From what I understand, some degree of nuclear power is always going to be necessary. This is because while we tend to think of excess power in the energy grid as being stored away, this in fact is not the case and we only use power as it’s actively available. Excess power is wasted. The major downside of renewables is that they’re circumstancial. Solar energy is only available during clear days, wind power is only available on windy days, etc. Until we massively improve our energy storage capabilities we’re going to need some kind of constant supply of power backing the other ones when they aren’t available. Without adequate nuclear energy available, that’s going to be fossil fuels. And when compared to coal, oil, and natural gas, nuclear energy is unbelievably better for the environment. The only byproduct is the spent fuel which is dangerous, but we have control over where it ends up which is more than can be said for fossil fuels.