@hatu mining makes our ecosystem energy intensive and environmentally unsustainable. The process (mining) has already consumed 0.15% of the world’s energy and that exceeds the electricity consumption of most African countries. According to Alex de Vries who said, and I quote:

“The computer power needed to create a single digital token consumes at least as much electricity as the average American household burns through in two years.”

And he also said that:

Each individual bitcoin transaction “currently requires 80,000 times more electricity to process than a Visa credit card transaction.”

So we can all see that's a lot of energy it consumes. It’s therefore necessary that we use renewable energy to supply the energy consumption needs of the blockchain ecosystem. Few hydro-electric plants can also be built on nearby rivers, providing a reliable and renewable power source. Also wind and solar are good sources of renewable energy but they are not always available, that's a disadvantage but thankfully, it's now possible to convert waste (biomass) into energy, so with this I think mining facilities should use renewable energy to reduce energy crisis and so we can have a more sustainable future.