NPTEL Environmental Science – Full Marks Study Guide

Environmental Concerns, Population Growth & Impact Measurement

Lectures 1–5 · IPAT · Ecological Footprint · EPI · LCA

🌍 Four Domains of Environment

Atmosphere – air layer up to ~100 km; air pollution, noise pollution
Hydrosphere – all water bodies; water quality, wastewater
Lithosphere – ground surface; primary productivity; soil pollution, solid waste
Biosphere – all living organisms; ecosystem stability, biodiversity

⚠️ Pollutant vs Contaminant — EXAM FAVOURITE

Pollutant = Chemical causing adverse biological effects on environment/organisms. Can be NATURAL (arsenic, fluoride in groundwater) OR anthropogenic (DDT, pesticides). Key word: ADVERSE BIOLOGICAL EFFECT.

Contaminant = Substance present where it should NOT be, OR above background concentration. Does NOT necessarily cause biological harm. Example: natural organic matter in rivers at excess levels = contamination.

A substance can be BOTH pollutant AND contaminant. Pollutants do NOT have to be anthropogenic. Contaminants do NOT have to cause harm.

📊 Key Environmental Statistics

21/30

Most polluted cities are in India

199

Species on India's Red List 2021

8 billion

Global pop. exceeded Nov 15, 2022

1.43 B

India pop. April 2023 (>China)

17.82%

India's share of global population

73%

India's electricity from coal (2021-22)

📐 Three Population Growth Models

Model	Formula	Key Feature
Arithmetic (Linear)	Pₙ = P₀ + nX	Fixed increment; only in planned growth; NOT natural
Geometric	Pₙ = P₀[1 + r/100]ⁿ	Fixed % rate; DISCRETE function
Exponential	Pₙ = P₀·eʳⁿ	Continuous form; BEST fits India's census data (R²=0.97)

India total pop growth rate (1911-2011) = 1.75%/yr | Urban pop growth rate = 2.85%/yr

R² > 0.95 = very good fit | R² > 0.9 = good fit | R² < 0.5 = poor correlation. Exponential > Geometric always. Do NOT force curve through origin.

🏭 Resource Types

Perpetual – Solar energy, wind, tides, flowing water (rate of use has no bearing on rate of arrival)
Renewable – Air, water, soil, plants, animals (renewed by natural processes)
Non-renewable – Fossil fuels, minerals, metals, deep groundwater (takes millions of years to form)

Deep groundwater = NON-renewable because recharge takes thousands of years. Shallow groundwater = renewable (rain-fed). Term used: GROUNDWATER MINING for deep extraction.

📐 IPAT Model — Proposed by Paul Ehrlich & Holdren (1971)

I = P × A × T

I = Environmental Impact (e.g., CO₂ emissions/year)
P = Population
A = Affluence (per capita energy use from fossil fuels; or GDP per capita)
T = Technology (CO₂ emissions in kg per kWh generated)

Country	Coal share	Per capita electricity	CO₂ from coal
India	73%	1,140 kWh/yr	1182 B kg CO₂/yr
USA	19.5%	12,742 kWh/yr	828 B kg CO₂/yr (coal)

India's CO₂ from electricity growing at 5.1% per year under business-as-usual scenario

🌱 Ecological Footprint & Biocapacity

EF_consumption = EF_production + EF_imports − EF_exports

Biocapacity = Aₙ × (Yₙ/Yᵥᵥ) × EQF

Metric	Global (2018)	India
Ecological Footprint/person	2.8 global hectares	0.8 gh
Biocapacity/person	1.6 global hectares	0.5 gh
Status	DEFICIT (since 1971)	DEFICIT

6 land-use categories: Cropland, Grazing land, Fishing grounds, Forest, Built-up area, Carbon footprint
EQF (Equivalence Factor): converts different land types to global hectares based on biological productivity
Global hectares = productivity-adjusted hectares

🗓️ Earth Overshoot Day

Year	Date	Note
1971	December (end)	First year footprint = biocapacity
2019	July 29	Pre-COVID baseline
2020	August 22	COVID lockdown effect (+24 days later)
2021	July 30	–
2022	July 28	–

COVID 2020: Carbon footprint reduced by 14.5%, Forest footprint reduced by 8.4%. Food footprint = NO CHANGE (people still eat same amount). Even global lockdown didn't delay EOD much!

⚡ Energy Performance Index (EPI)

EPI = kWh / m² / year

Uses only electricity bill + floor area — very simple to calculate
Factors affecting EPI: floor area, occupants, economic level, hours of use, climate, nature of activity, conservation practices, type of A/C, building materials
ATMs and pharmacies = HIGHEST EPI (run 24/7, fully air-conditioned)
Schools = LOWEST EPI (open only 6 hrs/day, 5 days/week)

♻️ Life Cycle Assessment (LCA) — US EPA Methodology

Tracks: Raw material extraction → Transport → Manufacturing → Packaging → Distribution → Use → Reuse/Recycle → Disposal

Paper Type	Wood used	Energy	GHG	Water	Solid waste
Recycled/Kraft	ZERO	LOWEST	LOWEST	LOWEST	LOWEST (106 kg/MT)
Newsprint	Low	Medium	Medium	HIGHEST	Medium
Printer paper	HIGHEST	High	High	High	590 kg/MT (HIGH)
Toilet paper	Medium	HIGHEST	HIGHEST	High	High

Recycled/Kraft paper = BEST on ALL environmental parameters. Newsprint = most forest disturbance. Toilet paper = highest energy and GHG per metric ton.

🌐 Planetary Boundaries (Critical Numbers)

Parameter	Pre-industrial	Proposed Boundary	Current Status
CO₂ (ppm)	280	350	~420 (OVERSHOOT)
Biodiversity loss (species/million/yr)	<1	10	>100 (OVERSHOOT)
Nitrogen fixation (MT/yr)	0	35	121 (OVERSHOOT)

CO₂ measured at Mauna Loa Observatory, Hawaii, USA. Rising at ~2 ppm/year — unprecedented in geological record.

🏙️ City Types (Agropolis → Petropolis → Ecopolis)

Agropolis (pre-industrial) – city within assimilative capacity of countryside; symbiotic relationship; no millions of people; waste returned to countryside for agriculture
Petropolis (industrial/post-industrial) – fully fossil fuel dependent; population in millions; waste EXCEEDS assimilative capacity; dumps waste to peripheral areas
Ecopolis (future goal) – circular economy; renewable energy; waste recycled within city; reduced countryside burden

Tragedy of the Commons (Hardin, 1968) – Individual benefit from using common resources leads to overuse and eventual destruction of those resources. Example: herdsmen adding sheep to common pastureland.

Urban Mining – Recovery of valuable materials (gold, silver, copper) from discarded electronic and other products within the city.

🔋 India's Electricity Mix (2021-22)

Source	Share
Coal-based thermal	73%
Natural gas + diesel thermal	2%
Total fossil fuel	75%
Large hydropower	10%
Small hydropower	1%
Wind	5%
Solar	5%
Biomass + other renewable	1%
Total Renewable	22%
Nuclear	3%

In 2011: 66% fossil fuel. In 2021-22: 75% fossil fuel → INCREASING despite target to decrease. Hydropower went DOWN from 14% (2011) to 11% (2021-22).

Sustainable Development, SDGs & Urbanization

Lectures 6–10

📅 Key Historical Timeline — EXAM FAVOURITE

Year	Event	Key Detail
1962	Rachel Carson — "Silent Spring"	Pesticide impacts; triggered global environmental movement; most important environmental book of 20th century
1968	Tragedy of the Commons (Hardin)	Published about nuclear race; part of it applied to resource use
1969	Santa Barbara Oil Spill	15 million litres of oil; worst spill at the time; California coast
1970	First Earth Day (April 22)	20 million people participated
1972	Stockholm Conference	113 countries; UNEP formed; first UN environmental conference; Indira Gandhi addressed it; poverty = main cause of environmental degradation
1983	Brundtland Commission formed	WCED; chaired by Norwegian PM Gro Harlem Brundtland
1987	Brundtland Report "Our Common Future"	First defined sustainable development; also: Montreal Protocol signed
1992	Rio Earth Summit (UNCED)	179 countries; produced Agenda 21; UNFCCC signed; 20th anniversary of Stockholm
2000	UN Millennium Declaration	8 MDGs; deadline 2015; 191 nations; extreme poverty halved by 2015 ✓
2015	17 SDGs adopted	169 targets; 232 indicators; 193 member states; 2030 Agenda
2017	Global SDG Indicators Framework	232 indicators adopted by UN General Assembly

🎯 Definition of Sustainable Development

"Development that meets the needs of the present without compromising the ability of future generations to meet their own needs." — Brundtland Report, 1987

Based on 3 concepts: (1) Development — socio-economic in line with ecological constraints; (2) Needs — redistribution to ensure quality of life for all; (3) Future generations — long-term resource availability

Three Pillars: Environmental, Social, Economic. All three MUST function as a whole. If any pillar fails → UNSUSTAINABLE. Supreme Court directive for environmental education: 1991 (MC Mehta case).

🌐 17 SDGs — The 5P Framework

P	Goals	Focus
People	1,2,3,4,5	No Poverty, Zero Hunger, Good Health, Quality Education, Gender Equality
Planet	6,12,13,14,15	Clean Water, Responsible Consumption, Climate Action, Life Below Water, Life on Land
Prosperity	7,8,9,10,11	Clean Energy, Decent Work, Industry/Innovation, Reduced Inequalities, Sustainable Cities
Peace	16	Peace, Justice, Strong Institutions
Partnership	17	Partnerships for Goals

SDG Index 2022 top countries: Finland #1, Denmark #2, Sweden #3, Norway #4. All top 10 are European. COVID-19 caused FIRST-EVER DECLINE in SDG Index score in 2020.

6 SDG Transformations (Sachs et al.)

T1: Education, gender and inequality
T2: Health, well-being and demography (responsible consumption)
T3: Energy decarbonization and sustainable industry
T4: Sustainable food, land, water and oceans
T5: Sustainable cities and communities
T6: Digital revolution for sustainable development

🏙️ Urbanization — Critical Facts

2007 — First time global urban population exceeded rural population
2018 — 55% of world (4.2 billion) in urban areas; 3.4 billion in rural
2030 target — 60% urban
2050 projection — 67% urban (reverse of 1950 distribution)
Currently 33 megacities (>10 million people); by 2050 → 47 megacities
Tokyo = world's largest megacity (37.3 million)
Urban areas = only 2% of land but consume 75% resources, produce 75% CO₂

3 components of urban growth: Natural increase (births > deaths), Migration (rural to urban), Reclassification (rural areas become urban). Africa and Asia urbanizing FASTEST.

🏙️ Urban Sprawl & Smart Growth

Urban Sprawl = Rapid expansion of cities geographically; low-density housing; single-use zoning; car-dependent. NOT always caused by population growth.

Smart Growth = Management strategy directing urban growth. New Urbanism = Physical design for livable, walkable neighborhoods.

Eco-Cities = Cities designed for ecological sustainability. Smart Cities = Use of digital technology for efficient urban services.

🏢 Green vs Sustainable Buildings

Feature	Green Design	Sustainable Design
Focus	Material aspects (recyclable/reusable)	Broader: Planet + People + Profit (3 pillars)
Timeframe	Current negative impacts	Long-term impacts (entire life of building)
Common to both	Good indoor air quality, renewable energy, efficient water/energy use

📊 Capital Stock Model (World Bank)

If we live off the INTEREST (surplus yield) and not the CAPITAL (natural resources stock) → prosperity is maintained. Depleting capital = endangering future generations.

Capital stock for SD = Environmental capital + Economic capital + Social capital

Principles of Sustainability (4 core): 1) Maximize renewable resources; 2) Stable ecosystems (biodiversity); 3) Maintain biogeochemical cycles; 4) Control population growth

Air Pollution — Sources, Types, Dispersion & Control

Lectures 11–15

💨 Definition of Air Pollution

Presence of substances in the atmosphere in concentrations high enough to harm organisms, ecosystems, or human-made materials.

Two types: (1) Outdoor/Ambient air pollution; (2) Indoor/Household air pollution

WHO estimates: 4.2 million die/year from outdoor air pollution | 3.8 million from indoor air pollution | 7 million total (NOT simply additive — some deaths attributed to both)

People spend ~90% of time indoors → indoor air often more polluted than outdoor even in industrial cities.

📍 Sources of Air Pollutants

Stationary Sources:
- Point sources – single emission point at a facility (boilers, spray booths)
- Area sources – many small sources (dry cleaners, gas stations, household heating)
Mobile Sources – vehicles, aircraft, ships, locomotives → considered LINE SOURCE (one-dimensional geometry)

Locomotives on tracks = LINE source. Locomotives in railyard = AREA source.

🔬 Classification of Air Pollutants

By Origin	By Formation	By Physical State
Natural (volcanoes, wildfires, dust)	Primary (directly emitted): SO₂, NOₓ, CO, PM, HC	Gaseous: SO₂, NOₓ, CO, O₃, HC, H₂S
Anthropogenic (vehicles, industry, power plants)	Secondary (formed in atmosphere): O₃, PAN, H₂SO₄, smog	Particulate: PM10, PM2.5, dust, soot, pollen

PM2.5 ≤ 2.5 μm — penetrates deep into lung alveoli; most dangerous. PM10 ≤ 10 μm — trapped in upper respiratory tract.

🌡️ Atmospheric Stability & Lapse Rates

Lapse Rate Type	Value	Condition
Dry Adiabatic Lapse Rate (DALR)	1°C per 100m = 10°C/km	Unsaturated parcel, no heat exchange
Moist Adiabatic Lapse Rate (MALR)	0.6°C per 100m = 6°C/km	Saturated parcel; latent heat released on condensation
Environmental (Normal) Lapse Rate (ELR)	~6.5°C per km average	Actual temperature change in atmosphere

Condition	ELR vs DALR	Atmospheric Stability	Pollution Effect
Super adiabatic	ELR > DALR	UNSTABLE — rising air continues to rise	BEST for dispersion
Sub adiabatic	ELR < DALR	STABLE — displaced air returns to original position	WORST for dispersion; pollutants build up
Neutral	ELR = DALR	Neutral stability	Moderate dispersion

Temperature Inversion = ELR is negative (temperature INCREASES with altitude) → extremely stable → pollutants trapped near ground. MOST dangerous for air quality.

🌆 Types of Smog — EXAM FAVOURITE

Feature	Industrial/London Smog (Winter)	Photochemical/LA Smog (Summer)
Conditions	Cold, humid, calm	Hot, sunny, calm
Primary cause	Coal/oil combustion	NOₓ + VOCs + sunlight
Key pollutants	SO₂, H₂SO₄, soot, particulates	Ozone (O₃), PAN, NO₂, aldehydes
Color	Grayish/yellow (GRAY AIR SMOG)	Brownish/grayish (BROWN AIR SMOG)
Type	REDUCING smog	OXIDISING smog
First described	London, 1952	Los Angeles, 1943

PAN = Peroxyacetyl Nitrate — characteristic product of photochemical smog. Formed: VOCs + NOₓ + sunlight → ozone accumulates when NOₓ reacts with VOCs instead of breaking down ozone.

🌧️ Acid Deposition

Acid Rain: pH < 5.6 (normal rain pH = 5.6 due to dissolved CO₂)
Formed: SO₂ + H₂O → H₂SO₃ (sulphurous acid) → H₂SO₄; NOₓ + H₂O → HNO₃
Wet deposition = acid rain, snow, fog; Dry deposition = acid particles settling on surfaces
Transboundary pollution: Acid rain from UK/Germany damaged Scandinavian lakes (1960s) — first recognized transboundary air pollution
Effects: Lake acidification, fish kills, forest damage, building/monument corrosion

Transboundary Haze — Southeast Asia: burning of peatland in Indonesia (Sumatra, Kalimantan) for oil palm plantations → smoke haze crosses to Malaysia, Singapore, Thailand. Indonesia = 4th largest peatland area. 1997 = first major episode; 2015 = worst episode (600,000 ha destroyed).

🛡️ Ozone Layer — Global Air Pollution Issue

90% of ozone in stratosphere (10-50 km); 10% in troposphere
Stratospheric ozone = "GOOD" ozone (shields UV radiation)
Ground-level ozone = "BAD" ozone (harmful to health)
Total ozone measured in Dobson Units (DU); global average ~300 DU; 300 DU = 3mm of pure ozone layer
Ozone-Depleting Substances (ODS): CFCs, HCFCs, Halons, CCl₄, methyl bromide
Key mechanism: CFCs → photodissociation → Cl atoms → catalytic destruction: Cl + O₃ → ClO + O₂ then ClO + O → Cl + O₂ (net: O₃ + O → 2O₂)
Bromine 40x more efficient than chlorine at destroying ozone
Montreal Protocol (1987) = most successful environmental treaty; phase-out of ODSs
Ozone Hole = springtime depletion over polar regions (especially Antarctica); distinct from general depletion

🔧 Air Pollution Control Devices

Device	Pollutant	Mechanism	Efficiency
Cyclone separator	Particulates (coarse)	Centrifugal force	Moderate; cheap
Electrostatic Precipitator (ESP)	Particulates (fine)	Electrical charge; collection on plates	Very high (>99%)
Bag filter (fabric filter)	Particulates	Filtration through fabric	High
Venturi scrubber	Particulates + gases	Wet collection; water spray	Moderate-high
FGD (Flue Gas Desulfurization)	SO₂	Absorption by limestone/lime slurry	High
SCR (Selective Catalytic Reduction)	NOₓ	Catalyst + NH₃ → N₂ + H₂O	High
Catalytic converter	CO, HC, NOₓ	Oxidation/reduction on catalyst	High

Wet FGD = higher SO₂ removal efficiency. Dry FGD = cheaper, less corrosion, lower operating cost. Limestone used in wet FGD; Lime used in dry FGD.

🏠 Indoor Air Quality

Sick Building Syndrome (SBS): symptoms (headache, dizziness, nausea, sore throat, burning eyes) caused by poor indoor air quality
Indoor pollutants: Radon (radioactive, from soil), Formaldehyde (from wood products), VOCs (paints, solvents), CO (unvented combustion), Asbestos (old buildings), Tobacco smoke, dust mites, mold
Sources: Building materials (carpets, paints, adhesives), unvented appliances (stoves, fireplaces), lifestyle (smoking, incense)

Climate Change — Evidence, Causes, Impacts, Mitigation & Adaptation

Lectures 16–20

🌡️ Weather vs Climate

Weather = Short-term changes in atmospheric variables (temperature, precipitation) over hours or days.

Climate = Statistical description of weather conditions over a long period. Minimum period = 30 YEARS (3 decades).

Climate Change = Long-term shifts in temperature and weather patterns; can be natural (solar cycles take 11 years, orbital variations) OR anthropogenic.

Enhanced Greenhouse Effect = Human emissions of GHGs amplify natural greenhouse effect → shifts rainfall/snow patterns, raises temperatures, creates extreme events.

🌿 Greenhouse Gases — Key Facts

Gas	GWP (100yr)	Origin	Note
CO₂	1 (reference)	Natural + Anthropogenic	Most important anthropogenic GHG; 50% of current warming
CH₄ (Methane)	~21	Natural + Anthropogenic	2nd largest forcing; also precursor to O₃, H₂O, CO₂
N₂O (Nitrous oxide)	~310	Natural + Anthropogenic (agriculture)	Long-lived; potent
CFCs (F-gases)	Extremely high	Anthropogenic ONLY	Being phased out (Montreal Protocol); still present
Water vapour	–	Natural	Most abundant GHG; acts as FEEDBACK (not forcing); NOT counted

Warming in TROPOSPHERE while STRATOSPHERE cools = signature of greenhouse gas forcing (NOT solar). Uniformly warming all layers would indicate solar forcing.

📈 Keeling Curve

Graph of atmospheric CO₂ since 1958 — named after Dr. Charles David Keeling (Scripps Institution, UC San Diego)
Measured at Mauna Loa Observatory, Hawaii (remote → not influenced by local sources)
Sawtooth pattern: higher in spring (decomposition releases CO₂), lower in autumn (photosynthesis uptake). Also higher at NIGHT (plant respiration)
CO₂ exceeded 400 ppm in 2013 — first time in human history
Current (2023): ~421 ppm — rising at ~2 ppm/year

CO₂ has oscillated between 180-280 ppm during entire human existence on Earth. Current 421 ppm is unprecedented in 800,000 years.

🔆 Albedo

Albedo = Fraction of incoming solar radiation reflected by a surface/object. Ice/snow = HIGH albedo (reflects more). Ocean/forest = LOW albedo (absorbs more).

As sea ice melts → less albedo → more heat absorbed → more melting → POSITIVE FEEDBACK LOOP that accelerates warming.

Aerosols = tiny atmospheric particles from natural or human activities; can REFLECT incoming solar radiation → cooling effect.

🌊 Key Impacts of Climate Change

Sea level rise: thermal expansion + ice sheet melting. Since 1992, Greenland + Antarctica lost >100 billion MT ice/year on average
Arctic sea ice: September 2021 = 12th smallest ever; melt season longer; ice thinner
Permafrost: perennially frozen soil in Arctic; holds 1,460-1,600 petagrams of carbon (organic matter). Thawing releases CO₂ and CH₄ → POSITIVE FEEDBACK
Ocean acidification: oceans absorb 30% of CO₂ → 26% more acidic since industrial revolution → threatens coral, shellfish
Coral bleaching: high temperature → corals expel zooxanthellae (symbiotic algae) → turn white
Extreme weather: more frequent/intense hurricanes, floods, droughts, heat waves
Human-induced warming reached 1°C above pre-industrial around 2017; rising at 0.2°C/decade; will reach 1.5°C around 2050

⚙️ Climate Change Mitigation — CCUS

Carbon Capture, Utilization and Storage (CCUS) = Removes CO₂ from industrial flue gases and stores/uses it.

Approach	How	Advantage	Disadvantage
Pre-combustion	Convert fuel to syngas; separate CO₂ before burning	High CO₂ concentration (20-80 bar); also removes SO₂, NOₓ	High capital; cannot retrofit existing plants
Oxy-fuel combustion	Burn fuel in pure O₂; flue gas = CO₂ + H₂O only	Near-zero emission; low NOₓ	Large O₂ volumes needed; high capital + energy penalty
Post-combustion	Capture CO₂ from flue gas AFTER normal combustion	Can be RETROFITTED to existing plants (most important)	Low CO₂ concentration (~15%); large gas volumes

CO₂ separation technologies: Absorption (amine solvents), Adsorption (activated carbon, MOFs), Membrane separation, Cryogenic distillation, Chemical looping

📜 Key International Climate Agreements

Agreement	Year	Key Point
UNFCCC	1992 (Rio)	Foundational framework; basis for all subsequent agreements
Kyoto Protocol	1997	First BINDING GHG reduction targets; Annex I (developed) countries; 1st commitment 2008-2012
Paris Agreement	2015	195 countries; limit warming to 1.5-2°C; NDCs (nationally determined contributions)
IPCC established	1988	By WMO + UNEP; scientific assessments on climate change

Carbon Credits / Carbon Trading = Market mechanism where countries/companies can buy/sell rights to emit CO₂; incentivizes emission reduction.

Adaptation = Adjusting to actual/expected climate changes (reduce vulnerability). Mitigation = Reducing GHG emissions to prevent change. BOTH must be pursued simultaneously.

Renewable Energy I — Solar, Wind & Energy Overview

Lectures 21–25

⚡ Energy Trilemma (Impossible Trinity)

Security – Uninterrupted availability; resilience to supply/demand changes
Affordability – Accessible and affordable to everyone; solar is now cheapest electricity in history
Sustainability – Meeting needs without negatively impacting future generations; fossil fuels = 80% of world energy mix

Solar energy intercepted by Earth = 10,000 times greater than humanity's total energy consumption. Capture 0.1% of 0.1% → energy problem solved.

☀️ Solar Energy — CSP & PV

Concentrating Solar Power (CSP): Mirrors concentrate direct-beam solar irradiance → heat → steam → turbine → electricity. Requires high Direct Normal Irradiance (DNI). Best in near-equatorial, cloud-free regions.

Solar Photovoltaics (PV): Light (photons) → electricity (voltage) via photovoltaic effect. Silicon semiconductors create electron-hole pairs when light strikes → voltage + DC current.

Tilt angle for fixed panels = Latitude of location (general rule for India)

Winter optimal tilt = (Latitude × 0.9) + 29° OR Latitude + 15°

Summer optimal tilt = (Latitude × 0.9) – 23.5° OR Latitude – 15°

In Northern Hemisphere → face panels SOUTH (toward equator)
In Southern Hemisphere → face panels NORTH (toward equator)
Cosine Effect: When ray not perpendicular to panel → reduced energy. Loss = 1 – cos(angle of incidence)
Example: 30° angle → G⊥ = 1000 × cos(30°) = 866 W/m² → 13.4% loss
PV cell → Module → Array → System (+ Balance of System = BOS)

Solar Thermal: Flat Plate Collectors (FPC) – for moderate temperatures, lower cost; Evacuated Tube Collectors (ETC) – better insulation (vacuum), works in cold/cloudy weather, higher temperatures

Solar thermal penetration: 90% of homes in Cyprus and Israel (mandated since 1980s). Largest market: China. Typical domestic system: 300L storage, 4-6 m² collector area → covers 60-90% annual hot water demand.

💨 Wind Energy

P = ½ ρ A v³ (Power ∝ v³ — cube of wind speed)

Betz Limit = 59.3% (maximum theoretical efficiency)

Doubling wind speed → 8× power increase (cube law)
Cut-in speed: ~3-4 m/s (turbine starts producing)
Rated speed: ~11-15 m/s (turbine reaches rated power)
Cut-out speed: ~20-25 m/s (turbine stops to prevent damage)
Standard modern design: 3-blade, upwind, horizontal-axis turbine
3 blades preferred over 2: better gyroscopic balance, lower noise emissions
Upwind (blades face wind) prevents tower wake → less noise and loading
Wind shear: wind speed increases with altitude → taller towers capture more energy
Hub height increased 66% since 1990s → ~94m in 2021 (tall as Statue of Liberty)
Rotor swept areas grown 600% since 1990s
Offshore wind → stronger, more consistent winds; fixed-bottom or floating foundations

Components: Blades → Rotor hub → Rotor shaft → Gearbox → Generator → Transformer → Transmission

Speed control: Pitch control (actively adjust blade angle) or Stall control (aerodynamic braking)

World technical potential for wind exceeds global electricity production. Commercial wind power started in 1970s in Denmark, then California.

Renewable Energy II — Geothermal, Ocean Energy, Hydropower & Bioenergy

Lectures 26–30

🌋 Geothermal Energy

Greek: Geo (Earth) + Therme (Heat). Earth's core = ~5000°C. Heat extracted by drilling; brought to surface using fluids.

Classified as renewable: tapped heat continuously restored by natural heat production, conduction, convection
Advantage over solar/wind: BASELOAD (24/7); high capacity factor; small land footprint
Best locations: tectonic plate boundaries (Ring of Fire), mid-ocean ridges (Iceland, Azores), rift valleys (East African Rift), hot spots (Hawaii)

Plant Type	Resource Temp	Mechanism
Dry Steam	>150°C	Steam directly drives turbine; 8-140 MW range
Flash Steam	>180°C	Most common; flashing process to get steam; single/double/triple flash
Binary Cycle	100-170°C	Low/intermediate heat; secondary working fluid (ammonia-water)
EGS (Enhanced)	Any	Artificially created permeability via hydraulic stimulation where no natural reservoir exists

Direct use: groundwater heated by geology used directly for heating, spas, agriculture (greenhouses), food processing

Geothermal Heat Pumps (GHP): Use shallow ground temperature (stable) for building heating/cooling

🌊 Ocean Energy

40% of global population lives within 100 km of coast. 5 sources of ocean energy:

Source	Technology	Potential
Tidal (potential energy)	Tidal barrage; Tidal stream turbines	1,200 TWh/yr (lowest; geographic limits)
Wave (kinetic + potential)	OWC, oscillating bodies, overtopping devices	High
OTEC (temperature gradient)	Open, closed, hybrid cycles	44,000 TWh/yr (highest among ocean)
Salinity gradient (osmotic)	PRO, RED	1,650 TWh/yr (lowest after tidal)
Ocean current (kinetic)	Turbines in currents	Moderate

OTEC requires ΔT ≈ 20°C between surface and deep water (1000m depth). Best in tropics (30°N-30°S). Deep water stays ~4°C. OTEC = only ocean source providing BASELOAD power.

PRO (Pressure Retarded Osmosis) and RED (Reverse Electrodialysis) for salinity gradient energy. Estuaries = prime locations.

Tidal barrage: more mature technology; estuarine developments; sluice gates fill basin at high tide, release through turbines at low tide

Tidal stream: like underwater wind turbines; approaching maturity; various designs (horizontal-axis, vertical-axis, Archimedes screw, tidal kite)

💧 Hydropower

Largest renewable electricity source globally: ~16% of world's electricity; >80% of world's renewable electricity.

P = mᵥᵥ · g · Δz (potential energy) → converted to kinetic → drives turbine → electricity

Components: Dam → Intake/Penstock/Surge chamber → Turbine → Generator → Transformer → Transmission lines → Tailrace (outflow)

Hydropower lifetime: 30-80 years (many >100 years with upgrades)
Water is NOT consumed — returned downstream (multipurpose: irrigation, flood control, navigation)
World's most untapped hydropower region: Africa (92% untapped)
First hydroelectric plant: 1870, England. Commercial use: 1880, Michigan, USA

Types: Run-of-river (no storage; environmentally friendlier), Storage/reservoir, Pumped storage (store excess grid energy by pumping water uphill; release when needed)

🌾 Bioenergy

Makes up largest share of renewable energy today: ~12% of world's total final energy demand. More than half = traditional use (cooking/heating in developing countries).

Traditional use: Direct combustion of wood, animal waste, charcoal on open cookstoves (2.5 billion people mostly in sub-Saharan Africa, South Asia). Very low efficiency. Health-damaging air pollutants.
Modern use: Liquid biofuels, biogas/biomethane, wood pellets, biomass for power

Feedstock types: Agricultural (herbaceous) biomass — residues (straw, bagasse) or purpose-grown crops; Forestry (woody) biomass — trees, branches, bark

Biomass properties: ~50% carbon, 40-45% oxygen, 5-7% hydrogen. Moisture reduces energy content. High ash = equipment damage/fly ash. Lignin = structural polymer (hardwood); more in woody than herbaceous.

India's biofuel target: E20 (20% ethanol blending in petrol) by 2025. Global average palm oil consumption: 8 kg/person/year. Indonesia + Malaysia = 85% of world's palm oil production.

Industrial Ecology & Circular Economy

Lectures 31–35

🔄 Linear vs Circular Economy

Linear Economy = Take → Make → Dispose (cradle to grave). Our current dominant model. Assumes unlimited resources and unlimited waste absorption capacity.

Circular Economy = Restorative and regenerative by intention and design. Minimizes resource input and waste by slowing, closing, and narrowing material and energy loops.

Based on 3 principles: (1) Eliminate waste and pollution; (2) Circulate products at highest value; (3) Regenerate nature

Two cycles in Butterfly Diagram: Technical cycle (non-biodegradable; reuse, repair, remanufacture, recycle) + Biological cycle (biodegradable; compost, anaerobic digestion → nutrients back to nature)

🔢 The 9R Framework of Circular Economy

R	Strategy	Description
R1	Refuse	Refuse to use products that create waste
R2	Rethink	Rethink product use patterns (sharing, renting)
R3	Reduce	Use less material/energy in production and use
R4	Reuse	Use product again as-is by different user
R5	Repair	Restore product to working condition; prolongs lifetime
R6	Refurbish	Restore used product; resell to new consumers (e.g., refurbished smartphones)
R7	Remanufacture	Return to original state; same warranty as new; most energy-efficient recovery
R8	Repurpose	Use product for different application (second life cycle)
R9	Recycle	Process materials into raw materials; LAST RESORT (loses embedded product value)

Repair generates 3x turnover of original purchase. Refurbishment = moves from first to second life cycle. Remanufacturing = same warranty as new product.

🏭 5 Circular Business Models

Circular Supply Chain: Renewable/recyclable/biodegradable inputs replace linear ones. (e.g., AkzoNobel's solar reflective paint)
Product as a Service (PaaS): Company retains ownership; sells access/performance. Forms: pay-per-use, leasing, rental, performance agreement. Can reduce environmental footprint 20-90%. (e.g., Rolls Royce "Power-by-the-Hour" for jet engines)
Product Life Extension: Extend useful life through repair, refurbishment, remanufacturing
Sharing Platforms: Multiple users share one product (cars, bikes, tools)
Recovery and Recycle: Recover materials at end-of-life; recycle into new inputs

🏭 Industrial Ecology & Kalundborg Symbiosis

Industrial Ecology (IE): Emerged early 1990s. Takes ecosystem as analogy for industrial systems. Studies material and energy flows. Shifts from linear (open-loop) to closed-loop systems.

Industrial Symbiosis: One company's waste = another company's raw material. "One's trash, another's treasure." Minimum criterion: 3-2 heuristic — at least 3 entities exchanging at least 2 different resources.

Kalundborg, Denmark — World's first and most famous industrial symbiosis:

Started 1961 (Statoil water pipe to Lake Tissø)
Term "industrial symbiosis" first used in 1989
Now: 8 private/public partners; ~50 symbiotic exchanges
Partners exchange: steam, gas, gypsum, water, heat, sludge, fly ash

3 types of resource exchange in IS: (1) By-product reuse; (2) Utility/infrastructure sharing; (3) Knowledge synergies

Urban Metabolism: City as living organism with anabolism (constructive growth), catabolism (breakdown), regulatory metabolism. External metabolism (exchanges with outside) + Internal metabolism (within city).

Cities = 2-3% of land but: create 75% of world's GDP, consume 75% of natural resources, use ~67% of fossil fuels, emit 70%+ of GHGs.

Water Quality, Treatment & Wastewater Reuse

Lectures 36–40

💧 Hydrologic Cycle & Water Resources

Water Category	Percentage
Total water on Earth	1.4 million km³ (100%)
Saltwater (oceans)	97.5%
Freshwater total	2.5%
Ice caps and glaciers	68.7% of freshwater
Groundwater	30.1% of freshwater
Surface water	0.3% of freshwater
Other (soil moisture, etc.)	0.9% of freshwater
Usable freshwater	0.014% of total

Of surface water: 87% in lakes, 11% in swamps, 2% in rivers. 80-90% of withdrawn water becomes wastewater. In urban high-rise: can exceed 100% (private tube wells add to municipal discharge).

🔬 Key Water Quality Parameters — EXAM FAVOURITE

Parameter	Definition	Key Value
pH	-log[H⁺]	Drinking: 6.5-8.5. Kw = 10⁻¹⁴ at 25°C
DO (Dissolved Oxygen)	O₂ dissolved in water	Max at 0°C/0 TDS = 14.62 mg/L; 30°C = 7.56 mg/L. As temp↑ → DO↓
BOD₅ (Biochemical O₂ Demand)	O₂ consumed by microbes to degrade organic matter in 5 days at 20°C	Class A water: <2 mg/L; CPCB drinking: <2 mg/L
COD (Chemical O₂ Demand)	Total O₂ for chemical oxidation (all organic)	Always COD > BOD
ThOD	Theoretical O₂ demand (calculated from chemical formula)	ThOD ≥ COD ≥ BOD₅
Total Coliforms (MPN)	Indicator of fecal contamination	Class A: <50/100mL; Class B: <500/100mL

📊 CPCB Water Body Classification

Class	Total Coliforms	pH	DO	BOD₅	Use
A	<50 MPN/100mL	6.5-8.5	>6 mg/L	<2 mg/L	Drinking (after disinfection only)
B	<500 MPN/100mL	6.5-8.5	>5 mg/L	<3 mg/L	Outdoor bathing
C	<5000 MPN/100mL	6-9	>4 mg/L	<3 mg/L	Drinking with adequate treatment + disinfection
D	–	6.5-8.5	>4 mg/L	–	Aquatic ecosystem + wildlife; free NH₃ ≤1.2 mg/L
E	–	6-8.5	–	–	Irrigation; industrial cooling; controlled waste disposal

📉 DO Sag Curve (Streeter-Phelps)

DO deficit D = DO_saturation − DO_actual

dD/dt = k₁·L − k₂·D (rate of deficit change = deoxygenation − reaeration)

k₁ = deoxygenation rate constant (BOD removal)
k₂ = reaeration rate constant (O₂ from atmosphere)
At critical point (minimum DO = maximum deficit): k₁·L = k₂·D → dD/dt = 0
Assumptions: Plug flow (no longitudinal mixing), complete radial mixing

Nitrogen in rivers: Organic N → NH₄⁺/NH₃ (ammonia) → NO₂⁻ (nitrite) → NO₃⁻ (nitrate). Organisms: Nitrosomonas (NH₃→NO₂⁻), Nitrobacter (NO₂⁻→NO₃⁻). Nitrate = most oxidized/final form.

💧 Water & Wastewater Treatment

Drinking Water Treatment: Coagulation (Alum) → Flocculation → Sedimentation → Filtration → Disinfection (Cl₂)

Wastewater Treatment Levels:

Primary (physical): Screening, grit removal, primary sedimentation → removes 30-40% BOD, 50-70% SS
Secondary (biological): Activated Sludge Process (ASP), Trickling filters → removes 80-90% BOD
Tertiary (advanced): Nutrient removal (N, P), pathogen removal, filtration, activated carbon → removes remaining

NSF Water Quality Index (1970): 9 parameters with weights:

Parameter	Weight
Dissolved Oxygen (% saturation)	17% (highest)
Fecal coliforms	16%
pH	11%
BOD₅	11%
Temperature change	10%
Total phosphate	10%
Nitrates	10%
Turbidity	8%
Total solids	7%

⚖️ NGT & Wastewater Standards

NGT = National Green Tribunal. Established 18 October 2010 under NGT Act 2010. Principal seat: New Delhi. Other seats: Bhopal, Pune, Kolkata, Chennai. Guided by principles of natural justice.

CPCB Wastewater Discharge Standards — 4 discharge locations: Inland surface water, Public sewers, Land for irrigation, Marine/coastal environments

Key standards: SS: 100 mg/L (inland surface water); pH: 5.5-9 (all); Temperature: not more than 5°C above receiving water body temperature

NGT 2018 revised standards: Based on city classification (mega/metropolitan >1 million, Class 1 >1 lakh, others). Parameters: pH, BOD₃@27°C, TSS, COD, Total N, Total P, Fecal coliforms.

Zero Liquid Discharge (ZLD) = No wastewater discharged from facility; all wastewater treated and recycled within plant.

Eutrophication = Excess nutrients (N, P) → algal bloom → DO depletion → fish kill → ecosystem collapse. Can occur in lakes and slow rivers.

Solid Waste & E-Waste Management

Lectures 41–45

🗑️ Solid Waste — Definitions & Categories

Solid waste = Any waste NOT in liquid or gaseous state. Includes containerized liquid/gaseous waste (paint cans, pesticide containers).

Categories:

Municipal Solid Waste (MSW): From residential, commercial, institutional sources within city/town limits
Agricultural waste: ~25% of total waste in India (crop residue after harvest)
Thermal power plant waste: Bottom ash + Fly ash (PM <2.5 μm); collected by ESP, bag filters
Industrial/mining waste: Mine tailings (from metal ore extraction)
Hazardous waste: From TSDF (Treatment, Storage and Disposal Facility)
E-waste: Discarded electrical and electronic equipment
Biomedical waste: From hospitals/healthcare (sharps, infectious waste)

📊 Waste Management Hierarchy (Priority Order)

Source Reduction (Reduce) — Best option; prevent waste generation
Reuse — Use product again without processing
Recycling — Process waste into new raw materials
Recovery (Energy) — Incineration with energy recovery (Waste-to-Energy)
Treatment — Composting, anaerobic digestion, biological treatment
Disposal (Landfill) — LAST RESORT

Solid Waste Management Rules, 2016 — mandates SEGREGATION AT SOURCE into wet (biodegradable) and dry (recyclables). Also: Construction & Demolition Waste, Hazardous Waste rules.

♻️ Waste Treatment Methods

Method	Process	Output	Key Fact
Composting	Aerobic decomposition	Humus/compost	C:N ratio 25-30:1 ideal
Vermicomposting	Earthworms decompose organic waste	Vermicompost	Higher quality than regular compost
Anaerobic Digestion	Microbial breakdown without O₂	Biogas (CH₄+CO₂) + digestate	Biogas = ~50-70% CH₄
Incineration	High-temperature combustion (>800°C)	Heat/electricity + ash	Volume ↓ by 90%, weight ↓ by 70%; risk: dioxins/furans if uncontrolled
Sanitary Landfill	Engineered disposal with liner	Landfill gas (LFG); leachate	LFG = ~50% CH₄ (can be captured); leachate collected
RDF (Refused Derived Fuel)	Process MSW into pellets	Fuel for cement kilns	Removes wet fraction first

📱 E-Waste Management

E-waste = fastest growing waste stream globally
Contains valuable: gold, silver, copper, palladium, rare earth elements
Contains hazardous: Lead (solder, CRT screens), Mercury (LCD backlights), Cadmium (batteries), Hexavalent Chromium (steel), Brominated Flame Retardants (circuit boards)
India = 3rd largest e-waste generator (after China and USA)
E-Waste (Management) Rules, 2016: covers 21 categories of EEE; mandates EPR; targets for collection/recycling
Extended Producer Responsibility (EPR): manufacturers/producers responsible for take-back and recycling of products at end-of-life
Urban Mining of e-waste: 1 MT of gold ore from mining yields ~5g gold; 1 MT of mobile phones = ~150g gold — 30× more efficient!

Basel Convention (1989) — controls transboundary movement of hazardous wastes including e-waste to developing countries.

Noise Pollution — Sources, Effects, Measurement & Control

Lectures 46–50

🔊 Sound & Decibel Scale

Sound Pressure Level (L) = 10 log₁₀(I / I₀) dB

I₀ = 10⁻¹² W/m² = reference intensity (threshold of human hearing = 0 dB)

Adding 2 identical sources: L_total = L + 10·log₁₀(N) dB | Two identical = original + 3 dB

Sound Level	dB	Example
Threshold of hearing	0 dB	Silence
Whisper	30 dB	Library
Conversation	60 dB	Normal speech
Busy traffic	80-85 dB	Damage threshold
Jet engine	120 dB	Pain threshold ~130 dB

dB is LOGARITHMIC (not linear). Doubling distance from source ≈ 6 dB reduction. Every 10 dB increase = 10× more intense. Prolonged exposure >85 dB = PERMANENT hearing damage (NIHL).

📋 CPCB Noise Standards — EXAM FAVOURITE

Zone	Day (6am-10pm)	Night (10pm-6am)
Industrial	75 dB(A)	70 dB(A)
Commercial	65 dB(A)	55 dB(A)
Residential	55 dB(A)	45 dB(A)
Silence Zone (hospitals, schools, courts)	50 dB(A)	40 dB(A)

Noise Pollution (Regulation and Control) Rules, 2000. dB(A) = A-weighted decibels (accounts for human hearing sensitivity across frequencies). WHO recommends below 53 dB daytime, 45 dB nighttime outdoors.

📊 Noise Measurement Parameters

L_eq (Equivalent Sound Level): Time-averaged sound energy level over measurement period. Most common for regulatory compliance.
L_10: Level exceeded 10% of time (high peaks)
L_50: Level exceeded 50% of time (median)
L_90: Level exceeded 90% of time (background noise)
TNI (Traffic Noise Index): Accounts for variability in traffic noise = 4(L₁₀-L₉₀) + L₅₀ – 30
CNEL (Community Noise Equivalent Level): Penalizes evening and nighttime noise
Ldn (Day-Night Level): 10 dB penalty for nighttime noise (10pm-7am)

🏥 Health Effects of Noise

Auditory effects: NIHL (Noise-Induced Hearing Loss) — permanent, irreversible
Non-auditory effects: Hypertension, cardiovascular disease, sleep disturbance, stress, reduced work performance, psychological effects
TTS (Temporary Threshold Shift): temporary hearing loss after noise exposure; recovers with rest
PTS (Permanent Threshold Shift): permanent; after chronic exposure or acute trauma

Control hierarchy: Source (engineering controls — vibration damping, mufflers, enclosures) → Path (barriers, distance, absorption panels) → Receiver (PPE — ear muffs: ~25-35 dB protection, ear plugs: ~20-30 dB).

Ecology & Soil Pollution

Lectures 51–55

🌿 Ecology Fundamentals — All Key Terms

Term	Definition
Ecosystem	Biotic + abiotic components interacting as a functional unit
Food chain	Linear sequence: Producer → Primary consumer → Secondary → Tertiary
Food web	Interconnected food chains; more stable than simple chains
10% Law (Lindemann's)	Only 10% of energy at one trophic level transfers to next; 90% lost as heat/respiration
Ecological pyramid	Biomass/numbers/energy DECREASE at each higher trophic level
Bioaccumulation	Progressive increase in substance concentration within an organism over time
Biomagnification	Increasing concentration UP the food chain (e.g., DDT, mercury, PCBs)
Keystone species	Disproportionately large ecological impact relative to its abundance
Ecological succession	Sequential change in species composition; Primary (bare rock) → Secondary (disturbed ecosystem)
Climax community	Stable, self-sustaining end state of succession
Carrying capacity (K)	Maximum population an environment can sustain

DDT biomagnifies: Phytoplankton → Zooplankton → Small fish → Big fish → Birds of prey. Eagles accumulate highest concentrations → eggshell thinning → population decline.

🌍 Soil Profile & Horizons

Horizon	Name	Contents
O	Organic	Fresh and decomposing litter; humus
A	Topsoil	Humus-rich; most fertile; agricultural importance
B	Subsoil	Clay, iron, aluminum accumulation; less organic matter
C	Parent material	Weathered rock fragments
R	Bedrock	Unweathered parent rock

A horizon = most important for agriculture. Loss of A horizon = loss of agricultural productivity. Soil takes 500-1000 years to form 1 inch of topsoil naturally.

⚠️ Soil Degradation & Pollution

Degradation types:

Erosion: Water (rill, gully, sheet erosion) and wind erosion; accelerated by deforestation, overgrazing, monoculture
Salinization: Salt accumulation from irrigation with high-TDS groundwater; destroys soil structure; common in arid irrigated areas
Nutrient depletion: Rapid succession of crops without fallow; leads to poor long-term productivity
Compaction: Heavy machinery, overgrazing; reduces pore space; impedes root growth and water infiltration
Waterlogging: Excess water → anaerobic conditions → crop death

Soil pollution sources: Pesticides (DDT, organophosphates), Synthetic fertilizers (excess N, P), Heavy metals (Pb, Cd, Hg, As, Cr, Cu), Industrial effluents, Municipal solid waste dumping, Mining activities

Remediation Method	How	Example
Bioremediation	Microorganisms degrade contaminants	Bacteria breaking down petroleum
Phytoremediation	Plants absorb/contain pollutants	Sunflower (heavy metals), Indian mustard (Pb)
Soil washing	Water/solvents flush pollutants	Ex-situ washing of contaminated soil
Incineration	Burn organic pollutants	High-temperature thermal treatment
Stabilization/Solidification	Immobilize pollutants	Cement binding heavy metals

Environmental Policy, Law & EIA

Lectures 56–60

⚖️ Key Indian Environmental Laws — EXAM FAVOURITE

Law	Year	Key Provision
Wildlife Protection Act	1972	Protection of wildlife; Schedule I (highest) to VI; Project Tiger, Project Elephant
Water (Prevention & Control of Pollution) Act	1974	Established CPCB + SPCBs; set up water pollution standards
Forest Conservation Act	1980	Restriction on diversion of forest land for non-forest purposes
Air (Prevention & Control of Pollution) Act	1981	Control air pollution from industries and vehicles
Environment (Protection) Act	1986	UMBRELLA legislation; enacted after Bhopal disaster; covers all environmental media
Environment Impact Assessment (EIA)	1986/1994/2006	Under EP Act; mandatory for Category A and B projects
Hazardous Waste Management Rules	1989/2000/2008/2016	Regulates generation, storage, treatment, disposal of hazardous waste
Biomedical Waste Management Rules	1998/2016	Color-coded segregation; treatment of hospital waste
Solid Waste Management Rules	2000/2016	Mandatory source segregation; EPR for packaging waste
E-Waste Management Rules	2011/2016/2022	21 equipment categories; EPR mandatory
Noise Pollution (Regulation & Control) Rules	2000	Zone-wise noise standards
NGT Act	2010	National Green Tribunal; quasi-judicial environmental body

EP Act 1986 was enacted as direct response to Bhopal Gas Tragedy (1984) — MIC (Methyl Isocyanate) gas leak from Union Carbide plant. Largest industrial disaster in history. MC Mehta case (1991) — Supreme Court ordered environmental education mandatory at all levels.

🌐 Key International Environmental Treaties

Treaty	Year	Focus	Key Detail
Stockholm Convention on POPs	2001	Persistent Organic Pollutants	12 "dirty dozen" chemicals; elimination/restriction
Basel Convention	1989	Hazardous waste	Controls transboundary movement of hazardous waste
Rotterdam Convention	1998	Hazardous chemicals trade	Prior Informed Consent for import/export
CITES	1963/1973	Wildlife trade	Convention on International Trade in Endangered Species
Montreal Protocol	1987	Ozone layer	Phase-out of ODSs (CFCs); most successful environmental treaty
Kyoto Protocol	1997	Climate change	First binding GHG targets; Annex I countries
Paris Agreement	2015	Climate change	1.5-2°C limit; NDCs; all countries
CBD (Biodiversity)	1992	Biodiversity	Conservation; sustainable use; fair sharing of benefits

🏛️ Regulatory Bodies

Body	Level	Role
MoEFCC	National	Ministry of Environment, Forest & Climate Change
CPCB	National	Central Pollution Control Board; standards setting; monitoring
SPCB	State	State Pollution Control Boards; enforcement; consent management
NGT	National	Quasi-judicial; fast disposal of environmental cases
UNEP	International	UN Environment Programme; formed 1972 post-Stockholm
IPCC	International	Intergovernmental Panel on Climate Change; established 1988

🔍 Environmental Impact Assessment (EIA)

Mandatory under EP Act 1986 for major projects (Category A: cleared by MoEFCC; Category B: cleared by SEIA/State)
Rapid EIA: One season of baseline data; faster; less accurate
Comprehensive EIA: Full year of data across all seasons; more accurate
EIA process: Screening → Scoping → Baseline data → Impact prediction → Mitigation → EIA report → Public hearing → Decision
Public hearing: Mandatory for Category A and B1 projects
EMP (Environmental Management Plan) must accompany EIA

River Ib Barrage case study (Lecture 60): Used satellite data → micro-DEM (digital elevation model) to delineate submerged area. Combined rapid EIA methodology with remote sensing data.