Last reviewed 4 Nov 2026 · Facts as of 4 Nov 2026 · 3 min read
1. Non-renewable (conventional) sources
| Source | Facts | Environmental cost |
|---|---|---|
| Coal | India's largest energy source; most electricity is still coal-based | CO₂, SO₂, NOₓ, particulates, fly ash, mining damage |
| Petroleum | Transport fuel; India imports most of its crude | CO₂, air pollution, oil spills |
| Natural gas | Cleanest fossil fuel (least CO₂ per unit energy) | Methane leaks |
| Nuclear | Fission of uranium-235; India's three-stage programme aims to use its large thorium reserves | Radioactive waste, accident risk; very low CO₂ |
2. Renewable and alternate sources
| Source | How it works | Merits | Limits |
|---|---|---|---|
| Solar | Photovoltaic cells convert light to electricity; solar thermal collectors heat water or generate steam | Abundant, no emissions, falling cost | Intermittent (night, clouds), land use, storage needed |
| Wind | Turbines convert wind's kinetic energy; power ∝ v³ | Clean, low running cost | Variable wind, noise, bird strikes, suitable sites only |
| Hydropower | Potential energy of stored water drives turbines | Renewable, fast start for peak load | Displacement, submergence, siltation |
| Biomass and biogas | Burning or gasifying biomass; anaerobic digestion of dung and waste gives biogas (~55–70% methane) | Uses waste, rural energy, slurry is manure | Land and water for energy crops, smoke if burnt openly |
| Geothermal | Heat from the Earth's interior | Constant supply | Few suitable sites (Puga valley, Ladakh; Manikaran) |
| Tidal | Height difference of tides drives turbines | Predictable | Few sites (Gulf of Kutch, Gulf of Khambhat, Sundarbans), high cost |
| Wave | Motion of ocean waves | Large potential | Technology still developing |
| Ocean thermal (OTEC) | Temperature difference between warm surface and cold deep water (needs ~20 °C) | Continuous | Expensive; pilot plants |
| Hydrogen and fuel cells | Hydrogen reacts with oxygen to give electricity and water; green hydrogen is made by electrolysis using renewable power | Zero emissions at use | Costly production, storage and transport |
FormulaWind power
Doubling wind speed gives 8 times the power. The theoretical maximum is 0.593 (Betz limit).