Renewable hot dry rock geothermal energy source and its potential in Pakistan

Geothermal energy source, one of the viable renewable energy sources, has encouraging potential to generate full base-load electricity, which has not been explored so far in Pakistan. Though the country can be benefited by harnessing the hydro-geothermal options of energy generation in areas where sources exist, but most of these sources lie in extreme remote and inaccessible rugged mountainous ranges away from the urban-industrial centers. On the other hand, the present study shows that the HDR geothermal option is one of the most viable renewable sources considering the tectonic setup of Pakistan. Results of the study highlight the HDR geothermal energy prospects at relatively deeper depths than hydro-geothermal resources in water-free condition. The basement tectonic analyses reveal that the HDR prospects could be found even just below the urban-industrial centers of Pakistan where there are no hot springs and/or geysers like southern Indus basin in Sindh province or the Kharan trough in the western Balochistan province. Presence of high earth-skin temperature gradient trends derived from satellite temperature data and the high geothermal gradient anomalous zone derived from scanty data of bottom-hole temperatures of some of the oil and gas exploratory wells, indicates encouraging prospects for HDR energy sources in southern Indus and Thar Desert regions inclusive of Karachi synclinorium area. These high geothermal gradients have been inferred to be the result of the deep-seated southern Indus and the Thar fossil-rift structures. Moreover, the prospects of the HDR geothermal energy sources have also been inferred in the Chagai Arc region and the Kharan-Panjgur tectonic depression in the western part of Pakistan based on the analysis of integrated geophysical data. If HDR prospects are developed, they can offer the sustainable, CO(2)-free and independent of time, of day, of weather or season, and the base-load energy-generation resource. (C) 2009 Elsevier Ltd. All rights reserved.