Geothermal resources of India: A country update from surface manifestation to subsurface heat flow

India’s energy demand is increasing rapidly due to its urbanization and economic growth, which necessitates a multi-source energy adaptation, as outlined in the first rule of India’s energy governance. At the same time, India has set a target to achieve net-zero emissions by 2070, which has already led to a shift in policy toward renewable energy resources. The recent launch of the National Policy on Geothermal Energy has transitioned India's nascent geothermal market from an exploratory stage to a structured framework ready for tapping its estimated potential. Despite a long-standing exploratory study of Indian geothermal resources, there is less agreement on the definitive estimate of the current reported potential that requires further research. The current study provides an up-to-date assessment of the country's geothermal surface manifestations and subsurface heat flow. The latest data from the Geological Survey of India reports 381 surface manifestations, including hot springs and geysers. The spatial distribution of these surface features has been mapped within 10 geothermal provinces of India to provide the latest map of India’s geothermal provinces. We have generated the latest Heat-Flow map of peninsular India with the latest borehole data available from the International Heat Flow Commission. The results of this study reveal that most surface geothermal manifestations in India are located along the tectonically active zones. Most of the elevated heat flow regions also follow the same pattern. In addition to tectonically active zones with deep extended faults (i.e., Himalayan Province), radiogenic heat sources (i.e., Ladakh Batholits), hot sedimentary basins (i.e., Cambay and Assam basins), and shallow magma chambers (i.e., Andaman Island) are the major sources of India’s geothermal resources. This study further suggests an exploratory investigation into the enhanced geothermal system, which is expected to be more promising, with an approximate potential of 14 terawatt-hours of electricity.