It's not clear that it would; the cost of renewable power has crashed so dramatically over the past ~15 years that it is now difficult for anything else to comp

It's not clear that it would; the cost of renewable power has crashed so dramatically over the past ~15 years that it is now difficult for anything else to compete. Even if one were to acquire a fusion reactor completely for free - if benevolent aliens saw fit to drop one off as a welcome-to-the-neighborhood gift, perhaps - the turbines and generators necessary to make use of its output would cost enough that investors would make a better profit just building more wind or solar instead. Fusion reactors, could they be built, might well change a lot of things in the polar regions, and perhaps on the Moon; but the era in which fusion power could have radically changed life in the habitable regions of Earth seems to be on its way out.