Do you know some kind of currency transaction that needs to use great amounts of energy? Due to the current configuration of the algorithms employed to prevent fraud in this system, bitcoins have to solve complicated mathematical processes to approve operations, consuming electricity and vastly.
In few words, the developers of this system didn't find another viable method but to use mathematical and computationally expensive operations to provide security in transactions where each peer shares processing power to be ahead of the theoretical individual that could cheat the system. It's obvious that if someone gains a lot of computational power, it could create a flaw. Recently someone did create noise stealing a great number of this curious currency, and maybe it's related with this possibility.
Then, all the banking standards are constantly handling operations in the network, with the common public and private keys plus strong security and it's interesting that nobody finds a method to proceed with bitcoin operations without the mining reality that of course is lucrative. Mining, or with other words, sharing computational power to solve the mathematical game in each operation produces bitcoins. This promotes the use of electrical energy in exchange for currency.
It's obvious that to use electricity in the present context produces more overall toxicity for our health because normally, it doesn't proceed from renewable sources so this idea doesn't help! The bitcoin algorithm is, finally, based in a method called brute force or guessing without clue, very used in finding passwords and that's why they should have multiple characters because each one more adds computational requirements for the brute force way.
Miners should go to the Sahara desert and go solar while the international organization continues polluting air and wasting much more energy than the one that is being used, there and in other places.