[beiller]

Not really. Heat pumps can't be used in cold climates due to ice forming on heat fins which breaks the efficiency. It's why we use a lot of baseboard heaters in Canada. Bitcoin mining would be perfect for electric heating of homes here. Plus the added bonus of eliminating green house gas emissions from burning natural gas in a furnace (how my house is heated). The problem with baseboard is that gas heating is far cheaper than electric. So could Bitcoin actually be used to make the world greener?

[goodpoint]

> So could Bitcoin actually be used to make the world greener?

No. The value of a PoW coin is based on the wasted electricity.

If mining does something useful (like heating) for a large fraction of the miners the mining difficulty will go up to adapt to such change, requiring additional mining.

At the end of the amount of wasted electricity will remain the same.

[beiller]

I think you need to research more. A computer is actually a heater that is 100% efficient. If you actually "waste electricity" to do useless computation, you still get 100% efficient heat output. 1000W of electricity pumped through your cpu is outputting 1000W of heat as well. Maybe imagine if your logic gates in your computer is water powered. You could still drink the water after it did it's computation.

[imtringued]

If running a Bitcoin heater costs half as much as running a regular Bitcoin miner then you can spend the savings on twice as many miners to get more Bitcoin. If everyone does then the effect is net zero. However, your miner can't be a heat pump so in practice it would be net negative.

[beiller]

Yes so now 20 million people (very small amount) install these space heaters, heck install 3. Now they are at equilibrium except the mining difficulty has gone wayyy up (because 20 million ASIC miners will double the global hashrate approximately). Now mining in server racks is no longer profitable because dealing with waste heat is a major expense for them. So not only is hashing now very distributed, but also not 100% wasted.

[goodpoint]

> I think you need to research more. A computer is actually a heater that is 100% efficient.

I have a degree in EE.

The wasted electricity is in additional heat that you don't want in your home and you have to vent.

Suppose millions of people could replace resistance heaters with mining rigs that cost exactly the same and consume exactly the same amount of energy every day.

Such people would be running the miners ever if the financial gain is very close to zero, because they were already using the same amount of electricity for heating.

That means they would push the mining difficulty up. But, if the demand for coin remains the same, other people will run mining rigs that releases increasing amount of heat in the environment.

You just pushed the amount of wasted heat from one place to another.

[beiller]

Ah I see what you meant by "work can't be useful", apologies. But I think you did jump to some conclusions for example, increase of difficulty does not require more miners. It is a side effect of miners joining. So the profitability of existing mining infra in server racks will go down due to the difficulty increase. It would most likely incentivize them to also somehow recycle their "waste heat" for profit. My comment elsewhere is maybe devoping space heaters that do computation (maybe hashing is not that computation but I think it can work), we could use them to migrate off existing heating tech used in my country (natural gas furnaces) and net lower greenhouse gas emissions because not all electricity is generated from greenhouse gas, only some, and it also has a path forward to no green house gas emissions from electricity generation.

[goodpoint]

The value of any PoW coin is based on the sacrifice being made. Something is valuable because you are throwing away something else that was valuable. There's no way around it.

Regarding heating things with electricity, a heat pump is way more efficient than resistance/mining heating because is moving existing heat from one place to another.

[throw0101a]

> Heat pumps can't be used in cold climates due to ice forming on heat fins which breaks the efficiency.

Define "cold". Mitsubishi units have 100% of capacity at 23F/-5C and 75% capacity at -13F/-25C:

* https://www.mitsubishicomfort.com/benefits/hyper-heating

They're used in Alaska:

* https://www.nrel.gov/news/features/2021/even-in-frigid-tempe...

Fujitsu says -15F/-25C as well:

* https://www.fujitsugeneral.com/us/residential/technology/xlt...

[beiller]

I guess I was trying to say its efficiency breaks down and isn't competitive with basic electric baseboard heat at some temperature below zero celcius (not sure what the break-even point is). I didn't think people in Alaska would be using that for home heating, is that a thing? The norm here is gas heat and the odd electric baseboard home which broken down elsewhere by another commenter is approximately 10x the price of gas heating.

[throw0101a]

> I guess I was trying to say its efficiency breaks down and isn't competitive with basic electric baseboard heat at some temperature below zero celcius (not sure what the break-even point is).

At the 'break down point' an air source heat pump (HP) is no worse than a baseboard heater: in both cases the COP is basically 1.0. So you might as well go with the HP as it'll be more efficient for probably the majority of the year.

You can get gas furnaces that are 'dual fuel': they'll run the HP refrigerant through the exchange and circulate the conditioned air, and once it's "too cold" switch to gas.

If you're going to buy a only-cooling AC unit, then spending a little more on a heat-cool HP is probably a smart idea. There's a payback period, and it depends on the price of your electricity and fossil fuel (NG, propane).

[karmakaze]

And apparently Fujitsu's work better in F but the same in C. I always thought these were display-only settings.

[minitoar]

In cold climates you bury the heat exchanger under the frost line.

[beiller]

That sounds really interesting but isn't that useless because at that point you may as well use geothermal. Doesn't the exchanger need air to flow over it hence the fins for it to work? I think geothermal is the biggest win environmentally however so there is that.

[saalweachter]

In most places, "geothermal" is just a "ground sourced heat pump". Circulate a liquid underground so that it keeps that 50-degree temperature, run a heat exchange with that as the source instead of the air.

(In other places and to a larger extent pop culture, "geothermal" refers to tapping into actual heat sources underground.)

[falcolas]

Heat pumps can be used down to around -15F. This does impose a limit, but it's a lot further north and/or a lot less frequent than most people assume.

They simply periodically pump a bit of heat back out to keep the exchanger free of ice.

You'll periodically need a backup source of heat, but most of the time you'll be fine with the heat pump alone.

[mogmog99]

For those of us living on boats (in the UK, so nothing close to Siberia temperatures) how feasible is solar powered off grid mining, using heat for hot water/heating?

[thehappypm]

I always hear this argument that baseboard is "way more expensive" than gas, how much are we talking? 2x? 10x?

[falcolas]

Somewhere in the 10x range.

The approximation for electrical use in heating is using heaters that can output roughly 10 watts per square foot of your house. 12-13 if your house is poorly insulated.

At full power, that means that a 1,600 sqft house requires 16 kW of electricity. At a cost of 13¢ per kWH, that's about $2.05 for that 16kW of electricity. Of course, no residential house will ever realistically have 16kW available to it, nor would heating ever require a 100% duty cycle. But this is for comparative purposes.

The equivalent amount of gas power would require about 54,000 BTUs from a gas furnace (about 3.4 BTUs per watt). One cubic foot of natural gas provides 1,032 BTUs which means that generating 54,000 BTUs of heat requires about 52 cubic feet of gas (we'll round that up to 65 to account for inefficiencies of a furnace; top end furnaces are in the 80-80% efficiency range). 100 cubic feet of natural gas costs about $0.48, so the cost for natural gas would be around 30¢

Again, neither will (nor could, nor should) run constantly, but it's a sobering comparison.

EDIT: Comparisons were hours vs. seconds; fixed.