It's not about the energy usage, it's about the cost: If you make energy two times as expensive, you would half the mining being done and half the energy usage.

It's not about the energy usage, it's about the cost: If you make energy two times as expensive, you would half the mining being done and half the energy usage. If you introduced a 50% global mining tax, you would also half the mining and the energy usage. If you invent technology that can do twice the mining for the same amount of energy, you would get twice the mining and the same energy usage.