This is a tweet thread from the CEO, the article is here (but paywalled) https://www.bloomberg.com/news/articles/2023-07-18/fervo-ene... and what it shows is something that readers of this site should be very familiar with; technology advances impact adjacent markets "invisibly."
My interest in PDC bits and the advancements in drilling related to how much simpler it would be to add fiber to the metro area by drilling horizontally 500' below street level (essentially no obstructions). The missing link there is lining the drill tube dynamically and going horizontally through water (for example) is not straight forward.
Is there a reason why you favor 500’ below ground level? My naive initial reaction is that seems like tremendous overkill in 99% of applications. Presumably in the vast majority of urban areas, 50’ would be more than enough to avoid any and all obstructions.
I suppose once you decide to do something more than shallow trenching, then the marginal cost of additional vertical feet is fairly minor, but even in, say, NYC it seems like 500’ is way, way more buffer than you’d need in the worst case scenario (I have a vague recollection that the very deepest subway line is around 200’ underground, and that’s primarily due to a specific quirk of geography - a hill surrounded by two valleys).
Three reasons, temperature stability, propensity to have rock vs sediment, and in the bay area, somewhat better earthquake resistance. When I was doing ops at Blekko we had a dark fiber run between our office and the data center to get our own "high speed" connection and part of that was a geo-technical survey. Of much of the SF Bay Area peninsula. The geologist suggested if we wanted to be subterranean and avoid both infrastructure and superfund sites, that we'd have to go down 500'. He expressed doubt that anyone would do that given the expense. And there are still some parts of the Santa Clara aquifer you can hit if you don't aim well.
Have you ever walked by a building under construction? It isn't uncommon to see foundation work going down >70 ft. The pilings themselves can be driven in even farther.
What percentage of the average urban area is covered by buildings with 70’ foundations? I assume, perhaps incorrectly, that this is something that’s only required for skyscrapers or other similar large commercial buildings? And the average CBD is, probably, what, a low single digit percentage point of the corresponding urban area?
I could certainly be wrong in my assumptions (hence my question!). But it still seems to me like it would be way more efficient to drill much shallower conduits in (what I assume is) the 99.999% of geography not covered by skyscrapers (and to either go deep or continue to go targeted in the remaining fraction).
Each pile was as about as high as the building. They pushed one in first and it went in like it was going through butter — literally seconds. They then stuck a second one directly on top which went in relatively easily. They then spent a thumping eternity putting a third one in on top of the other two. They repeated this process for days.
So, that little building is resting on piles around 2-3 times its height.
There is 'drive down to specified depth', 'drive down until you meet a particular layer' and 'drive down until you have a specified resistance'. All of this depends on the various strata underneath where you want to make your construction. In old days in 'bad ground' (such as pretty much all of NL that doesn't have sand immediately beneath it) those pilings would be made of wood, and if kept properly wet they can last a very long time (100's of years). But if the water table isn't stable they can rot out pretty quickly.
In Amsterdam this is now a serious problem. The pilings there are getting really old and the water table has been changing, sometimes quite dramatically because of deep construction and the waterships's decisions to either purposefully lower it and then later reversing that decision again. This has caused pilings to become exposed, and then to be dried out, re-exposed and dried out again, with significant chances of rot as a result. Lots of historical buildings have had to have their foundations re-done which is super hard given the limited access. Some very ingenious machinery has been built, including a pile driver that is small enough to take under an existing building that drives new piles in situ. The whole thing can be disassembled and then re-assembled under the building.
That's a wonderfully evocative image, and I am a total non-expert so this sort of depth may be common, but I do note that that map pin is in what looks like harbor landfill. It may require an unusually deep foundation to reach bedrock there.
Fascinating, thanks. Do you happen to know what material they used for the piles? I’ve always assumed some kind of concrete column, but that seems possibly incompatible with the process you saw.
Too interesting. I just saw your other comment about the longevity of properly maintained wood pilings. Never would have thought that preventing rot would require them remaining wet.
I think the answer varies widely based on the underlying geology and what you're building.
Ancedote: My neighborhood in Lousiana was a land-filled swamp. Building a single story house there required driving dozens of pylons in to keep the house from sinking into the dirt. When we put a pool into the backyard, it had to be partially filled with water while the concrete was still hardening because otherwise the surrounding water table (something like two feet below the surface) would have popped it out of the ground.
This is probably less of a concern on, say, the Colorado Plateau.
Sounds like your geography is very similar to mine, fellow gulf coaster/swamp dweller. I know my house sits on a bunch of piles as well, though I don’t know how deep they go. I would guess it’s likely less than 50’, though maybe not.
No, as far as I know you can't. The pool is essentially a boat floating on the water table. If you remove too much weight from it, it will float and pop up. It may be that the surrounding concrete decking is strong enough to hold it down, but I'm sure none of that was designed to hold a pool down against an upward force.
I think you probably just can't safely fully drain it.
> Presumably in the vast majority of urban areas, 50’ would be more than enough to avoid any and all obstructions.
This would definitely not be enough in, say, NYC. Grand Central Station is 150 feet below street level, for example. The Oculus is about 80 feet below street level. Things are deeper than they might first appear!
In many regions, the existing rock is hot enough but there isn’t enough permeability for fluid to flow through the hot rock. Through wells drilled deep underground, EGS injects fluid to create fractures, causing the permeability needed for electricity generation.
My gut says they're using the same methodologies as hydraulic fracturing for oil and gas extraction for this, but I'm not sure.
That raises a whole host of environmental concerns, particularly with regard to the high volume use of fresh water in places where it is scarce, and the impact of toxic high-pressure fracturing fluid on aquifers.
Both are issues that have plagued communities where oil and gas fracturing takes place.
> gut says they're using the same methodologies as hydraulic fracturing for oil and gas extraction for this, but I'm not sure
This is correct.
> the high volume use of fresh water in places where it is scarce, and the impact of toxic high-pressure fracturing fluid on aquifers
Petrochemical fracking constantly creates new fractures to unlock new seams; extracted resources don't replenish.
Geothermal energy is different. You can stimulate once, then circulate and recapture; the heat one extracts renews itself. ("The produced fluid was pumped through a series of holding tanks to provide the residence time for the water to cool sufficiently and was ultimately recirculated for injection," though it was supplemented with "saline brine sourced from a nearby groundwater well.")
Fundamentally, it has the capacity to be almost endlessly cleaner than its oil and gas counterpart.
Thanks. In principle I am wholeheartedly in support for geothermal as a renewable energy source, especially compared to fossil fuels. I think these kinds of developments to expand the potential for geothermal resources are super important.
I guess I just would like to understand some of the externalities to this particular methodology. Especially since many of the parallels to oil and gas fracking are present, and the environmental track record there is poor.
> I just would like to understand some of the externalities to this particular methodology
I would too. Their white paper devotes an entire section to induced seismicity. There is less attention paid to steady-state water requirements. (Given it's just water and brine, and assuming natural prop pants, the threat to the water table seems de minimus, barring something nasty dissolving out of the rocks.)
My reading of the comment above is that Geothermal uses the same chemical/physical process to fracture the rock and has to dispose of those chemicals afterwards (or leave them in place). Fossil fuel fracking needs a continuous supply of the chemicals and a continuous problem of finding a reservoir for the used chemicals so the impact is much, much higher.
Except twice as many wells, and less isolated geology.
Also, benefits of fracking is the generation of heat and positive pressure from the chemical reactions.
If they aren't netting the geothermal gains against the embedded energy in the injection chemicals, all we're seeing is energy accounting tricks, not a technical breakthrough.
The rate that geothermal energy replenishes is incredibly slow. Average heat flux through continental crust is around 70 milliWatts per square meter[0], so a single well with a horizontal drilling range of 3km would in steady state generate about 2 MW thermal, or around 0.8 MW of electricity. For comparison a single onshore windmill typically produces around 2 MW of electricity. As an example, to steady state power the state of Delaware, you'd need to completely frack 13% of the area of Delaware. You actually frack substantially less if you don't wait for the heat to regenerate, and you deplete an area bit by bit.[1]
[0] There are volcanic areas where the heat flux is substantially (~5-10x) higher, but they are few in number, generally far from population centers, and creating geologic instability in close proximity to a volcano carries its own risk. Viable in places like Iceland but not generally.
[1] Eventually of course you would wind up fracking the same total area, but it would take centuries to millenia, by which point you've probably either switched to a better power source or learned to deal with the issues of fracking.
IIRC (and I'm not an expert), you need to keep working on the cracks to keep water circulating. You don't need as much stimulation as you would for fracking since the goal isn't to crack new areas, but your well will stop working if you don't monitor and stimulate as needed.
"Fracking" for geothermal wells will supposedly not use toxic fluids. The reasons they're used for oil and gas extraction does not necessarily apply to geothermal wells.
There are some concerns about micro earthquakes and other disturbances if it's done near towns.
It seems like not using fracking, and just making several vertical lined bore holes might be better anyway though. In the best case you don't need any active pumps to drive the loop, so it can be much simpler.
People with a population centre that isn't atop a known and historically active fault (such as Basel), people that are already living in a geologically active fault zone such that risks introduced by fracking are dwarfed by straddling the "ring of fire" already.
I'd rate those as valid informed decisions.
The stress on 'informed' is because it many countries it's rare for industry to be open (or forced to be open) with the wider public and rare for the wider public to have an effective say in such decisions.
"The project involved drilling a first-of-a-kind EGS horizontal doublet well system, consisting of an injection and production well pair within a high-temperature, hard rock geothermal formation... During production testing, the system achieved flow rates of up to 63 L/s, production temperatures of up to 336 ◦F and a peak power production of 3.5 MW electric power equivalent."
The team believes they can increase "the power capacity up to 8 MW of electric power per production well" and unlock economies of scale "because multiple wells can be drilled from a single pad location," which gains from "minimizing in-field rig moves, reducing drilling risk by drilling closely spaced vertical well sections, co-locating surface facilities infrastructure, and minimizing pipeline costs."
Notably, "the rate and pressure responses between Injection Well 34A-22 and Production Well 34-22 were strongly correlated, with changes in one well causing a rapid response in the offset well typically on the order of minutes to tens of minutes." That means dispatchable generation.
I don't have any megawatt convertible statistics handy, but the distribution is HEAVILY skewed. Take this as a rough indication:
>An average marginal oil well in the United States produces about 2 barrels/day. Approximately 80 percent of all American oil wells are marginal wells, but they provide about 10-20 percent of American oil production. Approximately two-thirds of all American natural gas wells are marginal wells, averaging about 22 mcfd and providing 12 percent of American natural gas production
Uranium and Thorium decomposes into Radium, which themselves are found at 450m but the gas then rises through the Earths crust as it moves. I could see this kind of constant agitation releasing significantly more at least within a radius.
Interesting. In that part of the world, the crust is actually some of the thinnest on Earth. Shell drilled some thermal wells up there in the 70s - when it comes to tech, they have always been the most progressive of the E&P industry - that isn't saying much, but they have been more advanced/interested than any other. Because of the crust being thinnest there, the geothermal gradient is supposed to be better, but that being said, the original Shell wells weren't drilled deep enough - I reviewed them a long time ago, but think they were targeting some 300 feet. When done, all they did was make uncomfortably hot water and no steam - so they will probably need to go to that 500' mark someone here mentioned.
The oil companies rebranded themselves as energy companies because they're definitely not stupid: if they can take their existing capability and use that to enter a whole new area, they'll do it.
In particular because there's no actual competition between geothermal power and the petrochemical industry: oil is far and away a transportation fuel (and a bunch of other vital things), whereas stationary power is coal-generation.
If they can take drilling expertise and turn it into a geothermal power concern cost efficiently, then they'll do that.
the crucial competitiveness problem for geothermal is that pv is now selling power at trading hubs in much of the world at 20 dollars a megawatt-hour (5.6 nanodollars per joule) while running a large heat engine driving a generator typically costs about that much
at best, egs and other geothermal is free fuel to power a heat engine, but even if the drilling and fracking and whatnot costs zero dollars it is difficult for thermal energy to reach parity with current pv
plausibly, future developments in manufacturing could do it, which is appealing because the geothermal resource is orders of magnitude larger than the terrestrial solar resource, but those developments can also make pv cheaper
also, of course, pv is much less competitive in places like antarctica, england, or germany due to low capacity factor and long outages
right now, though, new thermal power projects are relatively scarce
Electricity markets give widely varying prices thru the day. Even just thinking competition betweeen clean energy sources, in early evening peak hours geothermal wouldn't be competing with PV directly but rather PV via battery storage. The extra cost of batteries makes geothermal more cost competitive.
> In evening peak hours geothermal wouldn't be competing with PV directly but rather PV via battery storage
And in many parts of the world, it would not be competing with PV at all during many days of winter, when cloud cover and incidence angle are so bad PV goes into single digit percentage of its peak output. Because then even batteries won't save PV.
mostly people don't live in those parts of the world, but you'll note my original comment does say 'pv is much less competitive in places like antarctica, england, or germany due to low capacity factor and long outages'
I remember a lot of pushback in Japan about geothermal power and the impact it would have on hot springs in general. I wonder if this drilling method would affect their concerns?
I am concerned about this as well. A number of geothermal projects in Nevada have reduced the flow of surrounding hot springs.
It sounds like they are doing injection, which is similar to what Bottle Rock is doing in the Calistoga mountains.
The real benefit I am hoping for is being able to revitalize the hot springs industry with soaking opportunities becoming more prevalent where they were not previously viable.
The white paper says: "The stimulation fluid was a slickwater treatment design with a low-concentration friction reducer additive."
I know secrecy like this is par for the course in fracking, but it would certainly help them escape the stigma of fracking if they broke the taboo and started talking clearly about what crap they are pumping down into the ground. I think if they said, "we put this much of this stuff down the hole", it would help to understand what the risks are.
"The produced fluid was pumped through a series of holding tanks to provide the residence time for the water to cool sufficiently and was ultimately recirculated for injection" [1]. They did add "saline brine sourced from a nearby groundwater well," but presumably the system stabilizes at some point.
I've long wondered if a deep well geothermal utilitie would work for small to mid-sized neighborhoods. I've seen dedicated water and sewer utils for mid sized neighborhoods so that part of the equation seems okay. It should hinge on what energy calcs show.
For what it's worth, there's a city in the Paris area, Champigny sur Marne, that is well suited for geothermal energy, and has a plant with a second one under construction, which provide heating and hot water to the adjacent neighborhoods.
It is endlessly frustrating to me that we're not just ploughing money into this. From a pure strategic perspective, creating fuel-independent electrical power and heat anywhere on the planet is a game changer.
Indeed, compared to the number of fusion startups, which IMHO will be many decades if ever to be practical, and will never be economically viable, EGS could be operating economically, and deep/supercritical geothermal could be proven, in a decade or less.
The large size of ITER is a serious defect, not something to justify government involvement.
"At $5B ITER is a good idea. At $25B+ ITER is a bad idea. The huge cost increases from ITER’s initial to present value are leading to a savaging of the base fusion program which puts the US on the fast track to disaster for the future of fusion research. More important, even if ITER works as expected, but does indeed cost $25B, this is essentially a proof of principle that tokamak fusion will never be an economical source of electricity." -- Jeff Freidberg, KEPCO Professor Emeritus, MIT, Nuclear Science and Engineering
While I do not disagree that it will be a ways off, never is a very long time. And the last century has seen so many things turn profitable, with scientific advances, presumption about the future seems inadvisable.
Yes you are probably right, but still, IMHO compared to the alternatives, I think 'never' is reasonable for the currently envisaged, highly complex technologies and the still-unaddressed issues of fuel processing (eg tritium generation) etc, for mainstream power generation.
I mean I can envisage solar being as cheap as dirt, roof shingles that are basically as cheap as slates. I can envisage geothermal getting cheap, it's just a hole in the ground. I can envisage fission getting cheap, eg the traveling-wave reactor is basically an enclosed lump of uranium.
But rings of superconducting magnets and their controllers, along with radioactive lithium blankets that have to be renewed and reprocessed regularly, or gigajoule banks of lasers and little ultra-precision gold-wrapped fuel pellets? None of this stuff is ever going to be cheap, compared to the alternatives.
It might find niche military, and of course, research use etc. And we might have a breakthrough in low-energy fusion or whatever, but the current crop are either scams or are simply never going to be viable.
> But rings of superconducting magnets and their controllers, along with radioactive lithium blankets that have to be renewed and reprocessed regularly, or gigajoule banks of lasers and little ultra-precision gold-wrapped fuel pellets? None of this stuff is ever going to be cheap, compared to the alternatives.
Are you familiar with how computer chips are made? There are hundreds of steps involving plasmas, ultra-high vacuums, ultraviolet lithography systems, and robotic handling throughout. And yet you can get a Raspberry Pi Zero 2 W for $15.
That much processing power would have cost thousands or tens of thousands of dollars in the early 90s, when I imagine someone might naively have said something similar about the prospects of it ever costing $15.
Or suppose suggesting after Kitty Hawk in 1903 that one day an international plane ticket could be had for (the equivalent of today's) ~$1000: preposterous, if they can even get it to work!
Of course, nobody really knows how this will shake out. You could ultimately be correct that fusion won't ever be cost-competitive with other sources of energy. But "that sounds complicated" is absolutely not a reliable heuristic for price, because over time complicated things become mundane, and whence mundane, cheap.
Also frankly that a nuclear reactor isn't simple - neither is a coal power plant really. Serious, large engineering is always complicated: argument from incredulity is a fallacy for a reason. Solar panels are cheap because the supply line of ultra-pure silicon is incredibly well-developed to service the computing industry (it basically runs on discards from it).
You have to do the actual engineering before you'll know whether or not a thing is viable, and you're likely to find some surprises - i.e. a lot of advanced capability these days has become possible due to things like cheap, fast computing power or ubiquitous high-accuracy GPS systems (differential GPS can get ridiculously accurate).
PV was made from discard Si from the IC industry for a while, but today poly-Si is going into PV directly. They grew beyond working on discards more than a decade ago.
Yes modern fabs are almost a miracle, but there's a large market for compute aka microchips that can't be made any other way, and of course flight has some unique benefits.
In contrast there are myriad other ways of making electricity that will be much cheaper than fusion ever will. IMHO.
I get what you're saying, never say never, etc, and fusion research is still worthwhile, as research, but there is just no economic case to spend billions to develop these current technologies for mainstream power generation.
If there's some major breakthrough in LENR, or muon-catalysed reactions, or whatever, that might be different.
Many technologies are only enabled as spin-offs from other tech, and there are plenty of examples of technologies that seem possible/plausible etc, but get cut off in development when it's clear the economics can't work or the unique capabilities are not compelling enough.
Finland had project for this, 6,4 km deep holes. It did not really work out in the end. In one sense it was representative of old geological formations.
Out of ignorant curiosity: I’ve heard that an anticipated problem of renewables is overproduction. i.e.: generators produce too much electricity, causing the grid frequency to exceed tolerance.
How does one throttle a geothermal plant? Are these geothermal plants operating turbines, and thus are throttled by redirecting steam away from the turbines?
This sort of system has a kind of built-in storage. It can overproduce steam for a while, if needed, even if that level of steam production is not sustainable in steady state. This is nice for countering some short-term variability of other renewable sources, particularly solar.
On the costs front, in 2022, Energy Secretary Jennifer Granholm announced the Enhanced Geothermal Shot, a target to reduce the cost of EGS by 90% to $45 per megawatt hour by 2035. Fervo’s costs for the Nevada project are “significantly higher” than that target, Latimer said, in part because it’s a first-of-a-kind project, but he said he expects next year’s EGS cost forecast to “decline rapidly.”
My interest in PDC bits and the advancements in drilling related to how much simpler it would be to add fiber to the metro area by drilling horizontally 500' below street level (essentially no obstructions). The missing link there is lining the drill tube dynamically and going horizontally through water (for example) is not straight forward.