Most energy produced is usually lost( due to the fact energy can't be stored efficiently or storing energy costs more than making more energy itself ) bitcoin mining gives another use for this energy preventing it from being wasted and giving it value. It also will force miners to use renewable resource because nonrenewable resource will keep on getting expensive. In fact here are already solar bitcoin farms. Yes not the best but the stats saying bitcoin mining is completely wasteful is not true.
And recent news has show that Bitcoin mining is moving on to greener sources as well. A Miner farm will be use Hydro power to power it miner. This hydro power comes from a Dam that was shutdown. https://coindelite.com/news/hydroelectric-dam-to-be-used-for-crypto-mining-in-new-york/
And this trend is not alone: https://www.bloomberg.com/amp/news/articles/2018-02-04/power-hungry-crypto-mines-clean-up-as-cost-of-electricity-grows
This is this future! Bitcoin mining will be completely green one day :)
Posted from my blog with SteemPress : https://bitcointribune.org/2018/09/02/pow-does-not-destroy-the-environment/