There's a very useful and up-to-date writeup of the four main types of geothermal projects, and the latest (AGS) that features 1) no injection wells or other fluid contact down-hole, 2) re-using existing oilfield wells when possible, 3) no need for "hot rock" steam flashing, and 4) no parasitic energy use for pumping (thermosiphon). Well worth the read.

The author, Dave Roberts, is a reliable read in the energy world and has recently launched a Substack dedicated to energy.

[1] https://www.vox.com/energy-and-environment/2020/10/21/215154...

Using Graphene to radiate heat from deep holes to the surface is also one other area being worked on.

Graphene has exceptionally high thermal conductivity, 12000x of copper:

https://futurism.com/thanks-to-graphene-we-may-harness-the-l...

On bigger scale, it seems this can sometimes cause earthquakes... One geothermal power plant is going to close in France https://www.connexionfrance.com/French-news/Geothermal-power...

That is correct, but not for the "two pipe approach" I outlined in my post.

There is a form of geothermal energy generation that is being used here, that injects water into the ground and taps into the heated water. This is somewhat similar to the way fracking is performed to extract oil and gas from the ground, but it's not the only method.

But to your point - to me it is surprising that these issues aren't being "worked on more".

Where's here?

Sidenote: how steampunk is it that "causes earthquakes" is just like a common externality of new industrial technology?

Could you imagine if "causes F-4 tornadoes" or "causes "golf-ball-sized hail" were just normal things that new tech might cause?

The Navy had to close one too after the 2019 Ridgecrest earthquakes :(

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

You are correct, and this is exactly what’s happening in Alberta, eg https://www.cbc.ca/news/canada/calgary/eavor-loop-geothermal...

>Extremely simplified, all you need to do is drill a hole deep enough for a high temperature difference.

>There's plenty of asteroids rich in gold/titanium just floating around. All you have to do is bring them here.

I don't think this snarky comment is justified. Geothermal energy plants as I describe them already exist - I'm just surprised that this source of energy is not exploited more.

Yup. The earth's crust is less than 1% of the earths radius. Just below the crust is all the energy we would ever need for a long long time.

Here in Reno, NV we've got the Peppermill, which is notable for being the only resort in the US (last I checked) that gets all its heating (both HVAC and water) from an on-site geothermal well.

Nevada in general is basically a giant blob of hot springs when looking at a hot spring map, which makes me strongly suspect that it could be a major geothermal energy hub for the Western US. Plus, pretty much all of it's desert, which is perfect for solar, too.

Solar / Wind is dropping 5-10% per year and that probably will continue for another 10 years.

No way geothermal will be cost competitive. Even if it has promise in today's marketplace, by the time you get the project completed solar/wind will have dropped in price 50% or more.

It's the same reason that nuclear projects should only be in research for another 10 years. Once the solar/wind hockey stick plateaus, then you have a rational target for these other alternative energy projects to pursue.

Rock isn't very thermally conductive. Geothermal plants work great where the crust is thin, but for the rest of the planet you have to do a lot of drilling to get not much heat. https://dothemath.ucsd.edu/2012/01/warm-and-fuzzy-on-geother...

To everyone saying this is impossible. This is proven tech and it's actually not uncommon to heat your house like this already today. Depth of a hole in your backyard is around 100-200m and one such hole provides more than enough for one big house.

Payoff for such investment to break even with more basic forms of heating is around 5-10 years in cold northern europe climates. Sadly most people have shorter foresight than that when it comes to economic planning.

I think you are confusing geothermal energy with ground source heat pumps. That said, both are being done where it makes economic sense to do so.

You need a deep hole.[1] Kilometers deep for most of the earth.

A hole in the ground is more useful for cooling in hot climates. You can use a well as a heat sink for air conditioning.

[1] https://en.wikipedia.org/wiki/Geothermal_gradient

You’re underestimating the cost and difficulty of scaling that to any meaningful energy output.

It's really good for heating/cooling buildings. Outside of that it's less clear. It's still extremely underused for heating/cooling. I think there isn't much incentive for people to incorporate it at the moment because it mostly saves on long-term costs, but let's face it most of our new buildings are made in the pursuit of short-term profit. The technology is also underdeveloped therefore expensive in most cases.

It's just not competitive with alternatives in most cases.

I agree with GP, this shouldn't be a discussion of, "we don't need geo-thermal because solar/wind is cheaper".

The issue is we are still heavily dependent on non-intermitent energy generation. Which for now is mostly Coal and Gas Power Plants. Coal is extremely poluting and Natural Gas is both polluting and has a geo-political mess of supliers.

Fusion is still years in the future and if even if there was a political will for nuclear it cannot be realistically rolled out quickly enough to decomission coal in terms of climate damage.

Without knowing all the details it seems like a much easier problem to solve:

- Get 24/7 heat out of deeper earth's crust without 'fracking' earthquake's

Vs

- Energy efficient time sustained nuclear fusion

As a bonus, if I'm allowed to be completely cynical, geo-thermal could enable much of the Oil and Gas drilling technology and know-how to transition to a new industry, giving them an exit strategy rather than continue this tactic of agressive lobbying and squeezing the final dollars out of the Petro-Chemical industry at the cost of Human Future.

Geothermal is a lot like nuclear: it's a capital intensive baseload source. As such, it suffers like nuclear in an environment with increasing intermittent penetration.

One might have imagined an environment in which geothermal replaced (say) diesel at remote locations, because diesel fuel is expensive. But add some wind/solar/batteries to that diesel and you save most of the fuel. The benefit of replacing it with geothermal is reduced.

It’s been turning up lately in the energy subreddit, with articles like: https://www.weforum.org/agenda/2020/12/geothermal-energy-ren...

Isn’t that similar to what dandelion is doing? https://dandelionenergy.com/

Drilling many kilometres deep inland is not proven technology, despite the fact we can do it at sea for oil.

My understanding is that it’s geographically limited due to depth issues.

I don't know if it's just depth issues, I think I saw a story about some sample projects in Alberta where they were looking for the right types of rock for the heat exchange to occur. It definitely sounded significantly more complex than just drilling holes, but finding areas with the correct properties to get worthwhile ROI.

One nice advantage is it draws on skills common to the oil and gas industries.

AGS systems (e.g. Eavor[1]) don't need "hot rock" to be cost effective and can supposedly be operated in just about any area.

[1] https://eavor.com/