Wow, glad to know you have the global carbon emissions problem in hand!
Back in the real world, until we have actually got that problem in hand, PoW cryptocurrencies are a huge extra amount of consumption, where we already have more consumption than green energy producers can keep up with. And now crypto miners are bringing decommissioned fossil fuel plants back on line in some places, purely to service PoW.
The planet burners are the buyers. Sorry.
2. Banks provide orders or magnitude more services than cryptocurrency ever will
Green and crypto are quite different things, supply and demand — green is about production, the only important part. How we generate energy in a clean and sustainable way.
Crypto is about consumption, and you have no business telling others how they should spend energy. You can however incentivize the consumers to do it cleanly. You can be green and also pro-energy usage.
Being green doesn’t mean being a bully and telling people what they can and can’t do.