There already exists a cryptocurrency that is both environmentally friendly, fast and fee-less - Nano [0]. It uses something called directed acyclic graph (DAG)

There already exists a cryptocurrency that is both environmentally friendly, fast and fee-less - Nano [0]. It uses something called directed acyclic graph (DAG) and while it does require proof of work it’s only for sending transactions to prevent spam, not for mining. It was created a few years ago but only recently it starts to get more traction. I used it a couple of times and it worked great. [0] https://nano.org/ https://nano.org/