Introduction: The Renewable Revolution
Renewable energy technologies are at the forefront of the global transition towards a sustainable and low-carbon future. They offer a critical pathway to mitigate climate change, enhance energy security, and foster green economic growth.
India, a nation with abundant renewable energy resources and ambitious climate targets, has emerged as a global leader in this transition. This module comprehensively explores key renewable energy sources, detailing their working principles, applications, advantages, and associated challenges. A significant focus is placed on India's national missions and schemes driving the accelerated adoption and indigenous development of these technologies, while also addressing the socio-economic and environmental implications of this transformative shift.
India's Commitment
India aims for Net Zero emissions by 2070 and targets 500 GW of non-fossil fuel energy capacity by 2030, showcasing its dedication to a sustainable energy landscape.
Solar Energy: Harnessing the Sun
Solar energy, harnessing sunlight, is the most abundant renewable energy source and a key component of India's energy strategy. India's total solar installed capacity reached over 73 GW by March 2024.
Photovoltaic (PV) Technology
Working Principle (Photovoltaic Effect):
Types of PV Cells:
Monocrystalline Silicon
Single pure silicon crystal. Efficiency: ~18-22%. Sleek black, higher cost.
Polycrystalline Silicon
Multiple silicon fragments. Efficiency: ~15-18%. Bluish, lower cost. Most common in India.
Thin-film Solar Cells
Thin semiconductor layers (CdTe, a-Si, CIGS). Efficiency: ~10-14%. Flexible, lightweight.
Solar Panels (Modules): PV cells connected in series/parallel.
Inverters: Convert DC electricity from panels to AC electricity for homes/grid.
Solar Thermal Technology
Uses sunlight to generate heat, rather than directly converting it to electricity.
Concentrated Solar Power (CSP):
Uses mirrors/lenses to concentrate sunlight onto a small area, converting sunlight into heat. This heat drives a steam turbine to generate electricity.
Parabolic Troughs
U-shaped mirrors focus sunlight onto a receiver tube with heat-transfer fluid.
Power Towers
Sun-tracking mirrors (heliostats) focus sunlight onto a central tower receiver.
Advantages of CSP: Can incorporate thermal energy storage (molten salt) for continuous power.
Disadvantages of CSP: Large land area, high capital cost, best for high DNI areas.
Other Solar Thermal Applications:
- Solar Water Heaters: Heat water directly for domestic/industrial use.
- Solar Cookers: Use concentrated sunlight for cooking.
Jawaharlal Nehru National Solar Mission (JNNSM)
2010
Launched as part of National Action Plan on Climate Change (NAPCC). Initial Target: 20 GW by 2022.
2015
Revised Target: Increased to 100 GW of solar power by 2022 (60 GW large-scale, 40 GW rooftop).
March 2024
Achievements: India's solar installed capacity > 73 GW. Dramatic price drop in solar tariffs. Spurred co-founding of ISA.
Key Solar Schemes in India:
PM-KUSUM
Promotes solar energy for farmers: solarizes agricultural pumps, standalone pumps, grid-connected solar plants on barren lands. Reduces diesel use, enhances farmer income.
PM-Surya Ghar: Muft Bijli Yojana
Promotes residential rooftop solar. Target: 1 Crore households by 2026. Offers Central Financial Assistance (CFA).
Solar Park Scheme
Facilitates large-scale solar projects in dedicated zones (solar parks) with common infrastructure. Target: 50 GW capacity in 65 parks by 2026.
International Solar Alliance (ISA)
Co-founded by India & France (2015). HQ: Gurugram. Mobilizes solar tech deployment globally. Open to all UN members.
Advantages of Solar Energy
- Clean & Renewable (no GHG emissions during operation)
- Reduces import dependence, enhances energy security
- Decentralized potential (rooftop, off-grid)
- Low operational cost (free fuel)
- Significant job creation potential
Disadvantages of Solar Energy
- Intermittency (daytime/clear skies only), requires storage
- Large land requirement for utility-scale farms
- High initial capital cost (though falling)
- Efficiency variations (insolation, temperature, dust)
- Grid integration challenges for variable input
- E-waste from panel disposal at end-of-life
Wind Energy: Capturing the Breeze
Wind energy harnesses the kinetic energy of wind for electricity generation. India's installed wind power capacity is over 45 GW by March 2024.
Working Principle & Types
Working Principle: Wind turns the blades of a turbine, which spins a rotor connected to a generator, producing electricity.
Types of Wind Turbines:
Horizontal Axis Wind Turbines (HAWT)
Most common. Blades like airplane propellers. Rotor shaft horizontal.
Vertical Axis Wind Turbines (VAWT)
Rotor shaft vertical. Captures wind from any direction. Generally less efficient for large scale.
Onshore Wind Farms
Turbines located on land. India has significant potential in states like Tamil Nadu, Gujarat, Karnataka.
Challenges:
- Land availability
- Visual impact & noise pollution
- Impact on local ecosystems
- Fluctuating wind resources
Offshore Wind Farms
Turbines in coastal waters. India has substantial potential along Gujarat and Tamil Nadu coasts.
Advantages:
- Higher & more consistent wind speeds
- Less visual/noise impact on populations
- Larger turbines possible
Challenges:
- Higher installation/maintenance costs
- Complex grid connection, harsh marine environment
- Impact on marine ecosystems
National Offshore Wind Energy Policy (2015)
Objective: To develop offshore wind power in India. MNRE is nodal ministry, National Institute of Wind Energy (NIWE) is nodal agency for resource assessment.
Advantages of Wind Energy
- Clean & Renewable
- Energy Security
- Low Operational Cost
- Distributed Potential
Disadvantages of Wind Energy
- Intermittency
- Visual & Noise Pollution (onshore)
- Impact on Wildlife (birds, bats)
- Land Requirement (onshore)
- High Initial Capital Cost
- Grid Integration Challenges
Biomass & Biofuels: Organic Power
Biomass energy uses organic matter for power/heat, and biofuels are liquid/gaseous fuels derived from biomass.
Biomass Sources & Conversion
Sources:
- Agricultural Residue (paddy straw, bagasse)
- Forest Waste (wood chips)
- Municipal Solid Waste (MSW - organic fraction)
- Industrial Waste (agro-industries)
- Energy Crops (jatropha, switchgrass)
Conversion Technologies:
Combustion: Direct burning for heat/power.
Gasification: Converts biomass to syngas.
Anaerobic Digestion: Produces Biogas (methane).
Pyrolysis: Produces bio-oil, bio-char.
Biofuel Generations:
1st Generation
From edible food crops (sugarcane, corn). Faces "Food vs. Fuel" debate.
2nd Generation (Advanced)
From non-food lignocellulosic biomass (agri residues, forest waste). Overcomes food vs. fuel.
3rd Generation
From algae. High yield, minimal land use.
4th Generation
Genetically engineered algae/microbes for enhanced production & carbon capture (Research stage).
Bioethanol
Produced by fermentation of sugars/starch. Ethanol Blending Program (EBP) Target: 20% ethanol blending in petrol (E20) by 2025-26.
India is promoting Flex-fuel Vehicles (FFVs) to support E20.
Biodiesel
From transesterification of vegetable oils (non-edible like Jatropha, Pongamia) or animal fats. National Biodiesel Mission promotes it.
Progress slower than ethanol due to feedstock challenges.
Biogas (Gobar Gas)
Primarily Methane (CH₄) and CO₂. Produced by anaerobic digestion of organic matter.
Benefits:
- Clean cooking fuel (reduces indoor air pollution)
- Organic fertilizer (digestate)
- Waste management
- Rural employment & sanitation (Gobar-Dhan scheme)
National Policy on Biofuels (2018, amended 2022)
Aims to promote indigenous biofuel production, reduce crude oil imports, address environmental concerns. Key target: E20 by 2025-26, allows more feedstocks, promotes 2G ethanol.
Advantages of Biomass/Biofuels
- Renewable (from biological sources)
- Potentially carbon neutral (lifecycle basis)
- Waste utilization
- Rural employment
Disadvantages of Biomass/Biofuels
- Food vs. Fuel debate (1st Gen)
- Land Use Change (LUC), deforestation risk
- High energy intensity for production
- Water consumption for some crops
- Air pollution (particulate matter from burning)
Hydropower: Energy from Water's Flow
Hydropower generates electricity by harnessing the energy of flowing water. India's installed hydropower capacity is around 47 GW by March 2024 (including large hydro).
Working Principle & Types
Working Principle: Water from a reservoir flows through a penstock (pipe), spinning a turbine connected to a generator, producing electricity.
Types of Hydropower:
Large Hydro
Large dams and reservoirs (>25 MW). Significant storage.
Small Hydro
Projects between 1 MW and 25 MW.
Micro/Pico Hydro
Very small scale (<1 MW). Often run-of-river, for remote areas.
India has significant hydropower potential, particularly in the Himalayan region and Northeast.
Advantages of Hydropower
- Clean & Renewable (no GHG emissions during operation)
- Reliable baseload power, flexible & dispatchable
- Load balancing for grid stability
- Multi-purpose (irrigation, flood control, water supply)
- Long lifespan of plants
Disadvantages of Hydropower
- Environmental Impact: Ecological disruption (aquatic life, fish migration), deforestation, reservoir-induced seismicity, sedimentation.
- Social Impact: Displacement & rehabilitation issues, loss of fertile land.
- High initial capital cost & long gestation period.
- Climate vulnerability (dependent on rainfall).
Geothermal Energy: Earth's Inner Heat
Geothermal energy taps into the Earth's internal heat. Heat from magma or hot rocks heats underground water, producing steam/hot water for turbines or direct heat applications.
Potential & Types
Types of Geothermal Resources:
- Hydrothermal (Wet): Most common. Hot water/steam reservoirs near surface.
- Petrothermal (Hot Dry Rock): Hot dry rocks; water injected to extract heat.
- Geopressured: Deep reservoirs of hot, pressurized brine with dissolved methane.
Potential in India:
Moderate to low, but promising sites include Puga Valley (Ladakh), Tattapani (Chhattisgarh), Cambay Graben (Gujarat), Godavari Basin.
Advantages of Geothermal Energy
- Clean & Renewable
- Baseload Power (available 24/7)
- Small land footprint per MWh
- High capacity factor
Disadvantages of Geothermal Energy
- Site-specific (limited to geothermal reservoirs)
- High initial capital cost (drilling)
- Minor emissions (H₂S, CO₂ from fluids)
- Potential for induced seismicity
- Reservoir depletion over time if over-extracted
Ocean Energy: Power from the Seas
Ocean energy harnesses the energy of ocean movements and temperature differences. Potential in India includes Tidal (Gulf of Khambhat/Kutch, Sunderbans), Wave (coastline), OTEC (Lakshadweep).
Tidal Energy
Uses rise/fall of tides. Technologies: Tidal Barrages (dam-like), Tidal Stream Turbines (underwater wind turbines).
Wave Energy
Harnesses energy of ocean waves. Various technologies (oscillating water columns, point absorbers).
OTEC (Ocean Thermal Energy Conversion)
Uses temperature difference between warm surface and cold deep seawater to drive a heat engine.
Challenges of Ocean Energy
- High capital cost
- Harsh marine environment (corrosion, biofouling, storms)
- Intermittency (tidal/wave predictable but variable)
- Potential environmental impact on marine ecosystems
- Technological maturity (many technologies in early stages)
Green Hydrogen: The Future Fuel
Green Hydrogen is emerging as a critical energy carrier for decarbonization, particularly for hard-to-abate sectors.
Understanding Hydrogen Types
Hydrogen is classified by its production method and associated carbon emissions:
Green Hydrogen Production
Process: Electrolysis – Using an electrolyzer to split water (H₂O) into hydrogen (H₂) and oxygen (O₂) using electricity from renewable sources (solar, wind).
Storage, Transport & Applications:
Storage/Transport
- Compressed Gas (high-pressure tanks)
- Liquefied Hydrogen (LH2 at -253°C)
- Chemical Carriers (Ammonia, Methanol)
- Metal Hydrides
Fuel Cells for Transport
FCEVs (cars, buses, trucks, trains, ships). Produces water & heat.
Industry Feedstock
Decarbonizing fertilizers (green ammonia), refining, steel production, methanol.
Energy Storage & Power Gen
Long-term storage for renewables. Hydrogen in gas turbines or fuel cells for electricity.
National Hydrogen Mission (NHM)
Approved Jan 2023. Nodal Ministry: MNRE. Objective: Make India a global hub for Green Hydrogen.
Targets by 2030:
- Production: 5 MMT Green Hydrogen per annum
- Renewable Energy Capacity: Add ~125 GW
- Investment: Attract > ₹8 Lakh Crore
- Job Creation: > 6 Lakh jobs
- Emissions Reduction: ~50 MMT annual GHG
Focus Areas (SIGHT Program): Incentivize electrolyzer manufacturing & Green Hydrogen production, pilot projects, R&D.
Opportunities for Green Hydrogen
- Abundant renewables in India
- Decarbonize hard-to-abate sectors
- Enhance energy security
- Export potential (green ammonia)
- Job creation, strategic advantage
Challenges for Green Hydrogen
- High cost of production (vs. grey)
- Energy-intensive electrolysis
- Lack of infrastructure (production, storage, transport)
- Technological gaps, need for R&D
- Water availability for large-scale production
- Safety concerns (hydrogen is flammable)
Prelims Quick Recap
Solar
PV (Mono/Poly/Thin-film), Inverters. Thermal (CSP, Heaters). JNNSM (100GW by 2022, >73GW Mar'24). PM-KUSUM, PM-Surya Ghar. ISA (HQ Gurugram).
Wind
HAWT/VAWT. Onshore/Offshore. >45GW Mar'24. National Offshore Wind Policy 2015. Intermittent, wildlife impact.
Biomass/Biofuels
Sources (Agri/MSW). Conversion (Combustion, Gasification, Anaerobic Digestion-Biogas). Biofuel Gens (1G-4G). EBP (E20 by 2025-26). National Policy on Biofuels 2018 (amended 2022). Food vs Fuel debate.
Hydropower
Large/Small/Micro. ~47GW. Baseload, multi-purpose. Env/Social impacts (displacement).
Geothermal
Earth's heat. Puga Valley, Tattapani. Baseload. Site-specific, high capital.
Ocean
Tidal, Wave, OTEC. Potential: Khambhat/Kutch (Tidal). High cost, tech maturity.
Green Hydrogen
Electrolysis + RE. Types (Grey, Blue, Green). NHM (2023): 5 MMT by 2030, 125 GW RE. SIGHT program. Apps: Transport, Industry. Challenges: Cost, infra.
Analytical Insights for Mains
Major Debates & Discussions
- Intermittency & Grid Integration: Balancing variable renewables with grid stability using storage and flexible power.
- Land Use Conflicts: Competition between large RE projects and agriculture/forests.
- Food vs. Fuel (Biofuels): Ethical and economic impacts of using food crops for fuel.
- Green Hydrogen Cost: High production cost vs. fossil-based hydrogen, need for scale-up incentives.
- Hydropower's Dilemma: Balancing clean energy with social (displacement) and environmental costs.
- Just Transition: Ensuring equitable shift from fossil fuels, supporting affected communities.
Long-term Trends & Significance
- Shift to Distributed Power: Rise of rooftop solar enabling decentralized generation.
- Falling Costs & Efficiency Gains: Making solar PV and wind increasingly competitive.
- Policy Evolution: Growing commitment reflected in comprehensive missions and targets.
- Climate Change Mitigation: RE central to India's Net Zero by 2070 & Paris Agreement.
- Energy Security: Reducing fossil fuel import dependence.
- Economic Growth & Rural Development: Green jobs, new industries, empowering rural areas.
- Technological Leadership: India's role in ISA & NHM.
Recent Developments (Last 1 Year)
February 2024
PM-Surya Ghar: Muft Bijli Yojana Launched
New rooftop solar scheme targeting 1 Crore households, aiming for free electricity up to 300 units/month.
January 2023
National Hydrogen Mission (NHM) Approved
Outlay of ₹19,744 crore. Aims for 5 MMT Green Hydrogen production by 2030, supporting electrolyzer manufacturing.
Ongoing 2023-24
Acceleration of Ethanol Blending Program (EBP)
Rapid progress towards E20 target (20% ethanol blending by 2025-26). Increased ethanol production and availability.
Ongoing 2023-24
Record Renewable Energy Capacity Additions
India crossed 180 GW total renewable energy capacity (excluding large hydro) by March 2024.
Ongoing
Progress in Offshore Wind Energy Exploration
MNRE efforts to identify potential zones (Gujarat, Tamil Nadu) and invite expressions of interest.
UPSC Previous Year Questions
Prelims 2023
Q. "The development of technologies for producing 'Green Hydrogen' is crucial for India to achieve its target of Net Zero by 2070." This statement is:
- (a) Correct, as green hydrogen is a key component of India's low-carbon energy transition strategy.
- (b) Incorrect, as India primarily relies on Blue Hydrogen for its energy needs.
- (c) Correct, but green hydrogen is mainly for power generation, not for Net Zero target.
- (d) Incorrect, as India has no targets for Net Zero.
Hint: Green Hydrogen is vital for India's Net Zero goal and decarbonization strategy.
Mains 2023 (GS Paper III)
Q. "The development of technologies for producing 'Green Hydrogen' is crucial for India to achieve its target of Net Zero by 2070." Discuss.
Show HintTest Your Understanding
Original MCQ for Prelims
Q. Consider the following statements regarding 'Green Hydrogen':
- It is produced by electrolysis of water using electricity generated from fossil fuels with carbon capture.
- The National Hydrogen Mission aims to produce 5 Million Metric Tonnes of Green Hydrogen per annum by 2030.
- Flex-fuel vehicles are primarily designed to run on Green Hydrogen.
Which of the statements given above is/are correct?
- (a) 1 and 2 only
- (b) 2 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Explanation: Statement 1 is incorrect; Green Hydrogen uses renewable energy for electrolysis (fossil fuels with CCUS is Blue Hydrogen). Statement 3 is incorrect; Flex-fuel vehicles run on petrol-ethanol blends. Statement 2 is a correct target of NHM.
Original Descriptive Question for Mains
Q. "India's ambitious target of Net Zero by 2070 places renewable energy technologies at the core of its energy transition." Discuss the role of solar and wind energy in achieving India's renewable energy targets. Critically analyze the key challenges associated with their large-scale integration into the national grid and environmental concerns. (15 marks, 250 words)
Show Key Points- Introduction: India's Net Zero target, RE's central role.
- Role of Solar: PV & Thermal, capacity, schemes (JNNSM, PM-KUSUM, PM-Surya Ghar), benefits.
- Role of Wind: Onshore/Offshore, capacity, policies, benefits.
- Challenges of Integration: Intermittency (storage, grid balancing), grid modernization, demand-supply management.
- Environmental Concerns: Land use (competition, displacement), raw material sourcing (rare earths), E-waste, wildlife impact.
- Conclusion: Importance of solar/wind, need to overcome challenges via policy, R&D for sustainable transition.