Comment by Animats | Hacker News Reader

Comment by Animats | Hacker News Reader

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Microwave drilling. It's a known thing at small scale.[1] If it can be done at larger scale, it ought to have other applications. Doing it downhole at the end of a long pipe string is going to be much harder than doing it in a factory. So why isn't this an industrial machining process already, like plasma cutting?

GA Drilling was pushing plasma drilling back in 2018.[2] They're still pushing it, but not making holes.

The University of Minnesota was pushing electro-pulse boring in 2015.[3] Again, no deep holes.

There's something called ThermoDrilling, which, despite the name, is more like a water jet cutter.[4]

Successful projects are still using mechanical drilling.[5]

So there are a lot of deep hole drilling approaches being studied. Anything that works would be used by the oil and gas industry, and if they're not trying it, one suspects it might not be working.

[1] https://www.researchgate.net/publication/270653673_Microwave...

[2] https://www.gadrilling.com/

[3] https://experts.umn.edu/en/publications/electro-pulse-boring...

[4] https://www.geodrillinginternational.com/deep-geothermal/new...

[5] https://geothermalengineering.co.uk/united-downs/

Conventional “mechanical” drilling isn’t very heat tolerant because heat softens metal. For oil and even gas drilling it doesn’t need to be; they’re located in cooler rock. For supercritical steam EGS heat tolerance is a sine qua non. Conventional approaches might still work best, but it’s also plausible that what’s best for gas isn’t best for EGS.

But if we get to temperatures that destory metals, isn't it enough?

Why don't we drill to whatever is the termal limit, make a big cavity there, install radiators there and just heat the watter to that temperature and take it out to surface where we can heat homes.

I know this is done in Bucharest for a water park (to much lesser depths because apparently we have hot springs near Bucharest).

Do we need to reach magma?

This is about running your air conditioner, charging your Tesla, and molding your kitchen sink, not heating homes. Think Carnot efficiency, power density, supercritical steam, and shutting down gas pipelines.

And the temperature to destroy steel under the immense mechanical stress of a drill string is surprisingly modest. Jet fuel can’t melt steel beams, but softening them is enough.

In a fire, A wooden ladder remains viable king after an aluminum one! Soft happens WAY before melt

Thermal mass and thermal conductivity also play a role in this example. Two more reasons a wooden ladder is better in this scenario. For ladders at the same temperature, the aluminum one would conduct more thermal energy, quicker, into a user's hand then a Wooden one. Making a wooden one more usable for longer in this scenario even though the aluminum one would technically last longer.

This is why wooden sauna seats work well, aluminum seats in the sauna would not go over so well.

Lots to consider when solving thermal problems, it's not just about turning up the dial to be able to withstand more heat. Sometimes it's about the nuance of moving the heat efficiently and putting it where it's wanted, and not where it isnt.

Wood has about the same specific heat as aluminum, but a wooden ladder weighs much more, so a wooden ladder at the same temperature contains much more sensible heat to eventually conduct into the user's hand.

I looked it up. Actually wood had about twice the specific heat as aluminum. So I must revise my original comment to remove specific heat as a driving factor. This leaves only thermal conductivity. A wood ladder would have more heat to give than an aluminum one, but it still is able to give it much slower, making it ok to touch for longer.

Agreed. I'm surprised the difference in specific heat is so large! Maybe that's fairly humid wood? Because glucose is about 220 J/mol/K https://webbook.nist.gov/cgi/cbook.cgi?ID=C492626&Mask=2#The... and 180.2 g/mol https://en.wikipedia.org/wiki/Glucose, working out to 1.2 J/g/K, and aluminum is 24.2 J/mol/K and 27.0 g/mol, giving 0.90 J/g/K.

My general rule is that everything is 1 J/g/K except water, which is 4.2. It's obviously not true, but almost always within a factor of 2, and 1 is an especially easy number to multiply and divide by.

Reading your first paragraph, I was thinking "water. the answer is always water", when it comes to estimating the properties of life-stuff vs everything-else-stuff within a factor of 2. Not obviously, of course, but it's just such a powerful heuristic.

Reading your second paragraph, I see you're familiar with the principle, and added a good heuristic to my stockpile, thank you.

Happy to share :]

> Jet fuel can’t melt steel beams

ISWYDT.

Metals start to get weaker at relatively low temperatures. https://www.engineeringtoolbox.com/metal-temperature-strengt... We want to extract 100’s of MW of heat which presents several issues.

You need a thermal gradient to move heat from the surrounding rock to the water your pumping in. The higher the initial temperature the larger the difference and therefore faster you can extract heat. Aka even if the working fluid is at a constant temperature you can simply pump it faster.

Also, Carnot efficiency limits means you want the hottest steam you can handle. Further, you have various inefficiencies such as losing heat as water moves back up a borehole.

> Do we need to reach magma?

Nope. Over the last ~20 years the drilling industry has gotten good at: angle drilling (not slant drilling but turning the drill angle at the bottom) and fracking, or pumping fluid through rock to break it up. This means conventional methods can dig far down, turn the drill and make a reserve with fracking. The heat is much less but it's conventional technology.

https://www.ted.com/talks/jamie_c_beard_the_untapped_energy_...

> Do we need to reach magma?

Nooo --- don't dig the Well to Hell!

https://en.wikipedia.org/wiki/Well_to_Hell_hoax

Steel in particular softens at a much lower temperature than it melts. And it doesn't need to soften much to make a really long thin drill bit bend.

> Anything that works would be used by the oil and gas industry, and if they're not trying it, one suspects it might not be working.

To flip that around: this would imply that the most under-investigated-in-industry approaches to deep hole boring would be the ones that destroy the economic value of any oil-and-gas in the ground, no? Ones that make the ground radioactive, perhaps. Or that would set any potential oil fields on fire, or react them away, or irrevocably mix a combustion-inhibiting azeotropic solvent into them.

Don't worry, we were doing nuclear fracking back in the days. Everything that could work has been tried for oil and gas exploration.

https://en.wikipedia.org/wiki/Project_Gasbuggy

Regarding drilling operations that destroy value: you're forgetting that drilling is 1D while oil fields are 3D (technically quasi-2D with horizontal dimensions 100x to 1000x larger than vertical dimensions). If your drilling messes up everything in a 10 meter radius from the drill string, you don't care.

> Don't worry, we were doing nuclear fracking back in the days. Everything that could work has been tried for oil and gas exploration.

Likewise, everything that conceivably could be done with nuclear was tried or at least designed for a while there - lighting watches with radium, digging canals with nukes, space travel by continuously exploding nukes behind you... good times. (Horrifying times, but w/e;])

> Likewise, everything that conceivably could be done with nuclear was tried or at least designed for a while there - lighting watches with radium, digging canals with nukes, space travel by continuously exploding nukes behind you... good times. (Horrifying times, but w/e;])

"The top secret plan to explode a nuclear bomb in Yorkshire", by Tom Scott: https://www.youtube.com/watch?v=ceWZslOfEjs

Not to mention https://gajitz.com/1950s-radioactive-science-kit-most-danger...

Why do you think that drilling is one dimensional? Drilling at an angle, and even at gradually changing angles is common.

Technically embedded in that case, as your drill line can be represented (often) by a single parameterized function.

Exactly. Unless you plan to zizag around all over the place, most of the reservoir won't be in the near-well region.

I've long wanted to put some money into an eco terror fund.

It would buy controlling interests in all the companies that make some critical, specialized and heavily patented piece of modern internal combustion engines or coal turbines. Then, it'd wreck the factories, and patent troll everyone else into not producing.

Money is speech, and that would be protected political speech, right? :-)

As my wise auntie says,”You can’t see clearly through the bottom of a pint glass.” Are you not drunk on energy? Warm or cool at will, well fed and clothed, able to travel and communicate? There’s no collecting if you bet on the apocalypse. <\wisdomnag>

>There’s no collecting if you bet on the apocalypse.

That's just not true. Misery and suffering is it's own reward, to some. This is arguably the main point of Orwell's 1984, when O'Brien explains to Winston Smith why they bother torturing people before killing them. O'Brien says that to knowingly cause suffering in someone is the ultimate expression of power, and it is axiomatic to him that power is good in-and-of-itself.

that will result in those devices will be manufactured by the Chinese instead, and them then having a near monopoly

Honest question: if something is patented, sure China could manufacture it, but wouldn't patent protection prohibit importing the counterfeit good into the USA?

I've never actually thought about whether patent protection covered just the sale, or the manufacture, or exactly what, so thanks for bringing that nuance to my attention!

Once it had demonstrated enough success to instill fear in the hearts of wall street bankers, I think it could start turning a profit. It would announce targets ahead of time, tanking the stock. On the way down, the companies would reinvest the money they make selling themselves for parts back into the fund.

You're not going to tank a stock by publicly telling people you're going to buy a bunch of it. A bunch of people will try to get in front of you and bid you up.

Hey, if a DAO can raise enough money to almost buy the Constitution, maybe you don't need to wait for Someone Else™ to start the slush fund required to pull off that stunt /s (but also not /s) -- err, specifically I meant the "fund" part, not the "wrecking factories" part, unless you meant economically wrecking, in which case I think it's still plausible

> this would imply that the most under-investigated-in-industry approaches to deep hole boring would be the ones that destroy the economic value of any oil-and-gas in the ground,

That is only one explanation to why a technology would be among the most under-investigated-in-industry approaches. There are many others, such as:

- It does not work at all.

- It is more expensive than traditional methods

- It is illegal in some way

- It is incompatible with the rest of oil&gas processing.

Option C: it doesn't solve enough problems for oil and gas to have been worth pursuing compared to iterative improvements to existing systems.

Whereas for geothermal, conventional drilling isn't useful enough for it.

Oil companies sell finite fuel for energy to people in cars, on the move.

Geothermal heating provides unlimited fuel for people in houses, staying still.

The technology is similar, and it's boring ;-) The market is different. This is an opportunity for entrepreneurs to hire expert drilling engineers out of the oil industry!

> Geothermal heating provides unlimited fuel for people in houses, staying still

This sounds like the beginning of a great sci-fi novel.

A future where Earth's core has cooled because of excess draws to power humanity. Now, the planet is losing it's magnetic field.

To save humanity, humans need to re-heat the core, build biospheres, or leave the planet.

"A future where Earth's core has cooled because of excess draws to power humanity."

Has anyone done the napkin math for how long that would take?

About as long as it would take to cool the surface of the sun.

https://www.forbes.com/sites/alexknapp/2013/04/28/the-center...

Core of earth: 6,000 ºC

https://www.space.com/why-sun-atmosphere-hotter-than-surface

Core of sun: 27 million ºC Surface of sun: 6,000 ºC

"The leading idea among experts is the sun's magnetic field is actually bringing energy from inside the sun up through its surface and into its atmosphere."

The "napkin math" will involve gathering some data about RF power harvesting, and some assumptions (e.g. cosmic rays)

https://news.mit.edu/2020/energy-harvesting-wi-fi-power-0327

https://en.wikipedia.org/wiki/First_law_of_thermodynamics

Do you believe in the 1st law of thermodynamics, that energy is neither created nor destroyed?

https://en.wikipedia.org/wiki/One-electron_universe

We could just balance the system:

core of Earth too hot -> use geothermal

core of Earth too cold -> use solar power

We basically can not accelerate the process. Almost all the resistance to heat movement is on layers we can not reach at all.

Do you think that reheating the core of Mars could reboot life there?

https://news.ycombinator.com/item?id=30476002

It's even more interesting that you mention the magnetic field, could we use solar panels to draw more energy from the sun to power a tesla coil and microwave the core?

sounds similar to the plot of The Core

(it was not great)

It's surprising how often that movie comes up, especially given how it's often accompanied by a note that it's not good. I suspect it's hit a pseudo-cult classic film status. The last few times I've seen it mentioned I've had the desire to seek it out and watch it again since I only remember bits and pieces.

That's what you get when you do a lot of publicity for a movie that is not good.

This could also have good use for ground source heat pumps - they're the most efficient, robust and consistent source of domestic heating we have, but require fairly deep (60m ish) boreholes. If digging could be quicker, easier or faster these heat pumps could be installed everywhere.

I have one of those. The well is 170m deep. Took 2 guys about half a day to drill it, so that actually doesn’t seem excessive in terms of time required (mostly sand, no rock below my house).

I assume you mean “2 guys and some heavy equipment”? As a kid it took me a whole summer of on-and-off digging to make a 1 meter deep hole for fun.

Out of curiosity, what were you digging with? Unless you were digging with a toy sand shovel or making a very large hole, that seems like a very long time.

As a kid, my cousin, my sister, and myself were able to dig a hole deep enough for me to be completely inside in an hour or two using a post hole digger. (Yes, this is a very stupid idea.)

You have to make sure it's straight, drop sheathing in to the hole, and then cap it if it isn't going to be used right away.

More importantly, geothermal/ground source is rarely 1 well either, in our case it was 8.

A shovel. I couldn't get past 1m because of the rocks were too difficult to shatter.

That’s fair. We were not digging through rocks.

That’s what they mean. My neighbor had one drilled and the contractors showed up with a huge well-drilling truck.

It’s just a huge vertical drill with segments you add on as it goes deeper, like an oil well drill.

Correct, it's big but I wouldn't say huge (maybe 4.5x2.5m). This is the machine they used: https://conrad-stanen.nl/nl/producten/boxer-200

Most drills I’ve used fit in your hand. Compared to that, it’s huge :)

(although on rereading I didn’t mean to say ‘huge’ twice in my previous post)

Awesome! Do you sink heat into it during the summer, or do you also use it for airco?

Sink directly into it for the summer. Heat exchanger between the source (approx 10-15C) and the water from the floor heating/cooling system. Because the heat pump is not involved it's very efficient (only the power of the well pump)

I'm actually considering if it makes sense to push a lot more heat into it in the summer (Deliberately leaving curtains open, then moving this heat into the well; or even PVT panels), but I'm not sure if the well would retain heat long enough to make a difference towards the winter.

It definitely should, I'm not sure making your A/C work harder deliberately makes sense economically, I guess you'd have to do the math. PVT or even just thermal panels (i.e. rolls of garden hose painted black in a glass covered box) would make a lot of sense if you're in a colder climate though.

Your system should give a an overview of your yearly input/output and any drift of the well temperature right?

Except this technology is for after you get to the plate of rock at the bottom of topsoil unfortunately. They mentioned it in the article. You use conventional drilling to get to depth first.

They can also be horizontal, covering a larger area at a much shallower depth.

Indeed horizontal (pipe network, like underfloor heating in reverse) is the most efficient solution, digging deep is for when the plot is too small or otherwise encumbered (or if one sits on top of a volcano).

A 60m borehole is not a source of energy, it is a store of energy. It only makes sense if you can sink enough heat into it in the summer, to use that energy in the winter. Or vice versa in warmer climates.

We have a ground source heat pump and one summer we were away and did not use out air conditioning that year much at all. Mid winter our return loop temperatures (the glycol being brought in to our heat pump after circulating in the ground) was at one point 3 degrees C cooler than it had been any other year. Quite a noticeable difference. For reference, our loops are 8 vertical at 250ft.

Wait, do you need eight 250ft wells?

Yeah for a family home that seems about right. 250ft is not very deep at all, and you need to store a lot of energy to past a whole winter/summer.

For a closed loop system, yes. I think that would be the minimum (6000 sq ft house) at 250ft depths.

Couldn't we have one big plant with a large hole that distributes heat to surrounding homes?

Very interesting context here, thanks. Do you know of any write-ups that give a deeper picture of the progress of any of these (or other similar) projects? It seems that there are tough problems to be solved, but we're just seeing the marketing materials.

Another thing that should be considered: how do you keep the hole open while drilling? At extreme P and T, the hole will close in on the drillstring. Also, fluids turn very nasty in those conditions. You'll need some unobtanium and some of Superman's suit material.

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