<p>I always considered geothermal energy a vast, emission-free green energy source. That is, if you happen to live in the right place. That also seems to be the sentiment online.</p>
<p>I live in Italy, in the &quot;right place&quot; — a seismically active area. A few “binary” geothermal plants are located nearby, with many more planned over the coming years, mainly due to the EU energy crisis. Here, many people vehemently oppose these projects. So, I did some research, and what I found surprised me. I would like to tap the wisdom of the crowd to understand if I got anything wrong and gain additional perspectives.</p>
<p>I found that geothermal refers to two different technologies.</p>
<ol>
<li><p>The first uses geothermal heat for heating houses. Water is injected into the ground in a closed loop, heated, and used as a heat source. The underground temperature needed for this system is not high. This seems to be a clean and sustainable system. The only problem is that it is only possible to transport the hot water a short distance before the water in the pipes cools down. It is, therefore, limited in its utility and economic value.</p>
</li>
<li><p>The second uses geothermal heat to drive a turbine. Electricity is then transported via the grid. The problem is that a much higher water temperature is required to turn water into steam. Also, much energy is lost in the conversion process from heat to electricity. To overcome these difficulties, fracking is used. Not just one time but periodically since the underground water temperature drops over time.</p>
</li>
</ol>
<p>This is problematic for several reasons:</p>
<ol>
<li><p>Fracking has been shown to trigger earthquakes [1], and since geothermal is viable mainly in areas that are already seismically active, such as where I live, it seems to be a bad match.</p>
</li>
<li><p>Since geothermal activity has started in the area, the level of arsenic, other toxic minerals, and heavy metals in the groundwater has risen. In some places, arsenic is now at twice the level recommended by the WHO and over the legal limit [2].</p>
</li>
<li><p>Since geothermal activity has started in the area, the water level in the aquifer has dropped by 200 to 300 meters. In addition, the flow rate of many rivers has decreased significantly or even ceased completely. This seems to be related to the fracking activity, and since this area provides water to several cities in central Italy, it seems to be a big problem [3].</p>
</li>
</ol>
<p>Even more surprisingly, according to my calculations, Solar seems to be a more economical option. The last plant built here has a 40 MW capacity, and the construction cost around 130 million euros [4]. An equivalent solar installation only costs 30 million euros [5]. In addition, the running costs for solar plants seem to be lower than those of geothermal ones. Solar does require more land, about 100 hectares for a 40 MW plant, but land is abundant around here.</p>
<p>Another important fact is that the Government of Italian incentivizes energy companies since geothermal electricity is considered green. For each MWh produced, a plant receives an incentive of 99 euros. Considering that it produces 300 gigawatt-hours annually, the incentive is 29.7 million euros. Incentives are given for a 25-year period, so overall, 742.5 million euros [6].</p>
<p>Am I getting anything fundamentally wrong in my reasoning? If not, should we consider geothermal electricity green? Any advice is appreciated.</p>
<hr />
<p>[1] <a href="https://doi.org/10.1126/science.aag2583" rel="nofollow noreferrer">https://doi.org/10.1126/science.aag2583</a></p>
<p>[2] <a href="https://www.ars.toscana.it/2-articoli/4707-geotermia-e-salute-in-toscana-presentato-il-rapporto-2021-di-ars.html#" rel="nofollow noreferrer">https://www.ars.toscana.it/2-articoli/4707-geotermia-e-salute-in-toscana-presentato-il-rapporto-2021-di-ars.html#</a> (Italian)</p>
<p>[3] <a href="https://www.intechopen.com/chapters/79332" rel="nofollow noreferrer">https://www.intechopen.com/chapters/79332</a></p>
<p>[4] <a href="https://www.ilgiunco.net/2016/07/25/bagnore-4-ecco-la-centrale-costata-130-milioni-produrra-310-milioni-di-kilowattora-allanno/" rel="nofollow noreferrer">https://www.ilgiunco.net/2016/07/25/bagnore-4-ecco-la-centrale-costata-130-milioni-produrra-310-milioni-di-kilowattora-allanno/</a> (Italian)</p>
<p>[5] <a href="https://www.pfnexus.com/blog/starting-a-solar-farm" rel="nofollow noreferrer">https://www.pfnexus.com/blog/starting-a-solar-farm</a></p>
<p>[6] <a href="https://www.internazionale.it/reportage/stefano-liberti/2020/07/24/italia-energia-alto-rischio" rel="nofollow noreferrer">https://www.internazionale.it/reportage/stefano-liberti/2020/07/24/italia-energia-alto-rischio</a> (Italian)</p>

CC BY-SA 4.0
2023-10-13T23:33:24.697Z
What is considered "green" is a matter of opinion, thus off-topic here. I live in California, and electricity from geothermal power plants is considered part of the renewable portfolio. Next to hydro power plants these are the largest renewable source power plants capable of supporting [base load](https://en.wikipedia.org/wiki/Base_load). They do have minor GHG emissions (I think mostly CO₂ and sulphur compounds). From my limited understanding, the oldest fields now require injection of treated water from sewage treatment plants for adequate steam production.
njuffa
CC BY-SA 4.0
2023-10-14T07:34:03.050Z
You may want to read Tom Murphy's [post](https://dothemath.ucsd.edu/2012/01/warm-and-fuzzy-on-geothermal) on geothermal energy.
Rodrigo de Azevedo
CC BY-SA 4.0
2023-10-15T22:10:02.083Z
fracking is not equal to geothermal, fracking is mostly used to produce natural gas. Also there are many places solar cannot be built. Are you talking about a specific place?
John
CC BY-SA 4.0
2023-10-16T10:01:15.273Z
@john, the plants in my area (southern Tuscany, Italy) pump high-pressure fluid in order to fracture the bedrock and extract more energy. I am not sure if the liquid used is precisely the same as is used for oil and gas, but it is literally hydraulic fracturing.
yoav.aviram
CC BY-SA 4.0
2023-10-16T21:31:52.100Z
Fracking is the same in both, but fracking is pretty rare in geothermal. Its use in your case is not representative of geothermal. fracking is rarely a good idea but that is about fracking not geothermal.
John
<geothermal-heat><fracking>
Should geothermal electricity be considered green?
yoav.aviram
# Should geothermal electricity be considered green?

(Asked by: username_0 on 2023-10-13)

I always considered geothermal energy a vast, emission-free green energy source. That is, if you happen to live in the right place. That also seems to be the sentiment online.

I live in Italy, in the "right place" — a seismically active area. A few “binary” geothermal plants are located nearby, with many more planned over the coming years, mainly due to the EU energy crisis. Here, many people vehemently oppose these projects. So, I did some research, and what I found surprised me. I would like to tap the wisdom of the crowd to understand if I got anything wrong and gain additional perspectives.

I found that geothermal refers to two different technologies.

1. The first uses geothermal heat for heating houses. Water is injected into the ground in a closed loop, heated, and used as a heat source. The underground temperature needed for this system is not high. This seems to be a clean and sustainable system. The only problem is that it is only possible to transport the hot water a short distance before the water in the pipes cools down. It is, therefore, limited in its utility and economic value.
2. The second uses geothermal heat to drive a turbine. Electricity is then transported via the grid. The problem is that a much higher water temperature is required to turn water into steam. Also, much energy is lost in the conversion process from heat to electricity. To overcome these difficulties, fracking is used. Not just one time but periodically since the underground water temperature drops over time.

This is problematic for several reasons:

1. Fracking has been shown to trigger earthquakes [1], and since geothermal is viable mainly in areas that are already seismically active, such as where I live, it seems to be a bad match.
2. Since geothermal activity has started in the area, the level of arsenic, other toxic minerals, and heavy metals in the groundwater has risen. In some places, arsenic is now at twice the level recommended by the WHO and over the legal limit [2].
3. Since geothermal activity has started in the area, the water level in the aquifer has dropped by 200 to 300 meters. In addition, the flow rate of many rivers has decreased significantly or even ceased completely. This seems to be related to the fracking activity, and since this area provides water to several cities in central Italy, it seems to be a big problem [3].

Even more surprisingly, according to my calculations, Solar seems to be a more economical option. The last plant built here has a 40 MW capacity, and the construction cost around 130 million euros [4]. An equivalent solar installation only costs 30 million euros [5]. In addition, the running costs for solar plants seem to be lower than those of geothermal ones. Solar does require more land, about 100 hectares for a 40 MW plant, but land is abundant around here.

Another important fact is that the Government of Italian incentivizes energy companies since geothermal electricity is considered green. For each MWh produced, a plant receives an incentive of 99 euros. Considering that it produces 300 gigawatt-hours annually, the incentive is 29.7 million euros. Incentives are given for a 25-year period, so overall, 742.5 million euros [6].

Am I getting anything fundamentally wrong in my reasoning? If not, should we consider geothermal electricity green? Any advice is appreciated.

---

[1] <https://doi.org/10.1126/science.aag2583>

[2] <https://www.ars.toscana.it/2-articoli/4707-geotermia-e-salute-in-toscana-presentato-il-rapporto-2021-di-ars.html#> (Italian)

[3] <https://www.intechopen.com/chapters/79332>

[4] <https://www.ilgiunco.net/2016/07/25/bagnore-4-ecco-la-centrale-costata-130-milioni-produrra-310-milioni-di-kilowattora-allanno/> (Italian)

[5] <https://www.pfnexus.com/blog/starting-a-solar-farm>

[6] <https://www.internazionale.it/reportage/stefano-liberti/2020/07/24/italia-energia-alto-rischio> (Italian)

**Tags:** geothermal-heat, fracking

> **Comments:**
> **username_1**: What is considered "green" is a matter of opinion, thus off-topic here. I live in California, and electricity from geothermal power plants is considered part of the renewable portfolio. Next to hydro power plants these are the largest renewable source power plants capable of supporting [base load](https://en.wikipedia.org/wiki/Base_load). They do have minor GHG emissions (I think mostly CO₂ and sulphur compounds). From my limited understanding, the oldest fields now require injection of treated water from sewage treatment plants for adequate steam production.  
> **username_2**: You may want to read Tom Murphy's [post](https://dothemath.ucsd.edu/2012/01/warm-and-fuzzy-on-geothermal) on geothermal energy.  
> **username_3**: fracking is not equal to geothermal, fracking is mostly used to produce natural gas. Also there are many places solar cannot be built. Are you talking about a specific place?  
> **username_0**: @username_3, the plants in my area (southern Tuscany, Italy) pump high-pressure fluid in order to fracture the bedrock and extract more energy. I am not sure if the liquid used is precisely the same as is used for oil and gas, but it is literally hydraulic fracturing.  
> **username_3**: Fracking is the same in both, but fracking is pretty rare in geothermal. Its use in your case is not representative of geothermal. fracking is rarely a good idea but that is about fracking not geothermal.  

---

## 0 answers

