Coal and Petroleum
A foundational look at fossil fuels — how coal, petroleum and natural gas formed over millions of years, the products refined from them, and why these exhaustible resources demand judicious use.
Prelims loves factual recall here: classification of natural resources, coal's products (coke, coal tar, coal gas), petroleum fractions and their uses, the firsts/dates (Pennsylvania 1859, Makum 1867), and India's oil-and-gas geography. For Mains it anchors GS-III themes of energy security, fossil-fuel dependence, conservation, air pollution/global warming and sustainable development. The 'generations sharing a container' activity also seeds the intergenerational-equity argument.
Understand the chapter
Natural Resources: Inexhaustible vs Exhaustible
Nature's resources are classified by availability. Inexhaustible resources exist in effectively unlimited quantity and survive human use; exhaustible resources are finite and can be wiped out. Coal, petroleum and natural gas fall in the exhaustible category, alongside forests, wildlife and minerals. The chapter's classroom activity of three 'generations' eating from one container is a metaphor for intergenerational equity — early users can either deplete a resource or conserve it for those who follow.
- Inexhaustible: present in unlimited quantity (sunlight, air)
- Exhaustible: limited, can be exhausted (forests, wildlife, minerals, coal, petroleum, natural gas)
- Activity = lesson in sustainable, judicious use across generations
Fossil Fuels and the Formation of Coal
Coal, petroleum and natural gas are fossil fuels — formed from the dead remains of organisms over millions of years. Coal arose about 300 million years ago when dense forests in low-lying wetlands were buried, compressed, and subjected to high temperature and pressure. Because coal is mainly carbon, this slow conversion of buried vegetation into coal is called carbonisation. Coal is used in thermal power plants, industries, cooking and (historically) steam railway engines; burning it gives mainly carbon dioxide.
- Coal = hard, black, mainly carbon
- Carbonisation = slow conversion of buried vegetation to coal under heat and pressure
- Uses: thermal power, industry, cooking, historically steam engines
Products of Coal: Coke, Coal Tar, Coal Gas
Industrial processing of coal yields three valuable products. Coke is a tough, porous, almost pure form of carbon used in steel-making and metal extraction. Coal tar is a black, foul-smelling liquid — a mixture of about 200 substances — and the raw material for synthetic dyes, drugs, explosives, perfumes, plastics, paints and even naphthalene balls. Coal gas, obtained while making coke, is burnt as fuel in industries near coal-processing plants.
- Coke → steel manufacture and extraction of metals; almost pure carbon
- Coal tar → mixture of ~200 substances; source of dyes, drugs, naphthalene balls
- Coal gas → industrial fuel; first used for street lighting in London (1810)
- Roads are now metalled with bitumen (a petroleum product), not coal-tar
Petroleum: Formation, Refining and Fractions
Petroleum (petra = rock, oleum = oil) formed from sea organisms that died, settled, and were buried under sand and clay; over millions of years, the absence of air with high temperature and pressure transformed them into petroleum and natural gas. Being lighter than water, oil and gas sit above the water layer in reservoir rock. Crude petroleum is a dark, foul-smelling mixture separated into useful fractions by refining in a refinery; its great commercial value earns it the name 'black gold'.
- Formation needs marine organisms + absence of air + high temperature/pressure
- Refining = separation of petroleum's constituents/fractions in a refinery
- Fractions: LPG, petrol, kerosene, diesel, lubricating oil, paraffin wax, bitumen
- Petrol → light vehicles; diesel → heavy vehicles; petrochemicals give detergents, fibres, plastics, urea
Natural Gas and CNG
Natural gas is a prized fossil fuel because it can be piped easily and burns cleaner than other fuels. Compressed to high pressure as CNG, it is used for power generation and increasingly as a low-pollution transport fuel, and can be piped directly into homes and factories. It is also a feedstock for chemicals and fertilisers, and India holds vast reserves.
- CNG = compressed natural gas; cleaner, less-polluting transport fuel
- Piped supply networks: Vadodara (Gujarat), parts of Delhi
- India's gas: Tripura, Rajasthan, Maharashtra, Krishna-Godavari delta
Limited Reserves and Conservation (PCRA)
Fossil fuels took millions of years to form, yet known reserves may last only a few hundred years, and their combustion is a major cause of air pollution and global warming. They cannot be manufactured in a laboratory because the slow natural conditions cannot be recreated. Hence judicious use is essential — in India the Petroleum Conservation Research Association (PCRA), under the Ministry of Petroleum and Natural Gas, advises motorists on saving fuel.
- Reserves finite (a few hundred years) and cannot be made in a lab
- Burning fossil fuels → air pollution and global warming
- PCRA tips: constant moderate speed, switch off at signals, correct tyre pressure, regular maintenance
Key terms
- Fossil fuel
- Fuel formed from dead remains of organisms over millions of years — coal, petroleum, natural gas.
- Carbonisation
- Slow conversion of buried dead vegetation into carbon-rich coal under heat and pressure.
- Coke
- Tough, porous, almost pure form of carbon used in steel-making and metal extraction.
- Coal tar
- Black, foul-smelling liquid; a mixture of about 200 substances feeding dyes, drugs and plastics.
- Coal gas
- Gaseous fuel obtained during coke production, burnt in industries near coal plants.
- Refining
- Process of separating petroleum into its useful constituent fractions in a refinery.
- Petrochemicals
- Useful substances from petroleum/natural gas — detergents, synthetic fibres, plastics, urea.
- Black gold
- Popular name for petroleum, reflecting its great commercial value.
- CNG
- Natural gas compressed under high pressure; a cleaner, less-polluting, pipe-transportable fuel.
Must-know facts exam-ready
- Coal formed about 300 million years ago; the process is called carbonisation, and coal is mainly carbon.
- Three products of coal: coke (almost pure carbon → steel), coal tar (~200 substances), coal gas.
- Coal tar is a mixture of about 200 substances; naphthalene balls (moth repellent) come from coal tar.
- Coal gas was first used for street lighting in London (1810) and New York (~1820).
- World's first oil well was drilled in Pennsylvania, USA, in 1859.
- Oil was struck at Makum, Assam, in 1867 — eight years after Pennsylvania (India's first).
- Petroleum = petra (rock) + oleum (oil); it is also called 'black gold'.
- Petroleum fractions: LPG, petrol, kerosene, diesel, lubricating oil, paraffin wax, bitumen.
- India's oil: Assam, Gujarat, Mumbai High, and the Godavari–Krishna river basins.
- India's natural gas: Tripura, Rajasthan, Maharashtra, Krishna-Godavari delta; piped supply in Vadodara and parts of Delhi.
- Bitumen (a petroleum product) has replaced coal-tar for metalling roads; hydrogen from natural gas makes urea.
- PCRA (Petroleum Conservation Research Association), under the Ministry of Petroleum and Natural Gas, promotes fuel conservation.
Timeline
- ~300 million years agoDense wetland forests buried and compressed; carbonisation slowly converts them to coal.
- 1810Coal gas first used for street lighting in London.
- ~1820Coal gas used for street lighting in New York.
- 1859World's first oil well drilled in Pennsylvania, USA.
- 1867Oil struck at Makum, Assam — India's first, eight years after Pennsylvania.
Memory tricks remember it for good
Traps to avoid
- Coal gas vs natural gas: coal gas is a by-product of making coke; natural gas is a separate fossil fuel stored as CNG. They are not the same.
- Coke (solid, pure carbon) vs coal tar (liquid, ~200 substances) vs coal gas (gaseous) — don't mix up the three coal products.
- Carbonisation forms coal from vegetation; petroleum and natural gas form from marine organisms — carbonisation does NOT make petroleum.
- Bitumen is a PETROLEUM product (it replaced coal-tar for roads), not a coal product — a favourite trap.
- 'Black gold' = petroleum, not coal; and CNG is LESS polluting than petrol (the True/False statement 'CNG is more polluting than petrol' is FALSE).
- First oil well: Pennsylvania, USA (1859) is the world's first; Makum, Assam (1867) is India's first — don't swap them. Petrol = light vehicles, diesel = heavy vehicles.
Exam focus
🧠 Prelims angles
- Classification: inexhaustible (sunlight, air) vs exhaustible resources.
- Products of coal and their uses — coke→steel, coal tar→dyes/drugs/naphthalene, coal gas→fuel.
- Matching petroleum fractions to uses (kerosene→stoves/jets, bitumen→road surfacing, paraffin wax→candles).
- Firsts and dates: Pennsylvania 1859, Makum Assam 1867, coal-gas street lighting London 1810.
- Oil- and gas-bearing regions of India (Mumbai High, Krishna-Godavari, Assam, Gujarat, Tripura).
- CNG/LPG properties, petrochemicals (urea from natural-gas hydrogen), and PCRA's role.
✍️ Mains angles GS-III
- Energy security and over-dependence on exhaustible fossil fuels.Note that reserves may last only a few hundred years; argue for diversification into renewables plus demand-side conservation.
- Fossil-fuel combustion, air pollution and global warming.Trace combustion → CO2 → climate change; advocate cleaner fuels like CNG and efficiency measures.
- Intergenerational equity and sustainable development.Use the 'generations sharing one container' idea and PCRA conservation tips to argue for judicious present-day use.
Last-minute revision tick as you recall
- Fossil fuels = coal, petroleum, natural gas — all exhaustible.
- Coal formed ~300 mya by carbonisation; it is mainly carbon.
- Coal → coke (pure C, steel), coal tar (~200 substances, dyes/naphthalene), coal gas.
- Petroleum = petra + oleum = 'black gold'; refined into LPG, petrol, kerosene, diesel, lubricating oil, paraffin wax, bitumen.
- World's first oil well: Pennsylvania 1859; India's first: Makum, Assam 1867.
- Oil in India: Assam, Gujarat, Mumbai High, Godavari-Krishna basins.
- Natural gas stored as CNG (cleaner fuel); found in Tripura, Rajasthan, Maharashtra, KG delta.
- Bitumen (petroleum) replaced coal-tar for roads; urea made using natural-gas hydrogen.
- PCRA (Min. of Petroleum & Natural Gas) promotes fuel conservation — reserves are finite, so use judiciously.
Distilled from NCERT Class 8 · Science (Class 8) for UPSC. Always cross-check facts with the original NCERT.