The share of hydel generation in the overall system during the year ending June 30, 2012 registered 31 percent, while the rest of 69 per cent electricity was generated mainly through gas, residual furnace oil (RFO) and high sulpher diesel (HSD)-based thermal power plants, said a press release.

How instrumental had been the hydel share in lowering the electricity tariff for the end consumers during 2011-12 can be assessed from the fact that the average purchase rate of the Central Power Purchasing Agency (CPPA) for hydel electricity was merely Rs.1.41 per unit, if compared it with the average purchase rate of Rs.5 to 8 per unit for gas-based, Rs.13 to 18 per unit for RFO-based and Rs.18 to 22 per unit for HSD-based electricity during the corresponding period.

Had this hydel share not been there, the average basket rate (consumers' rate) would have been about Rs.13.50 per unit instead of Rs.9.50 per unit, it added.

The total installed capacity of the WAPDA hydel power stations stands at 6516 mega watt (MW). Most importantly, this installed capacity, unlike thermal power plants, is not deteriorated by a single MW because of the efficient maintenance of the hydel power stations. On availability of the required water, as much as 6516 MW electricity can be produced through hydel power stations.

According to the details of hydel electricity generated during fiscal year 2011-12, the 3478 MW-Tarbela Power Station contributed 14,057 million units, the 1410-MW Ghazi Barotha 6,979 million units, the 1000 MW-Mangla 4,666 million units, the 243 MW-Warsak 991 million units, the 184-MW Chashma 1,067 million units, the 72 MW-Khan Khwar 176 million units, and other small hydel power stations produced 270 million units of low-cost and environment-friendly electricity.

In order to increase the share of hydel electricity in the National Grid, and to stabilise the power tariff, WAPDA is implementing a number of large projects in water and hydropower sectors. On completion, these projects will help generate about 20,000 MW of electricity and store around 12 million acre feet of water.