It's hydropower in 99% of the cases.
It could be also gas flaring or geothermal but I've never heard of the first being used in China and the setup for the second is expensive as f.
China has built in the past thousands, actually, tens of thousands of dams from huge ones to small capacity ones, especially in Sichuan, arriving at 100GW capacity, to understand this France has 130 GW in total. 
Most of them were never connected to the grid or in the big clamp down on illegal dams if not blown up they were disconnected from it and either went up for sale or they were selling energy to businesses that could afford to move and operate next to the dam.

And no, nobody mines completely off-grid with only solar or wind, unless you like losing money and receiving ROI after a decade.

It doesn't though. There is no direct link between the amount of hashrate we have and the amount of transactions being processed. After significant difficulty adjustments, we could process the same number of transactions with a single person mining on a single GPU, if we wanted to.

In terms of remaining secure, we still have plenty more hashrate than we need. The hashrate dropped by over 50% earlier this year, and there was not even a suggestion of a hint of a 51% attack. As recently as 2018 the hashrate was <10% of what it is now, and we were never 51% attacked then either.

It's hard to believe for me no one from China is involved with Bitcoin mining. The government would prevent big companies from mining. But it's quite impossible to prevent every small miner even individual miners as well. Also China many times banned Bitcoin before and after a few days seems they use it back. It's called China brain actually. I am just wondering where competitors countries adapting Bitcoin here China banned that. However, though government stop all official mining farms, but can't stop investing in entrepreneurs who are still mining Bitcoin IMO.

As in any place, there are going to be clandestine miners. Of course they cannot be "huge" anymore, since the State can seize everything and put them to prison if caught.

I bet some even use satellite links, a practice that is absolutely forbidden there, so they would need to hide it well. Bitcoin itself is illegal right? And yet, some people will accept it and pay with it, same thing, covering their tracks as best as they can.

oh you and your assumptions, guestimates. maybe you should keep referencing the cambridge sites link that has them same terminology in their explanations.

the dip in the hashrate was not just china taking asics offline. it was also america turning rigs offline when the first ATH price correction went below the profitable amount to keep mining. and also the upgrading of asics from s9 to s19pro where less asics were needed to run. as well as attempts to try and bring the difficulty down on purpose.

so atleast try to think of the other factors you ignored in your guestimates and assumptions. the same as what cambridge forget to do. but atleast they can admit to using guestimates and assumptions.

but it is funny, thinking that your maths must mean china must have had 82%, simply because you think the whole 100ex drop was "china".. you should be a comedian, im always laughing at the stuff you say.

..
but lets give you some positives.
3 years ago you thought it was impossible to have thousands of dams upstream from a megadam. you thought it would be a "perpetual energy machine" if such were true, or ever to happen... you literally thought it was an impossible thing
 
https://bt.irlbtc.com/view/4689016.msg45531108#msg45531108
.. well 3 years later your now atleast admitting or realising that there are like 25000 dams upstream from government superdams.  so +1 for learning. even if it took you 3 years to realise it.

in the recent year you thought cambridge had proof that there was 0% mining in china.
you did quote their explanation, even though the explanation page had words like "guestimate" "assumption". which you ignored. .. but now in this topic, you seem to be coming around to the idea to accept that not all mining in china has gone..
so another +1 for taking another step forward.

.. but seeing as it takes you 1-3 years to break out of the pains you cause for yourself. maybe you should stick to comedy

oh stompix. need it take another 1-3 years for you to have another lightbulb moment and realise?

let me try to make it simple

thats just 2 other factors you YET AGAIN forgot, even when i just said you forget other factors.
here are some more

when the price is too low for america to mine. that leaves more space for china to mine. the ratio of % of america:china mining changes.
when america switch off, china mine more, when america switch on china mine less.

china is not on a fixed % of mining all month,year,decade even during the times of no political risk to mining. it does vary month to month.

there are even times where all miners power down a bit when the difficulty is going up too much per fortnight.
there are times where some miners power down when the price is too low. and too many miners mine when the price is high(causing a difficulty jump) which then causes them to power down to re adjust and not cause another difficulty jump

you need to look into many factors at play and not ASSUME its all "china"


..
oh and your 8cents/THs.. 30cent/THs bad math...

an asic is 110ths pulling 3.25kwh
china electric being 4cent/kwh...
so 110thash/s=13cent AN HOUR for 396000TH in that hour

which is simple math
0.00003283cent per THs to break even.

so its not 8 cent per TH a second in any possible way
..
but you made me laugh. you thought it cost 8 cent a second per terrahash

by the way. i dont debunk math. i love math. i debunk YOU for your lack of math. YOUR lack of including all the variables in math, YOUR assumptions and guestimates that do not include full understanding of what goes into a math problem

if it were 8cent per THs
then the 160,000,000th/s network rate
would be 96000000000th/block(~600 seconds)
which would be $7,680,000,000 per block
which would be $1,228,800,000 per btc cost to mine

sorry but your math is off by millions

if you are using 1.3kwh for just 13thash (s9)
but then you upgrade to use just 3.25kw for 110thash (s19)

you no longer need 8x s9 asics at a cost of 10.4kw (40cent electric an hour) for ~104th
you can just run 1x s19pro asic at a cost of 3.25kw (13cent electric an hour) for 110th

and save yourself 27cents. meaning you dont need to run extra rigs or increase hashrate to be profitable. you are instead already making 3x profit by just having the same hashrate, due to the upgrade saving you money at the cost end of the equation..
resulting in you not needing to mine as much sats per block to break even.

infact if you exponentiate it out
you no longer need 80 s9 asics at a cost of 104kw ($4 electric an hour)
you can just run 10 s19pro asic at a cost of 32.5kw ($1.30 electric an hour)

and because your costs are now a third of what they were(3x profit). you can then take 2/3's of your s19's offline. and still break even

knowing the benefit of lowering your hashrate because the profits are there to allow you to lower your hashrate, means your not the one shooting yourself in the foot by over-mining to cause difficulty jumps that can hurt you later.

so you know you can go down to 3-4 asics and still profit. and so instead of 10 s19's running. you only put 5-6 asics running to reduce the risks of difficulty jumps, and infact cause a difficulty decline. which HELPS YOU EVEN MORE, next difficulty period..

maybe just maybe. some day. maybe it be 1 or 3 years.. but maybe you might come to the realisation as to why at no time has the hashrate been a straight line. perpetually rising. you might come to some conclusions about the wiggles and the dips in hashrate. and maybe if your a good boy and learn your lessons you might factor in more reasons for it. regular changes that dont make it a straight line of linear growth

Of course, a government ban cannot completely destroy mining in a country, especially one as big as China. There will always be people who will violate this ban. Moreover, I do not see that it will be adopted in the form of a law with sanctions for its violation. But nevertheless, there is no official cryptocurrency mining activity in China. The state still has a very strong influence on cryptocurrency.
This week, the Winter Olympics are already opening in China, where they promise to officially launch the digital yuan. Some time after that, a review of the decision regarding the ban on cryptocurrencies is possible there.

the most important thing is that he no longer has power over bitcoin, they don't have many miners anymore because they themselves sent all miners away, this is very good for bitcoin, I'm just afraid that later miners will start to focus on another country, I hope that this time the miners are scattered