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District heating and heat pumps can be combined in some clever hybrid ways.

You can have tiny heat pumps in every home that share a district-wide pipe as a heat source, you can use giant/deep heat pumps to supply the district-wide pipe and you can do both at the same time. And heat pumps can also be used to cool things, returning heat into the system and allowing for big solar gains in windows, since the heat generated can be re-used when it's more than needed rather than wasted.

Yep, and cooling is rapidly becoming a problem comparable to heating; summers are getting hotter but Finnish construction norms are still all about keeping homes warm in the winter as opposed to cool in the summer. Few Finnish homes have AC, except for those that have two-way heat pumps. Portable AC units have been in very high demand in the past few summers due to heat waves that used to be exceptional but are quickly becoming the norm.

>SMR nuclear reactors, if they ever become mainstream, would be an excellent source of clean heat and electricity for cities. Current nuclear power plants are located (by design) too far from cities for it to be economical to pipe their waste heat to where it's needed.

I don't believe that waste heat is plenty. Here, in Romania, we use the waste heat from the nuclear power plant as district heating but that is enough for a small town near it.

What kind of coefficients of performance are there in Finland, for heat pumps? And what kind of heat pumps are there? Are air-sourced pumps any use in the Finnish climate?

Our heat pump (older model, not sure how old it is since it was in the house when we bought it) works pretty well down to -15. After that it's better to shut it down, save the electricity, and use the good old wood heaters that have been installed since the house was built in the 50's.

Not an expert, but apparently the latest ASHPs still have a CoP of around 2 at –20°C and unity at –30°C, which is pretty much the extreme low for the less-sparsely populated parts of the country. Ground source HPs are of course better in that respect but the initial investment is larger. Apparently GSHP is the most popular mode of heating in newly built single-family homes.

Thank you! In that case, they are very much worth it. In Romania, with the current absurd gas prices, even resistive heating is cheaper when powered by the national hydroelectric supplier.

The price of gas has had an enormous effect on the waiting times for solar panel and heatpump installations here in Western Europe, how is this in Finland right now?

Right now it's too cold, but I imagine things will start rolling when the snow melts in a couple of months.

Geothermal boreholes are suddenly much more practical than anybody had guessed, with laser drilling.

Its operating cost will necessarily be quite a bit more than solar, but it works in the Arctic winter, 24x7, and provides cogen heat.

Knowing that we have test plant with geothermal and the depth required is 6,4km even with laser drilling the effectiveness might not be so great.

We will need to wait and see.

It might end up cheaper to ship in ammonia synthesized from solar in the tropics. Most likely it will be a combination of several: normally, delivery by transmission line because cheapest, but with geothermal held ready for strategic backup, and stockpiled ammonia for load peaks.

Shipping will get cheaper as fuel does, but is already astonishingly cheap.

In what way is shipping fuel expected to get cheaper?

I’m not aware of any significant and serious efforts to replace ships with a green fuel, and they comprise a huge percentage of our emissions.

To remain competitive, shipping will need to re-tank to burn tropically synthesized (most likely) anhydrous ammonia, which will soon be cheaper even than bunker oil. Ships still burning oil will find increasingly fewer ports open to them.

The west-African coastal Sahara, coastal Peru/Bolivia, Baja California, Arabia/Sudan/Eritrea, Yemen/Oman/Pakistan, Socotra, and north-western Australia all look like good places to site solar-driven ammonia synthesis. I don't doubt that less geographically-favored sites will dominate instead.

probably a stupid question, but is it a possibility that geothermal energy (if adopted to a great extent) could take away from the earths core energy and reduce the magnetic field?

From https://www.renewableenergyworld.com/baseload/can-geothermal...

Some 42 million megawatts of energy reach the surface continually and are radiated into space as the earth cools from its initial molten state more than 4 billion years ago. No feasible amount of geothermal development could make even a small dent in this process. Furthermore, the earth’s heat budget is continually replenished by the radioactive decay of naturally occurring elements, and almost all of the energy associated with each decay event is converted to heat. Plus, the heat content of the geothermal reservoir rocks is continually replenished by conduction of heat from the earth’s deeper interior.

I see. 42 million megawatts is 42,000 gigawatts. A quick google search tells me that typical power output of a nuclear power plant is around 1 gigawatt.

So a single nuclear power plant would be roughly equivalent to 0.002% of earths geothermal energy radiation. It doesn't sound like much, but for something as crucial as the earth's magnetic field, I wouldn't want to reduce it one bit.

I guess if the heat is radiated into space anyways and we simply capture that it doesn't speed up the core's energy loss, but if we start digging into the core and allowing energy to escape faster, we would effectively speed it up, right?

> if we start digging into the core and allowing energy to escape faster, we would effectively speed it up, right?

I don't think we're even digging through the crust - there'd still be the mantle (~100x thicker) before we got to the core.

In numbers, I believe the deepest borehole is ~12km deep... and the Earth has a radius of >6000km. We're barely scratching the surface.

My concern is fundamentally whether or not we are siphoning energy out of the core faster than it would otherwise escape.

Since the layers are directly connected, it doesn't sound like to me that you'd have to dig into the very core for that to happen.

Of course at the current state of affairs the effects are miniscule, but it doesn't sound like a very good investment as something to potentially scale up in the future to where it will actually matter.

If it turns out to be a problem, how hard would it be to insert fuel back into the earth's core to sustain the magnetic field?

Literally impossible to do. And, also, absolutely pointless to worry about.

In another century, if we don't blast ourselves back to the stone age first (increasingly likely), energy from hydrogen-boron fusion will dominate wherever solar is impractical, and the geothermal wells will become too expensive to continue operating. So, either way, the whole process is an imperceptible blip.

OK, good. But yeah the high likelihood of returning to the stone age repeatedly makes it even more important for the magnetic field to sustain for as long as possible.

We will never have any way to interfere with the planetary magnetic field, in any circumstance.

Blasting our way back to the stone age will succeed in chopping off CO2 output suddenly, though. The climate could then return to normal in only a century or three, if the sudden change did not instead trigger an ice age or something.

It is very, very, very unlikely to make any noticeable difference even on geological scales.

If only all problems were as trivially ignorable as this one.

The radius of the Earth is 4000 miles. A 10-mile hole is thus 1/400 of the way to the center. You may as well worry that scratching the skin of an apple might damage the seeds.

Actually scratching the skin of an apple does negatively affect the apple - the part of the "mantle" under the scratch begins to rot right away.

Look at a graph of the temperature of the Earth as a function of depth. The temperature jumps tremendously below the crust, and is much more stable per depth below. The crust is the insulation of the Earth - and damaging that crust might affect the mantle is ways we cannot yet imagine.

The answer remains "we don't know".

Hint: the mantle is not made out of apple flesh, it starts much, much deeper than 10 miles most places, and nothing exists that can eat it.

It could also leak out, loose heat, and drilling down to it could trigger earthquakes and eruptions.

The argument "it's big, we can't affect it" has been proven wrong in the case of the atmosphere, and again in the case of the ocean. It is no longer a sound argument.

"It's big, we can't drill more than a negligible fraction of the way to it" remains as true as ever. So, no, we cannot make it leak out, lose heat, or trigger earthquakes or eruptions. It will still be almost as hot in a half-billion years when the sun engulfs and vaporizes it, whatever we do.

Eruptions in Siberia, and later in India, not long ago geologically, released more heat in a (geologically) short time than we could use up in a million years, with no effect on the Earth's magnetic field.

Just because we haven't discovered giant planet-eating space aliens yet doesn't mean they don't exist.

The answer that I've always heard is "no". But that would have also been the answer to "do tailpipe emissions affect the atmosphere" in March 1922, so I'd say that we just don't yet know.

Global climate disruption by CO2 emissions was first predicted in the 1890s.

You should worry instead about the effects of excreted pharmaceuticals and neo-nicotinoid pesticides on wildlife, excess fertilizer runoff on coastal ecosystems, and ocean acidification from CO2 dissolving to produce carbonic acid, making sea life unable to fix calcium for shells, destroying the underpinnings of the food chain and the whole ocean ecosystem. Oh, and global climate disruption.

We have no need to borrow imaginary trouble, we are making plenty of actually real trouble already.

I agree that the concerns you mention are more immediate concerns, certainly.