America's Geothermal Breakthrough

It's expensive. A relative has one in the northern Great Lakes, they wouldn't have installed it if their house had access to natural gas.

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 though.

Nat gas and central AC are way cheaper.

In Finland around 50% of new single-family homes use ground source heat pumps. So it's definitely popular here.

3 schools in my neighborhood (barneskole, ungdomsskole & videregående) all use ground source heat pumps.

If by Nordics you mean Norway, Sweden and Finland, then the most correct way to say would be that ground source heat pumps for redidential heating are (very) common in Sweden and Finland, especially in newer and larger buildings. Norway is somewhat different in energy and climate perspective than its eastern neighbours.

The biggest reason to not install ground source heat pump is high installation cost. This means that it makes more sense for larger residential buildings. Also If you have district heating available then this might be more economical in the long run.

> pv in the UK doesn't work

tell that to 6% of UK electric production https://www.bbc.com/news/articles/cz947djd3d3o (up from 5% in 2024

I’ve never heard a claim that heat pumps won’t work well in a climate like San Francisco and, from looking at the annual temperature patterns, it seems like both air source and ground source heat pumps should work extremely well as they do in the “shoulder seasons” here in New England.

Wait Minneapolis is definitely very cold for about half the year.

Heat pumps have gotten a lot better, you need a pretty extreme climate for them to start to struggle, even the air-source ones.

(And PV works well enough in the UK for it to be a no-brainer to put on residentials roofs, which is on the whole the most expensive way to deploy it. Though this is in large part due to the way that it competes with retail prices and not wholesale prices)

This is nonsense, heat pumps are more efficient at smaller temperature differentials. I suspect we don't see them much in San Francisco only because there is so little need for heating and cooling the potential savings are smaller.

"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.

You brought the conversation in a circle, since the point of this new technology is the geology you speak of is rare.

There are also places in the US with boiling water at the surface. I live near one of those places so always curious about geothermal. There's a spot near my house in a creek bed where snow always melts even in deep winter so apparently I have some potential heat source. Our well water is cold though.

But the energy in boiling isopentane would be less right?

"I don't know how economical that is"

Sure you do. Think about it. Its just drilling a hole and making electricity from the heat. We have been able to do this for a very long time. So if people aren't really doing it much, its not economical. If it was now becoming economical, the article would describe some new way of doing it that makes it economical. The article doesn't, so you "know" it isn't.

PS This has been tried many time, it only works in very specific situations, usually places where building a full PP doesn't make sense or where you are making a lot of electricity for some other purpose (mining usually).

At least in parts of Eastern Europe (especially the former GDR) district heating systems were introduced as a response to the oil crises of the 70s, resulting price shocks and the transport of coal to households being very labor and resource incentive [1].

[1] https://www.ndr.de/geschichte/schauplaetze/Windkraft-und-Erd...

It’s uneconomical in an already built out area or a non central planned economy, and also the US is special case since we have dirt cheap natural gas that is used for heating.

Digging up streets to run distribution lines, running service drops to every existing house, installing a heat exchanger and valves in every house is astronomically expensive given the amount of energy used by a single residence.

If you’re building out a new neighborhood on a greenspace plot, installing the district heating/cooling piping is much cheaper since you’re already laying electric, water, sewer, and mane gas lines.

13 month summers lol :) Yeah, definitely if your interested neighborhood geothermal Whisper Valley seems to be the largest by far in the US, you might check it out.

> The water at these temperature / depths has a lot of dissolved salts and minerals so it's not (human / ag) usable.

To clarify, our 400' water source is the same aquifer that supplies drinking water to the state.

The water management districts will rubber-stamp permits for these wells. No one else gets off that easy.

Many data centers use evaporative cooling.

It's a closed loop on the geo side sure.

How do you cool the steam off enough to condense so it can go and be boiler feed water again?

Lots of power plants use cooling towers for this which are typically evaporative. Some are dry, sure, but most are wet.

> It is a closed loop system. The water aren't used at all.

Our method is open on both ends. It draws from one layer of the aquifer and then returns the water to an adjacent layer.

"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 the plant needs to be shutdown a lot of the time for repairs. And that's what makes it uneconomical. Also, the salts often contain things that require special handling which also increases costs.

PS This is why geothermal works in Iceland where there is so much geothermal heat they can use pipes. In CA, they can't so it doesn't work there.

> 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.

No. Current geothermal projects need very specific geology to work, its very rare which is why geothermal is such a small blip in the overall energy picture. Enhanced Geothermal Systems (EGS), the technique Fervo is using, can create the conditions to be able to generate electricity. The hope is this will greatly expand the number of projects that can be developed.

Doesn't that sound useful to you?

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.

These are typically representative of cost performance per watt of one part of a more complex deployed energy system. Things like the aluminum / steal for the container / framing, copper / aluminum for the transmission and wiring, land and labor for installation decline at much less aggressive rates or increase over time.

In almost all pareto optimal least cost energy system models that I've seen, high penetration of solar, wind, batteries plus some minority amount of (clean) baseload power is the most capital efficient energy system.

Just make everything part of the mix, even dam to dam hydro on rural hillsides plays a part in stabilising grid edges.

The more interesting use of geothermal power, IMO, is pushing heat underground with excess solar while the sun is high and the days are long, and pulling out electricity from heat in the darker times .. done large enough that carries across summer to winter.