can be made work at a cheap price then I am all for it. But as mentioned in the article a lot of things have to fall into place, including the REFIT payments. That’s the bit you and I have to pay for as taxpayers.

As most people are aware, geothermal heat derives from radioactive decay of isotopes of uranium, potassium etc with the earth. In other words, from nuclear fission.

It is illegal to generate power using nuclear fission in Ireland. Therefore GT Energy’s proposal is illegal.


Does it make any sense to YOU that a company would drill a 4km hole rather than a 2.5km hole, if the actual purpose is to generate electricity from geothermal sources?

As per Sporthog, “something does not add up with this one”.

@bg In that case solar power is also illegal; and if you want to take that argument to its ultimate conclusion, all forms of energy production are illegal as they involve material that was created by nucleosynthesis.


Section 18(6) of the 1999 Electricity Regulation Act prohibits electric power derived from nuclear fission

“18(6) An order under this section shall not provide for the use of
nuclear fission for the generation of electricity.”

No mention of fusion, so solar power appears to be legal.


“WHO is in South Dublin?”

A) You think if they drill down 4km in South Dublin they might find someone hiding down there?

B) Or did you mean, WHOSE South Dublin property might get purchased for €€€ for this project?

C) Or, WHAT SOUTH DUBLIN POLITICIAN might want kudos for such a scheme in their constituency?

D) Something else?

The TDs from the greater Edenderry area should wake up.

They probably don’t know they have closer-to-the-surface geothermal potential in their constituency.

They might find someone even better than Elvis.

I worked on a geothermal well in Idaho—-the water under pressure was 300C and the flashed steam was not hot enough to run a turbine—-the water was also very dirty—if you cooled it you got lots of deposits which would foul up a heat exchanger.
We were attempting to heat a secondary fluid with which to run a turbine.
The whole experiment ended in failure, and cost the US gov. a lot of dough.
We need to be told a lot more about this project, before any grants of our money are sunk into it.

I don’t know what the expected geo temperatures are in the Irish context but taking the example Denis gave, water at 300C is at a pressure in excess of 85 bar. At 85 bar and 300C in the liquid state water has a heat content of approx. 1345 kJ/kg.

I don’t have exact figures but a generator turbine would require steam pressures of around 40 bar and steam superheated to over 300C. Dropping the water pressure from 85 bar to 40 bar will result in having a water state and a steam state with the water containing 1087 kJ/kg and the steam 258 kJ/kg both at a temperature of 250C – but this is wet steam and will need to be dried by superheating to over 300C by the application of additional heat.

Where does the additional heat come from. It could come from the geothermal water as Denis said it wasn’t possible to use the 300C water as it was dirty and clogged up the heat exchangers.

Seems to me that there is some “free” heat to be obtained but to exploit it for electricity generations does pose some problems. It all depends on the temperature and pressures encountered. Perhaps turbines with a lower inlet pressure could be used and the 40 bar steam pressure further dropped to superheat it at the lower pressure. My memory of thermodynamics is a little rusty so any engineers out there might like to correct my musings.

Ireland is impoverished in geothermal energy resources, mainly because it lies outside the sphere of recent Alpine tectonic activity and is distant from plate boundaries. Geothermal gradients in Ireland, based on measurements in deep boreholes, range from 3oC/km to 43oC/km with a mean gradient of 25oC/km.

Such were the findings of the ‘World Geothermal Congress 2005’ here:

On domestic household level the story might look different. A friend build his 300SqFt house in Donegal a few years ago and uses GT to heat the house and water. It is quite a slick installation, a modem dials out, if Eircom is not offline, in case there is an error reported on the system. The company then contacts the owner and advises on a service date. The capital required for the installation was substantial, and no grants existed when he invested this six years ago.

“The legal framework for exploiting these resources has yet to be designed.”

Would you agree that the legal framework for the District Heating promised by Covanta also does not exist?

I understand that heating is more individual in Ireland than elsewhere is Europe. This reduces the potential for district heating. I’m not sure whether the issue is legal or cultural.


There are big legal impediments. There is a good opportunity for legal reform but a constitutional referendum might be required. We could group it with the constitutional referendum on the retrospective abolition of upwards only rent reviews.

Geothermal energy is the result of radioactive decay. It does qualify as nuclear fission either scientifically or legally. I’d have expected a self-described ‘climate scientist’ to have noticed this error.

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