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Geothermal energy could outperform nuclear power

economist.com

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Re: Geothermal energy could outperform nuclear power

#41

Post by Veedrac »

pb1729 wrote: post #26
rabf wrote: post #17

Earlier quoted context omitted.

"Our gyrotron-powered drilling platform vaporizes boreholes through rock and provides access to deep geothermal heat without complex downhole equipment. Based on breakthrough fusion research and well-established drilling practices, we are developing a radical new approach to ultra-deep drilling." This company looks promising in the geothermal space. They are looking to be able to create 10km boreholes in 100 days. Th…

Bhauth wrote an analysis of this idea, and tldr is that trying to get an energy payback on literally vaporizing such a long cylinder of rock is brutally difficult, probably enough to make the economics of the plan unworkable. https://www.bhauth.com/blog/flawed%20ideas/microwave%20drill...

This is a really interesting perspective but I wish they finished writing the equations out. My attempt at verification didn't match.

Per [1], “[wells] with a regular production casing diameter of 200-250 mm have an average capacity of 5.5 MWe”. Quaise has deep bores that could potentially have higher temperatures, but let's stick with 5 MWe.

At the article's 12 MWh/m³ for drilling, and 250mm bores of depth 10km, WolframAlpha tells me that is 6 GWh.

Divide through, you get 1000 hours or about a month. This doesn't match their “significantly over 10 years” they gave before mentioning waveguide losses.

The main difference I suppose is the thermal conductivity comment, where I didn't follow why Quaise wouldn't be able to use enhanced geothermal approaches. More specifically I think that if a Quaise well has ~1% the energy output of a normal geothermal well, it's pretty weird to frame the problem as about the energy cost of drilling, and not the whole factor-100 reduction in energy output.

To be clear, this seemed like an interesting article and I'm not claiming my napkin math is definitive, I really am neither an expert nor someone who has spent a lot of time investigating this. I do think some more clarity on how the math looks would help their case.

[1] https://www.thinkgeoenergy.com/report-success-of-high-temper...

Re: Geothermal energy could outperform nuclear power

#43

Post by lrkrsBlurkn »

hungie wrote: post #34
ViewTrick1002 wrote: post #25

Earlier quoted context omitted.

The problem is not how small the waste is, it is the effects. High level radioactive waste can cause Goiânia like outcomes, or leach into the groundwater. https://en.wikipedia.org/wiki/Goi%C3%A2nia_accident It is quite intellectually dishonest to try frame it as pixie dust rather than the true problem it poses.

If, and only if, you store it stupidly. There's plenty of ways to safely store it for millennia. It's not a truly difficult problem. And I'm just doing my best to present the facts as they are -- no fud.

[dead]

Re: Geothermal energy could outperform nuclear power

#44

Post by lrkrsBlurkn »

lucb1e wrote: post #39
OutOfHere wrote: post #27

Earlier quoted context omitted.

Nuclear waste slowly leaks into the groundwater and river water. Also, waste is only one of the two major concerns I noted. Comparing it with coal is 100% disingenuous. Coal is never an option going forward.

> waste slowly leaks into the groundwater You say that as if it's a given that it will always leak slowly. What % of the spent fuel actually ended up being leaked across the couple decades of storage we have had now? What effects did it have? How does the human cost stack up against mining activities we would need for the massive amounts of wind turbines and solar panels when we cut out nuclear's base load function c…

[dead]

Re: Geothermal energy could outperform nuclear power

#45

Post by MostlyStable »

bluescrn wrote: post #28
ViewTrick1002 wrote: post #23

Near everything outperforms nuclear power. Nuclear power is unfathomably expensive. Come back when it is in the same league as renewables or CCGTs.

We don't do nuclear because it's expensive, and that's why it stays expensive. No economies of scale, minimal opportunities to iteratively improve designs. Solar was expensive until we started building a lot of it (often due to heavy subsidisation)

And, importantly, we have chosen to make it expensive by mandating a level of safety that is orders of magnitude higher than for any other generation method.

Re: Geothermal energy could outperform nuclear power

#46

Post by thinkcontext »

rabf wrote: post #17
MichaelNolan wrote: post #5

I wish the best for the geothermal industry, but the phrase “could outperform” is doing a lot of heavy lifting. Geothermal thermal has essentially zero growth, in the US, in the last 20 years. And there is basically no growth planned in the near future, or at least nothing on the EIA’s or FERC’s upcoming generation list. I’m skeptical that geothermal will ever make a significant impact in the US. Though it might make…

"Our gyrotron-powered drilling platform vaporizes boreholes through rock and provides access to deep geothermal heat without complex downhole equipment. Based on breakthrough fusion research and well-established drilling practices, we are developing a radical new approach to ultra-deep drilling." This company looks promising in the geothermal space. They are looking to be able to create 10km boreholes in 100 days. Th…

So far they have only drilled INCHES in a lab. File this under extremely speculative.

Re: Geothermal energy could outperform nuclear power

#47

Post by bhauth2 »

Veedrac wrote: post #41
pb1729 wrote: post #26

Earlier quoted context omitted.

Bhauth wrote an analysis of this idea, and tldr is that trying to get an energy payback on literally vaporizing such a long cylinder of rock is brutally difficult, probably enough to make the economics of the plan unworkable. https://www.bhauth.com/blog/flawed%20ideas/microwave%20drill...

This is a really interesting perspective but I wish they finished writing the equations out. My attempt at verification didn't match. Per [1], “[wells] with a regular production casing diameter of 200-250 mm have an average capacity of 5.5 MWe”. Quaise has deep bores that could potentially have higher temperatures, but let's stick with 5 MWe. At the article's 12 MWh/m³ for drilling, and 250mm bores of depth 10km, Wol…

The article you linked is about conventional geothermal wells, which drill into reservoirs of hot water; they just have hotter water than has been typical. Extracting hot water is not limited by thermal conductivity of rock, but what Quaise plans to do is.

Enhanced geothermal involves fracking. Typical proposals involve creating crack paths between 2 nearby wells by fracking from both. It's been tested some but so far has not been economical.

Apart from the cost issues of enhanced geothermal so far, Quaise plans to drill deeper to higher temperatures to reduce power block costs. Sufficiently hot rock flows a little bit which makes fracking ineffective. Fracking also doesn't work as well with supercritical water. (If not drilling to rock hot enough to flow a little bit under high pressures, it would be much better to use conventional drilling techniques.)

Re: Geothermal energy could outperform nuclear power

#48

Post by bandyaboot »

So if I understand correctly, you create a network of fractures that connect to two boreholes and you pump water into one and out the other. Won’t the fractures erode significantly over time? Do we know what happens when we continuously erode a network of fractures deep underground? And won’t the amount of water that’s required to stay pressurized get larger and larger as the fractures erode?

Re: Geothermal energy could outperform nuclear power

#49

Post by Veedrac »

bhauth2 wrote: post #47
Veedrac wrote: post #41

Earlier quoted context omitted.

This is a really interesting perspective but I wish they finished writing the equations out. My attempt at verification didn't match. Per [1], “[wells] with a regular production casing diameter of 200-250 mm have an average capacity of 5.5 MWe”. Quaise has deep bores that could potentially have higher temperatures, but let's stick with 5 MWe. At the article's 12 MWh/m³ for drilling, and 250mm bores of depth 10km, Wol…

The article you linked is about conventional geothermal wells, which drill into reservoirs of hot water; they just have hotter water than has been typical. Extracting hot water is not limited by thermal conductivity of rock, but what Quaise plans to do is. Enhanced geothermal involves fracking. Typical proposals involve creating crack paths between 2 nearby wells by fracking from both. It's been tested some but so fa…

Thanks for the reply!

I'm afraid I'm not really following the argument though. I don't have the technical background to judge how economical EGS is or not, I just want to understand this energy-based argument. I checked to be sure, and Quaise's initial plans (per cofounder Matt Houde) are indeed EGS-based[1], just deeper. It seems correct to me that if they succeeded at building wells that way, they would produce at least comparable energy to standard wells.

It's entirely possible that EGS just doesn't work at really deep depths as you state here, but this seems like a qualitatively different argument to the one presented in the article.

[1] https://youtu.be/yz6rRw59Huw?t=675 "but what we're interested in in Quaise is this novel idea here all the way on the right which we call like to call superhot rock EGS systems"

Actually, they address the energy balance question at the end of that talk.

https://youtu.be/yz6rRw59Huw?t=3016 "[...] we could be using around five megawatts for the drilling process to drill our wells, and let's say we use that five megawatts over a year to drill three holes, so we get an injector and two producers. We predict that configuration of the two producers and an injector at superhot conditions can produce something around 50 to 100 megawatts of electrical energy, again owing to the benefits of producing this superhot, supercritical steam."

They also answer a question on borehole stability, admittedly claiming largely that they don't know.

https://youtu.be/yz6rRw59Huw?t=3254

Re: Geothermal energy could outperform nuclear power

#50

Post by skybrian »

bandyaboot wrote: post #48

So if I understand correctly, you create a network of fractures that connect to two boreholes and you pump water into one and out the other. Won’t the fractures erode significantly over time? Do we know what happens when we continuously erode a network of fractures deep underground? And won’t the amount of water that’s required to stay pressurized get larger and larger as the fractures erode?

> One concern in the Project Red test was that 10%-20% of the fluid pumped did not return to the surface. That number is much better than many legacy enhanced geothermal projects but needs improvement. Costs increase and site locations narrow to those with excess cheap water. It could also increase induced seismicity risk over time.

> The latest results released for Cape Station do not include the fluid loss number, so we don't know if it improved. Options remain even if it didn't, like reducing fluid throughput. That would hurt productivity, but further gains from drilling and completion intensification could compensate.

https://austinvernon.site/blog/geothermalupdate2024.html

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