Cost cogenerated products

Table II shows the estimated revenue requirements. Electricity and cogenerated products costs are based on regulated utility financing, while steam costs are based on non-regulated industrial financing. The cogeneration case costs are shown on a total product basis, since two products are involved. Figure 1 shows the selling price of electricity as a function of the selling price of steam for the cogeneration case.

The maj ority of these new plants are corn dry-grind ethanol plants. Approximately 2.5-2.7 gal of ethanol, 17.5 lb of dried distiller s grain (DDG), and 17 lb of carbon dioxide are produced from each bushel of corn processed through a corn dry mill (2). Since 1980, process improvements in enzymes, thermal-tolerant yeasts, molecular sieves, and cogeneration have achieved a 50% reduction in the energy required to produce ethanol from corn (2). Further improvements in efficiencies and reductions in production costs can be expected in the future. 

Erlach, B., Tsatsaronis, G., and Cziesla, F., A new approach for assigning costs and fuels to cogeneration products. In ECOS ol, Efficiency, Costs, Optimization, Simulation and Environmental... 

Globally, the hydrogen production costs for the RMM technology are more than 10% lower than those of the conventional H2 scheme coupled with the cogeneration unit, where electrical power is produced by process outlet mixture. 

A first-of-a-kind production cost of US 63 million (overnight cost, US as of 1997) has been calculated for the cogeneration plant. With traditional learning curves and series production advantage factors, a series plant production cost of US 52 million has been derived. This must be compared with the US 160 million needed for a single PBMR plant, the next cheapest plant with respect to capital investment. It is therefore advantageous to companies with not only a smaller demand per site but also those in a lesser position to raise large amounts of capital. 

Many cogeneration plants use PF coal, oil, or gas as a fuel, but if blast furnace (BF) gas, sawdust, bagasse, or other low-grade by-product fuels are available, these normally can be used to reduce overall fuel costs. Often a combination of fossil fuel and by-product fuel is employed. 

Cogeneration combines the production of heat and the generation of electricity to provide a higher total efficiency than that of either process occurring separately. As the costs of fossil fuels and electricity continues to increase, cogeneration becomes more attractive. 

Neither Dow nor GM has reported what the financial terms of the deal were. Dow insisted on a transaction that made economic sense for the company, and cogeneration is Dow s low-cost alternative to electricity from GM s fuel cells.30 When pems finally become a commercial product, it is very unlikely that their price will be competitive with industrial cogeneration, but this deal still makes sense for GM as part of its overall strategy to commercialize its fuel cells and get real-world testing. 

Costing Methods. The cogeneration example is the simplest type, with only two products. In many irtstances there are several utilities (perhaps including chilled water, compressed air, hot water, steam at different pressures) being delivered and/or there may be several products (say chemical) being produced. The money balance must then be complemented by additional equations, so that the number of equations equals the number of unknown unit costs to be determined. 

Table 26.14 shows the consumption figures of energy and chemicals necessary for operation of the plant. From the operation cost point of view, electrical power and fuel are the most expensive. In this plant, product oils are used for these purposes light oil for fuel, and heavy oil for electrical power through the cogeneration system. 

Another viable option for products treated with creosote and PCP (and presumable other organic treatments in the future) is burning to generate power (cogeneration). When added as a small percentage of the overall fuel load these types of treated wood can be burned without unduly increasing air emissions. As fuel costs and energy demands increase, disposal of treated wood in this manner becomes more attractive. 

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