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Basics of Energy & Environment – Study Notes

ESE / IES Paper I

Complete notes for Basics of Energy & Environment — ESE Paper I General Studies. Covers conventional and renewable energy sources, energy efficiency, environmental pollution and impacts, climate change, environmental legislation, and sustainability concepts.

Ch 1 · Conventional Energy Sources Ch 2 · Renewable Energy Ch 3 · Energy Efficiency & Conservation Ch 4 · Environmental Pollution Ch 5 · Climate Change & Global Issues Ch 6 · Environmental Legislation ★ Quick Revision

1Conventional Energy Sources►

1.1 Fossil Fuels

Fuel	Calorific Value (approx.)	Key Issues
Coal	25–35 MJ/kg	Highest CO₂ per unit energy; SOₓ, NOₓ, particulates; India has ~7% world reserves
Petroleum (crude oil)	42–44 MJ/kg	Transport fuel dominant; finite reserves; oil spills
Natural gas (methane)	50–55 MJ/kg	Cleanest fossil fuel; lower CO₂; methane leakage risk

1.2 Nuclear Energy

Fission: heavy nucleus (U-235, Pu-239) splits into lighter nuclei + 2–3 neutrons + energy
E = mc²; 1 kg U-235 ≈ 83 TJ (equivalent to ~2700 tonnes of coal)

Types of reactors: Pressurised Water Reactor (PWR), Boiling Water Reactor (BWR), PHWR (CANDU/RAPS in India)
India's nuclear programme: Thorium cycle (large thorium reserves at ~25% of world supply)

Issues: radioactive waste disposal; meltdown risk (Chernobyl 1986, Fukushima 2011); high capital cost

📝 ESE Tip: Calorific values comparison (coal < oil < natural gas) and nuclear energy basics (fission vs fusion, India's thorium reserves) are tested. India's installed nuclear capacity and PHWR type are factual questions.

2Renewable Energy►

2.1 Solar Energy

Technology	Principle	Application
Photovoltaic (PV)	Photoelectric effect; semiconductor converts sunlight → electricity	Rooftop, grid-scale solar farms
Solar thermal (CSP)	Concentrated mirrors heat fluid → steam → turbine	Large utility power plants
Solar water heater	Flat plate or evacuated tube collector; heats water directly	Domestic and industrial hot water

2.2 Wind Energy

Power in wind: P = ½ ρ A V³
ρ = air density (1.225 kg/m³); A = rotor swept area; V = wind velocity
Betz limit: theoretical maximum efficiency = 16/27 ≈ 59.3%
Practical efficiency of wind turbines: 35–45%

India: 4th largest wind power capacity in world; Tamil Nadu, Gujarat, Rajasthan are leading states

2.3 Hydropower

Power: P = ρgQH × η
Q = discharge (m³/s); H = net head (m); η = overall efficiency (typically 0.85–0.90)
Run-of-river vs storage (reservoir) plants
Small hydro: < 25 MW; Micro hydro: < 100 kW
India: 4th largest hydropower producer; Bhakra–Nangal, Sardar Sarovar major projects

2.4 Other Renewables

Source	Key Facts
Biomass	Combustion or biogas (anaerobic digestion → CH₄); carbon-neutral if sustainably managed
Geothermal	Earth's heat; Puga valley (Ladakh) potential in India; high capital cost
Tidal	Gulf of Kutch and Gulf of Khambhat (India) — 7,000 MW potential; high capital cost
Wave	Offshore wave energy; still largely experimental
Hydrogen	Green hydrogen from electrolysis using renewables; National Green Hydrogen Mission (India 2023)

📝 ESE Tip: Betz limit (59.3%) for wind turbines, power formula P = ρgQHη for hydro, and India's state-wise renewable energy leadership are frequently asked. India's 2030 renewable energy targets (500 GW non-fossil capacity) reflect in policy questions.

3Energy Efficiency & Conservation►

3.1 Energy Audit

Energy audit: systematic examination of energy flows to identify savings opportunities
Types: (1) Walk-through (preliminary); (2) Detailed (investment grade)

Specific Energy Consumption (SEC) = Energy consumed / Unit of production
Energy Performance Index (EPI): used to benchmark building energy use

Bureau of Energy Efficiency (BEE): apex body under Ministry of Power; mandates energy audit for designated consumers

3.2 Energy Conservation Measures

Sector	Key Measures
Industry	Variable frequency drives (VFDs); waste heat recovery; cogeneration (CHP); LED lighting
Buildings	Energy-efficient windows (double glazing); insulation; HVAC optimisation; green building rating (GRIHA, LEED)
Transport	Electric vehicles; fuel-efficient engines; modal shift to rail/public transport
Agriculture	Energy-efficient pumps; drip irrigation (reduces pumping); solar pumps

📝 ESE Tip: Energy Conservation Act, 2001 and BEE (Bureau of Energy Efficiency) are directly asked. Cogeneration = simultaneous production of electricity and useful heat — efficiency up to 80% vs ~35% for power alone.

4Environmental Pollution►

4.1 Air Pollution

Pollutant	Primary Source	Effect
SO₂	Coal combustion, smelting	Acid rain; respiratory damage
NOₓ	Combustion (thermal, vehicles)	Smog; acid rain; ozone formation
CO	Incomplete combustion	Haemoglobin binding; toxic
PM2.5	Combustion, construction dust	Deep lung penetration; cardiovascular disease
VOCs	Solvents, vehicles, industry	Ground-level ozone precursor
CO₂, CH₄, N₂O	Fossil fuels, agriculture, waste	Greenhouse effect; climate change

4.2 Water Pollution

BOD (Biochemical Oxygen Demand): oxygen required to decompose organic matter over 5 days at 20°C
Clean water: BOD < 2 mg/L; Sewage: BOD 150–300 mg/L

COD (Chemical Oxygen Demand): total oxidisable matter (chemical oxidation)
COD > BOD always (COD includes non-biodegradable organic matter)

DO (Dissolved Oxygen): saturation ≈ 9 mg/L at 20°C; fish need > 4 mg/L
Oxygen sag curve: shows DO drop and recovery downstream of sewage discharge

4.3 Solid Waste

Municipal Solid Waste (MSW): 4Rs — Reduce, Reuse, Recycle, Recover
Solid Waste Management Rules, 2016 (India): source segregation mandatory (wet, dry, hazardous)
Landfill (sanitary): lined cells, leachate collection, gas extraction
Composting: biodegradable fraction → manure
Waste-to-energy (WtE): incineration or RDF; calorific value of MSW ≈ 1500–2000 kcal/kg

📝 ESE Tip: BOD vs COD distinction (BOD = biological; COD ≥ BOD; COD includes non-biodegradable) is a very common question. Oxygen sag curve — point of minimum DO = critical point — is tested conceptually and numerically.

5Climate Change & Global Issues►

5.1 Greenhouse Effect

Natural greenhouse effect: CO₂, H₂O, CH₄, N₂O, O₃ absorb outgoing infrared radiation → Earth's surface warms by ~33°C
Enhanced (anthropogenic) greenhouse effect: excess GHG from fossil fuels raises global temperature

Global Warming Potential (GWP) over 100 years:
CO₂ = 1 (reference); CH₄ = 28; N₂O = 265; HFCs = 1,000–10,000; SF₆ = 23,500

5.2 Key International Agreements

Agreement	Year	Key Provision
Kyoto Protocol	1997	First binding GHG reduction targets for developed (Annex I) countries
Paris Agreement	2015	Limit warming to 1.5–2°C above pre-industrial; NDCs (Nationally Determined Contributions)
Montreal Protocol	1987	Phase-out of ozone-depleting CFCs; most successful international environmental treaty
Stockholm Convention	2001	Persistent Organic Pollutants (POPs) elimination
Basel Convention	1989	Control of transboundary movement of hazardous waste

5.3 Ozone Layer Depletion

Stratospheric ozone (O₃) absorbs harmful UV-B radiation (280–315 nm)
CFCs (chlorofluorocarbons): Cl radical chain reaction destroys O₃
Ozone hole: largest over Antarctica; measured in Dobson Units (DU)
Normal ozone level ≈ 300 DU; ozone hole < 220 DU
CFC alternatives: HCFCs (transitional), HFCs, natural refrigerants (NH₃, CO₂)

📝 ESE Tip: GWP values (CH₄ = 28; N₂O = 265), the Paris Agreement 1.5°C target, and the Montreal Protocol (ozone, not climate) vs Kyoto/Paris (climate) distinction are all tested. Dobson Unit for ozone measurement.

6Environmental Legislation (India)►

6.1 Key Environmental Laws

Act	Year	Scope
Water (Prevention and Control of Pollution) Act	1974	CPCB and SPCBs established; effluent discharge standards
Air (Prevention and Control of Pollution) Act	1981	Ambient air quality standards; stack emission norms
Environment (Protection) Act (EPA)	1986	Umbrella legislation; EIA notification; hazardous waste rules
Forest Conservation Act	1980	No diversion of forest land without Central Government approval
Wildlife Protection Act	1972	Protection of wild animals, birds, plants; National Parks, Sanctuaries
National Green Tribunal Act	2010	NGT established; fast-track disposal of environmental disputes

6.2 Environmental Impact Assessment (EIA)

EIA process (India, EPA 1986, EIA Notification 2006):
1. Screening — determine if project requires EIA
2. Scoping — identify key issues to study
3. Baseline data collection — present environmental status
4. Impact prediction and evaluation
5. Mitigation measures
6. Environmental Management Plan (EMP)
7. Public hearing (mandatory for Category A projects)
8. Appraisal by Expert Appraisal Committee (EAC)
9. Decision (Environmental Clearance or rejection)

📝 ESE Tip: EPA 1986 is the umbrella environment law in India — dates and scope are tested. EIA steps and the role of CPCB / SPCB in pollution control are common questions. NGT (National Green Tribunal) jurisdiction is a contemporary topic.

★Quick Revision►

Topic	Key Fact
Betz limit (wind)	59.3% = 16/27
Hydropower formula	P = ρgQHη
BOD (clean water)	< 2 mg/L; sewage 150–300 mg/L
COD vs BOD	COD ≥ BOD always
GWP of CH₄	28 (over 100 years)
GWP of N₂O	265
Montreal Protocol	1987 — CFCs / ozone layer
Paris Agreement	2015 — 1.5–2°C warming limit
EPA (India)	1986 — umbrella environment law
NGT established	2010
Ozone measurement	Dobson Units (DU); normal ≈ 300 DU

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Basics of Energy & Environment – Study Notes

1.1 Fossil Fuels

1.2 Nuclear Energy

2.1 Solar Energy

2.2 Wind Energy

2.3 Hydropower

2.4 Other Renewables

3.1 Energy Audit

3.2 Energy Conservation Measures

4.1 Air Pollution

4.2 Water Pollution

4.3 Solid Waste

5.1 Greenhouse Effect

5.2 Key International Agreements

5.3 Ozone Layer Depletion

6.1 Key Environmental Laws

6.2 Environmental Impact Assessment (EIA)