Dueling Studies

 Here's a report on the 2017 study showing that Wind and Solar have way lower lifecycle emissions than coal, gas, or nuclear.

The report mentioned an earlier study which reached opposite conclusions.

I was shocked to learn that wind farms require more concrete than nuclear plants.  (And that nuclear plants require less concrete than coal plants.)  My own experience of nuclear plants is that they are very very big, as in measured in square miles.  But the pedestals that wind turbines sit on are massive, go deep into the ground, AND you need hundreds of them for a 1GW wind farm.  So that is a lot of concrete.  But the world already produces a lot of concrete every year for other things.

But all that concrete (and steel too) is still only a small part of lifecycle emissions, according to study linked above.