2008 article on deep geothermal power plant.[1]
2016 article on shutdown of plant.[2] "The technology worked but unfortunately the cost of implementing the technology and also the cost of delivering the electricity that was produced to a market was just greater than the revenue stream that we could create."
There's a group called DEEP which is trying to combine deep geothermal with fracking technology, to get better heat transfer. This creates small earthquakes as a side effect. They're working on that.[3]
A startup called FERVO is still trying.[4]
Shallow geothermal for building heat works fine, but it takes a lot of drilling just to get some heat.
So far, nobody seems to have a profitable deep geothermal power operation.
Fervo isn't just trying, they are succeeding in bringing the drilling advances used in fracking, along with other innovation to get through the harder rocks typically encountered when not drilling for fossil fuels, to deliver dispatchable and storable energy. It's actually much better quality of power plant than nuclear because it can be scaled up and down throughout the day economically, whereas nuclear becomes even more uneconomic if it is forced to match the needs of the grid, and the reactors typically require far different designs than what is usually built (France has done a bit with this).
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 actually much better quality of power plant than nuclear because it can be scaled up and down throughout the day economically...
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.
This already makes a large assumption about the type of reactor you are using. For example, a liquid fluoride thorium reactor (LFTR) does not suffer from the xenon poisoning issue, as do many other designs.
Not quite, with geothermal the storage is built into the system by simply limiting the intake, which builds pressure and can shift energy production throughout the day.
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.
> Not quite …
The cost of enhanced geothermal is roughly the exact same cost as nuclear … shares similar economics of a very very low OpEx to CapEx ratio.
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.
Unlike nuclear, that time running at 50% isn't thrown away capital expense, it is merely delayed power output that can be utilized with slightly higher turbine capacity, which is the cheaper part of the capex, and would be needed for higher power output anyway.
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.
> that time running at 50% isn't thrown away capital expense
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.
Everyone is overthinking this. 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. This would not take 50% and make it 100% again, but it does give you something.
Geothermal is limited by the flux* of what you can pull from the ground, which sort of scales with capital costs.
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.
Drilling the well is the expensive part. It heats at a relatively constant rate depending on the geometry. You could size the plant to be exactly matched to the well output--but the generators and such are relatively cheap. So instead you make that part of the plant slightly oversized, so you can run at over the well's capacity when electricity is expensive, and under the capacity when it's cheap. The thermal mass of the rocks allows you to average this out over time.
So there are two capacities, that of the well and that of generation (oversized with respect to the well). On average this varying scheme utilizes the well at 100% of capacity (the expensive part to increase), and the turbine generation at less than 100% capacity (not expensive to oversize).
> 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.
Geothermal isn't cheap. Trimming those fixed costs means siting on fault lines/earthquakes and higher opex (insurance).
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.
Fervo's initial demonstration project was next to an existing power plant in Nevada which previously failed to produce at it's stated capacity over time (Battle Mountain) so they were able to tie in extra MWt capacity to an existing ORC turbine. Fervo's technology has to be located somewhat near existing traditional hydrothermal geothermal resources because it's the convection along an exiting fault for hundreds of thousands of years that produces an above background thermal gradient near enough to the surface for it to be economical. That is true for their demonstration area in Utah which is located near the existing Blundel geothermal power plant in Milford Utah.
I think as a tech demonstration project it was successful because they were a bit conservative in some ways that will make the economics look worse. I agree it's far from "geothermal everywhere" which seems to be the hype. You can't extrapolate that from one successful EGS well literally right next to an existing geothermal power plant.
They do a good job of publishing their results in technical industry publications (advancing the field overall in a surprisingly open way) but I agree can be misleading in their marketing.
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.
That's correct. There's nothing technically special about the French nuclear plants that load follow. It's just that France has so much nuclear power in the grid that some of their nuclear plants do load following.
Iceland has profitable geothermal, no? Maybe you meant that geothermal has not achieved profitability in non-especially favorable environments.
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.
Iceland has boiling hot water at the surface and so doesn’t need to drill far to reach hot rocks do to all the volcanism there. This does not apply to the vast majority of the world
Well the question was "Iceland has profitable geothermal, no?" and your answer appears to be yes. Which is important because it means the upshot is that there are viable applications, which contrasts against the argument that lack of generalized solution means we need to reject it wholesale.
The original comment stated that shallow geothermal can be useful for heating, but did not say anything about shallow geothermal electricity generation.
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.
Feasable, and the concept has been proposed, but doesn't look likely to be built in the near future. There are still lower hanging (more profitable) fruit when it comes to building undersea HVDC cables.
It's not carbon free. Iceland's geothermal fields have carbon emissions because gasses trapped beneath the surface are released along with the steam when they're extracted. It's still low-carbon compared to a natural gas power plant, of course, but not compared to wind/hydro/nuclear.
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 point is that smelting the aluminium takes tons of electricity, so doing it in Iceland where that's produced via geothermal is effectively exporting that electricity.
And it’s a relatively light material. So if you’ve got some place where the carbon footprint of collecting and transporting bauxite is relatively low, you can use excess power to smelt more aluminum.
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.
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 think the point of the Iceland example was to illustrate the local viability of geothermal. But your reply seems to be emphasizing the relative value of geothermal in the U.S. vs Iceland which I don't think is a question that anything important hinges on. The upshot of U.S. geothermal production should be "awesome, so much the better for geothermal!" I find it bizarre and unnecessary to decide that the upshot is supposed to be "yeah, suck it Iceland!" It just has nothing to do with anything.
Great for them, I guess. I live thousands of miles away from Java. You? The point isn’t “there are 1500 active volcanoes on the planet”, the point is is “there are many places not in the proximity of one of 1500 active volcanoes”.
I live in Martinique, in the Caribbean and there is a somewhat inactive [0] volcano.
To generate electricity, we are importing oil/biogaz from Europe.
Solar is ramping up but it makes sense to use volcano heat if:
- the associated risks are low (earthquakes, just got a 4.8 30 minutes ago [1])
- tropical climate does not make maintenance too costly
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.
I'm currently in the Caribbean with our sailboat. We spent almost a month on Martinique (St. Anne, Anse Mitan, St. Pierre), and were wondering a bit about the low amount of renewables being used.
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?
In the summer you can make tons of power with the almost 24/7 sunlight. Cruising in Finland and Sweden in summer we did more solar power than in the Canaries during the fall
> The technology worked but unfortunately the cost of implementing the technology and also the cost of delivering the electricity that was produced to a market was just greater than the revenue stream that we could create.
We said the same thing about solar and wind, also in 2008-2016. We found a way anyway
Probably still not competitive — given that PV and wind are in most places already the two cheapest electrical sources, the remaining part of the power equation that geothermal can still help with is then competing with one of either batteries or a global power grid.
(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).
> deep geothermal with fracking technology.... this creates small earthquakes as a side effect.
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.
> There's a group called DEEP which is trying to combine deep geothermal with fracking technology, to get better heat transfer. This creates small earthquakes as a side effect. They're working on that.
That hasn't stopped the fracking industry, so why would it be a bother for DEEP?
Does nuclear need large amounts of government support? I was under the impression that it was much cheaper on the margin than other forms of electricity. I can easily imagine the needed support for the initial cost to build.
This phenomenon is something I would like to learn more about. Of course there is an element of frequency illusion mixed in, but this happens every now and again. Some random subject is all of sudden talked / written about by unrelated actors.
It doesn't necessarily have to be anything nefarious about it, papers and YouTubers need stuff to write and talk about after all. But at the same time that can be very beneficial for e.g Quaise in this case. How does it work, I'm guessing a "publicist" is involved somehow? How much does it cost? Has anyone here done something similar?
I worked both as a reporter and in public relations (not at the same time) and stuff like this happens for various reasons:
- an institution can publish a report as part of a regular schedule (e.g. unemployment by the BLS) or as one shot thing (e.g. a study on clowns distribution in arid areas). This leads many reporters to publish articles about basically the same subject, but in an uncoordinated manner;
- PR agencies often coordinate with media outlets from various backgrounds and markets to publish about some particular topic (company, product, campaign, ...) either at the same time, or in coordinated waves;
- trends and public discourse can make it so that many sources cover almost the same thing at the same time (e.g.: bitch resting face, rat boy summer, ...);
- luck is, always, a factor.
Pretty common PR for a company/organisation to reach out to various media to get coverage. There was probably a embargo of 1st March so everybody publishing right after that.
I am highly suspicious of the Real Engineering channel. It seems like he does full on marketing videos for whoever is willing to pay or provide access. The video on Helios was suspect and so is this one.
I follow the channel, can you give me few examples of these errors, as I have not noticed any (I'm not a subject matter expert, or maybe not paying attention enough)
I checked my bookmarks file to see if I had summarized any of their videos there, but if I did, I didn't tag them with the channel name, as I usually do for especially terrible videos. So, unfortunately, to give you examples, I would have to watch another Real Engineering video. My consulting rate for this task is US$100 per hour, and I would timebox it at two hours, which I think is the minimum time it would take to do an acceptable job.
I've noticed the same is happening with the Undecided with Matt Ferrell channel. I really enjoyed his content on green energy projects at the beginning, but it seems like lately he's just creating press releases in video form.
It is an interesting application of technology, and hits the "good use of oil and gas tech" button as well. So there is a chance that this was just a natural pickup from the company press release.
... But it definitely smells like a guerrilla marketing campaign.
Finland tried a project, drilling two 6km deep holes. The temperature at 6km depth is 120C. The idea was to pump water down one hole, and get heated water up from the second hole. But the rock wasn't porous enough, they could not get enough water to flow from the bottom of one hole to the other hole. So in the end, they couldn't extract enough heat out of the setup.
It's really really hard to 'aim' a 6km deep hole. Hitting a slab of tough rock can deflect the drillbit off course. If you remember the Chilean miner rescue in 2010, who got rescued by a new hole being drilled - they had 3 seperate holes being drilled at the same time as backups, just because they were worried about the success rate of actually hitting their target. And that was only 0.7km underground.
directional drilling could work if they started nice and high up and aimed to meet somewhere, but turning 90 degrees at the bottom of a 6km borehole is going to require a 6km long directional drilling rig, and probably a fair bit of extra depth to make that turn. it might be possible, but at those depths everything becomes much more difficult to the point where it might make more sense to just give up and abandon the project.
it does like a good opportunity for the fracking techniques mentioned elsewhere in this thread - drop some explosives down those boreholes and see if you can artificially increase the porosity.
As pointed out in the intro to the article, the total amount of power generated in the earth's center is ~50TW.
Global total energy (not just electricity) consumption is currently 180,000TWh/year, or about 20TW. So we would have to capture nearly half of all available geothermal energy to replace current energy usage.
Meanwhile, Solar PV covering (a favorably located) 1% of the earth's surface area would generate 20TW. (This is based on the estimate of 400kwh/year for a 1m^2 panel in a sunny area from https://en.wikipedia.org/wiki/Solar-cell_efficiency.
I don't expect geothermal to do well in this showdown.
> So we would have to capture nearly half of all available geothermal energy to replace current energy usage.
No, you're completely misunderstanding the meaning of that number. 50TW is not the power generated in the earth's center, and definitely not the "available geothermal energy".
It's the heat flow that reaches the surface. The newly generated heat (from radioactive decay) is a fraction of that (estimates vary between 20% and 80%). The rest is a loss of the primordial heat that has been stored in those billions of cubic kilometers of magma for billions of years. And this loss has been happening for billions of years and there's plenty left.
So there are no physical reasons why we could not extract 500TW or 5000TW from geothermal energy. We'd be depleting the priomordial heat much faster than before, but it would still easily last for millions of years.
Of course, whether the engineering to do it on that scale would be feasible, let alone cost-effective, is a different question.
Ah, interesting. I had thought that any primordial heat would have long since cooled, with the remaining heat flux simply being the result of radioactive decay.
This whole discussion seems a bit confused. 50TW is the amount that does reach the surface naturally as far as I can see. The amount that escapes.
In the Earth itself there is some enormous amount, far far larger, with more energy being generated as well from radioactive decay
So it's not like some sort of oil situation where in 250 years we'll be at Peak Mantle, i.e. "The planet has spent millions of years generating this heat and we're draining it at an unsustainable rate!"
This is very different from the sort of geothermal being discussed for power generation.
Residential geothermal for home heating and cooling could make a ton of sense, but more likely based on the scale of a residential natural gas network.
Drilling a hole per home is super expensive. Replacing gas pipes with moderate thermal pipes would be about the same cost as gas infrastructure but allow the massive efficiency gains of larger scale. Heat pumps operating on pumped water through these sorts of pipes doesn't need very high or low delivered temperatures to be effective, as long as it's somewhat above the -20C of the extremes of winter.
Thermal storage quantity scales roughly with volume (x^3) and storage costs roughly scale with surface area (x^2). Though I'm not sure if storage plays much into the gas -> thermal plans that have been explored.
We have that in the Netherlands in plenty of cities called “stadsverwarming”. It is hot water pumped around in a closed loop and residences take heat out of it with heat pump. The source is the cooling off industries, power plants, or dedicated heaters.
They currently are efficient but still expensive because of a law that the pricing has to be similar to heating with would have been.
Thanks for the extra context! Could you explain the law on pricing a bit more? What was the motivation, and what is the usual alternative heating source?
Natural gas, from the Slochteren gas field, was the cheapest way to heat a home for the past 60 years. It's probably not so anymore, considering the Slochteren field is mostly shut down.
The city heating network operator is a monopoly, that is why the price is capped.
Even though city heating networks utilize 'waste heat', the capital cost of the network is significant. The price cap and the capital costs (especially now with higher interest rates) led to many proposed projects being cancelled in recent years.
The problem, as I understand it, is that one has to drill and hit the pocket where the geothermal power comes from. Now, here in Eifel, every drilling requires a permit (€€€), every drilling costs about €20k, you may have to drill more than once to hit the pocket. And Eifel sits on an old mega volcano.
This works well only in a few cases. If you live in an area like Pennsylvania or New York, then you're far better off with an air-source heat pump. It's cheaper to install, and the average air temperatures are warm enough for the air source to work well.
If you live in a place like Minnesota, then the ground-source pump needs a water table. Or you'll just be freezing the water in the ground. And you'll likely still be better off with an air-source pump.
The heat pump works by pumping the heat out of the ground. And the soil is a pretty good insulator, so you'll eventually just freeze the water in the soil around the pipes.
It looks like this: one day in winter, the temperature of the coolant in the loop outlet falls below 0C. And after that, it starts dropping down by about 1C a day, until the pump becomes a resistive heater. If you sized your loop correctly, it hopefully happens towards the end of the heating season.
If your ground heat system also provides cooling that's no longer a problem. I have that for my house. It's pretty great. You're basically time-shifting temperatures across the year. Cool temperatures get shifter to summer and warm to winter. The hole itself won't freeze, because you're not significantly pulling or pushing energy down it.
Even without running the AC, you generally will likely get enough heat flux from the surface and (hopefully) from the water table to thaw the ice during the summer for horizontal loops.
I don't have a personal experience with vertical loops.
With enhanced geothermal, especially that being explored by Fervo, a massive fraction of locations on earth are opened up to favorable geothermal.
Fervo is actually drilling and producing energy today, and scaling the technology, using existing technologies. If Quaise is successful, it will only enhance what Fervo is already accomplishing, but we don't need the huge technical advance of Quaise to get a massive amount of geothermal energy on the grid.
The Volts podcast has been following Fervo over the past few years, and they have met and exceeded all their milestones so far. (Unlike, say, big fission or fusion startups)
The problem is motivations in the capital investment market related to energy. Australia has hot rocks. We are ideally placed to capitalise on this. The last attempt failed at scale, when the test bore and fracking had problems and the money sucked out of the project, the entire thing ground to a halt and rusted in the tin shed in the outback for 5 years before being formally closed down.
You can make faster ROI in energy plays by doing other things. Thats the sad truth: It required public finance models of ROI, expectations on energy supply markets, basically a different approach to funding and returns to make it work.
But it definitely can work, and is used e.g. in New Zealand where its vented closer to the surface. But, we have the hot rocks. we have the deep water. we have all the mechanistic requirements to do the rock splitting to make a two or ten or twenty hole thermal energy extraction method work, and we even routinely do the fracking for gas well optimisation: we know how to do this.
It's just that other things make money faster, and thats what motivated people to do things: making money, not fixing climate
I've designed a lot of hardware in the Oil and Gas, HVAC and pump spaces. If anyone wants to design and build hardware in this space my contact info is in my bio.
One thing I have never quite understood about geothermal, maybe someone can enlighten me: the energy flow from the Earth's core to the surface is not that huge, less than 1 watt per square meter. Doesn't that fundamentally limit the usefulness of geothermal power as a general solution outside of exceptional spots where this gradient is locally much higher, or there is an opportunity to collect from a wide area with a single small borehole? And if I drill a hole and collect 500 watts from it on a 100 sqm plot, am I effectively siphoning the heat from my neighbors plots?
The cited value is the energy flow through the surface, which is about 0.1 W/m^2. But this is conducted through kilometers of rock and soil, which acts as insulation. Geothermal power works through convection instead of conduction. You inject cold water into a borehole, and hot water (steam) comes back, and spins a turbine.
Convection can extract energy at a much higher rate than conduction through the crust.
If you boil a pot of water, you can still comfortably hold the pot's handle if it's long enough, indefinitely. This is heat conduction. On the other hand, if you try drinking from the pot with a straw, you'll find it very painful. This is convection.
Perhaps a stupid question, but... what are the risks? Wolndn't extracting too much energy from the earth's core cool it down, at least a little bit? Or does it contain so much energy that extracting it to replace all of 'surface generation' won't make even a little difference?
Wouldn't drawing energy from the crust cool it down, and wouldn't a cooler crust in turn 'draw' more heat from the lower layers? I guess the earth already radiates out a lot of energy, the process of extracting geothermal energy will presumably lead it to radiate more energy. I don't know by how much though, or if it will make any real difference, or if that's how it even works.
I guess if you could extract enough energy from the core it would reduce convection which would in turn reduce the strength of the earth’s magnetic field.
The deepest bore of all time was 12 km deep. The crust is between 5 km and 100 km and thinnest under the ocean. The numbers involved here are staggering. One might as well hope to stop the Earth's winds with a windmill.
Earthquakes! There are couple comments mentioning "fracking" around, that's destabilizing the land by injecting acid to get energy out. The acid is dangerous, and so are breaking up soil deep down.
> Wouldn't extracting too much energy from the earth's core cool it down, at least a little bit?
The earth generates ~50 terawatts of energy through radiation/other processes, while global energy consumption over the last year was 0.003 terawatts. I think we're fine.
Where are you getting 0.003 terawatts? Another user elsewhere in the thread[0] claimed "Global total energy (not just electricity) consumption is currently 180,000TWh/year, or about 20TW."
Google is showing me other figures like 25,000 terawatt hours of electricity consumption annually.
One might also be careful to count energy properly. The fossil fuel industry has been counting "total energy" including losses to make fossil look bigger and harder to replace. But a gas car throws away like 70% of the energy, so going electric, you don't need the same energy to run the car. Not even close.
On what timescale? Over even just a few second timescale you are cooling rock, but digging deeper gives higher starting temperatures and more volume to remove heat. So, dig far enough and you can get an above some temperature an arbitrary long period say 100 years.
Given your geothermal power plant operates for 100 years and pulls from say 1w/m2. Then you move to a new location for 100 years, and then come back you’re limited to 1w/m2 + 1w/m2 = 2w/m2. Have not 2 locations but many and eventually you’re fully recharged.
But my guess is that the 1w/m² quoted by GP is no where near the energy we get from the sun. Quick Google says sunlight in the order of 1kw/m² (sure that's dependent on where you are, it sun doesn't shine at night, but we're off by 3 orders of magnitude here).
So probably it'll have no effect on surface temperature.
Besides, the heat is mostly released anyways when driving a steam turbine, and the electricity also becomes heat, in your computer or whatever.
Pulling heat from km below the surface isn’t going to reduce surface temperature by 1w/m2, but ~0.001/m2 over thousands of years. Thus the issue is warming the area more so than cooling it.
What matters here is the recharge rate, but all power plants have a finite lifespan. You can simply move somewhere else up to the point you run out of untapped geothermal energy across the surface of the earth which is a rather crazy number.
Enhanced geothermal uses fracking to expose absolutely massive amounts of m^2 through fracking between two parallel, long, horizontally drilled bore holes. Current efforts seem to show a minimum of 30 years before there will be loss of heat quality.
The sorts of drilling talked about for enhanced geothermal are on the scale far far above the needs of a house, IIRC about 5MW per bore hole pair, with many connecting from a single point on the surface. It's also at distances kilometers into the earth.
There is no way to tell yet what the longevity of the resource will be as it's too early. In fracked resources the main issue is "short circuiting" where increased flow rates travel along preferential paths between the doublet wells as the source rock cools and cooling rate of the source rock in general. This causes the MWt of the resource to decline per injection / production well. Fervo is getting around this by drilling extra wells per pad to be turned on in response. Many geothermal resources decline over time as heat is slowly extracted and these declines are somewhat manageable by tuning the injection production well rates and drilling new wells. They are built into the economics of existing plants. Geothermal is kind of extractive and not "renewable" in this way over medium term time scales, you need to continuously keep drilling at a certain rate. Rock is a good insulator and it takes a long, long time for it to heat back up.
It’s useful for HVAC for a home for example, where you aren’t trying to do a conversion to electricity but instead are directly leveraging the consistent temperature to reduce strain on the system.
Yea that is a heat pump scenario where you are also putting energy back in at certain times, that makes sense to me too, it doesn't have much to do with extracting geothermal energy from the core iiuc.
If you're interested in geothermal, David Roberts did an interesting podcast on Fervo who are experimenting with fracking style drilling but used for geothermal, which is now being called "enhanced geothermal".
Am I the only one who thinks that maybe tapping the planet for energy may not be a good idea? Every time we dig really deep we discover new things that surprise us, but we're 100% sure that this is perfectly fine to do?? I'm pretty sure this is how Krypton exploded :|
At least here in Finland, it’s becoming more and more common for houses to use this kind of energy. I’ve even noticed a few isolated apartment blocks using it. Finland obviously requires a lot of heat, and it seems that everyone I know who uses it is happy, so it’s certainly interesting technology.
Is that really geothermal, or is it a heat pump? A heat pump just uses the thermal mass of the earth to provide more efficient electric heating and cooling, it doesn't heat using geothermal power.
You're not wrong; however that is an unfortunate misnomer since ground source bore holes (along with horizontal soil collectors and lakebed collectors) on the order of 100-300 m deep are still utilizing heat from the sun stored in the ground, and not heat produced from Earth's core.
I'd say it's a pretty good idea to not conflate the two by using more precise language, even if not doing so might be "technically correct".
I think the Otaniemi project didn't pan out too great and that was proper geothermal. Ground source heatpumps are great. But those are often just capturing heat that comes from sunlight and get stored if I have understood right.
The big issue I'm not seeing any discussion of in the comments here is cost per watt. We can divide this into two big buckets: the cost of heat, and the cost of turning heat into electricity. This article is all about how geothermal can reduce the cost of heat (especially EGS), how immense that resource is, and how it's basically carbon-free.
But I think the bigger issue is the second bucket: the cost of turning heat into electricity seems to still be too high to compete with solar and wind, even if the heat were free. The article doesn't mention this at all, but I think it's the crucial issue. I don't understand why heat engines are still so expensive 250 years after James Watt, but they do seem to be. In January I came across https://www.eia.gov/analysis/studies/powerplants/capitalcost... which is an EIA-commissioned study of the capital cost of building different kinds of power plants, and I am hoping that studying it will give me the answer.
The article mentions the intermittency of wind and solar a few times as if it were a showstopper—as if no amount of solar and wind power generation capacity could be an adequate substitute for any amount of geothermal power, because you don't have solar power at night, for example. But actually that's just a question of how much it costs to store the energy until it's needed or transmit it from where it's still being produced. We have upper bounds on those storage costs from existing utility-scale storage facilities, and they already look pretty okay. We can expect that they will get cheaper over time.
> as if no amount of solar and wind power generation capacity could be an adequate substitute for any amount of geothermal power, because you don't have solar power at night, for example. But actually that's just a question of how much it costs to store the energy until it's needed or transmit it from where it's still being produced.
I guess this depends on the region, at least to some extent. In Northern Europe we've had these periods during fall/winter in recent years where it's cold, essentially dark, and (worst) no wind. It's not really feasible to store ≈multiple days of consumption for tens of millions of people.
In three of the four Swedish price regions I think we are essentially in a situation now where wind power is "worthless" and can't be built out any more, at least not without major changes to consumption patterns. When the wind is blowing there is such high production that prices go almost to 0, and the operators earn ish nothing, and when prices go up there is no wind so no-one can produce.
Storing multiple days of consumption is feasible but definitely harder than the usual case of storing hours.
The pricing problem sounds like an artifact of how you've structured the market, not a fundamental obstacle to the profitability of intermittent power sources.
An alternative structure that would solve the problem would be for generation operators to buy put options for energy they expect to be able to produce, eliminating the risk of a price collapse. Consumers who want access to such intermittent energy would have to write those put options, which would be limited to particular times on particular days when they could use the energy. Having written the option, they would have to accept the generation operator's decision whether or not to exercise it. Utility-scale storage providers could write puts for low-demand times and buy puts for high-demand times, or they could write puts for low-demand times, write futures contracts for high-demand times, and make up the shortfall on the spot market. This might produce major changes in consumption patterns, but, more likely, would enable continued investment to minimize those changes.
You are right there is no getting around that relatively low grade heat in geothermal is a big barrier for scaling in terms of energy production. Binary /organic rankine cycle geothermal plants used for these low / medium temperature resources operate at ~10% efficiency. Dry / flash steam resources are higher but produce waste in terms of emitted GHG and / or crap in the geothermal brine.
Deep geothermal promises to provide what is usually considered high-grade heat (800+°), but what I'm trying to understand is how cheaply you can convert that high-grade heat into electricity, because the answer seems to be "far too expensively to be competitive with wind and solar".
Supercritical geothermal is similar to talking about the economics of fusion. There is a DOE enhanced geothermal test site near the Newberry Volcano in central Oregon which has temperatures close to this range at reachable depths. That is more of a demonstration site for drilling technology.
Yes, but if (as I am claiming) there's no way to economically turn heat into electricity, it's irrelevant whether supercritical geothermal steam costs trillions of dollars per borehole or is free; either way it's uneconomic as a source of electricity.
Cost is an artificial construct (see: oil subsidies, corn subsidies, EV subsidies, and so on). "It's too expensive!" is such an uncreative response to technology we desperately need to stop overheating the planet.
Cost describes tradeoffs. Environmentalists ignoring costs and generating a backlash that completely undoes their work shouldn’t be a lesson needing relearning twice a generation.
Thank you for saying this. I didn't have the patience, and it's a rather subtle issue with a lot of nuance.
Tradeoffs are indeed inherent in any human effort, but actual market prices are an imperfect reflection reflection of those inherent tradeoffs, and can indeed be distorted by subsidies, externalities, etc. And often tradeoffs cannot really be reduced to a single scalar the way costs do—not everything can be traded off against everything else.
Yet that observation does not mean there aren't any real tradeoffs, or real tradeoffs that can be reduced to a single number.
Also, while this god's-eye viewpoint of the options available for collective action by humanity as a whole is important, for most of us it isn't useful tactical or even strategic information about the possible courses of action we could undertake to affect the world, much less our own lives. It's most useful if you're a billionaire, a Central Committee member, or a Civ player. For the rest of us, even Bilderbergers and the like, those subsidy-distorted costs and the failures of collective action that produce them are merely facts about the world; we cannot make them evaporate in a puff of logic by pointing out their irrationality.
I work for a O&G super major. You’d think that one of these groups would be more interested right? It’s all about money, if one can’t make huge profits (especially with huge gov subsidies) then they will continue to ignore the prospect.
Megacorps aren’t trying to save the world they are trying to get mega rich.
Recent video on the topic by Real Engineering, interviewing a start-up in this domain that aims at creating new technology to dig 10km+ bore holes using plasma to vaporise rocks https://www.youtube.com/watch?v=b_EoZzE7KJ0
Real Engineering just realeased a video on a drilling company using megawatt masers to vaporize rock to reach the depths required. It’s promising, but still experimental.
I wonder, if geothermal was somehow scaled to supply a large fraction of our current energy use, would we start influencing plate tectonics? Couldn't it actually thicken the plates under the power plants and influence how they respond to currents underneath?
I’m renovating an old building that doesn’t currently have any HVAC.
I tried like hell to get a geothermal heat pump set up for it.
This entailed researching companies that make good geothermal equipment and talking to all of their preferred vendors to get quotes.
Literally every shop I talked to, and they were over a dozen that are supposed to be installing these companies equipment told me they don’t install them because air source heat pumps are so much cheaper.
Even with tax credits and rebates (which may not exist by tax time next year when they would pay out), when I finally found a company that would do geothermal, they want 120K USD for a basic system.
if I want to be able to run different rooms in different modes (entirely possible given that it’s a 5500 square-foot building) we’re talking 180K total to work in a heat recovery option.
Meanwhile the same company will do Mitsubishi H2i air source heat pump set up for the entire building for 57K after credits and rebates.
The air source heat pump solution is less efficient and uses more electricity, but the clincher for me was that the cost of each as a complete system, ground source or air source plus the cost of solar raised to drive their respective loads…. Came out as a wash over their lifetimes. Except the air source plus solar solution costs 40K less upfront than even the cheapest and least functional ground source solution.
I would genuinely love it if it were otherwise, but I have months into this and ground source just doesn’t seem economically viable at this point
That's just economy of scale, though. It's always more expensive to be the early adaptor. In Switzerland, 15% of all buildings are heated using geothermal heat pumps.
Yes. And in Switzerland, I believe most new houses have some other type of heat pump (drilling for geothermal is not allowed everywhere, or too expensive). This all still needs electricity; but many houses now install photovoltaics. (At least where I live.)
Here are a few examples of drilling technology that will try and drill 10-30 km down through the crust into areas with enough heat to make supercritical steam.
Lasers, plasma, etc.
Russians did it the hard way back in the day.
“There’s a very decent chance you can do that with wind and solar,”
It is so pathetic that Standford professor spreads this kind of crap. No, wind and solar will not save us, as on majority of our planet we have long period of time without wind and solar.
Unpredictability of solar/wind energy forces to use something to balance the grid. Which, typically, has to be gas, as only gas power station has sufficiently fast start/stop cycle (about 1h in case of modern installation, lignite power plant has several hours cold start, coal power plant even more).
And gas means CO2 emission, even though in some countries, which were buying gas from Russia through Nord Stream, it was considered to be "ecological", similarly like "biomass", that is burning wood and corn (and as we all know burning wood does not emit CO2, right?).
In addition, this is economical idiocy. When there is too much wind/sun, you need to pay producers to stop producing, not to overload the grid. When there is no wind/sun you need to buy energy paying overpriced spot prices. That's why "renewable energy champion" - United Kingdom has the most expensive energy on the planet.
We have one ecological, 100% CO2 emission free, source of energy - nuclear energy (check France if you don't believe it works).
But how Standford professor might promote nuclear power plants when for long, long years all major universities and organizations, with Greenpeace on the head, were fighting nuclear energy, leading to the shitty situation we have now.
10 years ago anyone who wanted to work on nuclear energy research were treated like Holocaust denier, so there was almost no development of new tech in that area.
And now exactly the same people, who were telling us how bad is nuclear energy, are telling us to use wind/solar. What can go wrong...
> "nuclear energy (check France if you don't believe it works)"
France's latest nuclear reactor, Flamanville 3, was finally connected to the grid in December 2024 after 17 years (!!) of construction beset by problems, delays, and massive cost overruns.
Nuclear can be part of the solution, but renewables are much cheaper and faster to build. So for every $/€ spent, you are achieving more CO2 reduction, much more quickly, by building renewables compared
to building new nuclear.
US Navy has been building, commissioning, operating nuclear submarines successfully, literally every years for at least past two decades. The sub reactors are PWRs, only built with unadulterated high purity Uranium.
The "problems, delays, overruns" is basically euphemism for political sabotaging. I can't feel so sympathetic to those in denial of that.
It's just hot rocks boiling in a pressure cooker. 1940s technology. Not 1940s as in Portal timeline. Making assumptions that there must be complicated technical challenges that cannot be overcome or could delay construction as long as 17 years to mitigate is just stupid.
You'll note that the US Navy, despite this extensive experience and relative immunity to political sabotage, has not replaced its diesel fleet [correction: fossil-fuel-powered turbine fleet] with a nuclear fleet. Neither have the French, British, Chinese, Indian, Russian, or PRC navies, all of which have nuclear submarines. The Russian navy, which has built more nuclear submarines than any other, is actually transitioning to fewer kinds of nuclear-powered ships. That's because nuclear power is more expensive than diesel power, which in turn is more expensive than solar and wind power.
> The launch of the first submarine of the class, Yury Dolgorukiy (Юрий Долгорукий), was scheduled for 2002 but was delayed because of budget constraints. The vessel was eventually rolled out of its construction hall on 15 April 2007 in a ceremony attended by many senior military and industrial personnel.[11] Yuriy Dolgorukiy was the first Russian strategic missile submarine to be launched in seventeen years since the end of the Cold War. The planned contingent of eight strategic submarines was expected to be commissioned within the next decade, with five Project 955 planned for purchase through 2015.[12]
> Yuriy Dolgorukiy was not put into the water until February 2008. On 21 November 2008 the reactor on Yuriy Dolgorukiy was activated[13] and on 19 June 2009, the submarine began its sea trials in the White Sea.[14] By July 2009, it had yet to be armed with Bulava missiles and was therefore not fully operational, although it had been ready for sea trials on 24 October 2008.[15]
> On 28 September 2010 Yuriy Dolgorukiy completed company sea trials.
> A Type 094 was photographed by commercial satellites in late 2006 at the Xiaopingdao Submarine Base.[9] The first commissioned in 2007[1] and six were in commission in 2020.[5] They began nuclear deterrence patrols in December 2015.[10]
Admittedly, that's only 9 years rather than 17 years.
So, in fact, there are complicated technical challenges that create many-year-long delays. And they are not due to "political sabotaging". In cases like nuclear warfare where there is no alternative to nuclear power, it can clearly be made to work, but so far nobody has figured out how to make it economically competitive with other energy sources in situations where they are viable. That's a technical challenge nobody has been able to overcome yet.
When you talk about US "diesel fleet" are you talking about the surface fleet or submarines? Cause surface ships use gas turbines and jet fuel, not diesel. The Navy got rid of nuclear surface ships, except for aircraft carriers, in late 90s cause they were expensive.
If you are talking about submarines, the US Navy hasn't had diesel submarines since 1990.
The last US Navy diesel submarine, USS Dolphin (AGSS-555), was decommissioned in 2007.
And not all Navy surface ships are nuclear or turbine powered. Many classes of US Navy surface ships are diesel-powered, including some of the newest ones. Ships with gas turbine engines typically feature diesel powerplants also.
I'm sorry, I assumed the US Navy ship engines burned bunker fuel like container ships, in diesel engines like those Wärtsilä makes, rather than using turbines. Thank you for the correction. I was talking about primarily the surface fleet, but also didn't know the US had eliminated their non-nuclear submarines, which I have to admit undermines my point somewhat!
1. Building better/more transmission lines interconnecting carbon-intense grids with low-carbon ones. This is cheaper than ramping up nuclear, and will needed regardless of the technology.
2. Batteries are becoming more and more efficient. One can even mine with electric excavators.
3. Wind and solar not necessarily need to be connected to the grid initially. Look at ERCOT. This incentivizes demanding moving where electricity is generated, specially in small countries. Look at the UK.
You still do not solve the issues with nuclear waste (10k year problem) and its high prices (LCOE). Also, you cannot build nuclear everywhere, specially in the emerging world. We need a mix of solutions, there is no silver bullet in this situation.
France's nuclear provider has incredibly high debts, which is only possibly because they are state backed. So no, nuclear energy does not work economically.
Respectfully, who cares? Humanity needs electricity, and "cost" is an entirely made-up thing. "Sorry, it was too expensive to save civilization" is going to be the most obnoxious epitaph for Homo sapiens...
Solar and wind energy has a problem, which is storage. We have not yet developed a competitive solution to store energy on commercial scale that works everywhere.
Nuclear energy is stable but generally quite costly per kWh compared to renewable energy.
Nuclear energy and renewables in combination balances out disadvantages. Nuclear energy reduces the need for energy storage solutions in renewables by providing a base load, while renewables would enable cost-efficiency in even quite energy demanding uses (e.g. carbon capture, generating methane etc.).
Yeah when it comes to these discussions, I think most people are unaware just how much the cost of solar & BESS (at the large scale) has fallen in the past couple years.
The battery installed along solar farms is usually on the order of hours of energy delivery though. Like 5 hours. It’s fine, but not everyone will be able to ornaffors to buy electricity on when it is cloudy and still for a few days.
I love how your response conveniently ignores any mention of energy storage technologies, several types of which are having rapid technological advancement.
You’re right that there has been huge advancements but there’s still a pretty brutal economic cost with it. I generally use the Tesla Megapacks as an easy example because prices and specs are easy to find on Wikipedia (and my local utility is testing them, so it’s relevant to me).
A Megapack 2XL can output ~2MW and has a capacity of ~4MWh for $1.39M.
A GE BWRX-300 is rated for 300MW and an 18-24 month refueling cycle and allegedly costs ~$1B.
You can build 150x Megapacks for $208M to match that 300MW output, but there is only enough energy stored to provide that output for two hours. If you want to provide 12 hours capacity (to run through the night), you need 900 units at a cost of $1.25B. That’s just for the storage though, you still need the source of electricity to charge the packs, overprovisioned to deal with the capacity factor issues that solar and wind have.
Will the nuclear plant go over budget? Almost certainly. Will it then provide a long-term baseline source of power? Also yes.
I’m pro-renewables and pro-storage, but there’s a mix needed here. Even with storage tech, there needs to be something else that can just sit there and run and produce reliable and controllable power output long-term.
I wonder what affects we might have when cooling the earth (ground). Smacks of the same sort of hubris that we couldn't possibly warm the earth. I guess conservation of energy is a hard concept to comprehend.
Not guaranteeing I got these conversions correct, but I believe the rough estimate for the thermal energy of the Earth is on the order of 10^31 Joules.[0] while the rough estimate for human energy use is 10^20 Joules per year.[0]
So if we switched to 100% geothermal (a few orders of magnitude more than we're actually discussing using), we'd be using on the order of a hundred trillionth of the energy per year?
This also ignores that the Earth already has a flux of 50TW per year, so it's only an increase of about 40% (and even less, when you consider that intentional extraction would slow the flux of all surface area above it).
Not only that, but Earth's internal heat is being renewed constantly via things like radioactive isotopes and tidal forces.
So what happens if we slow that flux? That's spread across the globe. What's the impact if those numbers are localized?
Radioactivity and tidal forces create a fixed amount a heat and that heat dissipates at a given rate, right? So what happens if we change that rate of dissipation/extraction?
The point is, it's all handwavy. Seems familiar to just about everything we've done before - fossil fuels, plastics, PFAS...
This sounds rather dismissive that anyone could have thought about this. I never looked up what effect this has either (in my defense, I'm not a user of this type of energy), but that doesn't make me conclude conservation of energy is hard to comprehend
In many places it makes sense to heat the earth (yes) in summer using the heat pump (using electricity from photovoltaics) so that efficiency in winter is better.
