Natural and energy resources
Renewable sources (solar, wind, hydro, biomass, geothermal) are replenished naturally; fossil fuels and uranium are finite. Soil and forests stay renewable only within their regeneration limits.
Energy sources at a glance
| Source | How it works | Indian note |
|---|---|---|
| Solar | Photovoltaic cells turn light into electricity; solar thermal uses the heat | National Solar Mission (2010), part of NAPCC |
| Wind | Turbines turn moving air into electricity | Tamil Nadu and Gujarat lead in capacity |
| Hydro | Falling water turns turbines | Small hydro means projects up to 25 MW |
| Geothermal | Heat from inside the Earth | Puga Valley (Ladakh), Manikaran (Himachal Pradesh) |
| Biomass | Burning or digesting crop residue, dung or wood | Biogas plants give fuel (methane) and manure |
| Nuclear | Fission of uranium-235 releases heat | Three-stage programme to use India's thorium |
| Tidal | Rise and fall of the tides | Potential in the Gulfs of Khambhat and Kutch |
Renewable and non-renewable
Nuclear power is low-carbon but not renewable: uranium and thorium are finite minerals.
India's three-stage nuclear power programme
Planned by Homi J. Bhabha to tap India's large thorium reserves in monazite sands.
Soil and forests as resources
- Soil forms very slowly, so erosion by water and wind is effectively a permanent loss.
- Soil conservation: contour ploughing, terracing, strip cropping, shelter belts, mulching, cover crops.
- Forests give timber, fuel, fodder and medicines; they protect watersheds, store carbon and shelter biodiversity.
- The National Forest Policy 1988 aims at one-third of India's area under forest or tree cover.
- The Forest Survey of India reports forest cover every two years (India State of Forest Report).
How NET asks this: classify sources as renewable or non-renewable, match a source with its Indian site or mission, or test the three stages of India's nuclear programme.
Typical MCQ: “Is nuclear energy renewable?” No. It is low-carbon, but uranium and thorium are finite minerals.
Typical MCQ: “What is the main fuel gas in biogas?” Methane, produced when dung and plant waste are digested without oxygen.
India's nuclear ladder: uranium → plutonium → thorium, climbing towards its large thorium reserves.