## Solved Problem 7.1 - Exergy Analysis of a Geothermal Power
Plant

Assume that a village has discovered an underground
geothermal well containing water at 95°C, 100m below the surface.
They are evaluating the option using the water from this well
to provide power to the village. Determine the maximum available
work [kJ/kg] that could be obtained from a power plant that will
pump water from the well, extract energy from the water and discharge
the water to a lake at the surrounding temperature T0 = 25°C.
Assume that the water temperature can be reduced to 35°C at
the outlet of the power plant.

We now do an Exergy Analysis to determine the
maximum available (reversible) work by eliminating q from the
above Energy and Entropy equations:

This equation could have been derived directly
from the definition of exergy:

Finally, we obtain our numerical answer by
considering the question "__What__" above,
in which we substitute the enthalpy (h) and entropy (s) values
for liquid water, an incompressible liquid:

______________________________________________________________________________________

Engineering Thermodynamics by Israel Urieli is licensed under a
Creative Commons Attribution-Noncommercial-Share
Alike 3.0 United States License