Because we know how to build them, and have already built them. If you want to build more low-carbon power tomorrow, you can pour more money into turbines and g

Because we know how to build them, and have already built them. If you want to build more low-carbon power tomorrow, you can pour more money into turbines and get more turbines approximately immediately. Small reactors are still an area of research, not a functioning industry. Also, the politics of a Fukushima means that when something does go wrong, the entire fleet of reactors gets taken offline due to politics, and now you're burning fuel oil for light. It's not good if your overriding interest is in decarbonizing immediately. Even if wind turbines killed birds by the millions, they're still better, because dead birds don't cause global climate catastrophe (but climate catastrophe will cause dead birds).