Geothermal energy is the heat energy stored inside the Earth. It comes mainly from the Earth's internal heat and radioactive decay of minerals. This heat can be used to produce electricity and for direct heating.
How geothermal energy works
EARTH'S SURFACE│ Production well ↓ ┌─────────────────┐ │ Hot water / │ │ steam reservoir│ └────────┬────────┘ ↓ Steam / hot fluid ↓ TURBINE ↓ GENERATOR ↓ ELECTRICITY │ ↓ Reinjection well ↓ Geothermal reservoir
Working
- Heat from inside the Earth heats underground water.
- Hot water or steam is brought to the surface through production wells.
- The steam—or heat transferred to another working fluid—drives a turbine.
- The turbine rotates a generator, producing electricity.
- The cooled geothermal fluid can be returned underground through a reinjection well.
Types of geothermal power plants
- Dry steam plant: Natural steam from the geothermal reservoir directly drives the turbine.
- Flash steam plant: High-pressure hot water reaches the surface and partially "flashes" into steam, which drives the turbine.
- Binary cycle plant: Geothermal water heats a separate fluid with a lower boiling point. The vaporized secondary fluid drives the turbine.
Advantages
- 🌱 Renewable source of energy.
- ⚡ Can provide continuous, reliable power.
- 🌍 Generally has low greenhouse-gas emissions compared with fossil fuels.
- ☀️ Not dependent on sunlight like solar energy.
- 💨 Not dependent on wind like wind power.
- 🏭 Can also be used directly for space heating, greenhouses, bathing and industrial processes.
- Requires relatively little land at the surface.
Disadvantages
- 💰 High initial cost, particularly for exploration and drilling.
- 📍 Suitable geothermal resources are geographically limited.
- 🪨 Drilling can be technically difficult and expensive.
- ⚗️ Geothermal fluids may contain minerals and gases that cause scaling and corrosion.
- 🌎 Poorly managed projects can cause environmental impacts or induced seismicity.
- ❄️ Developing geothermal projects in remote/high-altitude locations can be particularly challenging.
Geothermal energy in India
India has several areas with geothermal potential, including:
- Puga Valley, Ladakh
- Chumathang, Ladakh
- Tattapani, Chhattisgarh
- Cambay Basin, Gujarat
- Manikaran, Himachal Pradesh
- Bakreshwar, West Bengal
The Puga Geothermal Project in Ladakh is one of India's most important geothermal-development efforts.