India’s geothermal provinces are closely aligned with major structural anomalies, deep-seated faults, rifts, and areas of recent volcanism. Unlike countries situated on active plate boundaries (such as Iceland or Indonesia), India’s geothermal resources are primarily non-volcanic, liquid-dominated hydrothermal systems hosted within intracratonic rifts and grabens. The Geological Survey of India (GSI) has mapped over 340 hot springs across the country, grouping them into seven distinct geothermal provinces.
The Himalayan Geothermal Province
This province is a result of the ongoing continental collision between the Indian and Eurasian plates. The intense crustal shortening and structural deformation have created deep-seated thrust faults (such as the Main Central Thrust) that act as conduits for deeply circulating meteoric water. High heat flow (>100 mW/m2) and thermal gradients exceeding 60°C/km characterize this zone.
The SONATA (Sone-Narmada-Tapti) Lineament
This major intracratonic mega-shear zone cuts across central India from Gujarat to West Bengal. It represents a zone of crustal thinning and deep mantle upwelling, providing high geothermal gradients. The thermal waters are regulated by deep faults trending parallel to the Narmada and Tapti river rifts.
The Godavari and Mahanadi Graben Systems
These are Paleozoic-Mesozoic Gondwana sedimentary rifts. Deep circulation of groundwater through permeable sandstone aquifers, coupled with the radioactive decay of elements in basement granites, generates significant low-to-medium temperature geothermal reservoirs.
The Seven Geothermal Provinces of India
| Geothermal Province | Key Tectonic / Geological Feature | Major Hot Springs & Sites | Surface Temp Range (∘C) |
| Himalaya | Collisional plate boundary, active tectonics, deep thrust faults. | Puga, Chumathang (Ladakh); Manikaran (HP); Tapovan (Uttarakhand). | 50°C to 95°C (boiling point at altitude) |
| SoNaTa | Intracratonic shear zone, crustal thinning, mantle upwelling. | Tattapani (Chhattisgarh); Unai, Tuwa (Gujarat); Anhoni (MP). | 60°C to 90°C |
| West Coast | Deccan Trap volcanism, structural rifting of western continental margin. | Vajreshwari, Unhavre, Khed (Maharashtra). | 45°C to 72°C |
| Cambay | Tertiary graben, thick sedimentary basin, high thermal gradient. | Tuwa, Lasundra (Gujarat). | 40°C to 55°C |
| Godavari | Gondwana rift valley, deep fracture-led circulation. | Bhadrachalam, Manuguru (Telangana). | 35°C to 60°C |
| Mahanadi | Gondwana graben, crustal fractures in crystalline basement. | Tarabalo, Atri (Odisha). | 40°C to 65°C |
| Bakreswar-Surajkund | Proterozoic mobile belt, radiogenic granitic basements. | Bakreswar (West Bengal); Surajkund (Jharkhand). | 65°C to 88°C |
Key Geothermal Exploration Sites and Projects
Puga Valley (Ladakh)
Located in the Himalayan province at an altitude of over 4,400 meters, Puga is considered India’s most promising geothermal field. High-pressure steam and hot water emerge close to the surface. It exhibits a high heat flow of several hundred mW/m2. Oil and Natural Gas Corporation (ONGC) is executing India’s first utility-scale Geothermal Field Development Project here, aiming to drill deep wells to tap high-temperature reservoirs for electricity generation and local space heating.
Tattapani (Chhattisgarh)
Situated within the SONATA lineament in the Balrampur district, Tattapani hosts a massive network of hot springs. The thermal water is rich in silica and sulfur. NTPC (National Thermal Power Corporation) has undertaken exploratory work here to establish a binary-cycle geothermal power plant, exploiting reservoir temperatures that reach up to 110°C at shallow depths.
Manikaran (Himachal Pradesh)
Located on the banks of the Parvati River, this site features highly active hydrothermal activity with surface temperatures reaching the boiling point of water at that altitude (95°C). While primarily utilized for religious tourism and direct heating applications (such as community kitchens), it has been extensively studied by the GSI for its micro-pilot power generation potential.
Application Typologies: Direct vs. Indirect Use
India’s geothermal resources are predominantly low-to-medium enthalpy (100°C to 150°C), making them highly suitable for a mix of direct and indirect applications.
Indirect Use: Binary Cycle Power Generation
Because reservoir temperatures in India rarely exceed 200°C (required for conventional dry-steam plants), Binary Cycle Power Plants are the standard technological choice. In this system, moderately hot geothermal water passes through a heat exchanger to vaporize a secondary working fluid with a much lower boiling point (such as iso-butane or iso-pentane). The expanding vapor drives a turbine to generate electricity before being condensed and recycled.
Direct Thermal Utilization
Direct use circumvents the efficiency losses of converting heat to electricity. Prominent geographical and industrial applications in India include:
- Space Heating and Greenhouse Cultivation: Crucial for cold, high-altitude regions like Ladakh to maintain agricultural output during sub-zero winters.
- Cold Storage Infrastructure: Utilizing geothermal absorption chillers to preserve perishable horticultural crops in remote areas.
- Industrial Processing: Providing process heat for textile dyeing, milk pasteurization, and timber drying in central and western India.
- Balneology and Tourism: Extracting mineral-rich thermal waters for wellness tourism and therapeutic hot-water spas.
Technical, Spatial, and Economic Challenges
Location-Demand Asymmetry
The highest-potential geothermal fields (like Puga in Ladakh or Tapovan in Uttarakhand) are located in remote, rugged, high-altitude terrains. These areas feature fragile mountain ecosystems, lack high-voltage grid transmission infrastructure, and are far from major industrial load centers.
High Exploratory Risk and Capital Expenditure
Geothermal exploration requires high upfront capital for deep exploratory drilling (1 to 3 km) without an absolute guarantee of finding a commercially viable reservoir flow rate. The gestation period is significantly longer compared to solar or wind projects.
Corrosion and Scaling Issues
Thermal fluids in Indian provinces, especially along the Himalayan belt and SoNaTa, carry high concentrations of dissolved solids, silica, boron, and corrosive gases like Hydrogen Sulfide (H2S) and Carbon Dioxide (CO2). This causes heavy chemical scaling and corrosion inside turbine components, piping, and reinjection wells.
Key Facts and Trivia for UPSC Prelims
- First Geothermal Plant: India’s first operational commercial-scale geothermal power plant is being developed by ONGC at Puga Valley, Ladakh, designed to provide clean power to remote border regions.
- Highest Surface Temperature: The hot springs at Surajkund in Jharkhand and Manikaran in Himachal Pradesh record some of the highest surface water temperatures in India, hovering near the local boiling point (88°C – 95°C).
- Radiogenic Heat Source: The geothermal anomaly at Bakreswar (West Bengal) and Surajkund (Jharkhand) is driven by high levels of radioactive decay of Thorium and Uranium isotopes embedded within the underlying ancient granitic rocks.
- Helium Extraction: The Ministry of Science and Technology has conducted pilot experiments at Bakreswar Hot Springs to extract Helium gas from geothermal emissions. Helium is a critical element for cryogenic and strategic defense applications, and India currently relies almost entirely on imports.
- Nodal Agency: The Ministry of New and Renewable Energy (MNRE) handles policy formulation for geothermal energy, while the Geothermal Energy Development Cell within the Geological Survey of India (GSI) remains the premier body for resource mapping and exploratory drilling database management.