Abstract:
Cogeneration is the simultaneous generation and use of
both electricity (or mechanical power) and thermal energy
from a single fuel source. It is a technology that has been
used for years by industries, commercial institutions, and
municipalities that need both heat and electrical power. An
analytical approach has been developed to determine
cogeneration feasibility. The analysis is designed to
estimate economic feasibility based on the performance
characteristics of different types of equipment, including
wood-fired boilers. It can be used to compare several
options for cogeneration systems. The economic analysis is
based on simple payback. A microcomputer spreadsheet
application program performs the technical analysis.
The program offers many features that are designed to
improve and simplify prediction of cogeneration system
performance:
1) Available energy calculation for wood fuel based on
species and moisture content. Also uses natural gas
and fuel oils.
2) Hourly steam and electrical load profiles for up to 6
typical operating days per year.
3) Three steam turbine types:
Condensing,
Backpres sure,
Autoextraction.
4) Full and part load performance modelling.
5) Three operating modes:
Thermal load following,
Electrical load following,
Constant load operation.
6) Steam enthalpy calculation for any operating
conditions.
7) User-defined utility rate structure.
8) Independent value for excess electricity sold.
Our approach is to compare the annual cost of providing
thermal and electrical power separately and independently
(i.e., electric utility power and a steam boiler) to that of
producing the required power simultaneously (cogeneration).
This requires an understanding of the power requirements,
the utility rate structures, fuel costs, operation and
maintenance costs, and available technology for power
production.
The program calculates fuel requirements, electrical
energy and power production, costs, equipment size and cost,
total cost savings, and simple payback for several
cogeneration alternatives.
