Application of information theory for the analysis of cogeneration-system performance

Successful cogeneration system performance depends critically upon the corr ect estimation of load variation and the accuracy of demand prediction. We need not only aggregated annual heat and electricity demands, but also hour ly and monthly patterns in order to evaluate a cogeneration system's perfor mance by computer simulation. These data are usually obtained from the actu al measurements of energy demand in existing buildings. However, it is extr emely expensive to collect actual energy demand data and store it over a lo ng period for many buildings. Here we face the question of whether it is re ally necessary to survey hourly demands. This paper provides a sensitivity analysis of the influence of demand-prediction error upon the efficiency of cogeneration systems, so as to evaluate the relative importance of various demand components. These components are annual energy demand, annual heat- to-electricity ratio, daily load factor and so forth. Our approach employs the concept of information theory to construct a mathematical model. This a nalysis provides an indication of the relative importances of demand indice s, and identifies what may become a good measure for assessing the efficien cy of the cogeneration system for planning purposes. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.