Environmental Issues and Green Energy
Overview
Environmental Issues and Green Energy is a high-yield topic for TNPSC Group II/IIA, appearing consistently in both General Studies and Current Affairs sections. Questions typically test your understanding of pollution types and their control measures, India's climate commitments, renewable energy targets, and government schemes related to sustainability.
This topic bridges science, geography, and governance. You must understand the scientific basis of environmental problems (what causes air pollution, how climate change works) and also know India's policy responses (National Action Plan on Climate Change, renewable energy missions). Tamil Nadu-specific environmental initiatives—such as solar power projects and e-vehicle policies—are frequently tested.
Mastery requires memorizing key facts (pollution standards, emission targets, installed capacities) while understanding conceptual frameworks (greenhouse effect, carbon cycle, sustainable development goals). Current affairs integration is essential—international agreements like Paris Agreement and COP outcomes appear regularly.
Key Concepts
- Pollution classification: Air, water, soil, noise, and radiation pollution—each has distinct sources, effects, and control measures under specific legislation.
- Greenhouse effect and global warming: Solar radiation absorbed by Earth is re-emitted as infrared; greenhouse gases (CO₂, CH₄, N₂O, CFCs) trap this heat, raising global temperatures.
- Carbon footprint: Total greenhouse gas emissions caused by an individual, event, organization, or product, expressed in CO₂ equivalent.
- Renewable vs non-renewable energy: Renewable sources (solar, wind, hydro, biomass, geothermal) are naturally replenished; non-renewable (coal, oil, natural gas, nuclear fuel) are finite.
- Sustainable development: Development meeting present needs without compromising future generations' ability to meet theirs—balances economic growth, social equity, and environmental protection.
- Ozone layer depletion: CFCs and halons break down stratospheric ozone (O₃), increasing UV radiation reaching Earth's surface; addressed by Montreal Protocol (1987).
- Biodiversity hotspots: Regions with high endemic species concentration facing significant habitat loss—India has 4 hotspots: Western Ghats, Himalayas, Indo-Burma, Sundaland.
- Circular economy: Economic system aimed at eliminating waste through continual use of resources—reduce, reuse, recycle, recover.
Formulas / Key Facts
| Category | Key Data Points |
|---|---|
| India's RE target | 500 GW non-fossil fuel capacity by 2030 |
| Net Zero commitment | India aims for Net Zero by 2070 (COP26, Glasgow) |
| Paris Agreement | Limit warming to 1.5°C above pre-industrial levels; India's NDC: 45% emission intensity reduction by 2030 |
| Solar capacity (2024) | India has ~70+ GW installed solar capacity; Tamil Nadu among top 3 states |
| Air Quality Index | Six categories: Good (0-50), Satisfactory (51-100), Moderate (101-200), Poor (201-300), Very Poor (301-400), Severe (401-500) |
| PM2.5 and PM10 | Particulate matter ≤2.5 and ≤10 micrometers respectively; PM2.5 more dangerous as it enters bloodstream |
| BOD/COD | Biochemical/Chemical Oxygen Demand—indicators of water pollution; higher values mean more pollution |
| Noise standards | Industrial: 75 dB (day); Residential: 55 dB (day), 45 dB (night) |
Key Legislation:
- Environment Protection Act, 1986 (umbrella legislation)
- Air (Prevention and Control of Pollution) Act, 1981
- Water (Prevention and Control of Pollution) Act, 1974
- National Green Tribunal Act, 2010
Important Missions under NAPCC (8 missions):
- National Solar Mission
- National Mission for Enhanced Energy Efficiency
- National Mission on Sustainable Habitat
- National Water Mission
- National Mission for Sustaining Himalayan Ecosystem
- National Mission for Green India
- National Mission for Sustainable Agriculture
- National Mission on Strategic Knowledge for Climate Change
Worked Examples
Example 1: A factory releases effluents with BOD of 350 mg/L into a river. The permissible limit is 30 mg/L. What action can be taken?
Solution:
- BOD exceeds permissible limit by more than 10 times
- State Pollution Control Board can issue closure notice under Water Act, 1974
- NGT can impose penalties and order compensation for environmental damage
- Factory must install Effluent Treatment Plant (ETP) to reduce BOD below 30 mg/L before discharge
Example 2: Calculate the percentage of India's electricity from renewable sources if total installed capacity is 425 GW and renewable capacity is 180 GW.
Solution:
- Renewable percentage = (180/425) × 100 = 42.35%
- Note: Actual generation percentage differs from installed capacity percentage due to capacity utilization factors
Example 3: Which greenhouse gas has the highest Global Warming Potential (GWP)?
Solution:
- CO₂ has GWP of 1 (baseline)
- CH₄ (Methane) has GWP of 28-36 over 100 years
- N₂O has GWP of 265-298
- CFCs have GWP of 1000-9000
- SF₆ (Sulphur hexafluoride) has highest GWP: ~23,500
- Answer: SF₆, though CFCs are more commonly asked
Common Mistakes
- Confusing weather with climate → Weather is short-term atmospheric conditions; climate is long-term average pattern over 30+ years. Climate change refers to long-term shifts, not daily variations.
- Mixing up ozone depletion and global warming → Ozone depletion (caused by CFCs) creates holes in stratospheric ozone allowing UV radiation; global warming (caused by CO₂, CH₄) traps heat in troposphere. Different problems, different causes, different solutions.
- Assuming nuclear energy is renewable → Nuclear is non-renewable (uranium is finite) but is considered clean/low-carbon energy. Don't confuse "clean" with "renewable."
- Forgetting that India is NOT an Annex-I country → Under UNFCCC, Annex-I countries are developed nations with binding emission targets. India, as developing country, has voluntary NDCs, not legally binding targets.
- Confusing installed capacity with actual generation → Solar may have 70 GW installed capacity but generates less due to ~20% capacity utilization factor. Thermal plants have ~55-60% utilization.
Quick Reference
- NAPCC: 8 National Missions launched 2008; Solar Mission most prominent
- Paris Agreement: 1.5°C target; India's NDC: 45% emission intensity cut, 50% non-fossil electricity by 2030
- India's Net Zero: 2070 (announced at COP26 Glasgow, 2021)
- Tamil Nadu: Leading state in wind energy; among top 3 in solar
- AQI 'Severe': Above 400—health emergency, restrict outdoor activities
- Montreal Protocol: Ozone protection; Kigali Amendment (2016) added HFCs