Supplementary thermal power for hydroelectric systems

A HYDROELECTRIC SYSTEM must be engineered to carry the anticipated firm peak and energy loads even under “critical” water conditions. When conditions are more favorable water will therefore either have to be spilled, or at best, used to generate secondary power to be sold at dump rates, provided there is a market for it. Substantial economic gains are frequently possible through “firming up” such secondary hydroelectric power by a supplementary thermal plant. The level of firming up can be measured by the equation “Firm Up Ratio” x = firm capability — critical capability/median capability — critical capability. The higher the firm-up ratio, the greater will be the gain in firm power, and at the same time, the quantity and cost of thermal energy required. For a given set of local conditions, there will be an optimum level of firming up which will produce the greatest economic gain. The objectives are to determine the optimum firm-up ratio, the optimum size of thermal plant, and the relative economy of a gas turbine plant vs a conventional steam turbine plant for firm-up service. Equations are obtained for the desired quantities and solved on an IBM 604 computer for a wide range of hydroelectric, thermal plant, and fuel costs, using an IBM 604 computer.