Topic 26: Renewable Energy
The energy-transition core of the Environment paper — how India moves from fossil fuels to clean power. Scoring core: solar (National Solar Mission, ISA), wind (onshore & offshore), hydro & small-hydro, biomass, biogas & biofuels (ethanol blending), the emerging green hydrogen, and India's headline targets — 500 GW non-fossil by 2030 and the Panchamrit pledges. Built from concept to the latest Green Hydrogen Mission, PM-Surya Ghar and offshore-wind current affairs.
On this page
- 1.Renewable Energy — Concepts & Transition
- 2.Solar Energy
- 3.Wind Energy
- 4.Hydro & Small Hydro
- 5.Biomass, Biogas & Biofuels
- 6.Green Hydrogen & Emerging Sources
- 7.India's Targets & Institutions
- 8.Storage, Grid & Challenges
- 9.Policy, Finance & International
- 10.Current Affairs Link (2024–2026)
- 11.Prelims PYQ Practice
- 12.Mains PYQ Practice
- ★15-Minute Revision Box
Conceptual Clarity — Why this Topic Matters
Renewable energy is where UPSC tests the climate-energy-policy link. Three question patterns recur:
- Definitional / static: "which is a renewable source?", full forms (NSM, ISA, SECI, PM-KUSUM), define capacity factor, solar PV vs solar thermal, biofuel generations. Pure recall — a source↔feature table settles it.
- Statement-elimination (2–4 statements): matching scheme↔ministry↔target — e.g. PM-KUSUM (solar pumps), ISA (headquartered at Gurugram), Green Hydrogen Mission (2023), ethanol-blending 20% target. One wrong pairing sinks the option.
- Applied / current: 500 GW-by-2030 progress, green hydrogen, PM-Surya Ghar rooftop scheme, offshore wind bids, ISA/OSOWOG diplomacy. Mains GS-III links these to energy security, climate commitments & Atmanirbhar manufacturing (PLI).
Highest-frequency themes: solar schemes & ISA · ethanol blending & biofuel generations · green hydrogen · 500 GW / Panchamrit targets · wind (offshore) · storage & grid balancing.
1. Renewable Energy — Concepts & Transition
Renewable energy is drawn from sources that replenish naturally on a human timescale — the sun, wind, flowing water, biomass, geothermal heat and tides — unlike finite fossil fuels.
1.1 Renewable vs Non-Renewable
| Feature | Renewable | Non-renewable | Example |
|---|---|---|---|
| Replenishment | Continuous, natural | Finite, exhaustible | Solar vs coal |
| Emissions | Low/zero at use | High GHG & pollutants | Wind vs diesel |
| Cost trend | Falling (tech curve) | Volatile, rising | Solar tariff ↓ |
| Reliability | Often intermittent | Firm/despatchable | PV needs storage |
1.2 Why the Energy Transition
- Climate: decarbonise power — India's Panchamrit & net-zero-2070 pledge.
- Energy security: cut ~85% crude-oil import dependence.
- Air quality & health: replace coal/biomass combustion.
- Economics: solar & wind now cheapest new generation; jobs & PLI manufacturing.
1.3 Key Metric — Capacity Factor
Capacity Factor (CF) = actual energy generated ÷ energy if run at full rated power. Solar ~19%, wind ~25–40%, hydro ~40%, coal/nuclear ~60–80%. Low CF is why "installed capacity" (GW) ≠ "energy delivered" (GWh) — a favourite trap in Prelims.
2. Solar Energy
India receives ~5,000 trillion kWh of solar energy a year — the single largest renewable resource. Two conversion routes: solar PV (photovoltaic, direct electricity) and solar thermal / CSP (heat → steam → turbine).
2.1 PV vs Thermal
| Type | Principle | Feature | Example |
|---|---|---|---|
| Solar PV | Photovoltaic effect (semiconductor) | Modular, rooftop to utility | Bhadla Solar Park, Rajasthan |
| Solar thermal (CSP) | Concentrate sun → heat fluid | Can store heat → despatchable | Concentrated Solar Power plants |
| Solar water heater | Direct thermal use | Domestic hot water | Rooftop panels |
2.2 Key Solar Programmes
- National Solar Mission (JNNSM, 2010): flagship under NAPCC; scaled target to 100 GW solar within the 175 GW (2022) goal.
- PM-KUSUM: solar pumps & grid-connected solar for farmers — de-dieselising agriculture.
- PM-Surya Ghar: Muft Bijli Yojana (2024): rooftop solar for 1 crore households, free units up to a limit.
- Solar parks & PLI: ultra-mega parks (Bhadla, Pavagada); PLI for domestic solar-cell/module manufacturing (Atmanirbhar).
- International Solar Alliance (ISA): India–France initiative (2015, COP21), HQ at Gurugram — treaty-based body of solar-rich (sunbelt) nations.
3. Wind Energy
Wind is India's second-largest RE source. Kinetic energy of wind turns turbine blades → generator. Output rises with the cube of wind speed, so siting is critical.
3.1 Onshore vs Offshore
| Type | Location | Feature | Example |
|---|---|---|---|
| Onshore | Land (windy states) | Mature, cheaper | Muppandal, Tamil Nadu |
| Offshore | Sea (coastal shelf) | Higher, steadier winds; costly | Gujarat & TN coast bids |
3.2 Key Points
- Leading states: Tamil Nadu, Gujarat, Karnataka, Rajasthan, Maharashtra — the wind corridor of peninsular/western India.
- Repowering: replacing old small turbines with modern high-capacity ones on existing sites.
- Offshore wind policy: National Offshore Wind Policy (2015); VGF support and targets off Gujarat & Tamil Nadu; NIWE is the nodal technical body.
- Hybrid: wind-solar hybrid parks smooth output and share transmission.
4. Hydro & Small Hydro
Hydropower converts the potential/kinetic energy of moving water into electricity. It is firm and despatchable, and pumped-storage hydro acts as a giant battery for balancing intermittent solar/wind.
4.1 Classification
| Type | Capacity | Feature | Example |
|---|---|---|---|
| Large hydro | >25 MW | Firm power + storage; ecological concerns | Tehri, Bhakra |
| Small hydro (SHP) | ≤25 MW | Counted as RE under MNRE | Himalayan & W.Ghats streams |
| Pumped storage (PSP) | Variable | Stores surplus RE; grid balancing | Off-peak pump, peak generate |
4.2 Key Points
- RE definition: only small hydro ≤25 MW is classed as "renewable" by MNRE; large hydro was separately declared RE (2019) for RPO purposes.
- Advantages: zero fuel cost, long life, flood control & irrigation co-benefits, black-start capability.
- Concerns: submergence, displacement, seismicity in Himalayas, altered river ecology & sediment flow.
- Pumped-storage push: central to firming a high-RE grid; new PSP guidelines to enable round-the-clock clean power.
5. Biomass, Biogas & Biofuels
Bio-energy uses organic matter — crop residue, wood, animal & municipal waste — for heat, power or transport fuel. It is central to rural energy and to India's ethanol-blending drive.
5.1 Forms of Bio-energy
| Form | Feedstock | Use | Scheme/Example |
|---|---|---|---|
| Biomass power | Crop residue, husk | Grid electricity, cuts stubble burning | Biomass co-firing in thermal plants |
| Biogas | Cattle dung, food waste | Cooking gas, CBG | GOBARdhan, SATAT (CBG) |
| Bio-ethanol | Sugarcane, grains, cellulose | Blended in petrol (E20) | Ethanol Blending Programme |
| Bio-diesel | Non-edible oils (jatropha, UCO) | Blended in diesel | National Biofuel Policy 2018 |
5.2 Biofuel Generations
- 1st generation: from food crops (sugarcane, corn) — raises food-vs-fuel concern.
- 2nd generation (2G): from non-food crop residue/cellulose — e.g. 2G ethanol from paddy straw (Panipat bio-refinery).
- 3rd generation: from algae — high yield, research stage.
5.3 Ethanol Blending
- Target: 20% ethanol in petrol (E20) — advanced from 2030 to 2025–26.
- Benefits: cuts crude imports, lowers emissions, supports farmers & sugar sector.
- SATAT & GOBARdhan: compressed biogas (CBG) from waste for transport & clean cooking.
6. Green Hydrogen & Emerging Sources
Beyond the big four lie the frontier renewables — above all green hydrogen, plus geothermal, tidal and ocean-thermal energy.
6.1 Hydrogen Colour Code
| Colour | Source | Emissions |
|---|---|---|
| Grey | Fossil gas (SMR), no capture | High CO₂ |
| Blue | Fossil + carbon capture | Lower |
| Green | RE-powered electrolysis of water | Zero at production |
6.2 National Green Hydrogen Mission (2023)
- Target: 5 MMT/year green-hydrogen production capacity by 2030; ~125 GW added RE.
- Use: hard-to-abate sectors — refineries, fertiliser (ammonia), steel, long-haul transport, shipping.
- Tools: SIGHT incentives for electrolysers & H₂ production; export ambition.
6.3 Other Emerging Sources
| Source | Principle | India status |
|---|---|---|
| Geothermal | Earth's internal heat | Puga (Ladakh), Tattapani (Chhattisgarh) |
| Tidal | Rise/fall of tides | Gulf of Kutch, Khambhat potential |
| Wave | Ocean-surface waves | Pilot stage |
| OTEC | Ocean thermal gradient | R&D (NIOT) |
7. India's Targets & Institutions
India's renewable push runs on headline climate targets executed by a dedicated institutional stack.
7.1 Headline Targets
| Commitment | Target | Source/Year |
|---|---|---|
| Non-fossil capacity | 500 GW by 2030 | Panchamrit, COP26 (2021) |
| RE share of energy | 50% of installed capacity by 2030 | Updated NDC |
| Emissions intensity | Cut 45% (vs 2005) by 2030 | Updated NDC (2022) |
| CO₂ avoided | 1 billion tonnes by 2030 | Panchamrit |
| Net-zero | By 2070 | Panchamrit |
7.2 The Panchamrit (COP26, 2021)
- 500 GW non-fossil capacity by 2030.
- 50% of energy from renewables by 2030.
- Reduce projected emissions by 1 billion tonnes by 2030.
- Cut emissions intensity of GDP by 45% by 2030.
- Net-zero by 2070.
7.3 Key Institutions
| Body | Role |
|---|---|
| MNRE | Nodal ministry for renewable energy |
| SECI | Solar Energy Corporation of India — tenders/off-take |
| IREDA | Indian Renewable Energy Development Agency — financing |
| NIWE | National Institute of Wind Energy |
| NISE | National Institute of Solar Energy |
| ISA | International Solar Alliance (HQ Gurugram) |
8. Storage, Grid & Challenges
Solar & wind are intermittent — the biggest barrier to a high-RE grid is matching variable supply to demand. Storage and grid-firming are the frontier.
8.1 Storage Options
| Option | How | Use |
|---|---|---|
| Battery (BESS) | Chemical (Li-ion) | Short-duration, fast response |
| Pumped hydro (PSP) | Water uphill/downhill | Bulk, long-duration |
| Green hydrogen | Store energy as H₂ | Seasonal, hard-to-abate |
8.2 Key Challenges
- Intermittency & the "duck curve": midday solar glut, evening demand peak — needs storage/flexible backup.
- Grid integration: transmission to load centres, Green Energy Corridors, forecasting.
- Land & water: large solar/wind footprints; land acquisition delays.
- Discom finances: weak state distribution utilities delay RE payments (a key investment risk).
- Manufacturing & imports: dependence on imported solar cells/modules — addressed via PLI & ALMM.
- E-waste: end-of-life solar panels & batteries need recycling (links to Topic 24).
9. Policy, Finance & International
Renewable growth is powered by a policy-and-finance ecosystem and India's clean-energy diplomacy.
9.1 Domestic Policy & Incentives
- RPO & REC: Renewable Purchase Obligation on discoms; tradable Renewable Energy Certificates.
- PLI schemes: for high-efficiency solar modules & advanced-chemistry batteries (domestic manufacturing).
- ALMM: Approved List of Models & Manufacturers — quality & local-content gate.
- Green Energy Corridors: transmission to evacuate RE-rich zones.
- Waiver of ISTS charges: interstate-transmission incentive for solar/wind & green hydrogen.
9.2 International Initiatives
| Initiative | Focus |
|---|---|
| ISA | Coalition of solar-rich nations (India-France, 2015) |
| OSOWOG | One Sun One World One Grid — trans-national solar grid |
| Green Grids Initiative | Launched at COP26 with UK |
| Mission Innovation / CDRI | Clean-energy R&D & resilient infrastructure |
| Global Biofuels Alliance | Launched at G20 New Delhi (2023) |
10. Current Affairs Link (2024–2026)
Renewable energy is one of the most dynamic areas of the Environment paper — almost every year brings a new scheme, target milestone or global initiative. Verify the latest figures before the exam.
10.1 Recent Developments
| Development | Year | Exam relevance |
|---|---|---|
| PM-Surya Ghar: Muft Bijli Yojana check latest | 2024 | Rooftop solar for 1 crore homes, free units |
| National Green Hydrogen Mission progress check latest | 2023–26 | SIGHT incentives, electrolyser bids, 5 MMT goal |
| 500 GW non-fossil milestone tracking check latest | 2024–26 | Progress vs 2030 target, RE crossing ~200+ GW |
| Offshore wind bids (Gujarat, TN) | 2024–25 | VGF support, first offshore capacity |
| Global Biofuels Alliance (G20) | 2023 | India-led, ethanol diplomacy |
| E20 ethanol-blending advanced | 2025–26 | 20% blend target pulled forward |
| PSP & BESS storage guidelines | 2024–26 | Firming intermittent RE, viability-gap funding |
10.2 Recurring Exam Hooks
- India's non-fossil target for 2030? (500 GW)
- Net-zero year? (2070, Panchamrit)
- ISA headquarters? (Gurugram, India)
- Cleanest hydrogen? (green — RE electrolysis)
- Small-hydro RE cut-off? (≤25 MW)
- Ethanol-blend flagship? (E20 by 2025-26)
- Alliance launched at G20 Delhi 2023? (Global Biofuels Alliance)
11. Prelims PYQs
Q: Which of the following is not a renewable source of energy?
Ans: (c) — Natural gas is a fossil (non-renewable) fuel. Solar, wind and small hydro replenish naturally.
Q: The International Solar Alliance (ISA) is headquartered at:
Ans: (c) — ISA HQ is at Gurugram (National Institute of Solar Energy campus). Co-founded by India & France in 2015.
Q: "Green hydrogen" is produced by:
Ans: (c) — Green H₂ = electrolysis powered by renewables. Grey = SMR of gas; blue = fossil + capture.
Q: Under MNRE, "small hydro" projects are those with capacity up to:
Ans: (b) — Small hydro ≤25 MW is classed as renewable under MNRE; larger hydro is under the Ministry of Power.
Q: Consider India's Panchamrit commitments (COP26): 1. 500 GW non-fossil capacity by 2030 2. Net-zero emissions by 2070 3. 50% of energy from renewables by 2030. Which are correct?
Ans: (d) — All three are Panchamrit pledges — along with cutting 1 bn tonnes CO₂ and 45% emissions-intensity reduction.
Q: The scheme PM-KUSUM is primarily aimed at:
Ans: (b) — PM-KUSUM de-dieselises agriculture via solar pumps & farm-based solar. Rooftop = PM-Surya Ghar.
Q: "2G ethanol", promoted in India's biofuel policy, is produced from:
Ans: (c) — 2G ethanol uses non-food cellulosic residue (e.g. paddy straw) — avoids food-vs-fuel conflict. 1G = food crops; 3G = algae.
Q: The Global Biofuels Alliance was launched at the:
Ans: (b) — India launched the Global Biofuels Alliance at the G20 New Delhi Summit (2023) with the US & Brazil.
Likely: PM-Surya Ghar (rooftop) targets, National Green Hydrogen Mission (SIGHT) numbers, ALMM/PLI for solar manufacturing, and round-the-clock RE + storage (BESS/PSP) mandates are hot hooks — expect scheme-to-objective matching. check for latest update or data
12. Mains PYQs + Model Answers
Questions below are original, exam-style formulations built from real UPSC GS-III themes — paraphrased to be copyright-safe. Each framework = intro angle → structured body → way-forward, with examples to quote.
Q: "India's target of 500 GW non-fossil capacity by 2030 is ambitious but achievable." Critically examine.
Model Answer Framework
- Introduction — context: Panchamrit pledge; current ~200+ GW RE base, falling tariffs.
- Enablers: cheap solar/wind, PLI manufacturing, PM-Surya Ghar, green-hydrogen mission, strong policy stack.
- Challenges:
- Storage & grid intermittency, discom finances, land acquisition, import dependence, financing.
- Conclusion: scale BESS/PSP, strengthen discoms, Green Energy Corridors, domestic manufacturing.
Q: Discuss the significance of green hydrogen for India's decarbonisation and the challenges to its scale-up.
Model Answer Framework
- Introduction — what: RE-electrolysis H₂; National Green Hydrogen Mission, 5 MMT by 2030.
- Significance: decarbonises hard-to-abate sectors (steel, ammonia, refineries, shipping); energy security; export potential.
- Challenges: high cost, electrolyser imports, water use, storage/transport, demand off-take.
- Conclusion: SIGHT incentives, demand mandates, R&D, port hubs.
Q: "Storage, not generation, is the real bottleneck of India's renewable transition." Comment.
Model Answer Framework
- Introduction — premise: solar/wind already cheapest but intermittent (duck curve).
- Storage options: BESS (short), pumped hydro (bulk), green H₂ (seasonal).
- Barriers: battery cost/imports, PSP site & clearances, grid flexibility.
- Conclusion: storage obligations, VGF, ACC-battery PLI, round-the-clock RE tenders.
Q: Examine how the ethanol-blending programme advances India's energy and rural-economy goals.
Model Answer Framework
- Introduction — goal: E20 by 2025-26 — blend ethanol in petrol.
- Benefits: cut crude imports & forex, lower emissions, farmer income, sugar-sector stability.
- Concerns: food-vs-fuel, water-intensive cane, engine compatibility.
- Conclusion: 2G/cellulosic ethanol, diversified feedstock, GOBARdhan/CBG.
Q: "Through the ISA and OSOWOG, India is turning solar energy into an instrument of global diplomacy." Discuss.
Model Answer Framework
- Introduction — vehicles: ISA (solar-rich nations, HQ Gurugram), OSOWOG (trans-national grid), Global Biofuels Alliance.
- Strategic gains: leadership of Global South, green-tech markets, climate credibility, countering rivals.
- Challenges: financing developing nations, manufacturing competition, grid interconnection.
- Conclusion: soft-power + climate action + Atmanirbhar manufacturing in one frame.
Q: India's solar-manufacturing push (PLI, ALMM) seeks to cut import dependence while meeting the 500 GW goal. Examine the trade-offs between rapid deployment and Atmanirbhar supply chains. check for latest update or data
15-Minute Revision Box
Must-Remember Facts — Renewable Energy
- Renewables: solar, wind, hydro, bio, geothermal, tidal — naturally replenished, low emissions.
- Capacity factor: solar ~19%, wind ~25-40%, hydro ~40% — GW ≠ GWh.
- Wind: TN & Gujarat lead; output ∝ speed³; offshore emerging (NIWE).
- Hydro: small = ≤25 MW (RE under MNRE); PSP = storage.
- Green H₂: RE-electrolysis; Mission 2023, 5 MMT by 2030; hard-to-abate sectors.
- Solar: NSM (2010), PM-KUSUM (pumps), PM-Surya Ghar (rooftop 2024), ISA (HQ Gurugram), OSOWOG.
- Bio: E20 by 2025-26; 1G food, 2G residue, 3G algae; GOBARdhan/SATAT (CBG).
- Targets (Panchamrit, COP26): 500 GW non-fossil by 2030; net-zero 2070; 50% RE; 45% intensity cut; 1 bn t CO₂ avoided.
- Institutions: MNRE, SECI, IREDA, NIWE, NISE; RPO/REC, PLI, ALMM.
- Challenge core: storage + grid + discom health, not generation cost.