This year, the southwest monsoon has been just about normal and the Idukki reservoir has, at the moment, over 59 tmc ft of water against its full capacity of over 70 tmc ft. The reasoning in the KSEB is that there is enough room in the reservoir to receive an unexpected influx of water from Mullaperiyar reservoir in the event of such an eventuality. The Mullaperiyar reservoir now holds over 11 tmc ft of water.
Electricity Minister Aryadan Mohammed said the first priority was the safety of people. "We will generate maximum electricity possible from the Idukki stations on a daily basis [to keep the water level in the reservoir low without wasting the storage]. The safety of people is more important than electricity," he told The Hindu.
A top official of the KSEB told The Hindu that "sufficient precaution would be taken." The annual planning for optimising power generation would be gone into once again. The KSEB may also have to look into the technical factors relating to dam safety.
The Idukki reservoir, the largest in the State, affords the KSEB quite a lot of flexibility in planning power generation and power purchase. In this normal "water year," the KSEB expects to generate 2,367 million units of power at the Idukki station. (Water year is a term used by the KSEB to describe the one-year-period from June to next May, coinciding the beginning of one monsoon and the beginning of the next). This quantum of electricity is 33.55 per cent of a total of 7,055.65 million units of energy the KSEB expects to generate from 22 hydroelectric stations during the water year. Most of the reservoirs feeding the other hydroelectric stations are small ones.
The total energy requirement expected during the current water year comes to 18,534.53 million units. Thus, the hydro power stations are expected to provide only 38 per cent of the total energy required to meet the projected total energy demand during the water year. The remaining energy would come from the KSEB's own thermal stations (533.81 million units), Central generating stations (8,398.24 million units), independent power projects (1,283.15 million units), and purchase through traders or power exchanges.
Scheduling the flow of power from all these sources to optimise cost is an intricate exercise, because of fluctuations in availability and cost, difference in cost between one source and the other, and a host of other factors, including the big fluctuations in demand during the course of each day. Demand shoots up to its peak during the evening hours because of the consumer profile of the State.
The huge storage of water in Idukki reservoir helps the KSEB to calibrate power generation and purchase as well as possible in a situation of constant flux. If the storage in Idukki reservoir is consumed too fast, it will cause difficulties, especially during the summer months.