Comment by ori_prior

60% is feasible for e.g. nuclear and gas, if you use more than one turbine and there is a big constant temperature differential. This typically isn't the case for gas plants which are intentionally variable and often intended to be cheap to build. While at peak temperature, they might run at peak efficiency around the theoretical maximum of 60% (thermal to electric) with a multi-turbine assembly, typically efficiency is far lower because gas plants usually don't run at peak efficiency and only have one turbine.