Detailed study notes for BEVAE-181 Block 2 Unit 7. Covers India's energy consumption (16% population, 3% world energy), energy demand doubling every 14 years, seven non-conventional energy sources (biomass gasifier, solar SPV, fuel cells, wave and tidal, geothermal, co-generation, wind, biogas) with technical specifications, conventional sources (coal, oil, natural gas, hydropower, atomic energy), biophysical vs social carrying capacity, energy demand trends during industrialisation, and India's non-polluting energy initiatives (improved chulhas, Okhla sewage plant, solar PV pumps, wind pumps, Urjagrams). Includes seven SVG diagrams, SAQs and terminal question answers. Free PDF download.
Unit 7 · Index
Energy is essential to modern life. The demand for energy doubles every 14 years. India has 16% of world's population but consumes only 3% of world's energy. This unit covers conventional and non-conventional energy sources, carrying capacity of Earth's energy base, energy demand trends with population growth and industrialisation, and India's development of non-polluting energy systems.
Modern industrial societies are characterised by intensive use of energy. There is a close relationship between energy consumption and economic growth (GDP). The cost and availability of energy are two major factors in promoting economic growth.
Energy demand doubles every 14 years — one of the key indicators of development. India's energy needs are met by two broad categories:
Derived from plant resources, animal waste, and waste of human activities. Most important fuel worldwide after coal, oil, and natural gas. Does NOT add net CO₂ — absorbs the same amount while growing as it releases when burned.
India's Biomass Use: Biomass = ~1/3 of total fuel. Over 90% of rural households use biomass fuels (wood, cowdung cakes, crop residues, sawdust). About 15% of urban households also use it.
Biomass Gasifier: Converts solid biomass → gas via thermochemical gasification. 1890 Kcal of heat from 0.5 kg dry plant tissue = heat from 250g coal! Biomass can be compressed into briquettes for easier use in chulhas/furnaces.
⚠️ Problem: Inefficient burning in traditional chulhas → indoor air pollution → serious health hazards. Unsustainable use → deforestation → desertification.
Most readily available, abundant, free, and non-polluting source. Coal and oil are actually "ancient solar energy" — trapped in plants millions of years ago via photosynthesis.
Solar passive buildings cut energy use for heating/cooling. India's target: 1,00,000 MW of solar energy by 2022. 60 million sq.km of tropical seas absorb solar radiation equivalent to 245 billion barrels of oil!
Convert chemical energy of fuel directly and efficiently into electricity + heat — without combustion. Fuel: hydrogen. O₂ + H₂ → electricity + water + heat (only clean emissions). Used in space flights. Can reduce urban air pollution in vehicles. Energy conversion efficiency almost DOUBLE that of current engines.
Perpetual energy from ocean waves and tides. Tidal dam holds back tides; difference in water levels drives reversible turbines → electricity in both directions. India: 150 MW wave project at Vizhinjam, Thiruvananthapuram. Rs. 5000 crore tidal project proposed at Hanthal Creek, Gulf of Kachchh, Gujarat.
Heat from Earth — hot springs, geysers, volcanoes. India has 46 hydrothermal areas with spring water >150°C. Geological Survey identified 350+ hot spring sites. Experimental 1 KW project in Puga Valley, Ladakh — used for poultry farming, mushroom cultivation, pashmina-wool processing.
Producing TWO forms of energy from one fuel — heat AND electricity simultaneously. Conventional plants: ~35% efficiency (exhaust steam wasted). Co-generation: uses exhaust steam for heating → efficiency 75–90%! India's potential: more than 20,000 MW (conservative estimate).
Turbines transform kinetic energy of moving air → electricity. India: average wind density 3 kwh/m²/day; some areas >10 kwh/m²/day. Target: 60,000 MW by 2022. DNES installed 924 wind pumps nationwide. Wind generators at Ladakh (2 MW aggregate) for lighting + water pumping.
Cattle dung → fermentation → gas with 55–70% methane. Water weeds supplement dung. Uses: cooking, lighting, running turbines for electricity. Residual slurry = free agricultural manure! Okhla (Delhi) plant: gas for 800 households at 50% of LPG cost.
🌍 International Solar Alliance: Established in 2015 with major initiatives by India. Aims to develop clean and green solar energy. India's total renewable energy target for 2022: 1,75,000 MW (1,00,000 MW solar + 60,000 MW wind + 10,000 MW biomass + 5,000 MW others). Raised from 35,776 MW in 2015!
💧 Hydropower: Cheapest and cleanest source of electricity. Small hydro plants serve remote/rural areas without grid supply. However: Large dams inundate forests, farmland, and wildlife habitats and displace indigenous communities — causing major social and environmental controversy.
i) a) Renewable non-conventional ii) b) Solar energy iii) c) Both cheap and pollution-free iv) c) Atomic energy v) b) Sun's energy (fossil fuels = ancient trapped solar energy)
The long-term sustainable carrying capacity for humans on Earth varies with resource availability, culture, and level of economic development. Two measures of human carrying capacity:
A socially sustainable carrying capacity must be based on a level of consumption that meets basic human needs of food, water, and space as well as provides opportunity to enjoy socio-political rights, health, education, and well-being. Inequitable distribution of wealth leads to social instability.
a) maximum b) energy c) more d) sustainable
The developing world's population is predicted to grow from 4 billion to over 8 billion by 2050, comprising ~90% of world population. This, combined with per capita economic growth, will drive unprecedented energy demand — a 2–3× increase in world energy consumption.
Energy Intensity = energy input per dollar of GDP. It rises during heavy industrialisation (more energy per unit output). It falls as services and light industry grow. But transportation continues to grow throughout development, eventually accounting for over half of all energy use.
📊 Key Statistic: Average person in less-developed countries currently consumes only 1/6th of the energy consumed by an average person in Western Europe or Japan. Even a modest doubling of per-capita energy use in developing countries, combined with population growth, will lead to a 2–3× increase in world energy consumption.
From the 1950s, energy consumption increased dramatically worldwide due to: (1) Rapid population growth — more people needing food, housing, and transport; (2) Industrialisation — heavy industry (infrastructure) requires enormous energy; (3) Rising living standards — more appliances, vehicles, and services per capita.
The developing world's population grew from ~2 billion (1950s) toward 8 billion (2050). Currently, average person in less-developed countries uses only 1/6th of a Western European's energy. Even a modest doubling of per-capita energy use × population growth = 2–3× increase in global energy demand by 2050. Asian developing economies (China, India) show the most pronounced increases. More than half of total CO₂ emissions originate from the energy sector.
India's per capita commercial energy consumption is only 1/8th of the world average. The answer to India's energy needs lies in adopting non-conventional sources. A beginning has been made by the Government of India to give equal resources and support to alternative energy sources as have been extended to conventional sources.
1,00,000 MW Solar + 60,000 MW Wind + 10,000 MW Biomass + 5,000 MW Other = 1,75,000 MW Total (raised from 35,776 MW in 2015!). More than 100 manufacturers in India produce renewable energy systems and devices.
Commercial sources are produced on a large scale for the purpose of sale: coal, petroleum, electricity. Non-commercial sources serve only local needs and are NOT produced on a large scale: firewood, cowdung, and agricultural wastes. Commercial energy accounts for a little over half of total energy used in India; the rest comes from non-commercial sources. India's per capita consumption of commercial energy is only 1/8th of the world average.
i) ✗ FALSE — City sewage CAN be used (anaerobic digestion of sludge → methane, as at Okhla, Delhi — 800 households at 50% LPG cost).
ii) ✓ TRUE — Improved chulhas do permit shorter cooking time and save fuel.
iii) ✓ TRUE — Biogas (methane 55–70%) can be used for cooking, lighting, and running engines/turbines for electricity.
iv) ✓ TRUE — Urjagrams are exactly this — remote villages electrified by solar, biogas, and wind energy.
Conventional systems (coal, petroleum): non-renewable (finite, exhaustible); use old technologies; less efficient (~35% for power plants); highly polluting (SO₂, CO₂, acid rain, oil spills, nuclear waste); centralised requiring large infrastructure; cause environmental damage.
Alternate/Non-conventional systems (solar, wind, biogas): based on renewable resources (virtually inexhaustible); newer technologies; higher efficiency (co-generation 75–90%, fuel cells double conventional); minimal pollution (no oil spills, no acid rain); decentralised — can serve rural poor in remote areas; no fuel cost (free sunlight, wind, biomass).
Exam-style questions from the IGNOU textbook.
| Feature | Conventional Sources | Non-Conventional Sources |
|---|---|---|
| Renewability | Non-renewable; finite and exhaustible | Renewable; virtually inexhaustible |
| Environmental impact | High pollution (SO₂, CO₂, acid rain, oil spills) | Minimal pollution; clean and green |
| Technology | Old, well-established technologies | Newer, innovative technologies |
| Efficiency | Power plants: ~35% efficiency | Co-generation: 75–90%; Fuel cells: double conventional |
| Availability | Centralised; large infrastructure needed | Decentralised; available to rural poor remotely |
| Examples | Coal, petroleum, natural gas, nuclear | Solar, wind, biogas, tidal, geothermal, fuel cells |
1. Solar Energy via Photovoltaic (SPV) Cells:
Solar radiation is converted directly into electricity in SPV panels. Electricity is stored in batteries for domestic lighting, street lighting, water pumping, desalination, and telecom. India has 160+ solar PV pumps in rural areas and SPV street lighting in 150+ villages (Urjagrams). India's target: 1,00,000 MW of solar by 2022 — one of the world's largest solar programs. 60 million sq.km of tropical seas absorb solar radiation equivalent to 245 billion barrels of oil.
2. Wind Energy:
Wind turbines transform kinetic energy of moving air into mechanical power (grinding, lifting water) or electricity. Can be used singly or in clusters ("wind farms"). India has average wind density of 3 kwh/m²/day; some areas have >10 kwh/m²/day in winter. DNES has installed 924 wind pumps nationwide. Wind electricity generators in Ladakh (2 MW) for lighting and pumping. Target: 60,000 MW wind energy by 2022.
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