[lawn]

Of course Bitcoin's energy consumption isn't ideal, but you've got to realize something: Bitcoin mining is only profitable if you have access to very cheap energy. This is why there are so many miners in China that use hydroelectric power, because there's so much excess energy that wouldn't be used otherwise.

Miners don't really use coal power or use up renewable energy that could be used elsewhere. That would be too expensive for them.

[zaarn]

Even if Bitcoin only uses CO2-free energy, they hog energy that would be available for other projects, so those projects need to use more coal power in return, hence it creates pollution.