Compare that to the turbine in a coal or gas plant, which can archive up to 90% efficiency.

Nope, you might have seen 90+% efficiency when talking about steam power plants, but that’s the efficiency of the generator(converting the mechanical energy of the the rotating turbogenerator to electricity). You have to multiply with the efficiency of the turbine(converting the energy of the heated gases into the mechanical energy) and there the efficiency is much lower, ~40% for a coal fired and maybe <60% for a gas combined cycle.