Bitcoin is good for the environment. The things that affects the environment is not the bitcoin itself but the tecnology that we used to generate bitcoin. Like mining and other power source that produced radiation.
Compared with the traditional monetary system, the energy consumption of bitcoin is not only its fatal wound, but can be said to be a very economical. Bitcoin consumes a lot of power, but it maintains the operation of the entire Bitcoin network supported by the network. No need for a banknote printing machine Mint, do not need the central bank and the banking system at all levels, do not need complex international exchange system.
A systema such as bitcoin can also benefit from using the net services in places where there are more renewable sources or electricity is cheaper. So it is, in a way, decentralising the cost of the banking system.