Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

You can have geothermal power everywhere if you drill deep enough

treehugger.com

Post reply on HN
Print view View original

241–250 of 314 posts

Re: You can have geothermal power everywhere if you drill deep enough

#241

Post by anonporridge »

pbhjpbhj wrote: post #116
anonporridge wrote: post #14

Earlier quoted context omitted.

Yeah. All civilization consumes around 17 TW of energy while the sun is constantly bombarding the Earth with 173,000 TW. We could rebase all of civilization on geothermal and the extra heat in the atmosphere would be a rounding error to the sun's energy.

I don't think "it's a rounding error" is enough analysis here. A couple of meters of sea level rise, a couple of degrees temperature rise; these could be termed rounding errors.

It's far less than the variance of direct solar irradiation hitting the Earth given varying differences in distance from the sun in the Earth's orbit. https://en.wikipedia.org/wiki/Solar_constant#Solar_irradianc...

It looks like direct solar radiance is actually 173,000 TW plus or minus 6,000 TW.

Re: You can have geothermal power everywhere if you drill deep enough

#242

Post by doikor »

There is a project for deep geothermal heat in Finland. They specifically chose to do it here as it is one of the worst places to do it (have to drill really deep to get anything useful also the first 4 to 5km is just pure bedrock instead of some softer material).

So they ended up making 6.4km deep holes where they got 121 degree (celcius) water. Once pumped up to ground level it cools down to 110 degrees but it is more then hot enough for district heating.

The original plan was to got 9km deep but it was already hot enough at 6.4km so they stopped there to save money.

https://www.st1.com/geothermal-heat

Re: You can have geothermal power everywhere if you drill deep enough

#243

Post by Dylan16807 »

onlyrealcuzzo wrote: post #161
anonporridge wrote: post #14

Earlier quoted context omitted.

Yeah. All civilization consumes around 17 TW of energy while the sun is constantly bombarding the Earth with 173,000 TW. We could rebase all of civilization on geothermal and the extra heat in the atmosphere would be a rounding error to the sun's energy.

So if our energy consumption increases by 4% per year (current global average) for ~110 years, we'd need to capture / produce as much energy as the Sun hits us with. Crazy!

That would also mean going from kilowatts per person to megawatts per person, so yeah that's pretty crazy.

Re: You can have geothermal power everywhere if you drill deep enough

#244

Post by ChuckMcM »

fly-guy wrote: post #230
ChuckMcM wrote: post #58

Earlier quoted context omitted.

I believe you may have missed what these folks are doing differently. To put it into context, geothermal energy that taps underground water reservoirs near heat sources has been shown to cause earthquakes and other not good side effects. All of those effects are associated with water being released from aquifers that were previously sealed, or ground changes due to water incursion into previously dry structures (whic…

Great start, but one important factor is missing from this analysis: The surface area (for heat exchange) of a closed-loop borehole is tiny compared to the surface area in a natural hydrothermal system. The walls of the borehole will cool off relatively quickly due to the low thermal conductivity of rock, and you'll soon be unable to make power. Conventional geothermal gets around this by pulling from very large rese…

You may be right. Back of the envelope kinds of computation though, 6 miles of 12" diameter bore hole is 99,525 sq ft of surface area for thermal transfer. If you think of the lower half of that as the heat injection surface (so 3 miles -> 6 miles and then back up to 3 miles on the way out) call it 100k sqft of rock surface. Now some people have spent a lot of time studying rock (https://pubs.usgs.gov/of/1988/0441/report.pdf) I'm not one of them (more of a casual geologist because I like hiking in the mountains) but if I'm reading the heat transfer equations from pg 91 of that report it still seems like you'd get a decent amount of heat transfer (order of 10's of MJ) into the water.

Re: You can have geothermal power everywhere if you drill deep enough

#245

Post by pmoriarty »

ijidak wrote: post #163
peterburkimsher wrote: post #151

Earlier quoted context omitted.

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?

Re: You can have geothermal power everywhere if you drill deep enough

#246

Post by freedomben »

3pt14159 wrote: post #212
oceanplexian wrote: post #167

Earlier quoted context omitted.

There is no such thing as sustainable growth. Eventually, one day, sooner or later a very unsustainable chunk of high speed space rock will hit the planet and wipe us out, or some other completely natural and “green” disaster, like a supervolcanic eruption, as has happened repeatedly in history. The only thing that will matter is if we advance our technology to a point to divert the problem or make ourselves sufficie…

> The only thing that will matter is if we advance our technology This is your objective to meet your end which is survival. I don't agree with it, but I'll respond as if I took it for a given. > As far as I know, the best way for humanity to advance technology is with growth. What you mean by growth here matters. More people with a higher standard of living is two types of growth. One is economic the other is popula…

I tend to agree with you philosophically, but when it comes to implementation that's where I really struggle. How do you curtail either of the two types of growth? It seems like the only options include authoritarian and borderline human rights violating. A group of progressive countries could band together and try to invade China and force them to slow their growth, but even ignoring the ethicality of forcing our will on others, most people would agree that the death and suffering would be pretty bad.

So far the best form of population control has been prosperity. Birth rates tend to fall as quality of life goes up (not always of course because there are many factors in that). The other option is outlawing reproduction much like China did for a long time. That seems questionable re: human rights also.

Re: You can have geothermal power everywhere if you drill deep enough

#247

Post by Dylan16807 »

Fiahil wrote: post #26
eru wrote: post #16

Earlier quoted context omitted.

Assuming this is a real problem, wouldn't you just put your geothermal power plant well outside of any city? Doesn't even have to be somewhere where there are no buildings. Just somewhere where hardening the few existing buildings against small earthquakes etc won't be too expensive.

> Just somewhere where hardening the few existing buildings against small earthquakes etc won't be too expensive. So, expending twice on a bad idea ? Seriously, what do you think will happen ? And even it was technically possible, how do you insure a company like that ? Will the plant operator be responsible for the repairs and damages when they destabilize an entire region ?

I don't think the "entire region"s involved would be big enough to make insurance difficult to implement.

Re: You can have geothermal power everywhere if you drill deep enough

#248

Post by freedomben »

hedora wrote: post #210
popcube wrote: post #94

Earlier quoted context omitted.

yes, until now, scientists always can save us. but they just need one time...

Scientists have done more than enough. The issue now is entrenched interests blocking progress. We had all the technology we needed to go carbon neutral back in the 1980's. Back then, even the American Petroleum Institute (yes, the planet burners) were raising alarms over CO2 and global warming. We have many technological doublings ahead of us before technology fails to provide opportunities for growth. That's not th…

We may have had the technology in the 80s, but the economics is only just getting close. We could have switched but it would have meant a drastic reduction in quality of life for everyone who wasn't rich. We might still be in 80/90s technology had we done that, because the wealthier we are as a society, the faster we can develop technology.

Re: You can have geothermal power everywhere if you drill deep enough

#249

Post by [deleted] »

throwaway9870 wrote: post #198
hedora wrote: post #195

Earlier quoted context omitted.

Putting the heat exchanger on a tethered weather balloon and floating it into low earth order addresses all those concerns. It also doesn't involve rocket science. QED.

I think you just proved my point better than I could have ever done: Those most vocal about energy are generally the least informed. Let me guess, you have no formal engineering training, do you? EDIT: to make this comment more constructive, here is a link to an excellent book on energy processes: https://www.amazon.com/Fundamentals-Renewable-Energy-Process... I took a class with da Rosa and at the time this book was…

[deleted]

Re: You can have geothermal power everywhere if you drill deep enough

#250

Post by iancmceachern »

aaronblohowiak wrote: post #219
kragen wrote: post #192

Earlier quoted context omitted.

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.

Post reply on HN