I would bet on geothermal over nuclear in a second for future electricity generation. Its so much more promising, has a tech curve, and has far more innovation and advanced tech adoption.

It's not that nuclear reactors can't be built to vary their output. It's that nuclear power is almost all fixed cost. If the average power level over a year is 50%, the power cost doubles. Geothermal has similar economics.

The cost of enhanced geothermal is roughly the exact same cost as nuclear today (if you exclude the very high cost of failed build attempts for nuclear), and it shares similar economics of a very very low OpEx to CapEx ratio. However the economics differ massively in that enhanced geothermal is getting cheaper as we build more, but nuclear tends to get more expensive as we build more. Geothermal is a technology, nuclear is a monument.

It can’t be both not quire and the same.

All else being equal, a five billion dollar geothermal plant running at 50% has the same problem as a five billion dollar nuclear plant running at 50%: where’s my profit?

Sure, load following is trivial with geothermal, but nuclear generally isn’t trying to compete in that space, so we can discount the difference there.

For nuclear, adding thermal storage for time shifting would be the most equivalent to what's happening with geothermal storage, but with geothermal there's no additional capex or engineering needed.

I don’t understand how you think capex works?

You outlay x on capital expenses to get the plant running, that’s all the plant and equipment. You run the plant at 50% it takes you twice as long to recoup your capex.

Always happy to be corrected.

Reducing the draw from the well at time X, leaves more available at time Y. In this way, the capital cost is reasonably preserved and your correction is offered.

--It's not exactly the same thing as flux ---I haven't verified the relative losses here of delaying utilizing the available heat, but rather am assuming the OP is correct about what I believe to be their point*

If the geothermal plant isn’t ran at or near capacity all the time, the capex takes longer to recoup.

You can’t just, say, run it at 50% for a while, and then at 150% later, because a) ya typically can’t run plant at 150%, and for power generators ya can only run them at whatever you’re contracted to supply, so you’d typically want to run geothermal at capacity all the time.

This is true of anything that requires capital expenditure.

> They just let pressure build up higher than normal for 6-8 hours and then the turbine generates more power than normal until the pressure falls back to normal levels again.

So they can run at more than 100%.

The expensive bit is drilling and that gives you roughly X heat per month. You can use that at a constant rate or all in one week.

Of course we can build something less efficient to allow "pressure build up", but that's another trade off.

Isn't this logic flawed?

> Sure, Metric A is better with Option A, but Option B is so bad in that space they are avoiding it, therefore we can discount the difference there.

Fervo/Google got dogged for announcing their plant in UT because they avoided disclosures about the capacity [0]. It's more of a very small scale pilot of a couple MWs, but they buried key facts about the project assumedly on purpose due to lack of significance.

[0] https://blog.google/outreach-initiatives/sustainability/goog...

I don't agree with the above comment:

> Fervo isn't just trying, they are succeeding

Or they simply ran into headwinds on a speculative project. I'll "take the under" when your PR is cagey about basic project attributes.

It will be interesting to see the results of the Cape project once they do multi-well laterals from a single pad power plant with larger diameter wells. That is really more a demonstration of power plant economics beyond the technical feasibility of creating a horizontally fracked reservoir that can be operated for a year.

Cape Station does look much more significant. [0] 400MW of power plant capacity with 2028 COD and mostly contracted with SoCal Edison? Good job.

[0] https://www.utilitydive.com/news/cape-station-enhanced-geoth...

They don't because I fuel costs are so low that the power is essentially free when compared to idling.

I'm pro nuclear, but I don't think using hypotheticals and futures is how to convince people nuclear is good, it's good because it works and it doesn't poison the planet (Yes there have been accidents and they have been dramatised but count deaths and it becomes as irrational as being afraid of flying)

Though due to the xenon poisoning, they apparently use the reactors which at the moment have the freshest fuel for the load following, as they have more excess reactivity available to overpower the xenon. They can ramp at something around 5% of rated capacity per minute between around 30-100% of full power.

Most other countries with nuclear power plants have a much lower share of nuclear in their grids, so they haven't needed to do it, as due to the economics of nuclear it makes the best sense to run flat out as much as possible in order to recoup capital costs.

https://www.oecd-nea.org/upload/docs/application/pdf/2021-12...

There were a lot more factors at play in the chain, but the burnoff of the xenon wasn't itself the proximal cause of the explosion.

Granted you then have to built of of those power-using-things and only run it when grid demand drops.

That's done a lot in France, but there's a limited amount of pumped hydro available in the end.

Until recently, countries with lots of available nuclear energy didn't really need to produce fresh water, and non-gas-produced hydrogen is still a WIP.

If you find a cheap solution to power storage, you can make a lot of money. This is the key enabler for a 100% renewable grid.

Although presumably if you set up one of these facilities you need it running 24/7 to be profitable not just when there is a lull in demand elsewhere.

Major footnote here that I'm wayyyy out of my wheelhouse on this stuff, so there may be reasons that this doesn't work. I invite correction if that's the case so we can all learn some stuff :)

David Roberts

Yeah, we have a lot of hills. And that's it. So, other than that, you could plop one of these down almost anywhere.

Erik Steimle

That's correct, yeah. You need some proximity, obviously, to transmission and load.

Doesn't the ground itself act as an energy reservoir for geothermal? I haven't looked this one up, but it definitely seems like geothermal should be very dispatchable.

I don't understand that though; geothermal power is on paper much more low-tech, safer, cheaper, and deployable everywhere compared to nuclear. Why didn't it become the default way to generate power?

Or is deep drilling in fact more difficult or expensive than nuclear fission?

It's because unlike nuclear technology, drilling technology has advanced massively. It was spurred on by natural gas fracking, trying to get very hard to recover fossil fuels as the easy stuff ran out.

So there's an entire industry around this new technology that already exists but which has not yet been applied to geothermal. And for a long time there was little no no growth in electricity demand, which greatly suppresses the demand for new generation technology; basically everybody was competing to replace the natural gas, coal, and nuclear generation plants that were reaching their end of life.

Now, the hype of AI has made for a great excuse to build a bunch of new technology, which brings a flood of new investment money, political will at Pubic Utility Commissions, and end-users looking to sign PPAs to secure electricity which helps raise that money for new builds.

If you go based purely on when the technology was developed, sure, deep drilling is more difficult than nuclear fission, and in turn uses tons of new technologies at its base.

And until this new drilling technology was developed, fission was cheaper, but it won't be cheaper for long. Drilling is a technology with a learning curve which means that costs fall as we do more of it. Nuclear has not had a significant learning curve, and in fact in many cases it has gotten more expensive as construction labor gets more expensive over time.

I'm glad that you are so bullish on a technology that still has very little to show for itself.

It should also be noted that the economics of geothermal installs also are the same ones as drilling for oil and gas -- so the cheaper drilling gets, the cheaper access to competitive resources.

Majority of electrical power - solar + nuclear is our best energy shot. Heating probably go with heat pump for 90% of the market.

That said - all of the above approach (including geothermal) - it shouldn't be this insipid argument of Geothermal vs Nuclear.

The economics of enhanced geothermal are vastly different in that geothermal has a learning curve where by merely drilling more wells, we make future geothermal cheaper by innovating technology. Nuclear reactors do not have a positive learning curve, and in fact are getting more expensive due to the ever increasing cost of construction labor (see Baumol's cost disease).

> insipid argument of Geothermal vs Nuclear.

First, expressing a preference for the future of one technology direction over the other is fundamental to discussing technology. It makes a huge difference in terms of getting better understanding of them, and is a core facet of any sort of planning. Sure, we should produce both, but we should also make predictions of what we think will happen in the future so that we can learn from the outcomes, and also do proper allocation of relative amounts of funding.

Nuclear has proven time and again to under deliver on all promises, results, and even ability to construct projects that have full regulatory approval. Geothermal is exactly the opposite. It has made realistic promises, overdelivered, and been fully transparent so far.

To not take into account these histories would itself be absolutely "insipid" and poor planning. That's not to say that nuclear should be fully excluded, but let's take into account the huge amount of risk with funding anything nuclear due to the inability of the industry to meet goals.

Any investment decision is a "vs." argument and must absolutely be looked at very very closely. And when we do that, every technology must be given a completely fair and honest assessment, we shouldn't put our thumb on the scale for nuclear just because we thought it wasn't given a fair shot in the past. We must look at it fully honestly without rose colored glasses, and I have yet to find somebody bullish on nuclear that doesn't wear extremely dark rose-colored glasses.

2. How can you say Nuclear has underdelivered? Have you ever looked at the amount of nuclear deployment globally - does geothermal even get up to 0.1%? The cost of new Nuclear is a large function of the regulatory burdens especially in North America.

Don't read me wrong -- I'm all for geothermal but it certainly hasn't delivered on its promises and has only really worked out in uniquely favorable conditions (i.e. Iceland).

I think we should be subsidizing geothermal to make the technology cheaper and cheaper, like we had with solar and wind. Seems plausible that we could make the technology economically feasible in more geographic areas (similarly to solar) and mitigate duck curve inefficiencies other green energy technologies suffer from.

Also to hedge my statement: solar is not economically feasible everywhere, but it is now economically feasible in many more environments (with sufficient sun coverage) than before.

https://en.wikipedia.org/wiki/Icelink

And aluminium production is certainly not carbon free: the smelting process reduces aluminium oxide to aluminium metal using carbon electrodes, producing around 14 tonnes of CO2 per tonne of aluminium.

The problem with opportunistic loads like wind and solar is whether you can afford to strand expensive factories full of equipment for hours or days at a time while the power availability is compromised. At least with geo this is a smaller problem.

There is some R&D work going on though to do this reduction step without CO2 emissions using other electrode materials, see e.g ELYSIS.

AKA: "Smelting"

I did not maintain that the aluminum was carbon free.

In the current situation Europe would profit immensely by sending excess renewable energy to Iceland's pumped hydro and Aluminium smelters while using their geothermal baseload capacity. But in 15 years that might no longer be the case and by then the investment would not have paid off and there might be regret that the money wasn't spent on a different HVDC line like another North Africa - Europe link or Bulgaria - Caucasus (which has a lot of undeveloped hydro potential).

The original comment (by @animats) specified shallow (viable) versus deep (unviable).

> nobody seems to have a profitable deep geothermal power operation.

That nuance got lost.

See the first paragraph. [0] The reference explicitly gets into "deep geothermal" (i.e., EGS) and talks about power applications that are viable because of limited drilling (i.e., shallow).

> The more than 1 gigawatt of geothermal power currently produced globally — from California to Iceland to the Philippines — relies nearly exclusively on such natural outpourings of the earth’s heat.

The building heat comment is just a reference to another residential/C&I application with ground loops. They're not dismissing or not acknowledging the grid-scale power applications.

[0] https://news.ycombinator.com/item?id=43234465

From my understanding, this is all the original comment says about shallow geothermal. Correct me if I am misunderstanding.

Moreover, I do not see the quote: "The more than 1 gigawatt of geothermal power currently produced globally — from California to Iceland to the Philippines — relies nearly exclusively on such natural outpourings of the earth’s heat" anywhere.

Are we referring to the same comment, or am I misunderstanding something?

Insofar as it relates to the commenter I'm replying to, they also seem not to be making a distinction about deep geothermal, but insisting that the difference between Iceland and the rest of the globe is an indictment of geothermal's viability deep or otherwise. Which doesn't follow.

Geothermal is currently deployed in 32 countries and is regarded as the most abundant source of renewable energy outside of solar, impressively ranking ahead of wind.

So I think the most charitable interpretation of Iceland's example is that it represents one of many regions where geothermal is viable.

https://www.edengeothermal.com/about/geothermal-energy/world...

Even if it's not the cheapest option, if it can provide some backup, that could be an option. Because solar panel and hurricanes are not best friends.

[0] that kills 30k people in 1902 : https://en.wikipedia.org/wiki/1902_eruption_of_Mount_Pel%C3%... [1] https://www.emsc-csem.org/Earthquake_information/earthquake....

Theory was that both wind and solar are too risky due to the frequent hurricanes. But maybe there's more local nuance? Too cheap diesel?

Iceland doesn’t have natural gas. (I also imagine the winds and high latitude make solar complicated.)

https://www.visiticeland.com/eruption/

The USA actually produces far more geothermal power than Iceland. So does New Zealand.

The Geysers geothermal complex in California alone has more than double the capacity of all geothermal plants in Iceland combined: https://en.wikipedia.org/wiki/The_Geysers

(I really should turn my notes on global power grid into an actual blog post, so I can link to it, given how much it comes up).

So, the same as nuclear, wind, solar, gas, and coal, all of which which largely don’t work without significant government support.

We said the same thing about solar and wind, also in 2008-2016. We found a way anyway

That hasn't stopped the fracking industry, so why would it be a bother for DEEP?

In typical HN form I'll say: "That's a bit of an oversimplication". Apologies, please don't hate me. Thanks for quoting all your sources though btw.

The wrong geology absolutely will create minor earthquakes. This is because any fluids injected into certain rocks layers provide "lubrication" and things start slipping. Pretty crazy how much pushing is happening down there and things remain at equilibrium most of the time!

However, all is not lost. Certain geologies absolutely can take external fluids no problem, because they previously contained fluids... yeah... I'm talking depleted oil wells. A bit ironic I guess. This happens all the time already in the midwest, depleted oil wells are turned into saltwater injection wells.

The problem is most of the time, you can't just plunk a depleted well down anywhere that happens to have the right geology underneath it, which the geothermal guys were hoping for. Pushing high pressure water into previously dry formations will likely cause problems. No free lunch, but it is possible in certain areas. A lot of said areas aren't likely near population centers unfortunately.

> The campus geothermal well offers a unique full scale research infrastructure of global relevance. This project will be the first geothermal system built including an extensive research infrastructure in the low-enthalpy energy range. Low-enthalpy (direct-use) geothermal systems produce water <100°C that can be used directly for domestic and horticultural heating. Equipped with a broad range of advanced technologies for monitoring and data acquisition, it will deliver essential information on processes affecting deep geothermal energy provision in sedimentary basins and give valuable insight into an operating geothermal system.

[0] https://www.tudelft.nl/citg/over-faculteit/afdelingen/geosci...