Since 1960 Wapda is managing the Pakistan’s power grid, except in Karachi city, where it is managed by the KESC. The grid managed by Wapda consists of a large network of power generation, transmission and distribution systems, which always had a varying surplus power generating capacity, as well as the loadshedding, characterized by lower the surplus power, heavier the loadshedding.

A relatively low surplus power from 1982 to 1994 (varying from 8 to 26 per cent of the maximum power demand) resulted in a heavy loadshedding.

After 1994 as the surplus power increased, the loadshedding decreased. In the year ending June 2001 there was 15,179 megawatt (MW) installed generating capacity and 10,128 MW maximum power demand, leaving 5,051 MW or 50 per cent surplus power. The installed capacity comprised 5,009 MW hydropower plants, 4,740 MW Wapda thermal plants and 5,430 MW IPP thermal plants. The following table, based on the data given in Wapda’s annual report, shows that despite the huge surplus power some load had to be shed in every month.

The annual report explained: “Load shedding and load management measures were implemented because of the transmission and transformation bottlenecks, restriction of water outflows from Mangla and Tarbela dams only”.

The annual report presented an unsatisfactory performance of the grid, as a huge investment in 5,051 MW surplus power remained non-productive, which could supply electricity to 45 per cent of the population still waiting for the electricity. Furthermore, 13.8 billion kilowatt hour of energy (24 per cent of the net generated energy) was lost in the transmission and distribution systems. The loss of power and energy in the year ending June 2002 increased to 5,710 MW and 14.3 billion kilowatt an hour, respectively. Obviously, an investment worth several billion dollars in the grid is not performing its intended role and the huge losses in the grid are making electricity unaffordable.

The rising power and energy losses can ultimately bankrupt the entire energy sector. That eventuality can be avoided by a prudent utility planning and by finding viable options to mitigate the losses. In this regard a critical review of the performance of the grid deserves immediate consideration of the GoP and Wapda. The objective of this review should be to identify and rectify the shortcoming of the grid, to ensure full utilization of the excess capacity, to reduce the losses and to develop a reliable grid that would be capable of supplying affordable electricity to the entire population. This task can be handled by the qualified and experienced utility planners, who should particularly look into the following aspects of the grid.

1. Thermal plants: The lowest output of the IPP and Wapda plants in the year ending June 2001 was 59 per cent and 38 per cent of their installed capacities respectively. A very low output of Wapda plants may be due to the unreliability of old plants commissioned before 1975. It is difficult to rehabilitate these old plants at a reasonable cost because some of their equipment is obsolete. The planners should consider replacing these plants with more efficient and environment-friendly new thermal plants.

A master plan should be prepared to carry out this work systematically ensuring optimum utilization of the existing facilities and available land at the old sites, which would make it cheaper and faster to install the new plants at these stations than developing the new sites. If due to financial difficulties, Wapda is unable to arrange funds for this purpose, the public and private sector partnership should be considered for replacing the old thermal plants. This step will ensure the utilization of the existing facilities of the old power stations as well as the operation and maintenance experience of Wapda in the best interest of the country.

The old policy of constructing large oil/gas fired thermal plants far away from the power demand centres should also be reviewed in the light of the latest research carried out in the US by the Electric Power Research Institute, Carnegie Mellon University and others, which indicates that the distributed power generation is more reliable and cheaper than the large plants located far away from the load centres. The distributed generation is a term used for micro, mini and small power plants located near the load or demand centres and close to consumers. The planners should also determine an optimum hydro and thermal power mix required to ensure a minimum cost of electricity as well as a stable and reliable power system.

2. Hydropower plants: The lowest output of hydro plants in the year ending June 2001 was less than 25 per cent of their installed capacity. A low dependable power (or capacity) of our major hydro plants and a dry weather were responsible for this low output. The dependable hydro power is an output of a hydropower station which is available throughout a year. Any capacity of a project which is above its dependable power is called secondary power. The above table indicates that the dependable power of our hydro plants is less than their secondary power. The dependable hydropower has these advantages:

* It ensures low and stable cost of the electricity in the long run.

* It reduces the adverse environmental impacts.

* It is a renewable resource, provided the project is sustainable.

* It reduces dependence on the imported fuels and attendant risks to the national economy and security.

* It can enhance reliability and flexibility of the power system through prudent planning.

On the other hand the secondary hydropower has only two significant advantages, it saves the cost of imported fuel and it can play an important role in meeting the peak power demand. As secondary hydropower is not available throughout a year, in order to avoid power shortage, the thermal power is required to substitute for it. The dependence of the secondary hydropower on the thermal power can be seen from the above table, as the output of hydro plants decreased, the output of thermal plants increased. The loadshedding took place when there was not enough thermal power to replace the secondary hydropower. The secondary power some time has these disadvantages also:

* It necessitates investment in two power plants, a hydro plant for harnessing the secondary hydropower and a substituting thermal plant for replacing the secondary hydropower when there is no water to generate it.

* It requires investment in two power transmission systems, one for transmitting secondary hydropower and the other for substituting thermal power.

* It makes the operation and maintenance of dual generation and transmission systems more complex, less reliable and more expensive.

The development of secondary hydropower is only beneficial if its advantages outweigh the disadvantages. The planners should look into this matter and propose realistic criteria for optimizing the secondary power of a hydropower project. They should also recommend an optimum ratio between the dependable and secondary hydropower for ensuring reliability and stability of the power system. 3. Transmission system: Our grid is designed to transmit hydropower from Tarbela and Mangla hydropower stations when reservoirs’ levels and irrigation demand are the highest and thermal power from large power stations in the south when reservoirs’ levels and irrigation demand are the lowest. There are four 500 kilovolt (KV) and twelve 220 KV transmission circuits linking Tarbela and Mangla hydropower stations (of 4,800 MW maximum capacity) to the grid. These circuits can transmit up to 8,000 MW power, however, most of the time, particularly when water level in the reservoirs and irrigation demand are very low, these circuits operate at a fraction of their capacity. There is a similar transmission system, three 500 KV (fourth is under construction) and twelve 220 KV circuits, which transmits thermal power (from Guddu, Kot Adu, Lal Pir and Muzaffargarh) to north. The planners should find cost-effective options for full utilization of the capacity of these 500 KV and 220 KV circuits.

Some transmission and transformation bottlenecks can be overcome by opting for the distributed generation as mentioned earlier. Other bottlenecks may require upgrading the grid capacity. However, the planners should consider the use of the latest communications and monitoring systems, if these can help in the optimum utilization of the existing capacity. The planners should also propose less strict design criteria and contingency requirements for transmitting the secondary hydropower, than the dependable power.