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America's Geothermal Breakthrough

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Re: America's Geothermal Breakthrough

#91

Post by Animats »

lostlogin wrote: post #12
Animats wrote: post #9

Earlier quoted context omitted.

Shallow geothermal works fine for heating. And you can use the ground as a heat sink. But if you want to generate power, you need to get down to where temperatures can boil water. That's deeper than most oil wells. Fervo Energy claims to have found 270C at 3350 meters well depth. That's progress.

> if you want to generate power, you need to get down to where temperatures can boil water. That's deeper than most oil wells. That’s going to be very dependant on location. Here in NZ there are regions where water is boiling at surface level. According to the below, 18% of our power is produced with it. https://www.eeca.govt.nz/insights/energy-in-new-zealand/rene...

"New Zealand has an abundant supply of geothermal energy because we are located on the boundary between two tectonic plates. ... Total geothermal electricity capacity in New Zealand stands at over 900 MW, making us the fifth largest generator of geothermal in the world. It has been estimated that there is sufficient geothermal resource for another 1,000 MW of electricity generation."

That's not all that much. That total would be about equal to the 75th largest nuclear plant in the world.

Good sites where high temperatures are near the surface are rare. California has a few, but no promising locations for more.

Re: America's Geothermal Breakthrough

#92

Post by IncreasePosts »

zdragnar wrote: post #84
jjtheblunt wrote: post #28

Earlier quoted context omitted.

There was a new in 1988 house in Champaign, Illinois, USA that used the same system, and i mention that because it was a normal modern house, and it's the only one i've heard of with that system. It seems so smart.

There's a pretty significant upfront cost in getting them drilled, and many homes need the vertical drilling if they don't have sufficient yard space for a horizontal system. It gets harder if you have your own septic drain field too, as that will complete for yard space. The cost difference is pretty massive- 3-10x for a vertical system. If you live in a city or a suburb with tiny lots, that's your only option thoug…

Air source heat pumps are insanely more efficient and just plain better these days too. It used to be that if the air was below 40F you couldn't heat your house with a heat pump. Now, you can heat your house even when it's -10F

Re: America's Geothermal Breakthrough

#93

Post by micro2588 »

jeffbee wrote: post #90
emmelaich wrote: post #87

Earlier quoted context omitted.

But the energy in boiling isopentane would be less right?

Yes, the efficiency is worse, but as is also the case for solar power you need to get used to not caring much about efficiency. It is nuclear energy where the primary side is provided free of charge. The Carnot efficiency is almost without relevance.

In geothermal there is still a lot of interest in efficiency and exploring different working fluids because binary systems now have efficiencies of 10-20%. That is why you see companies like Sage Geosystems working on developing / deploying supercritical CO2 turbines to try and boost practical power densities.

Re: America's Geothermal Breakthrough

#94

Post by micro2588 »

hunterpayne wrote: post #61
Animats wrote: post #49

Earlier quoted context omitted.

They're way ahead of the microwave drilling people. There's no reason why this shouldn't work. But they've been at it for 9 years, with considerable funding, and it doesn't really work yet. That's a concern.

"There's no reason why this shouldn't work." Geothermal has had the same problem for its entire history. That problem is that the water being heated goes through the ground (not in a pipe) to "gather" more energy. But this means that when the water comes back up, it has a lot of weird salts in it (and other things). Those salts cause corrosion, lots and lots of corrosion, far more than even a maritime environment. So…

Fervo uses engineered reservoirs in granitic basement rock so this is less of an issue. Hot rock in a working fluid can still dissolve silicates out of the granite and lead to scaling / degradation of the flow rates through the reservoir and that is a risk but chemical anti scaling treatments are used to reduce this.

CA has the worlds largest geothermal power complex in the Geysers. That one field produces an equivalent amount of power as all the geothermal in Iceland and there are others.

Re: America's Geothermal Breakthrough

#95

Post by micro2588 »

nandomrumber wrote: post #65
hn_throwaway_99 wrote: post #48

Earlier quoted context omitted.

4th paragraph of TFA: > Several companies are now building upon existing techniques for accessing geothermal resources by integrating enhanced geothermal systems (EGS) into operations. While conventional geothermal systems produce energy using hot water or steam, pumped from naturally occurring hydrothermal reservoirs trapped in rock formations underground, EGS use innovative drilling technologies, such as those used…

Sounds like marketing hype to me. Geothermal reservoirs exist at depth. Drilling horizontally doesn’t magically reduce the depth, nor the problem that drilling in to hot rock is like drilling in to plasticine, at least for temperatures worth working with.

In traditional fault hosted (not magmatic) geothermal the convection of the water up the fault brings the thermal energy closer to the surface where drilling depths are economical. This convection heats the surrounding rock and over hundred thousand - million of years brings the background temperature around a large volume at depth surrounding these systems considerably above traditional background geothermal gradients. By drilling into a much larger volume of impermeable hot rock surrounding a very small permeable fault hosted section you can considerably enhance the power potential of a traditional fault hosted geothermal system (the E in EGS). That is what Fervo is doing and why their projects are situated right next to traditional geothermal power plants.

The assumption is that if you can increase drilling efficiencies enough then you don't even need a fault hosted or similar system to bring that energy close to the surface, you can just drill down deep enough to get at similar temperatures. That is a big assumption in the economics.

Re: America's Geothermal Breakthrough

#96

Post by mgfist »

Animats wrote: post #49
w1 wrote: post #14

Earlier quoted context omitted.

This isn’t really an evaluation of the company, just explaining how they had to use different financing approaches as they grew and derisked their technology (which makes sense). Compared to some other new approaches for getting clean base load power, it seems like they’ve been pretty grounded and methodical.

They're way ahead of the microwave drilling people. There's no reason why this shouldn't work. But they've been at it for 9 years, with considerable funding, and it doesn't really work yet. That's a concern.

> There's no reason why this shouldn't work. But they've been at it for 9 years, with considerable funding, and it doesn't really work yet. That's a concern.

It does work. They've had a pilot project producing 3 megawatts since 2023. But scaling takes a lot of time and money, particularly when it's something new and you have to go through a lot of operational learning.

Shale took something like 30 years to become a thing. 9 years is nothing in the energy space.

Re: America's Geothermal Breakthrough

#97

Post by SR2Z »

IncreasePosts wrote: post #92
zdragnar wrote: post #84

Earlier quoted context omitted.

There's a pretty significant upfront cost in getting them drilled, and many homes need the vertical drilling if they don't have sufficient yard space for a horizontal system. It gets harder if you have your own septic drain field too, as that will complete for yard space. The cost difference is pretty massive- 3-10x for a vertical system. If you live in a city or a suburb with tiny lots, that's your only option thoug…

Air source heat pumps are insanely more efficient and just plain better these days too. It used to be that if the air was below 40F you couldn't heat your house with a heat pump. Now, you can heat your house even when it's -10F

If you can tolerate the price, I am _confident_ that you will pretty much always have better results using the Earth as your thermal exhaust, because you don't have to dig very far to find a large region that's pretty much always at 50 F.

Re: America's Geothermal Breakthrough

#98

Post by mgfist »

hunterpayne wrote: post #55
pedalpete wrote: post #47

According to google, this would be almost 30% of total US energy production (135gw-150gw) and nearly 5% of total US energy consumption. But what is the "breakthrough" if there is one? The article doesn't really suggest any breakthrough that is unlocking this potential energy? Or maybe I'm looking for a technological breakthrough where there isn't one.

There isn't one. They are trying to politically pressure a utility to build some geothermal plant. But utilities have engineers who will tell their bosses that this plan doesn't work. So the companies selling the geothermal plant are trying to politically pressure the utility to do yet another thing that they know won't work. PG&E for example has several geothermal plants which have been economic disasters and were a…

> PG&E for example has several geothermal plants which have been economic disasters and were and are being shutdown.

Those are very different from EGS

Re: America's Geothermal Breakthrough

#99

Post by micro2588 »

hunterpayne wrote: post #55
pedalpete wrote: post #47

According to google, this would be almost 30% of total US energy production (135gw-150gw) and nearly 5% of total US energy consumption. But what is the "breakthrough" if there is one? The article doesn't really suggest any breakthrough that is unlocking this potential energy? Or maybe I'm looking for a technological breakthrough where there isn't one.

There isn't one. They are trying to politically pressure a utility to build some geothermal plant. But utilities have engineers who will tell their bosses that this plan doesn't work. So the companies selling the geothermal plant are trying to politically pressure the utility to do yet another thing that they know won't work. PG&E for example has several geothermal plants which have been economic disasters and were a…

The core breakthroughs were working with partners to develop PDC bits that enable high rates of penetration in drilling out these horizontal wells in high temp granitic rock and then demonstrating plug / perf fracture networks that have a high engineered permeability in these source rocks to support economical flow rates and heat transfer. These were considerable advances over previous efforts.

There will be other learning by doing advances in how you structure your power plant design to take advantage of these to make practical long term power production possible (well spacing and injection / production placement / flow rate and temperature decline management).

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