Re: How do I calculate energy content of steam at known P, T, and V?

The property you should be working with is the enthalpy (h) which 
represents the total useful energy of a substance.  Useful energy consists 
of two parts.  The first part is the internal energy (u) and the second is 
the flow energy (pv).  Enthalpy is the sum of these two parts,

h = u + pv


Given the temperature and pressure of the steam one can look up the 
enthalpy in standard "steam tables" of properties for steam at any given 
temperature and pressure.  There are several on line resources for such 
properties.  One you might try,
 http://webbook.nist.gov/che
mistry/fluid/

The work from a turbine (W) can then be calculated if you also know output 
conditions.  Alternatively, if you know the work you want to extract from 
the steam you can calculate what the output conditions would be for an 
ideal turbine. 

W = m (h1  - h2)

where h1 is the enthalpy of the steam going into the turbine and h2 is the 
enthalpy of the steam coming out of the turbine.  m is the mass of steam.

To calculate the work and heat inputs and outputs for an entire steam cycle 
is more complicated, but the above will get you started.  For the entire 
cycle you can try one of the following web pages
 http://www.n
e.ncsu.edu/Acadm/Classes/Labs/project2.html
 http://chemengineer
.about.com/cs/thermodynamics/

or a thermodynamics text book.