The Puga hot spring area, located at the junction of the Indian and Tibetan plates along the Indus Suture Zone, has the greatest potential for the near term development of geothermal energy in the Indian subcontinent. The area exhibits vigorous geothermal activity in the form of hot springs, mud pools, sulphur and borax deposits covering an area of c.15 km2. The discharges are concentrated in an east-west elongated area of some 4 km2, near the mouth of the Puga Valley. The Puga geothermal field is bounded by faults and its reservoir rocks consist of granite, gneiss and schist. There is both direct and indirect evidence to support the existence of an active magmatic system at a depth of 5-7 km. Geophysical surveys have delineated a conspicuous low resistivity zone below the Puga field. Systematic and comprehensive evaluation of the geothermal potential of the Puga area began in 1973. Thirty-four wells have been drilled in the Puga geothermal field to date, at least 17 of which have resulted in mixed steam and water blow-outs. The discharges from some of the wells have temperatures of more than 120 掳C. Thermal studies indicate temperatures of more than 220 掳C at a depth of about 2.5 km below the Puga Valley, corresponding to the main reservoir level. Chemical thermometry also suggests a reservoir temperature of 250 掳C, while reservoir modelling studies suggest temperatures of up to 160 掳C at a depth of 450 m. The high concentration of lithium, rubidium and cesium in the geothermal water has been interpreted as indicating a magmatic source and young granitic intrusions and shallow crustal melting processes have been postulated as the most-likely heat source for the Puga geothermal field.
It is estimated that more than 5000 MWh of geothermal energy is available at Puga, which could be used for heating, for greenhouse cultivation and, eventually, to generate electricity. Studies have indicated that there is a 90% probability that the Puga field could sustain a 20 MWe power plant. If the Puga geothermal field could be developed, it is very likely that it could be followed by the development of the Chamuthang and Panamik fields. Jammu & Kashmir State suffers from an acute shortage of power, particularly in the mountainous region of Ladakh. The development of geothermal potential would provide for baseload needs, especially in the winter months when the region's hydro-power stations are frequently either shut down or working at significantly reduced efficiency because of freezing of the Indus River. However, any development would need to be undertaken with great care to avoid damaging Ladakh's vulnerable high-altitude desert environment and its unique plant and animal life.