The deepest hole we've dug is probably the Mir diamond mine in Siberia, at 525m [0]
(A quick internet search will probably say that the Bingham copper mine in the US is deeper, but that was dug at the bottom of an existing canyon, giving it a head start; the Mir mine started... Well, basically with a bunch of guys with shovels in the middle of the tundra.
What criteria are you using for that? I argue any excavation counts as a hole so my first instinct is that surely the Africans hold the title with their crazy mines. They go very deep looking for gold (& diamonds from what I recall).
I doubt the borehole in the original article goes straight down. Boreholes tend to list left and right.
While I am no authority on the subject of holes, I'd argue that a borehole is not dug as such, hence any borehole is disqualified from the 'deepest hole dug' contest.
A mine of the crazy deep variety, then, in my book, is more of a tunnel than a hole in the strict sense - hence it, too, is disqualified.
The deep sea drilling vessel Chikyu will drill through the crust where it is the shallowest using tech which wasn't available in any of the previous attempts. Looking forward to this one starting!
My wife and I were talking about this borehole a few weeks ago and wondering why similar projects hadn't been undertaken with newer technology. So thanks for this, interested to see how it turns out!
> It’s not clear exactly what you hear on Geeven’s recording. She guesses it could be something small like a data transmission that is resonating, but she can’t be sure. In a Heisenberg-ian twist, it seems possible that some of the sounds were created by the devices themselves. "Exactly knowing what it is is not important I believe," she says. "Mysteries are important. They act as engines for new thoughts and ideas."
Were are you pulling that link from? I'm interested to learn more about this - I'm also interested in the technical details about things like what dB the sound was originally. That's quite the rumble - I suspect there was quite a bit of amplification involved.
First off, this borehole isn't that deep. Over the continents, you'd need to drill to 40-70km to reach the mantle (sometimes even 100km). However, oceanic crust is much thinner. It is technically feasible to drill into the mantle in ocean basins, where the mantle can be only a few km below the seafloor.
Regardless, the mantle isn't molten. It's different types of rocks, but they're still rocks.
In fact, the mantle is exposed at the surface in a handful of locations (and a good chunk of the ocean floor). We have learned a lot from what's exposed at the surface, but these rocks have been significantly chemically alerted. Many of the minerals we expect to be there are unstable at near surface conditions. We'd learn a _lot_ from "fresh" mantle rocks
If you were to maintain the same temperature but drop the pressure to surface conditions, yes, deep mantle rock would melt. A hole with nothing in it going deep enough would cause a volcano (even if it didn't hit the mantle). However, not all of the mantle is hot enough for that to occur. (Again, the mantle is quite shallow beneath the oceans) We also have to keep the pressure at the bottom of the hole the same as the rock around it, so a well doesn't usually release pressure.
At any rate, in any case where you'd try to drill into the mantle, it would be impossible for a volcano to form.
All that having been said, geothermal drilling in Iceland has hit magma chambers by accident and caused a "mini volcano".
If the hole is not wide enough, like less than 1m in diameter, then rising magma would likely cool off and seal the shaft long before the flow would reache the surface.
The mantle is solid. You would have to drill way deep into the mantle before you encountered liquid rock.
Volcanoes don't work like that. Even if you drilled directly into a magma chamber, not much would happen. This has been done inadvertently a handful of times. https://phys.org/news/2009-06-scientists-drill-magma.html Basically volcanoes only happen when there's an extreme amount of pressure from below.
It's interesting what they said near the end... Most of the cost of a project like this isn't going to be spent on the actual drilling. Most of it will go into supporting the people who are supporting the infrastructure that enables the drill team to do the work of doing the actual drilling...
I've just finished applied for a government grant, and am starting to realize just how inefficient these projects need to be to support the people doing the work.
I've probably underestimated my own costs by a lot, and allocated too much toward the actual science I'll be doing.
I was under the impression that the Kora borehole went unfinished because the drill broke due to temperature (7 miles down and you're talking hundreds of degrees C), not the breakup of the Soviet Union.
While the article says the time at which drilling was stopped was after the breakup, it gives the reason as the high temperatures encountered.
"Then it was the turn of the Kola Superdeep Borehole. Drilling was stopped in 1992, when the temperature reached 180C (356F). This was twice what was expected at that depth and drilling deeper was no longer possible."
You absolutely can, and probably should if your intent is to go really, really deep — sort of a "nuclear jackhammer". The usual concerns are a little bit shifted in that context, you're likely to explode your stuff into billions of tons of e.g. mercury (some heavier-than-earth compound) to help with extraction of dirt... good times in perspective.
Have fun with it, https://youtu.be/jZQP2oNDkAM?t=525 (he talks specifically about nukes at 8:45, but I really recommend watching the whole if you're into this kind of 'crazy-but-great' ideas. ;-)
I don't think heating up nuclear waste would be a good idea. Even if you don't reach the mantle, it's hundreds of degrees (celsius) down there already.
That said, putting nuclear waste deep underground and sealing the hole is probably the best best.
I would like to argue that waiting for partitioning and transmutation technology to mature and temporarily storing the waste until then makes more sense than putting nuclear waste into a place where we can not easily (or at all!) reach it when we can use it (and thereby actually solve the problem).
Some half-lifes are so long that just any progress over a fraction of these time-scales should be be enough to be better off to wait for the tech to be ready than to bury the material.
Nuclear waste is already used to being hot in the reactor core (way hotter than the temperatures in the article), and are still hot after removal from a reactor. That's why spent rods are put into a cooling pool for a year or more after removal from a core.
Still, the idea of dumping waste that deep doesn't sound like a good one.
I wonder as well. The self-proclaimed world's largest spa, Therme Erding [1], is the result of an oil drilling attempt hitting a hot sulphur/fluoride spring instead at ~2.3km depth. Today, it powers the entire spa and close by communities with geothermal energy.
Just need a way to efficiently extract the heat from whatever depth and convert it to electricity by usual means.
It's really an almost surreal experience, with encrusted hot spring water pipes and steam everywhere in the district. Sometime you even need to be careful where you step to avoid to be scolded by steam coming up from the ground, likely due to overflow from the hot water boreholes flowing to the rainwater drainage system.
And it's not just the modern hot water boreholes they use to supply the hot spring baths & other users. One time we even saw a traffic code & couple sandbags placed on a random hillside next to the road, as there was steam escaping out of it. :D
I've had an idea that is probably impractical and/or impossible, but seems like it would be neat: Every house should have a super deep hole drilled in their back yard, and a small self-contained Stirling engine [1] generator lowered into it, with wires up to the house. Free electricity on a micro scale, 24/7. I'm sure the idea has been explored by people with a much better grasp of physics and engineering than myself. But we've done crazier things as humans - like covering half of the ground in asphalt and stringing wires point to point around the globe, so it doesn't seem unreasonable to me.
For any heat engine - including a stirling engine - you need a heat difference between the hot and cold side, ideally as big as possible. If you put the stirling engine at the bottom of the hot hole, the whole machine will be hot, there will be no difference in temperature and it will not run.
This also discounts stuff like the need for maintenance, that is hard to achieve at the bottom of a hot & likely very humid if not water filled borehole.
For that reason, most geothermal systems pump water down & then back up again (possibly using multiple wells) & have the heat engines at the surface, where they can be easily serviced & a good heat differential can be achieved, via air or water cooling.
This in the end, is generally an industrial operation though, not really something suitable for every single house. Still helps with maintenance, as you can provide energy for many houses & don't hat to maintain the geothermal power production equipment for each house separately.
Lots of potential uses indeed — also for travel, potential megastructures, and mining beyond the wildest hopes of asteroids but it's likely to be harder to get the stuff (gold, iron, etc) down there than it is to travel millions of kilometers out there through the void and radiations...
And yes, potentially much more heat than we'd know what to do with currently.
Interesting hard sci-fi (well, basic physics principles mostly) about it by Isaac Arthur: https://youtu.be/jZQP2oNDkAM
Disclaimer: absolutely not affiliated with the man but deeply hoping that such perspectives become maintream, normal expectations. Not holding my breath, but one hacker at a time, we'll get there!
Yes. The problem is that the thermal conductivity of rock isn't great, so it needs to be in a "hot" area and to have some kind of underground fracturing allowing water to spread out and heat up.
It must be easier to get environmental permits for geothermal since it has such a small footprint compared to wind and solar and won’t kill any birds, make noise, make pulsing light, etc.
Let me check Wikipedia for you: "The Earth's geothermal resources are theoretically more than adequate to supply humanity's energy needs, but only a very small fraction may be profitably exploited. Drilling and exploration for deep resources is very expensive. Forecasts for the future of geothermal power depend on assumptions about technology, energy prices, subsidies, plate boundary movement and interest rates."
When the article mentioned that the temperature was twice what they had expected, I wondered the exact same thing.
Could they cover the hole, pour water into it and use air pressure changes in the hole to generate electricity? There must be a way to make the hole air tight. I suspect that the rock near the bottom of the hole would already be air tight.
Also I never understood why steam engines release all the hot stream into the air? Doesn't that waste energy to let the hot steam out? Isn't it better to keep the heat trapped inside the system and generate electricity from the pressure only?
Isn't it better to keep the heat trapped inside the system and generate electricity from the pressure only?
Steam engines are old technology. They've been replaced by modern steam turbines, in which the steam is either cooled and recirculated, or used for other processes, or both.
Geothermal steam turbines typically use a heat exchanger and release the original steam, as geothermal steam tends to be very corrosive.
> Also I never understood why steam engines release all the hot stream into the air?
They don't. All practical steam engines have condensers that recover most of the water and as much of the heat as current technology and the laws of thermodynamics allow.
Yes, but not at a viable cost. Drilling is extraordinarily expensive and complicated.
There's the added issue that rock's thermal conductivity is low, and any thermal borehole would have a limited effective lifespan as it reduced the temperature of adjacent material.
Geothermal energy is a viable and widely tapped energy resource, where it's available. In almost all such locations, it's been substantially exploited, with two notable exceptions: the African Rift Valley (mostly in Kenya), and the Yellowstone supervolcano, a national park in the US.
Substantial developments exist in California (The Geysers), Hawaii, Iceland, Japan, the Philippines, New Zeland, and quite probably elsewhere. 1GW+ plants are possible, comparable with the largest practical thermal and nuclear power plants (generally 1-4 GW, though multiple plants or reactors may be co-located). Worldwide capacity as of 2015 is about 12.5 GW.
The two principle variants are standard and enhanced geothermal. A standard plant utilises naturally-occurring steam, and is far less expensive to develop. "Enhanced geothermal" involves boreholes and often water injection to provide power generation.
I'd followed the case of one such project in Australia, the Geodynamics Habanero project. I'd first read of that in 2014 through a grossly misleading and fatuously optimistic report which struck me as both odd and curiously fact-free. Digging showed that in reality the project was running years late, at 1/50th originally-planned capacity, well over budget, and with significant technical challenges.
Even had the project gone as initially scoped, the wells would have had a useful life of about 20-40 years, after which all available useful thermal energy would have been extracted, and would have to be replenished over ... long time, possibly centuries or more. There's a reason the Earth's interior remains molten -- rock is a very good insulator.
I'm not an opponent of geothermal power -- where appropriate it's highly useful, dependable, safe, and proven. In Africa it stands to make a tremendous difference, where even a small plant would make a tremendous increase in the availability (and probably reliability) of electricity. I'd encourage consideration of developing even such normally off-limits natural park resources such as Yellowstone (specifically excluded from a USGS geothermal resource survey I'd checked on some years back).
But enhanced development through borehole-based wells looks like a very long shot.
Readit News
The deepest hole we've dug is probably the Mir diamond mine in Siberia, at 525m [0]
(A quick internet search will probably say that the Bingham copper mine in the US is deeper, but that was dug at the bottom of an existing canyon, giving it a head start; the Mir mine started... Well, basically with a bunch of guys with shovels in the middle of the tundra.
[0] https://www.atlasobscura.com/places/mir-diamond-mine
Shout out for the deepest hand dug well: https://www.mybrightonandhove.org.uk/places/utilities/woodin...
I doubt the borehole in the original article goes straight down. Boreholes tend to list left and right.
https://en.wikipedia.org/wiki/List_of_deepest_mines
A mine of the crazy deep variety, then, in my book, is more of a tunnel than a hole in the strict sense - hence it, too, is disqualified.
YMMV. :)
These were done using power equipment, but they aren’t boreholes.
https://en.m.wikipedia.org/wiki/Mining
The deep sea drilling vessel Chikyu will drill through the crust where it is the shallowest using tech which wasn't available in any of the previous attempts. Looking forward to this one starting!
https://www.jstage.jst.go.jp/article/jscejam/71/2/71_I_3/_ar...
https://vimeo.com/80266870
Regardless, the mantle isn't molten. It's different types of rocks, but they're still rocks.
In fact, the mantle is exposed at the surface in a handful of locations (and a good chunk of the ocean floor). We have learned a lot from what's exposed at the surface, but these rocks have been significantly chemically alerted. Many of the minerals we expect to be there are unstable at near surface conditions. We'd learn a _lot_ from "fresh" mantle rocks
If you were to maintain the same temperature but drop the pressure to surface conditions, yes, deep mantle rock would melt. A hole with nothing in it going deep enough would cause a volcano (even if it didn't hit the mantle). However, not all of the mantle is hot enough for that to occur. (Again, the mantle is quite shallow beneath the oceans) We also have to keep the pressure at the bottom of the hole the same as the rock around it, so a well doesn't usually release pressure.
At any rate, in any case where you'd try to drill into the mantle, it would be impossible for a volcano to form.
All that having been said, geothermal drilling in Iceland has hit magma chambers by accident and caused a "mini volcano".
https://en.m.wikipedia.org/wiki/Sidoarjo_mud_flow
The mantle is solid. You would have to drill way deep into the mantle before you encountered liquid rock.
Volcanoes don't work like that. Even if you drilled directly into a magma chamber, not much would happen. This has been done inadvertently a handful of times. https://phys.org/news/2009-06-scientists-drill-magma.html Basically volcanoes only happen when there's an extreme amount of pressure from below.
I've just finished applied for a government grant, and am starting to realize just how inefficient these projects need to be to support the people doing the work.
I've probably underestimated my own costs by a lot, and allocated too much toward the actual science I'll be doing.
"Then it was the turn of the Kola Superdeep Borehole. Drilling was stopped in 1992, when the temperature reached 180C (356F). This was twice what was expected at that depth and drilling deeper was no longer possible."
Have fun with it, https://youtu.be/jZQP2oNDkAM?t=525 (he talks specifically about nukes at 8:45, but I really recommend watching the whole if you're into this kind of 'crazy-but-great' ideas. ;-)
That said, putting nuclear waste deep underground and sealing the hole is probably the best best.
Some half-lifes are so long that just any progress over a fraction of these time-scales should be be enough to be better off to wait for the tech to be ready than to bury the material.
Still, the idea of dumping waste that deep doesn't sound like a good one.
https://www.imdb.com/title/tt0059065/
Just need a way to efficiently extract the heat from whatever depth and convert it to electricity by usual means.
[1] https://en.wikipedia.org/wiki/Therme_Erding
https://en.wikipedia.org/wiki/Beppu
It's really an almost surreal experience, with encrusted hot spring water pipes and steam everywhere in the district. Sometime you even need to be careful where you step to avoid to be scolded by steam coming up from the ground, likely due to overflow from the hot water boreholes flowing to the rainwater drainage system.
And it's not just the modern hot water boreholes they use to supply the hot spring baths & other users. One time we even saw a traffic code & couple sandbags placed on a random hillside next to the road, as there was steam escaping out of it. :D
1. https://en.m.wikipedia.org/wiki/Stirling_engine
This also discounts stuff like the need for maintenance, that is hard to achieve at the bottom of a hot & likely very humid if not water filled borehole.
For that reason, most geothermal systems pump water down & then back up again (possibly using multiple wells) & have the heat engines at the surface, where they can be easily serviced & a good heat differential can be achieved, via air or water cooling.
This in the end, is generally an industrial operation though, not really something suitable for every single house. Still helps with maintenance, as you can provide energy for many houses & don't hat to maintain the geothermal power production equipment for each house separately.
And yes, potentially much more heat than we'd know what to do with currently.
Interesting hard sci-fi (well, basic physics principles mostly) about it by Isaac Arthur: https://youtu.be/jZQP2oNDkAM
Disclaimer: absolutely not affiliated with the man but deeply hoping that such perspectives become maintream, normal expectations. Not holding my breath, but one hacker at a time, we'll get there!
An example: https://www.cnbc.com/2018/11/06/drilling-to-start-at-the-uks...
Not quite there yet: https://www.uniteddownsgeothermal.co.uk/future-programme
In both construction time and cost it's a bit meh compared to wind/solar, its only advantage is dispatchability.
https://en.wikipedia.org/wiki/Geothermal_energy
Could they cover the hole, pour water into it and use air pressure changes in the hole to generate electricity? There must be a way to make the hole air tight. I suspect that the rock near the bottom of the hole would already be air tight.
Also I never understood why steam engines release all the hot stream into the air? Doesn't that waste energy to let the hot steam out? Isn't it better to keep the heat trapped inside the system and generate electricity from the pressure only?
Steam engines are old technology. They've been replaced by modern steam turbines, in which the steam is either cooled and recirculated, or used for other processes, or both.
Geothermal steam turbines typically use a heat exchanger and release the original steam, as geothermal steam tends to be very corrosive.
They don't. All practical steam engines have condensers that recover most of the water and as much of the heat as current technology and the laws of thermodynamics allow.
If you want a single project at a huge scale, check out https://news.ycombinator.com/item?id=15596350
There's the added issue that rock's thermal conductivity is low, and any thermal borehole would have a limited effective lifespan as it reduced the temperature of adjacent material.
Geothermal energy is a viable and widely tapped energy resource, where it's available. In almost all such locations, it's been substantially exploited, with two notable exceptions: the African Rift Valley (mostly in Kenya), and the Yellowstone supervolcano, a national park in the US.
Substantial developments exist in California (The Geysers), Hawaii, Iceland, Japan, the Philippines, New Zeland, and quite probably elsewhere. 1GW+ plants are possible, comparable with the largest practical thermal and nuclear power plants (generally 1-4 GW, though multiple plants or reactors may be co-located). Worldwide capacity as of 2015 is about 12.5 GW.
The two principle variants are standard and enhanced geothermal. A standard plant utilises naturally-occurring steam, and is far less expensive to develop. "Enhanced geothermal" involves boreholes and often water injection to provide power generation.
I'd followed the case of one such project in Australia, the Geodynamics Habanero project. I'd first read of that in 2014 through a grossly misleading and fatuously optimistic report which struck me as both odd and curiously fact-free. Digging showed that in reality the project was running years late, at 1/50th originally-planned capacity, well over budget, and with significant technical challenges.
https://old.reddit.com/r/dredmorbius/comments/1wpa90/how_not...
Checking now, it appears the firm plugged the remaining wells in 2015 and cancelled the project.
http://www.thinkgeoenergy.com/geodynamics-plugging-wells-and...
Even had the project gone as initially scoped, the wells would have had a useful life of about 20-40 years, after which all available useful thermal energy would have been extracted, and would have to be replenished over ... long time, possibly centuries or more. There's a reason the Earth's interior remains molten -- rock is a very good insulator.
I'm not an opponent of geothermal power -- where appropriate it's highly useful, dependable, safe, and proven. In Africa it stands to make a tremendous difference, where even a small plant would make a tremendous increase in the availability (and probably reliability) of electricity. I'd encourage consideration of developing even such normally off-limits natural park resources such as Yellowstone (specifically excluded from a USGS geothermal resource survey I'd checked on some years back).
But enhanced development through borehole-based wells looks like a very long shot.
Wikipedia's treatment of geothermal is good:
https://en.wikipedia.org/wiki/Geothermal_power