Energy (renewal & non-renewal)

Overview & Fundamental Concept

Complete preparation guide for Energy (renewal & non-renewal) under AISSEE Class VI General Knowledge (Syllabus Item 12). Master high-yield facts, exam matrices, solved models, and 10 interactive drill MCQs with detailed explanations.

• Definition of Energy: Energy is defined as the quantitative capacity or capability of a physical system to perform work; the Standard International (SI) unit of energy is the Joule (J); the commercial billing unit of electrical energy is the Kilowatt-hour (kWh), where 1 kWh = 3.6 × 10⁶ Joules (also called 1 Board of Trade Unit).
• Law of Conservation of Energy (First Law of Thermodynamics): Energy can neither be created nor destroyed in any physical or chemical process; it can only undergo transformation from one form to another, preserving the total energy of an isolated universe.
• Renewable Energy (Non-Conventional Sources): Energy harvested from natural sources that replenish themselves continuously on a human timescale without depleting planetary stocks; characterized by negligible carbon emissions, low operational pollution, and long-term environmental sustainability.
• Non-Renewable Energy (Conventional Sources): Energy extracted from finite subterranean fossil geological deposits and mineral ores that accumulated over hundreds of millions of years; once consumed, they cannot be regenerated within meaningful human timescales; primary drivers of greenhouse gas emissions (CO₂), atmospheric particulates, and global climate change.

• Solar Energy: Harnesses radiant solar photon energy using Photovoltaic (PV) cells fabricated from semiconductor silicon; Solar Thermal collectors (solar cookers with plane mirrors and glass sheets that trap heat via greenhouse effect, solar water heaters); International Solar Alliance (ISA) is headquartered in Gurugram (Haryana), India; World's largest operational solar parks include Bhadla Solar Park (Rajasthan, 2,245 MW) and Pavagada Solar Park (Karnataka, 2,050 MW).
• Wind Energy: Converts the kinetic energy of air masses into rotational mechanical energy via wind turbines, which drive electric dynamos/generators; operational cut-in threshold requires minimum steady wind speeds of 15 km/h; India's largest operational wind power cluster is the Muppandal Wind Farm (Kanyakumari, Tamil Nadu, 1,500 MW); Denmark is globally nicknamed the 'Country of Winds'.
• Hydroelectric Energy (Hydel): Converts the gravitational potential energy of water held behind dams into mechanical kinetic energy by channeling water through penstocks to rotate hydraulic turbines; Tehri Dam (Uttarakhand - highest dam in India at 260.5 m, built on the Bhagirathi river); Bhakra Nangal Dam (Himachal Pradesh/Punjab - concrete gravity dam on the Sutlej river); Hirakud Dam (Odisha - longest earthen dam in India on the Mahanadi river).
• Biomass & Biogas (Gobar Gas): Biogas is generated via anaerobic microbial decomposition (fermentation by methanogenic bacteria in the absence of oxygen) of animal dung (cow dung), sewage, and agricultural plant wastes inside an airtight dome digester; raw Biogas is composed of 65% to 75% Methane (CH₄), with the balance being Carbon Dioxide (CO₂) and trace hydrogen sulfide; leaves behind pathogen-free slurry rich in nitrogen and phosphorus used as premier organic fertilizer.
• Geothermal Energy: Taps thermal heat naturally stored in Earth's deep crust and volcanic magma chambers; subterranean water contacts hot rocks, forming pressurized steam that vents through fumaroles and geysers; harnessed at Puga Valley (Ladakh) and Manikaran (Himachal Pradesh).
• Tidal & Wave Energy: Uses the kinetic movement of oceanic tides driven by lunar and solar gravitational pull to turn submerged bidirectional marine turbines; prime Indian prospects located in the Gulf of Kutch and Gulf of Khambhat (Gujarat) and Sundarbans delta (West Bengal).

• Fossil Fuel Genesis: Formed from the buried, fossilized remains of prehistoric aquatic organisms (petroleum & gas) and terrestrial swamp forests (coal) subjected to extreme geological heat and pressure over 300 million years.
• Coal & Carbonisation: Carbonisation is the slow geochemical conversion of buried dead plant biomass into carbonaceous coal; Coal ranks are determined strictly by carbon percentage, calorific energy density, and volatile moisture content.
• The 4 Ranks of Coal: Anthracite (Premier grade, > 90% carbon, jet-black, shiny, nearly smokeless combustion, highest calorific value, found in J&K); Bituminous (Most abundant industrial grade, 70-80% carbon, used for thermal electricity and metallurgical coking, mined in Jharia and Bokaro in Jharkhand, Raniganj in West Bengal); Lignite (Soft 'Brown Coal', 40-55% carbon, mined at Neyveli in Tamil Nadu); Peat (Initial geological stage, < 40% carbon, low heat, heavy smoke and ash residue).
• Petroleum ('Black Gold' / Crude Rock Oil): Dark, viscous hydrocarbon liquid extracted from subterranean sedimentary rock traps; refined into commercially useful fractions via Fractional Distillation in refinery columns based on distinct boiling points (petroleum gas, petrol, naphtha, kerosene, diesel, lubricating oil, paraffin wax, bitumen/asphalt).
• India's Petroleum Milestones: Digboi (Assam) is the oldest operating oil refinery in India and Asia, drilled in 1889 and commissioned in 1901; Mumbai High (Bombay High) is India's largest offshore oilfield, located 160 km off the Mumbai coast in the Arabian Sea (drilling platform named 'Sagar Samrat').
• Compressed Natural Gas (CNG): Composed primarily of Methane (CH₄, 85-95%); compressed to 200-250 atmospheres; eco-friendly automotive fuel with minimal carbon monoxide and unburnt particulate emissions.
• Liquefied Petroleum Gas (LPG): Used in domestic cooking gas cylinders; composed primarily of Butane (C₄H₁₀) and Propane (C₃H₈) liquefied under moderate pressure; naturally odorless, but deliberately blended with an intensely pungent chemical odorant named Ethyl Mercaptan (C₂H₅SH) so that any hazardous cylinder leak is smelled instantly!

• Nuclear Power Principles: Generates enormous thermal energy through controlled Nuclear Fission, where heavy fissile atomic nuclei (Uranium-235 or Plutonium-239) absorb a thermal neutron and split into lighter fission fragments, releasing massive binding energy (E = mc²) to produce steam for turbo-generators.
• India's Nuclear Power Landmarks: Tarapur Atomic Power Station (Maharashtra, commissioned 1969) was India's first commercial nuclear power facility; Kudankulam (Tamil Nadu - largest nuclear plant in India, 2,000 MW); Madras / Kalpakkam (Tamil Nadu); Narora (Uttar Pradesh); Rawatbhata (Rajasthan); Kakrapar (Gujarat); Kaiga (Karnataka).
• Gas Chemistry Exam Traps: Biogas / Gobar Gas consists predominantly of Methane (CH₄, 65-75%); Compressed Natural Gas (CNG) consists predominantly of Methane (CH₄, >85%); Domestic LPG consists predominantly of Butane (C₄H₁₀) and Propane (C₃H₈); The safety odorant in LPG is Ethyl Mercaptan.
• Energy Conservation Habits: Switching off idle electrical appliances; using energy-efficient LED bulbs (Light Emitting Diodes) and BEE Star-rated appliances; riding bicycles or utilizing public electric metro transit; promoting rooftop solar rainwater-solar hybrid systems; practicing the 3Rs (Reduce, Reuse, Recycle).