I think it's wrong to say that Bitcoin generates electricity. The Bitcoin mining process uses electricity, and any renewable source of electricity miners use is mostly strictly used for the mining. So BTC consumes electricity, but as o_e_l_e_o pointed out, a significant part of miners use renewable sources.

As for the mining part, it's going to be extremely hard to change the algorithm that has been only used and strengthened ever since Bitcoin started to exist. The core functions and principles of Bitcoin are the hardest to change at the moment, especially when Bitcoin's decentralization and security is in a better spot than ever before. Even if a better algorithm is found, it needs testing and so we would probably need an altcoin as a long-term testing ground.