Computer model for estimating cogeneration system performance and economic feasibility

Graduation date: 1991Cogeneration is the simultaneous generation and use of\ud both electricity (or mechanical power) and thermal energy\ud from a single fuel source. It is a technology that has been\ud used for years by industries, commercial institutions, and\ud municipalities that need both heat and electrical power. An\ud analytical approach has been developed to determine\ud cogeneration feasibility. The analysis is designed to\ud estimate economic feasibility based on the performance\ud characteristics of different types of equipment, including\ud wood-fired boilers. It can be used to compare several\ud options for cogeneration systems. The economic analysis is\ud based on simple payback. A microcomputer spreadsheet\ud application program performs the technical analysis.\ud The program offers many features that are designed to\ud improve and simplify prediction of cogeneration system\ud performance:\ud 1) Available energy calculation for wood fuel based on\ud species and moisture content. Also uses natural gas\ud and fuel oils.\ud 2) Hourly steam and electrical load profiles for up to 6\ud typical operating days per year.\ud 3) Three steam turbine types:\ud Condensing,\ud Backpres sure,\ud Autoextraction.\ud 4) Full and part load performance modelling.\ud 5) Three operating modes:\ud Thermal load following,\ud Electrical load following,\ud Constant load operation.\ud 6) Steam enthalpy calculation for any operating\ud conditions.\ud 7) User-defined utility rate structure.\ud 8) Independent value for excess electricity sold.\ud Our approach is to compare the annual cost of providing\ud thermal and electrical power separately and independently\ud (i.e., electric utility power and a steam boiler) to that of\ud producing the required power simultaneously (cogeneration).\ud This requires an understanding of the power requirements,\ud the utility rate structures, fuel costs, operation and\ud maintenance costs, and available technology for power\ud production.\ud The program calculates fuel requirements, electrical\ud energy and power production, costs, equipment size and cost,\ud total cost savings, and simple payback for several\ud cogeneration alternatives