Available energy money balances

The circulating process stream passes through the reboller and condenser extracting and depositing available-energy. From this perspective it is only reasonable to price the process stream at a constant cost X, which is analogous to the extraction method (15). This constant price X, obtained from the reboller money balance, is used to cost the inefficiencies in both the tower and the condenser. 

The use of available energy in optimization of a complex energy system is quite similar to its use in costing of energy flows as presented above, inasmuch as the keys are (i) the use of money balances, and (ii) the assignment of unit costs to available energy. 

The cost of process steam is then obtained from a money balance on the turbine. Nevertheless, the commodity of value is available energy—any method which assigns costs on any other basis such as energy or mass is usually invalid. Furthermore, only with available-energy costing can co-generating power plants be analyzed by other methods—equality, extraction, by-product steam— discussed in the preceding paper (2). 

Af a(j,j is the additional boiler fuel required when the heater is ou of service, cB is the unit cost of steam in the i - 1 bleed line, and cp is the unit cost of boiler fuel (coal). These available-energy flows are calculated in the usual manner and are given in Table II and reference (6). The unit costs are obtained with exactly the same techniques discussed by Reistad and Gaggioli (2)—by applying money balances to each component (boiler, high-pressure turbine,. . . ) of the system of interest to get the dollar flows and then by the subsequent division of the appropriate available-energy flows to obtain the unit costs. 

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