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WarOnPrivacy 6 hours ago

I worked on geothermal control systems a decade or so back. There are some less obvious applications for geothermal that reduce electric use (as opposed to generating electricity).

The systems I worked on were for cooling larger structures like commercial greenhouses, gov installations and mansions. 64° degree water would be pumped up from 400' down, run thru a series of chillers (for a/c) and then returned underground - about 20° or 25° warmer.

I always thought this method could be used to provide a/c for neighborhoods, operated as a neighborhood utility. I've not seen it done tho. I've seen neighborhood owned water supplies and sewer systems; it tells me the ownership part seems feasible.

wood_spirit 6 hours ago | parent | next [-]

In the nordics it is common to have ground source heat pumps (brine in closed circuit pipe or bore hole) that are run backwards in summer to cool the house while actually assisting in storing heat back in the ground to extract in the winter. It’s a bit like regenerative breaking on electric cars.

jjtheblunt 4 hours ago | parent [-]

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.

zdragnar 28 minutes ago | parent | next [-]

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.

maxerickson 2 hours ago | parent | prev [-]

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.

zrail an hour ago | parent [-]

Our house came with one and we upgraded the unit a few years ago. It's very efficient in terms of units of energy consumed, but in my area of the world gas is significantly cheaper than electricity so it ends up being expensive to run.

That said, we will install solar at some point and then it'll be "free" HVAC.

Animats 5 hours ago | parent | prev | next [-]

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.

lostlogin 5 hours ago | parent | next [-]

> 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...

quijoteuniv 3 hours ago | parent | prev | next [-]

I think this looks interesting, but still very early stage. The “150 GW revolution” sounds more like theoretical potential, not something we will see soon in real deployment.

Main problems: drilling is still expensive, managing induced seismic activity is not trivial, permitting can take long time, and you also need transmission infrastructure. Also not yet proven that companies like Fervo can scale this in reliable and low-cost way.

jeffbee 32 minutes ago | parent | prev [-]

Nope. To efficiently tap geothermal energy, you need to boil something but not necessarily water. Isopentane, for example, boils at 28º at standard pressure, so they pressurize the secondary loop to raise the boiling point close to whatever the primary loop temperature is.

The idea that geothermal only works well at steam temperatures is outdated 20th-century thinking.

emmelaich 20 minutes ago | parent [-]

But the energy in boiling isopentane would be less right?

limagnolia an hour ago | parent | prev | next [-]

Whisper Valley in Austin Texas is one example of a neighborhood geothermal installation: https://www.canarymedia.com/articles/geothermal/texas-whispe...

Maybe not quite exactly what you envision.

solarpunk 5 hours ago | parent | prev | next [-]

I think you're describing what is known as "district energy" systems.

mlwiese 4 hours ago | parent | prev | next [-]

Framingham, MA has a geothermal system using ground source heat pumps like what you are describing

https://www.smartcitiesdive.com/news/first-networked-geother...

quickthrowman 4 hours ago | parent | prev | next [-]

District heating and chilled water is uneconomical for single-family homes. It does work well in medium to high density areas.

gambiting 4 hours ago | parent [-]

I don't know how economical that is, but just as an anecdote - the town I'm from in Poland has district heating to all single family homes, town of about 20k people. And coincidentally, I now live in the UK and a new estate near me has district heating to all the houses they are building, not apartment blocks. So it must make some sense to someone, or they wouldn't be outfitting 100+ houses this way.

mschuster91 3 hours ago | parent | next [-]

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...

hunterpayne 3 hours ago | parent | prev [-]

"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).

LeFantome 34 minutes ago | parent [-]

The “new” way is plasma drilling.

readthenotes1 6 hours ago | parent | prev [-]

Isn't that similar to how neighborhood heat pumps work?

https://www.araner.com/blog/district-heating-in-sweden-effic...

hunterpayne 2 hours ago | parent [-]

Heat pumps require a specific temperate differential to work. So they work in zones with are a bit hotter or colder than you would like and so require moderate amounts of heating or cooling. They don't work in temperate zones nor in very hot or cold places. So Santa Fe or Minneapolis for example they work but Mexico City or San Francisco they don't. If you are in a place where they work and that isn't too dense or has earthquakes, go for it. If not, don't. There are businesses that will help you understand when they do and don't make sense. Those businesses don't sell heat pumps though (the businesses that sell things will almost always tell you it works, even when it doesn't, for example PV in the UK doesn't work).

adgjlsfhk1 an hour ago | parent | next [-]

> 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

sokoloff an hour ago | parent | prev | next [-]

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.

hyperbovine 39 minutes ago | parent | prev [-]

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