The Real Power Generation Potential of KBD Project

The need for electric power has been increasing at a tremendous rate. This is evident from the analysis of our annual power requirements, which shows that between 1985 to 1989, 12.5% more power was required each year, and the power consumption doubled every 4 years, before 1985. Presently, despite the economic recession of the last number of years, demand for electric power grows by an estimated 8.3% each year.

Presently, Pakistan produces 11869 Megawatts (MW) of electric power (6907 MW by thermal power generating units, 4825 MW by hydel and 137 MW by the Pakistan’s only nuclear power station at Karachi)

According to a World Bank study, the country will be needing upto 21267 MW electric power by the year 2002, and between year 2002 to 2010, another 10358 MW will be needed, raising the total required generating capacity to 31265 MW.

The following data pertain to the large power generation units, both hydel and thermal, already in operation in 1992-93 

Reference: Energy YearBook 1993, KBD; The Sindh Case by Abrar Kazi

It can be observed that, the present cost of production of power, varies between hydel and thermal as 5.65 paisa per kWh to 72.12 paisa per kWh respectively, indicating that the hydel power is the most suitable source of cheap power generation.

 However, there are certain disadvantages inherent in the hydel power systems because of their dependency on the waters to flow through the turbines.

 From the above table, it can be observed that; the top three stations in terms of installed capacity are Tarbela, Pipri and Kot Addu, whereas the top three in terms of power output are Tarbela, Mangla and Pipri Power Station.

Further the Cost-wise, lowest are Mangla, Tarbela and Guddu (5-10), whereas Cost-wise, most expensive unit is Kot Addu Thermal Power Station. The total generation of the utility system was 48,156 GWH in 92-93, in which the share of Tarbela in the total generation was 28.98 % at 7.34 pa/kWh.

In the flood season (June to September) each year, hydel power peaks to the maximum, thereafter tapering off to insignificance in the winter months, generating less than 25% energy. Therefore the constant supply of energy from each hydel power unit will need an additional thermal unit for back up in the winter months, unless some method is used to maintain a constant flow of water into a hydel power dam.

 The most important aspect of our present power generation system of the country is that, all the power stations are independent, in structure and in operation, which will not hold true for the relation of KBD to Tarbela. In which case, the water to the Power Station at KBD will first have to flow through Tarbela, to a very large extent. In fact the two power stations will work in tandem.

An interesting problem is to find out how the two reservoirs on the same river, will behave while generating power and supplying irrigation water to the downstream command areas.

The problem has been thoroughly studies by Saeed A. Rashid in his book; "KBD, A Scientific Analysis", through a mathematical model analysis (with the given installed capacity in the upper and lower reservoirs). Which makes the important revelation that, it is practically not possible to maintain generation capacity over a period of 8 weeks (appears to have been provided for by design of the project).

 Even if high peaks are obtained in the IRS within the time period, it is not possible to avoid load shedding towards the end of December and beyond, in any year. And it is particularly important to note that the marked difference in behavior of the two reservoirs, when they will be working in tandem.

From the WAPDA’s calculations, it appears that the average inflow is about 92 MAF above Kalabagh, of which 70 MAF is utilized in Thal, Haveli, Rangpur, Sidhnai, Paharpur, Panjnad, Taunsa, Guddu, Sukkar and Kotri canals and other outlets of Tarbela Command.

Of the total inflow, 68 MAF (73%) occurs in June to September and by December the inflow is reduced to a trickle i.e. 1.86 MAF with which the power generation also is reduced to a minimum at Tarbela.

 When the level in the upper and lower reservoir drops to the same point for power generation, it is not possible either to distribute more irrigation water or to generate more power. And by that time, the country has to revert to thermal power, unless there are some run-of-the-river type power generation arrangements.

 Therefore, to get additional power at a lower cost for ensuring reliability and protection against drop in pressure, it would be necessary to get out of the "water cycle". And the conjunctive operation of KBD and Tarbela Dam will be of not much help in providing cheap hydropower, because of their inter-dependence for water releases.