MIRPUR (AJK) - The Water and Power Development Authority (WAPDA) generated 31.45 billion units of hydel electricity during the fiscal year 2010-11, registering an increase of 3.84 billion units as compared to 2009-10, it was officially declared. This increased hydel generation was made possible due to efficient operation and management of hydropower stations and availability of more water in the reservoirs, Wapda sources told this correspondent on Monday. This additional contribution of low-cost hydel electricity to the national grid saved about Rs41.64 billion of the national exchequer, which otherwise would have been incurred on generating the equivalent quantum of electricity from thermal resources. Quoting the data compiled by the authority, the sources revealed that more than 31.45 billion units of hydel electricity were contributed to the system during the fiscal year 2010-11, while about 27.61 billion units were supplied during the year 2009-10. Tarbela, the largest hydel power station in the country, generated 15.833 billion units during 2010-11 while 13.833 billion units in 2009-10. Similarly, Ghazi Bartoha, the second in line, produced 7.356 billion units against 6.715 billion units, Mangla, the third in row, 5.953 billion units against 4.638 billion units, and Warsak and other small hydel power stations shared 2.308 billion units in 2010-11 against 2.425 billion units during 2009-10. It is pertinent to mention that the installed capacity of hydel power generation in the country stands at about 6,500 megawatt (MW) - about one third of the total installed capacity. The Wapda is executing a least-cost energy generation plan on priority basis with a view to improve the ratio of hydel electricity in the national grid. The Wapda will add 1,500 MW to this capacity through its under construction projects. Besides, the authority is also executing a number of mega hydropower projects with a cumulative capacity of more than 20,000 MW including 4,500-MW Diamer Basha Dam, 1350-MW Tarbela 4th Extension, 7,100-MW Bunji, 4,320-MW Dasu and 740-MW Munda hydropower projects etc, the sources added.