I found above that we have diverted from the main question what has been asked in this thread.
Isentropic efficiency of steam turbine used in large fossil power plants are in the range of 87% to 92%.
In the same way water turbines like Francis or Kaplan have same range of efficiency just a little bit more than steam turbine.
Steam is a compressible fluid but water is not compressible. This is also a reason for higher efficiency of water turbines.