bitcoins impact on the world eco system due to electricity use is small, in comparison.

bitcoin (world wide) 145mwatt per day
las vegas (one city) 5000mwatt per day.

other protocols use less electric. such as proof-of-stake. but these do not protect their blockchain, using difficult 'puzzles' (excuse my laymans use of description)

Proof -of stake is weak security and us only to make the rich, richer. (those that hold most coin get most reward). with bitcoin the electric is used to create difficult blocks that a simple computer could not break.