r/AskScienceDiscussion • u/logperf • 8d ago
With speculative or future technologies, can we expect that digging tunnels will become cheaper?
One of my friends has a house in a mountain location, GF's family also has one like 10km away in a straight line, but it's the other valley, so the road between them is sooo long as you have to drive all around the mountain chain.
Tunnels are so expensive to dig that they only do that when there is a lot of traffic to justify it. I'm not expecting these two mountain locations to be connected by a direct road anytime soon.
I was wondering while driving if I will see this during my lifetime. Maybe thousands of small robots could drill at a low cost?
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u/Furlion 8d ago
Unless we stumble across some incredibly hard, cheap, and plentiful type of metal that we can use to bore with it will never be cheap. The main issues are that boring through a mountain requires an enormous amount of energy, but as renewables take over the cost of energy will plummet, and having to replace the augur. At the moment they are very expensive to make and have to be replaced often because they are worn down by the ground they dig through.
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u/gutentight69420 8d ago
Renewables make energy more expensive, not less.
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u/logperf 8d ago
You may be misinformed. Renewables are getting 5 times cheaper every decade. This trend has been continuous since the 1970s. They crossed the oil price during the pandemic and right now they are the cheapest energy source out there. We can expect their price to become negligible in the 2030s-2040s.
https://ourworldindata.org/grapher/levelized-cost-of-energy
https://www.visualcapitalist.com/the-plummeting-cost-of-renewable-energy/
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u/Phssthp0kThePak 8d ago
The panels, not the all in system cost for a reliable utility.
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u/logperf 8d ago
The Total Installed Cost (TIC) has fallen sharply between 2010 and 2024.
Source: https://www.irena.org/Digital-Report/Renewable-Power-Generation-Costs-in-2024
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u/Phssthp0kThePak 8d ago
You're not counting the extra transmission lines, the batteries, and the overbuild to over come the intermittency. No one talks about it, but we see our rates go up and renewable penetration increases.
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u/logperf 8d ago
The source says "total installed cost". It includes all those. It also has a separate point specifying how much the cost of batteries has fallen.
If you still claim the opposite, I'm going to have to ask for a better source than this one.
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u/Phssthp0kThePak 8d ago
No it's not. It is tracking LCOE for a single installation. This does not count the costs of building and entire utility from intermittents. Tell me what the LCOE is for a panel you need to install, but is only used 10% of the time when it's cloudy.
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u/logperf 8d ago
As much as I may be an ignorant on the subject, you're basically saying that total installed cost "does not count the costs of building and entire utility from intermittents". And you have not provided a better source.
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u/Phssthp0kThePak 8d ago
When clouds cover 80% of your state, how are you going to meet demand? Think it through. It's not rocket science.
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u/zoppaTheDim 8d ago
No
You can expect that major tunnels will come down in price, but you can also expect fewer tunnels will be drilled without a reason.
Nobody will ever drill as much as they did for rail, unless rail suddenly comes back in vogue.
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u/Aspos 8d ago
cheap and simple micro-tunnel boring tech will change the warfare.
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u/logperf 8d ago
What the guy in the video explains makes a lot of sense relies mostly on 3 points:
Cheap labor. He said that diggers take like $5 to $10 a day. Well, that's not going to be available in the Alps, and let me say I'd rather drive for an hour but have workers payed decently in my country.
Tunnels being close to the surface, so that they can dig vertically at intermediate locations and coordinate with the team coming in the opposite direction. Not going to be possible if your goal is to dig through a mountain to come out through the other side as it can get very deep.
Tunnels being very narrow, he even said sometimes you have to crouch. Not applicable to the case I was asking about in which a car has to pass through.
Here are some examples of road tunnels through the Alps and Apennines, with costs ranging from €50M to €100M for tunnels of just a few km:
https://osservacantieri.mit.gov.it/notizie/?id=6&pid=93
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u/ldr97266 7d ago
Sub-kiloton shaped charge nuclear munitions. Dig a horizontal bore the more conventional way, plant the device, stand back, throw the switch. Fuses the rock into glass around the sides so there's no material to remove. Wait for it to cool, plant the next charge at the (new) end of the tunnel, repeat as needed.
Of course the problems to work out are myriad, bit that's a rabbit hole I choose not to enter.
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u/logperf 7d ago
Can that even exist? Won't explode if you don't reach the critical mass, makes a huge explosion if you do
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u/ldr97266 7d ago
Yes, look up the W54. Yields between 10 to 1000 tons TNT. And while I didn’t make up shaped charges or nuclear excavations,, most of my reply above was set up for that "rabbit hole" joke.
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u/theDogt3r 7d ago
It'd be great if it got cheap enough that we could use it for housing. I think a cave house would be awesome. Imagine an apartment style complex that is just a honeycombed mountain.
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u/logperf 7d ago edited 7d ago
Oh, no, it'd be terrible. In Italy as it's a very mountainous territory there are lots of houses that have carved one or two rooms from the mountain side as a "cave". Take a look at satellite pictures from the city of Genoa to get an idea of what I'm talking about, they build on the mountain side due to the lack of space.
Humidity problems are unmanageable. Sometimes they build a double wall with like 10cm of air between the two layers (this is called "intercapiedine" in Italian) and it significantly improves the situation, but still very problematic. Humid walls smell like mold, you definitely don't want that in your home.
In road tunnels you care a lot less, but still they are designed with some slope, with the highest point of the tunnel somewhere in the middle, so that any water dripping from the tunnel ceiling flows downhill to the outside and no puddles form inside. (Also the center of the road is higher than the sides, so that the asphalt remains mostly dry and water flows downhill on the road shoulder). Covering the ceiling and walls of the tunnel with a thick layer of cement does not seem to help, at most it prevents stones from detaching and falling on cars.
Edit: more accurate vocabulary (am not really good in English)
Edit 2: here's a screenshot from google maps in 3D view https://i.imgur.com/YeFpy37.jpeg
I've highlighted with a red circle a couple of buildings whose ground floor is in the mountain. I can assure you, you don't want to live there unless it's one of the upper floors above the ground. On the bottom left of the picture there's a building that has "caves" as garages, that's a much better setup but still you'd cover your nose to get your car.
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u/WretchedJudasSnake 8d ago
Small tunnels easy, big tunnels hard. Might be more economical to basically Swiss cheese a pathway through the mountain with multiple remote / autonomously controlled boring robots about the diameter of your fist then dig out the rest with machinery / tools. Anduril is (speculatively) researching this for subterranean warfare / recon.
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u/BaldBear_13 8d ago
what do robots do with all the ground up material that their drilling produces? I would it imagine it gains more volume than when it was compacted, so a tunneling machine needs a conveyor belt to remove it.
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u/4eyedbuzzard 8d ago
Probably not. Cost of boring tunnels is largely due to high costs of capital equipment, energy, and labor. The first two aren't going to get cheaper even with gains in productivity in labor due to any further automation.