g) Types and combinations of drivers, such as steam condensing turbines,
extraction condensing turbines, back pressure turbines, gas turbines, and diesel
Comparative Cost of Alternate Methods
Load Duration Curves. For electric generating plants, block out each method
of satisfying electric and export steam demands on a load duration graph (with a curve
for electricity and each export steam condition), as shown in Figures 1, 2, 3, and 4 for
a particular job. The example is for a plant generating electricity and exporting steam
at three different conditions: 135 pounds per square inch (psig) (930 kPa gage), 35
psig (241 kPa gage), and 6 psig (41 kPa gage).
Comparative Owning and Operating Costs. Estimate and tabulate the owning and
operating costs for the alternate methods. Tabulate total annual costs for each project
year in Format A or Format A-1 of SECNAVINST 7000.14, and apply discount factor for
discounted annual cost.
Choice of Individual Components. The same economic analysis can be applied to
individual components within a utility system. Since the only variables will be initial
cost and energy, only these factors need be considered in the analysis.