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<br />c, <br /> <br />~ <br />~ <br />~ <br />~ <br /> <br />This demonstrates the concept of peaking power and why it is important <br /> <br />in an electrical power system. <br /> <br />FIGURE 1 shows a typical daily demand pattern and FIGURE 2 is illus- <br /> <br />trative of a typical annual demand curve. These charts demonstrate what is <br /> <br />meant by daily peak load and annual peak load. <br /> <br />These figures also show that a substantial part of the load is on a <br /> <br />continuous basis. The problem of the electric utility is to develop an <br /> <br />economic'method of generating the right amount of electricity so as to <br /> <br />meet the anticipated demands of everybody using power on that system. <br /> <br />Just meeting the continuous demand, or the low point (valley), is not <br /> <br />enough because the next light that is turned on creates an overload on the <br /> <br />system. Conversely, continuously generating enough power to meet the peak <br /> <br />maximum demand is wasteful and expensive. <br /> <br />In the above example even the 200,000 kW plant would probably not be <br /> <br />sufficient. Records show that the energy demand per hour at 1:00 p.m. is <br /> <br />much greater than at 7:00 a.m. 'Power demand generally follows a fairly <br /> <br />predictable daily pattern. FIGURE 1 shows the demand will reach a peak in <br /> <br />the late afternoon and be at its lowest in the early morning. The daily <br /> <br />peak demand must always be met to prevent a brown- or black-out. Studies <br /> <br />show there is also a daily minimum below which the demand never drops. <br /> <br />Corresponding weekly, monthly, and annual values can be found as well. <br /> <br />There are several ways the peak demand can be met, The single plant <br /> <br />designed with an output capable of meeting the maximum annual peak demand <br /> <br />would, except fo~ the one time each year when the maximum daily demand occurs, <br /> <br />run at a prohibitively low efficiency; that is, energy consumed as fuel <br /> <br />would be far greater than energy produced as electricIty, A second method <br /> <br />2 <br />