ah, well the more efficient numbers are because they are recycling much of the "waste" heat, a good plan generally speaking. They basically have a supply of water hooked up to the exhaust to make steam, and drive another turbine with that, fairly trivial to do with a land based plant.
Of course if you have some cold buildings nearby it is more efficient to use the "waste" heat to warm them directly than to burn more fuel to warm them and/or spin a steam turbine to make electricity to warm them.