[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.