In India nearly 400 thermal springs occur (Satellites
like the IRS-1 have played an important role, through
infrared photographs of the ground, in locating
geothermal areas. The Puga valley in the Ladakh
region has the most promising geothermal field.),
distributed in seven geothermal provinces. These
provinces include The Himalayas: Sohana: West coast;
Cambay: Son-Narmada-Tapi (SONATA): Godavari
and Mahanadi.
These springs are perennial and their surface
temperature range from 37 to 90o
C with a cumulative surface discharge of over
1000 l/m. The provinces are associated with
major rifts or subduction tectonics and registered
high heat flow and high geothermal gradient.
For example the heat flow values and thermal gradients
of these provinces are 468 mW/m2;
234o C/km (Himalayas); 93 mW/m2;
70o C/km (Cambay); 120 - 260 mW/m2;
60-90o C/km (SONATA); 129 mW/m2;
59o C/km (west coast); 104 mW/m2;
60o C/km (Godavari) and 200 mW/m2;
90o C/km (Bakreswar, Bihar).
The reservoir temperature estimated using the above
described geothermometers are 120o C
(west coast), 150o C (Tattapani) and
200o C (Cambay). The depth of the reservoir
in these provinces is at a depth of about 1 to 2
km (Chandrasekharam, 2000; Minissale et al., 2000).
These geothermal systems are liquid dominated and
steam dominated systems prevail only in Himalayan
and Tattapani geothermal provinces. The issuing
temperature of water at Tattapani is 90o
C; at Puga (Himalaya) is 98o C and at
Tuwa (Gujarat) is 98o C. The power generating
capacity of these thermal springs is about 10,000
MW (Ravi Shanker, 1996).
These are medium enthalpy resources, which can be
utilized effectively to generate power using binary
cycle method.
Since majority of these springs are located in
rural India, these springs can support small scale
industries in such areas. Dehydrated vegetables
and fruits have a potential export market and India
being an agricultural country, this industry is
best suited for India conditions.
Map of India showing the geothermal provinces,
heat flow values (mW/m2: in italics) and geothermal
gradients (oC/km). I: Himalaya; II: Sohana; III:
Cambay; IV: SONATA; V: West coast; VI: Godavari;
VII: Mahanadi. M: Mehmadabad; B: Billimora.
All the geothermal provinces of India are located
in areas with high heat flow and geothermal gradients.
The heat flow and thermal gradient values vary from
75–468 mW/m2 and 59–234°C respectively. Deep Seismic
Sounding (DSS) profiles were carried out across
several geothermal provinces (Son-Narmada-Tapi;
West coast and Cambay ) to understand the crustal
structure.
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