I believe PoW is called mining because it relates not to burning bank notes but to using energy to dig for gold.
I am sympathetic to your cause, my life and business is devoted to environmental sustainability, it is the allocation of capital that has the biggest impact on our environment, not consumer choices.
This.
And PoW allocates capital more efficiently than PoS. PoW rewards those who do the most work by risking their time and resources, rather than those who hold the most capital. The electricity spent on PoW (that can go to useful heat) is dwarfed by the natural resources and human labour wasted when capital is misallocated (like we see in our current debt-based fiat system).
The bitcoin economy will be good for the environment.