A lot has been said about mining and about the electricity consumption of the activities related to bitcoin mining. However, I have thought of the alternatives and how other systems produce not just energy waste, but also plenty of useless work and "human waste".
To have a network that can ensure the completeness of transactions, the global accessibility and all the features that bitcoins, and many alts, have at the moment, would probable produce a huge carbon footprint. Just think of the VISA system or the banking system... the amount of people working on it, the waste of commuting to works, the infrastructure.
Thinking of all that, would you still say Bitcoin is bad for the environment?
Bitcoin mining is using electricity, obviously and 24/7 mining a bitcoin. However banking system also used electricity when doing transactions as well as paper receipts and records and bank books. Comparing these two, bitcoin although using electricity it is very safe in the enviroment, there is an alternatives to use electricity like solar power it conserves power consumption in some power plants, also coalfire power plant can also be used as a power source.