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Geothermal's path to relevance: cheap drilling

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Re: Geothermal's path to relevance: cheap drilling

#31

Post by larsalmen »

serpix wrote: post #26
brtkdotse wrote: post #23

Earlier quoted context omitted.

Geothermal heat pumps are very common in the Nordics. It’s a one day operation, they come in, drill a 150M hole and run a brine loop hooked up to a heat pump. Sorts the heating and hot water for a 180 m2 house above the attic circle with less than 7000 kWh per year.

that is a ground-source heat pump as the heat energy is mostly from ambient solar. But yes very common and I used to have one in my home before I moved away. It cost practically nothing to keep the house at t-shirt temperature during -25c cold weather snaps.

No it's not. The bore-hole is lined with a outer steel pipe until the drill hits bedrock, keeping it very much insulated from the ground. And the upper-most part of the energy-well that's lined is considered inactive, and is not counted in the "150 m deep energy well".

Re: Geothermal's path to relevance: cheap drilling

#32

Post by chris_va »

Drilling cost is usually estimated as ~depth^2.

So, a 1km geothermal well? Break even, and you are limited to only a few places in the world.

A 5km geothermal well (needed for broad power availability)? 25x the cost...

So, sure, if you can get a 25x cost reduction in an already cutthroat industry, all power to you (no pun intended).

Re: Geothermal's path to relevance: cheap drilling

#33

Post by wkearney99 »

rudedogg wrote: post #20
turtlebits wrote: post #19

Earlier quoted context omitted.

Yes, ground source/loop is considered geothermal. The problem is that you need to a dig up a large area of possible natural vegetation to do it.

You can go vertical instead of horizontal

We have two 350' wells for loops at our house in Maryland. Tripled square footage in the new house and energy costs stayed the same. Moved from natural gas for heat, but still have it fir backup (which in a decade has never been needed).

Re: Geothermal's path to relevance: cheap drilling

#34

Post by animal_spirits »

chris_va wrote: post #32

Drilling cost is usually estimated as ~depth^2. So, a 1km geothermal well? Break even, and you are limited to only a few places in the world. A 5km geothermal well (needed for broad power availability)? 25x the cost... So, sure, if you can get a 25x cost reduction in an already cutthroat industry, all power to you (no pun intended).

It's okay to intend a pun every now and then. Take credit for your poetry ;)

Re: Geothermal's path to relevance: cheap drilling

#36

Post by Accujack »

cdeonier wrote: post #5

Cheap drilling would be a large boon for geothermal, considering the cost of surveying/exploring/drilling is > 50% of the cost of the development of a geothermal site. I don't understand the articles goal of 300C target, though. While some types of geothermal plants do require temperatures that high, binary cycle power plants can use lower temperatures (130C) [1], which seems to open up more area for geothermal devel…

I think the 300C target is to support the article's assertion that geothermal could replace e.g. nuclear plants. Geothermal for heating can work well with a lower approach temp, but industrial processes/power generation needs a higher differential.

Re: Geothermal's path to relevance: cheap drilling

#37

Post by infogulch »

uuddlrlr wrote: post #14
Factorium wrote: post #11

Are ground-source heatpumps considered 'geothermal'? Its much less sexy than a giant plant connected to a magma stream, but if we made these routine for all new suburban constructions, alongside passivhaus standards, we could eliminate residential fossil fuel connections for huge sections of the Western world. Like another commenter mentioned, we could even have communal systems for individual streets, drilled beneat…

There's a 52-home community in Alberta that provides ~all of their winter heating by storing heat in the ground throughout the summer: https://www.dlsc.ca/borehole.htm It gets up to nearly 80C, but took a few years of operation to get there. The website covers it really well and I'd recommend checking it out.

Wow that's amazing! Basically a community-sized thermal battery. I find the design curious; they use insulation around the outside, but still bored 144 holes on the inside, I guess the bottom is just left alone as solid rock.

They heat it with solar energy, and pull out heat during the winter. I wonder how well this would work to provide both AC/cooling during the summer and heating during the winter in climates that experience both, like the midwest US. Perhaps using the pumped water as a stable, biased thermal source for a reversible heat pump.

Re: Geothermal's path to relevance: cheap drilling

#38

Post by avernon »

chris_va wrote: post #32

Drilling cost is usually estimated as ~depth^2. So, a 1km geothermal well? Break even, and you are limited to only a few places in the world. A 5km geothermal well (needed for broad power availability)? 25x the cost... So, sure, if you can get a 25x cost reduction in an already cutthroat industry, all power to you (no pun intended).

Drilling cost is usually estimated for drilling in sedimentary rock with assumptions about how casing is run ;)

It is possible that drilling 30,000' of granite has conditions that make the estimation model irrelevant. 5 km isn't really deep enough, anyway. My next post will cover the thermo. It is pretty dang hard to get down to anything approaching $50/MWh. Definitely need more than cheap drilling.

Re: Geothermal's path to relevance: cheap drilling

#39

Post by cdeonier »

Accujack wrote: post #36
cdeonier wrote: post #5

Cheap drilling would be a large boon for geothermal, considering the cost of surveying/exploring/drilling is > 50% of the cost of the development of a geothermal site. I don't understand the articles goal of 300C target, though. While some types of geothermal plants do require temperatures that high, binary cycle power plants can use lower temperatures (130C) [1], which seems to open up more area for geothermal devel…

I think the 300C target is to support the article's assertion that geothermal could replace e.g. nuclear plants. Geothermal for heating can work well with a lower approach temp, but industrial processes/power generation needs a higher differential.

Could I get your help understanding your statement "industrial processes/power generation needs a higher differential"? Why does geothermal need a higher differential for power generation?

Power generation is already accomplished with lower heat cycles (e.g., binary plants mentioned earlier would probably use a rankine cycle to deal with the low heat), though we'd expect those power plants to have less nameplate capacity than something like a double flash-steam plant.

I think you're correct you'd get more efficiency with higher gradients, but I don't understand what's limiting about the lower temperatures. Is it economics?

Re: Geothermal's path to relevance: cheap drilling

#40

Post by aaron695 »

The USA is the geothermal king, top of the world, so it'd be exciting for them to up their game, no one else is.

The depths they are talking about here would be in the top 10 deepest holes and they need to go sideways, unheard of, so it's pushing technology which is also exciting.

Geothermal doesn't rely on supply chains for fuel so the military might help with funding.

I expect it's not economical, but it's a cool thing to try, bring back 50's science, we need to continue fighting the Woke.

This is just a 'study' which generally is code for won't happen, but it would be good if it did, good on Texas - https://www.thinkgeoenergy.com/sage-geosystems-to-explore-ge...

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