Geothermal energy
Topic: Energy Resources of India: Conventional and Non-conventional · NCERT: Class 10, Ch 5 "Minerals and Energy Resources"; Class 12, Ch 5 "Mineral and Energy Resources"
Meaning
Geothermal energy is heat from inside the earth. It can be used where the ground gets hot quickly as you go deeper. This is called a high geothermal gradient. Groundwater soaks up heat from hot rocks and rises to the surface as hot water or steam. The steam can turn turbines to make electricity, or the heat can be used directly. It is renewable and clean, but only a few places have enough heat close to the surface. Its first successful use was at Boise, Idaho (USA), in 1890.
Example
India's experimental geothermal project is at Manikaran in the Parvati valley, Himachal Pradesh. ONGC has been drilling in Puga valley, Ladakh. Tattapani in Chhattisgarh is another hot-spring site. India has several hundred hot springs, and a geothermal policy was notified in 2025 (verify current).
Don't confuse with
- Ocean thermal energy conversion: also uses heat, but it comes from the sun-warmed surface of the sea. Geothermal heat comes from inside the earth.