Turbines extract work primarily from enthalpy, not kinetic energy of steam

A turbine increases the pressure of a gas and extracts work from it. For most turbines, the power is generated from the specific enthalpy drop rather than the change in velocity.

Even though the steady-flow energy balance equation contains many terms, the following is generally true: \(\Delta h >> \Delta(KE)\)

Consider some typical values for a (superheated steam) turbine:

[ \begin{aligned} \Delta h &= 1000\,\mathrm{kJ/kg}
v &= 50\,\mathrm{m/s}
P &= 20\,\mathrm{MW} \end{aligned} ]

note that specific enthalpy actual has the same dimensionality as the square of velocity, i.e

\[kJ/kg = 1000 J/kg = 1000 m^2/s^2\]

the specific KE of the incoming velocity is:

\[1/2 \times v^2 = 1/2\times (50 m/s)^2 \approx 1000 m^2/s^2 = 1000 J/kg = 1 kJ/kg << \Delta h\]