Analysis showed Satoshi used 5 computers or something like that to mine bitcoins initially so it seems fair to limit it to the same ammount he used. The number is arbitrary it could even be limited to 1 or lowered from 5 to 3 eventually.
However I like the idea of "electricity costs" cannot rise above a certain limit. This would allow computer hobbists to have as much "stored" computers as they want, but can only run so many at a time.
More's law is doubling of transisters every 1.5 years though this years number may vary a bit. It doesn't really say anything about electricity usage and also bitcoin's user and hashrate seems to be 10-folding and thus is outrunning more's law.
A legal solution for bitcoin would also apply to other similiar coins so the discussion is a bit broader than just bitcoin. Other coins may be mined with GPUs and these run hot and consume 300 watts per gpu.
Big gpu mining farms exist which is somewhat worriesome if these are multipled in the near future.
One super computer/data center was used to analyze heat output and came to conclusion that it itself was also contributing to warming... so another sign of worry... surely these big mining farmings are also contributing heavily to heat output. And this is just a sign of things to come.
We in the developed nations should shown the less developed nations how to proceed in this regard concerning electricity usage and heat production. By giving a good example and perhaps negotiating with them in the future they can also implement limits like these. One has to start somewhere.
I am skeptical of how much electricity can be generated with solar panels, especialy in europe and usa, england, etc. Perhaps weather and space is ok, however solar panels also use up precious minerals.
There is also a chance that Africa/desert/arab will become a big "power/energy" player in the future, it kinda already is with "oil". There is also the possibility with poorer countries perhaps building more nuclear reactors which could also lead to environmental problems if such a nuclear reactor were to explode. So there are many issues which huge adoption and mining of cryptocurrencies in general could cause.
Currently it seems people are used to thinking of "electricity" as being "free". Many do not recgonize the "costs / underlieing" value of bitcoin. Which is basically electricity costs. Electricity is just there... one pays a monthly or yearly bill and that's that.
Again my worry is that in a couple of years this might all change !
Think of what would become problematic:
1. Microwave usage
2. Television/news
3. Internet/Computer
4. Washing machine
5. Dish washer
6. Lights
7. Telephony
Etc.
Now ask yourself the following question:
If you had to choose between: "spending electricity on producing bitcoins" or "spending electricity on the things above and beyond" what would you choose ?
My point with this question is that there are more usefull things to spent electricity on then producing a "computer code" for "security reasons" and such.
Is our money/us dollar/euro this unsafe that we must spent huge ammounts of electricity to secure something as "trivial/hackish" as bitcoin ? 99.9% of all computers sold currently haven proven to be vunerable to meltdown/spectre attacks just to give one exampe of the futility currently of storing wealth on a computer.
See this as a political debate about what electricity should be spent on in the case of shortage.
Also with this tenfolding usage... pointing towards countries which produce it cheaper seems somewhat irresponsible and short-sighted. It will not be long before they too run out of electricity.
To me it seems somewhat unethical to be running these huge mining farms out of profit/greed.
I do like the freedom that bitcoin might or might not give to people vs goverment/bank/fiat money. So bitcoin/cryptos do have some merit. But should it be let run out of control ? or should it be constrained ?
Constraining it may give oppertunities to 'secret organizations' which might have huge processing power so this may be an issue.