1. Coal
- Types (by carbon content): anthracite (highest; small deposits in Jammu and Kashmir) > bituminous (most used; coking coal for steel) > lignite (brown, moist) > peat (lowest, smoky).
- Gondwana coal (over 200 million years old, most of India’s coal): Damodar valley — Jharia, Bokaro, Giridih (Jharkhand), Raniganj (West Bengal); Mahanadi valley — Talcher (Odisha), Korba (Chhattisgarh); Son valley — Singrauli; Godavari valley — Singareni (Telangana).
- Tertiary coal (younger, high sulphur): Makum (Assam), Meghalaya, Arunachal Pradesh. Lignite: Neyveli (Tamil Nadu), Panandhro (Gujarat), Palana (Rajasthan).
- Advantages: large home reserves; steady power in all seasons; coking coal for steel; by-products (coal tar, gas).
- Disadvantages: non-renewable; carbon dioxide, sulphur dioxide and fly ash; high ash content of Indian coal; mining damages land and forests; bulky to transport.
| Valley | Coalfields |
|---|---|
| Damodar | Jharia, Bokaro, Raniganj |
| Mahanadi | Talcher, Korba |
| Godavari | Singareni |
Key terms
- Coking coal
Bituminous coal that can be heated to make coke for smelting iron ore.
- Gondwana coal
The older coal of the peninsular river valleys that supplies most of India’s coal.
2. Petroleum and natural gas
| Region | Type | Fields |
|---|---|---|
| Assam | Onshore | Digboi, Naharkatiya, Moran |
| Gujarat (Cambay basin) | Onshore | Ankleshwar, Kalol, Lunej, Mehsana |
| Rajasthan | Onshore | Mangala (Barmer) |
| Arabian Sea | Offshore | Mumbai High, Bassein (gas) |
| East coast | Offshore and onshore | Krishna–Godavari basin |
- Petroleum occurs in sedimentary rocks, trapped in folds and faults; India imports most of its crude oil (as of the early 2020s).
- Natural gas is cleaner than coal: burns almost completely, almost no ash or soot, little sulphur dioxide, less carbon dioxide per unit of heat. Carried by pipelines (HVJ). Uses: power, fertiliser (urea), petrochemicals, piped cooking gas, CNG.
| Fuel | Ash | Sulphur dioxide |
|---|---|---|
| Coal | High | Often high |
| Natural gas | Almost none | Very low |
Key terms
- Offshore oil field
An oil field under the sea floor, usually on the continental shelf, such as Mumbai High.
- CNG
Compressed natural gas, a cleaner fuel used by buses and autos in many cities.
3. Hydel power
- How: water stored behind a dam falls through a penstock and turns turbines linked to generators.
- Needs: perennial river, large head (height of fall), narrow valley with strong rock, demand nearby.
- Bhakra Nangal: river Sutlej; Bhakra dam in Himachal Pradesh (Gobind Sagar reservoir), Nangal dam in Punjab. Irrigation for Punjab, Haryana, Rajasthan; power; flood control.
- Hirakud: river Mahanadi, near Sambalpur, Odisha; one of the longest earthen dams. Flood control in the Mahanadi delta; irrigation; power.
- Advantages over thermal: renewable; no smoke or ash; low running cost; multipurpose (irrigation, flood control, fishing, tourism).
- Disadvantages: high construction cost; displacement of people; submerged forests; less power in drought; silting.
| Project | River | State |
|---|---|---|
| Bhakra Nangal | Sutlej | Himachal Pradesh, Punjab |
| Hirakud | Mahanadi | Odisha |
Key terms
- Multipurpose project
A river valley project that serves several aims at once, such as irrigation, power and flood control.
- Head
The height through which water falls from the reservoir surface to the turbine.
4. Solar, wind and tidal energy
| Source | Important areas | Advantage | Disadvantage |
|---|---|---|---|
| Solar | Bhadla (Rajasthan), Charanka (Gujarat), Pavagada (Karnataka) | No fuel, no smoke | No output at night; land |
| Wind | Muppandal (Tamil Nadu), Kutch coast (Gujarat), Jaisalmer, Satara | Clean, cheap to run | Varies with wind; noise |
| Tidal | Gulfs of Khambhat and Kutch, Sundarbans | Predictable | Very costly; few sites; harms mangroves |
Tidal power needs a large tidal range in a narrow, funnel-shaped inlet.
| Source | Leading area |
|---|---|
| Solar | Western Rajasthan |
| Wind | Tamil Nadu |
| Tidal | Gulf of Khambhat |
Key terms
- Photovoltaic cell
A device that changes sunlight directly into electricity.
- Tidal range
The difference in sea level between high tide and low tide.
5. Geothermal, nuclear and biogas
- Geothermal: heat from inside the Earth, seen as hot springs — Puga valley (Ladakh), Manikaran (Himachal Pradesh). Clean and steady but few, remote sites.
- Nuclear: uranium from Jaduguda (Jharkhand); thorium from monazite sands of Kerala. Stations: Tarapur (Maharashtra), Rawatbhata (Rajasthan), Kalpakkam and Kudankulam (Tamil Nadu), Narora (Uttar Pradesh), Kakrapar (Gujarat), Kaiga (Karnataka). Much power from little fuel, no smoke; but radiation risk, radioactive waste, high cost.
- Biogas: dung and water in an airtight digester; bacteria act without air; gas mainly methane; slurry becomes manure. Benefits: smokeless fuel, saves firewood, manure, cleaner villages.
| Station | State |
|---|---|
| Tarapur | Maharashtra |
| Kaiga | Karnataka |
| Kakrapar | Gujarat |
Key terms
- Biogas
A fuel gas, mainly methane, made by bacteria breaking down dung or plant waste without air.
- Geothermal energy
Energy obtained from the natural heat of the Earth’s interior.
6. Comparing sources and reading energy data
- Conventional: coal, petroleum, natural gas, large hydel — long in use, mostly non-renewable (except hydel).
- Non-conventional: solar, wind, tidal, geothermal, nuclear, biogas — newer, mostly renewable and cleaner.
- Share of a source = (its capacity ÷ total capacity) × 100.
- In a capacity table, add all sources for the total first; then compare renewable and non-renewable shares.
| Group | Examples |
|---|---|
| Conventional | Coal, oil, gas, hydel |
| Non-conventional | Solar, wind, tidal, geothermal, nuclear, biogas |
Key terms
- Installed capacity
The maximum electricity that all the power stations of an area can produce, measured in megawatts.
Exam tips
Common mistakes
- Placing Hirakud on the Sutlej or Bhakra on the Mahanadi.
- Calling Mumbai High an onshore field or placing it in the Bay of Bengal.
- Saying biogas is mainly carbon dioxide (it is mainly methane).
- Writing that tidal power suits any coast.
How marks are usually awarded
- Location answers (1 mark each): name the place with its state, river or valley.
- Advantages and disadvantages (1 mark each): one clear, different point each time.
- Process answers (3 marks): biogas or hydel steps in the correct order.
- Data (2–3 marks): total, working and answer with unit.