Another point that is not widely communicated ... is that the amount of energy bitcoin consumes today is related to the price, not to any actual need for that to be 15 GWs.

Put simply, miners will add facilities and hashing equipment as long as their plans are that such investment will be profitable. So if the price doubles (or is expected to double), the miner's revenues double, ... and for the most part, the hashrate (and the amount of energy consumed) will double -- all else being equal.

Now the reason that doesn't actually happen is that more of those revenues end up going to capital expenditures (CapEx) than to electricity. That CapEx is spent on more efficient hardware, ... so even though a higher BTC/USD price results in more hardware being acquired, the total amount of electricity won't rise anywhere near at the same level.

And then halvings (every four years), result in the miner's revenues being cut in half, ... which ends up forcing "marginal" miners offline/out of business, or to cause them to de-commission obsolete hardware and invest in the more efficient hardware.

In other words, it's not a strict liner relationship ... where when bitcoin price jumps 4X doesn't mean the amount of electricity consumed will also rise 4X. But electricity consumption and price are indeed related.