The most audacious vision for geothermal is to drill six miles or more underground where temperatures exceed 750 degrees Fahrenheit. At that point, water goes supercritical and can hold five to 10 times as much energy as normal steam. If it works, experts say, “superhot” geothermal could provide cheap, abundant clean energy anywhere.
Folks in Finland recently tried exactly that, drilling 2 holes 6.4 km deep in Otaniemi, Vantaa. Unfortunately their fracking attempts failed and sufficient flow could not be established between the two wells. Also, temperature at the bottom was 120 C, not enough to get supercritical water (374 C is required). They donated the boreholes to scientific use, someone will try again and try better…
Once the “how” can be sorted out, it should be usable anywhere on Earth, not just volcanic regions. :) But it’s not easy.
Geothermal is one of the few technologies that could serve as a drop-in replacement for nuclear, not to mention coal and gas. Hopefully at least one approach succeeds.
Quaise seems the most interesting, as it’s basically a phaser drill.
It is interesting, though I’m dubious about Quaise without an actual full-scale test of it. Lots of things can go wrong between lab and full industrial use.
So techniques developed to deep drill for oil can be repurposed to drill for geothermal energy? That’s a tiny silver lining. I imagine, as we run out of oil, the drilling companies will start lobbying really aggressively for geothermal in order to keep in business.
And at least geothermal counters all the complaining about “solar panels don’t work at night” and so on. The Earth’s internal temperature doesn’t change much 😆
If I remember correctly some geysers stopped working natural hot springs stopped being hot. Things like that. I’ll see if I can find some other than an old man’s memory to back it up.
Yeah, this is a thing according to my recent visit to Yellowstone. Natural geysers are very rare and increasingly rare as people tap geothermal energy.
Geologist by training here and it’s been many years but as I recall, subsurface geothermal systems can be quite complex, especially in regional systems like Yellowstone, Iceland, New Zealand etc.
The hope, as I understand it, revolving around geothermal in the United States is tapping into much larger areas, namely the basin and range region, where subsurface temperatures are much higher than other areas. In this area, while there are many natural hot springs, they are remote and less commercial so disruption would have less impact. The benifits could also be fantastic since there is a huge area that has potential. (Most of Nevada and Western Utah). The biggest challenge is the complexity of underground faulting throughout the region. We can understand the general structure (hence the name “Basin and Range”), but the details are a challenge. At each macro fault you have lots of microfaulting and if you are attempting to scale up an energy production facility over an area you risk disrupting the system with each fracked well.
If we can very accurately map the subsurface, it’ll go a long way towards making this energy source much more viable. (We’ve had years to get better at microfracking so getting an accurate map of what’s down there is most important)
Thanks for this, I didn’t mean to say it was a bad thing, just more that we should take all their data into account. I know there are places in California that might work as well.
There are AFAIK two main risk with using geothermal energy:
risk of inducing (minor) earthquakes during drilling. I think this risk is slightly elevated with these new fracking like techniques the OP text mentions
creating mud geysers, which is very low risk but if it happens can be a major calamity.
Both these risks are during the development of new wells, and once things are completed there is basically no other problems other than that geothermal energy is not infinite and the hot aquifers lower their temperature after some decades. This can make the system too inefficient to be worth continuing operation.
Iceland keeps using geothermal for nearly 1/3 of its energy production. However, Iceland is a really poor benchmark to compare with the rest of the world - in some places, you can cook food on the surface there. :)
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