Bhai believe me, summarization is not so easy when there is so much information: First thing to know is unit used. Many get confused even in units, though it is not their fault, as that is technical terms. For instance:
When we talk about electricity generating installed capacity, we talk in terms of Watts … i.e. 20,000 MW = 20 GW = 20,000,000,000 Watts. Electricity generating installed capacity is maximum theoretical possible output of electricity at any instance. For Pakistan it is 20,000 MW.
When we talk about production and consumption, we talk in Watt hour or Wh … i.e. 100 billion KWh = 100 Trillion Wh (100 TWh) = 100,000,000,000,000 Wh. [If there is installed capacity of one watt and thus one watt is produced for a year continuously, than it means production is 8760 Wh … because there are 8760 hours in a year]
Pakistan has capacity to produce 20,000 Mega Watts (that is maximum possible output) … and if that amount of electricity is produced at all time than production would be 175.2 billion KWh. Once electricity is produced than it has to get consumed at the same time (electricity are not stored after production for later use). Thus, a country produces according to need (consumptions, line losses plus electricity theft). This need goes up and down according to weather and time of industrial activities, so consumption and production varies every hour. Increasing consumption increases production (limited to possible output from installed capacity). If consumption increases that cannot be satisfied by increasing production, we get load shedding.
Now coming to your questions (according to my best knowledge, understanding and belief):
- How much is peak hour demand?
I do not know, but earlier this year Pakistan was producing around 15000 MW (peak output), still we were having load shedding. It means that peak demand could be much more than 15000 MW. At present, Pakistan peak output is around 10000 MW and thus load shedding has increased. I believe that peak demand could be around 18000 MW.
- How much are we lacking/have-surplus in peak-hour demand?
It is possible that if Pakistan could produce around 18000 MW than peak demand can be satisfied. In theory, that is possible with present capacity of 20000 MW, but in practice there is lot of problems. It is very unlikely that all producing units can produces electricity to their maximum at the same time. In practice there could be number of hindrance in producing electricity equal to installed capacity. Some are technical and some financial. For instance, dams may have large installed capacity but shortage of water in dams could means maximum output could not be produced when required … it is also possible that particular thermal plant (or section of a power-plant) at any particular time might shut down due to fault or maintenance. Sometime, it is uneconomical to switch on production plants as required increase in electricity demands does not justify extra cost. Hence, even if there might be surge in demand at any particular time and that demand is below installed capacity that can be satisfied, still that demand do not get fulfilled, resulting in load shedding.
I think that if Pakistan decides to fulfil all demands regardless of financial constrains and technical problems, then possibly 22000 to 23000 MW capacity may fulfil all demands (at present, though it might increase or decrease in future).
[Note, one hindrance could be no desire to meet ‘peak demand’ by government, as cost of producing that extra electricity to fulfil peak demand can be too high. Extra revenue do not justify cost of fulfilling peak demand … because of theft, corruption in the system, electricity pricing, and line losses … and thus government feels that they could not afford those demands. One should realise that it is economical to produce electricity closer to average demand (regular output) and not fulfil extra demand, reason being, average output cost less and average output is what country needs most of the time. Minimum demand could be slightly less than average demand].
- What about off-peak demand/supply?
I do not know exact figures but I believe that it could be anywhere around 7 MW. Pakistan fulfils this minimum demand all the time (that includes consumption + theft + losses) and that comes to 60 billion KWh of electrical production. Average demand could be 9 MW and I think that this demand is also available to Pakistanis at all times whenever required (9 MW if produced throughout the year, it would be 80 billion KWh of production). … Pakistan produces around 100 billion KWh.