The deepest hole we've dug is probably the Mir diamond mine in Siberia, at 525m 
(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.
Shout out for the deepest hand dug well: https://www.mybrightonandhove.org.uk/places/utilities/woodin...
(This is where the 'deepest hole dug' contest gets a whiff of 'No true Scotsman...')
On some levels I find the well more impressive than the mine, though. A 4ft diameter hole dug 1285ft deep means some 400 cubic meters of dirt was removed. By hand. That's an awful lot of blisters by anyone's standards.
I doubt the borehole in the original article goes straight down. Boreholes tend to list left and right.
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.
>"I was almost physically sick watching this last night," said Mark Stevens, chartered safety and health practitioner at The Building Safety Group. "In fact, I had to turn over straight away I couldn’t watch it anymore."
But personally attacking strangers on the internet is acceptable too.
These were done using power equipment, but they aren’t boreholes.
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!
> "I later learned that blind people can 'hear' thunderstorms because the low frequency can be sensed in the body"
Huh. Amazing no one has commented on that.
the Goopists are actually telling lies
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".
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.
Yucca Mountain was supposed to be the solution this temporary storage; but the budget for Yucca Mountain got suspended, so the US are back to the temporary solution.
But postponing forever in the hope of a better solution is a bad solution; because in the meantime they are in unsafe locations.
Still, the idea of dumping waste that deep doesn't sound like a good one.
But the article sounds like a sales pitch
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
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.
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.
For this reason most steam engines in ships and elsewhere generally did have condensers & reused the steam as feedwater, as you describe.
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.
Checking now, it appears the firm plugged the remaining wells in 2015 and cancelled the project.
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:
This free-fall calculator (with air resistance) reports a fall duration of 229 seconds (3m49s) with 121mph velocity for a 72kg mass with the default air resistance coefficient as used in skydiving.
And showing relative depths -- it always surprises me that modern oil wells aren't actually _all_ that shallower: https://xkcd.com/1040/
> reached 12,262 metres (40,230 ft; 7.619 mi) in 1989
While Deepwater Horizon's deepest drill:
> In September 2009, the rig drilled the deepest oil well in history at a vertical depth of 35,050 ft (10,683 m) and measured depth of 35,055 ft (10,685 m)
It's maybe not a useful technical measure, but it's a lot closer in "depth" than I imagined it would be given the amount of attention given to the Kola borehole, and especially the tales of the difficulties they faced. Makes me think that one of the big oil companies could probably beat the record if they wanted.
There is a theory that oil is actually generated as a by product of the mantle itself, not by buried prehistoric plants.
If that's the case, oil could truly be a limitless resource, which is bad news for the climate.
Sounds like more like alchemy than actual science. What magical process transmutes rock into long chain hydrocarbons?
I think the best argument against abiogenic petroleum in the mantle is that if the theory had any merit Exxon would have figured out a way to bore into the mantle decades ago.
Great article, but does anyone have any insight as to what those techniques were?
I hadn't seen the Onion video parodies before, so I'm glad someone is holding a mirror up to that crap, but truth be told, it is as equally unwatchable as the originals.
Warning: nerd alert!
Set it up so the digger's progress only continues with a donation so you can "buy" a foot of the depth.
That hole makes me unnervingly angry. And I can't be the only one.
"Destroying the planet"? Come on. It's a hole in the ground. We make a hole ten times bigger than this every time we build a building.
this is the same forum where people minimize their consumer garbage output to one bag a year and reduce aviation usage to reduce carbon footprint. I find it EXTREMELY condescending that you ridicule my opinion. Whats the scope for scales of environmental impact that matters?
Every single construction project in an area where an endangered species lives, the USAF must conduct an environmental impact study for said species from the project, even if its a toilet.
I am very much extremely reactionary, this is a news forum. People post news and react to it.
Why don't you donate some money to charity to offset your fake moral outrage?
What I don't understand is why you're so clearly and idealistically virtue signaling, and taking other people's commentary so deeply personally, while your profile says:
>This is my avatar for participating in a community full of idealists, virtue signallers, hardworkers, and paid advertisers.
>To take personal any of my commentary is a folly of the reader.
You sound like a troll to me.
PS: You misspelled "signalers" and "hard workers", and just forgot two apostrophes. Did you know that your web browser has a built-in spelling checker and corrector? Look for misspelled words with squiggly red lines underneath them, then click the right mouse button on them to pop up a menu with correct spellings. Also, you should brush up on the simple easy-to-remember apostrophe rules -- it will improve your trolling:
>Live long and prosper.
I hold a genuine desire for strangers to live a fruitful life.
Please, consider revisiting the source of your anger and hate to a stranger and ask yourself "what is the effect I aim to have?" If you are aiming to hate as a cathartic release, I suggest writing a journal. If you are aiming to hate as a means of cruelty to a stranger online, do it anonymously without your real name attached to it.
And Don I have to tell you, I am not a troll and I have to ask what crime did I commit expressing myself?
Was the post script necessary?
Maybe I get heated because this forum claims a standard is being held while I see bias persist
Maybe i believe it is important in a healthy democracy that the right conversations happen.
Maybe I hate bullies. You def. Are being a bully.
You disregard a real talking point on how little liability we hold people to disrupting land, and just attack me, AND YOU CLAIM YOU CAN BC YOU PERCEIVE ME AS A TROLL.
I stand by my profile description bc this is a diverse community.
I have a question for you, what is your purpose of your rant? To make me feel bad and you feel superior?
PS: That's "PostScript" (TM Adobe).
>Is the hole bad for the environment?
>No, this was just a bunch of empty land. Now there’s a hole there. That’s life.
>Why aren’t you giving all this money to charity?
>Why aren’t YOU giving all this money to charity? It’s your money.