India has been building up its renewable power. Installed capacity is now at 275 gigawatts (GW), which more than doubles the 136 GW of 2020 and brings the country closer to its target of 500 GW by 2030.
Yet there has been a key absence in the operational power mix: geothermal energy.
As India pushes toward its 2070 net-zero commitment, and seeks reliable round-the-clock renewable sources to support intermittent solar and wind, geothermal is beginning to move from the margins into national energy planning, with a policy on generation published last year. As of 2024, the country has an estimated potential capacity of 10.6 GW drawn from 381 hot springs.
Geothermal energy harnesses the Earth’s internal heat, and is capable of delivering uninterrupted electricity, direct heating and storage. In 2023, existing projects worldwide had an average utilisation rate exceeding 75%, far surpassing wind and solar projects.
Home to numerous unexplored hot springs, the north-eastern state of Arunachal Pradesh in the Eastern Himalayas is especially promising. The state is estimated to contribute around 2 GW to the national potential, says Tana Tage, director of the Centre for Earth Sciences and Himalayan Studies (CESHS), an autonomous organisation within the Arunachal Pradesh state government’s Department of Science and Technology.
In May 2025, CESHS drilled north-east India’s first geothermal production well in Dirang, West Kameng district, for direct-use applications such as space heating and drying facilities for fruits and meat. It is also eyeing a new project in Tawang district, which based on current assessments could generate an estimated 0.25-1 megawatt (MW) of electricity, according to Tage.
For the Tawang project, a focus on homegrown technology offers potential breakthroughs for India’s geothermal power sector. But while the region has much untapped potential, several factors pose challenges to these ambitions.
Geographical advantages
Geothermal resources are reservoirs of steam, hot water or hot rocks located beneath the Earth’s surface. To access this heat, wells are drilled, ranging from a few hundred feet to several kilometres deep. The depth, location and temperature of these wells determine whether a geothermal project is technically and economically viable.
Due to its location near the Main Central Thrust, a major geological fault, Arunachal Pradesh is especially conducive for geothermal projects, explains Rupankar Rajkhowa, head of green energy studies at CESHS.
The ongoing collision of the Indian and Eurasian plates causes faults and fractures, creating pathways for fluid to circulate deep into Earth where it is heated and rises back up. This leads to geothermal activity.
While Arunachal Pradesh’s location makes it prime for geothermal, it also poses certain complications.
The state lies in seismic zone five in India’s earthquake mapping, indicating the highest risk of earthquakes. In such regions, “drilling through hard rock carries the risk of induced seismic activity”, says Tage. To mitigate this, he explains that detailed structural mapping of the region has been undertaken, to be followed by geophysical surveys and 3D modelling to map underground conductivity and enable more accurate and safer drilling.
Other potential risks include geothermal fluid leaks as seen at Ladakh’s Puga Valley project, where warm water from underground containing various dissolved minerals flowed into a nearby stream. To avoid this, CESHS has partnered with Oil India Limited to oversee drilling and install blowout preventers – safety devices to prevent dangerous, uncontrolled eruptions during drilling.
Many geothermal-rich areas in Arunachal Pradesh are logistically isolated, making it difficult to transport heavy drilling rigs and specialised equipment, Tage notes. This slows project timelines and raises initial capital costs. However, he adds that the long-term economics are favourable, with geothermal generation costing nearly 50% less than solar energy.
Homegrown technology
The most ambitious aspect of the Tawang project is the development of homegrown technology capable of generating electricity from a lower-than-usual temperature for a binary geothermal power plant. This type of plant uses heat from geothermal water to vaporise a “working” fluid that has a lower boiling point, using that vapour to power the turbine that generates electricity. The technology being developed can operate from 68C, compared to binary power plants’ conventional requirement of above 100C. The ability of the technology to operate efficiently at lower temperatures enables access to geothermal resources in the Eastern Himalayas, where underground heat is limited.
Rajkhowa explains that the project’s long-term success is dependent on a secure, sustainable Organic Rankine Cycle (ORC) fluid supply, the cycle referring to the closed-loop system where the water vaporises the ORC fluid. Such fluids can vaporise at much lower temperatures, compared to the water or steam used in conventional geothermal plants, making them especially suited for Himalayan conditions.
Indigenous technology ensures cost-effectiveness, repairability and self-relianceRupankar Rajkhowa, head of green energy studies, CESHS
Unlike geothermal fields driven by volcanic activity, Himalayan geothermal systems are driven by tectonic forces, with heat coming from the pressure and movement of rocks deep in the Earth’s crust, rather than from magma. Rainwater and snowmelt seep through faults and fractures, get heated and rise back up as thermal sources.
The Himalayan region’s tectonic forces and faults mean the environment is more sensitive, and geothermal exploration in the area requires additional studies like remote sensing, geophysical surveys and chemical and structural analysis. But the imported instruments currently used to carry out these activities are expensive, large and not optimised for Himalayan logistics and maintenance in high-altitude terrain lacking paved roads. “Indigenous technology ensures cost-effectiveness, repairability and self-reliance,” Rajkhowa noted.
The technology was developed by CESHS alongside Delhi’s Shriram Institute of Industrial Technology (SIIR), which also helped develop India’s first operational geothermal power pilot project in Manuguru, Telangana. It was designed and tested in India, used in the Manuguru plant, and is now progressing toward a 0.25-MW demonstration unit in Arunachal Pradesh.
Other homegrown engineering innovations have been incorporated by SIIR researchers to adapt the system for the area’s low temperatures. These include integrating technology to reuse thermal energy, and adding a pre-heater to raise the initial temperature of the working fluid, enhancing system efficiency.
Rajkhowa added that SIIR and Pandit Deendayal Energy University in Gujarat have been conducting research to develop ORC fluids suitable for the low temperatures of the Himalayan geothermal projects.
If these are successful, they could be a game changer for India’s geothermal industry.
”India still lacks the expertise to establish large commercial geothermal plants,” said Dornadula Chandrasekharam, a former professor in the Department of Earth Sciences at IIT-Bombay and an ex-board member of the International Geothermal Association.
The drilling rigs currently available in India are suited for oil wells rather than deep geothermal reservoirs in the granite formations commonly found in the Himalayan region, he noted. “Developing ORC fluids and mastering granite drilling technology will be critical if India wants to leapfrog in this sector.”
Navigating cultural and spiritual dimensions
Beyond scientific challenges, geothermal development in Arunachal Pradesh must consider the cultural and spiritual significance of hot springs, which are sacred, historically revered and central to healing and purification rituals for Tibetan Buddhists – many of whom live in the same areas eyed for geothermal projects, such as Dirang and Tawang.
”The most efficient drilling site is often at the mouth of the spring, but local communities have built kunds [bathing pools] there,” explains Tage. “Respecting their sentiments, we trace the underground source and drill away from the visible outlet, which requires more effort and resources.”
However, recognising that they may need to drill at spring mouths in the future, CESHS is conducting awareness campaigns on clean energy, explaining geothermal power, its safety and potential community benefits, says Tage.
“The hot spring [being drilled] is on my private land, but people from nearby villages have been using it for generations, believing its waters ease body pain and improve skin health. We even drink from it,” says Karma Tsering, a resident of Dirang.
“When we were first told about the project, it sounded like a promising opportunity for the community, so I agreed. After the initial drilling, further work [and] related discussions are yet to take place, but I’m happy to cooperate,” Tsering adds.
Geopolitics adds another layer of complexity. Some of the geothermal sites in Tawang lie close to the Indo-China border, and special clearance is required from the Ministry of External Affairs for these projects, Tage adds. The border has been the subject of a long-standing bilateral dispute.
A national policy for geothermal energy
According to Tage, limited knowledge sharing and research silos hamper progress. Restricted access to, and the often scattered locations where existing geological and hydrological data are stored means teams must often start from scratch on surveys and baseline mapping. The lack of baseline data also makes it difficult to conduct comparative studies to assess temporal changes.
“Compared to the Western Himalayas, where geothermal systems have been studied extensively, the Eastern Himalayas remains poorly understood,” Tage says, noting that extensive exploration of the region has been delayed due to its geological complexity, accessibility challenges and strategic constraints.
“Most existing research here relies heavily on spatial data, remote sensing and modelling, with limited fieldwork,” he notes. “India must invest in dedicated institutions focused on the Himalayan geology of the north-east, including geothermal, seismic, hydrological and ecological complexities.”
India’s National Policy on Geothermal Energy, published by the Ministry of New and Renewable Energy in September 2025, envisages the creation of a comprehensive geothermal resource data repository built through inter-agency and international collaboration.
It will consolidate datasets from government bodies, research institutes, and the oil and gas sector, including technical expertise, and equipment and well data. Eligible geothermal operators can access the repository if they commit to submitting data acquired from their surveys, ensuring coordinated research, resource evaluation and development planning.
Tage says the policy will boost the centre’s work, noting that it “facilitates access to dedicated financial schemes for exploration and pilot plants, streamlines approvals with state, defence and forest authorities critical in border districts like Tawang, and opens opportunities for public-private partnerships and foreign technology transfer”. The policy text noted that the government may look into the possibility of preferential tariffs and viability gap funding, which Tage says reduces regulatory uncertainty, accelerating the path from exploration to pilot demonstration.
However, Chandrasekharam countered that the policy is too general and vague. “Without greater clarity and specificity, especially on tariffs, it is unlikely to attract serious investment from international geothermal companies into India’s programme.”
He adds: “Just as India’s space programme began with international collaborations and gaining access to proven technology and expertise, we should approach geothermal development similarly and gradually build homegrown solutions to make the sector self-reliant.”
