Renewable Power Generation (EX-503 (C)) - Unit 3 Short Notes

1.0 INTRODUCTION & OVERVIEW OF POWER GENERATION

1.1 Classification of Energy Sources

• Conventional (Non-Renewable): Fossil fuels (coal, oil, gas), Nuclear, Large Hydro. Mature technology, high capacity factor, but cause pollution & resource depletion.

• Non-Conventional/Renewable: Solar, Wind, Biomass, Small Hydro, Geothermal, Tidal, etc. Inexhaustible, low environmental impact, but intermittent & lower capacity factor.

• Merits & Demerits Comparison:

  | Source | Merits | Demerits | |------------------|-------------------------------------------------|-----------------------------------------------| | Coal | Abundant, cheap, reliable | High pollution (CO₂, SOx, ash), carbon emission | | Hydro (Large) | Renewable, low operating cost, flood control | Displacement, ecological impact, site-specific | | Nuclear | High energy density, low fuel cost, baseload | Radioactive waste, safety risks, high capital | | Solar PV | Modular, noiseless, low maintenance | Intermittent, low efficiency, high initial cost | | Wind | Clean, cost-competitive, quick installation | Intermittent, noise, bird strike, visual impact | | Biomass | Renewable, waste utilization, rural employment| Land use, emissions if not managed, seasonal |

1.2 Indian Renewable Energy Scenario

• Current Capacity (as of 2024): ~190 GW renewable (excluding large hydro). Wind: ~45 GW, Solar: ~80 GW, Biomass: ~10 GW.

• Policies & Targets: National Solar Mission (100 GW solar by 2022, now 280 GW by 2030), Wind targets, Perform, Achieve and Trade (PAT), International Solar Alliance (ISA).

• State-Level: Tamil Nadu leads in wind (~10 GW) and solar; Gujarat, Rajasthan, Karnataka major solar states.

• Future Strategies: Green Energy Corridors, solar rooftop promotion, hybrid systems, green hydrogen mission.

1.3 Advantages & Limitations of Renewables

• Technical: Intermittency requires storage/grid integration; lower efficiency vs fossil fuels.

• Economic: High capital cost, but decreasing (solar/wind LCOE now competitive); fuel cost zero.

• Environmental: Low GHG emissions, reduced air/water pollution; but land use, material sourcing impacts.

• Social: Job creation in installation/maintenance; rural electrification; but land acquisition issues.

• Prospects in India: High solar insolation (4-7 kWh/m²/day), long coastline for wind/tidal, vast agricultural residue for biomass, government push, decreasing technology costs.

[!TIP]

Exam Focus: Compare renewables vs conventional in terms of cost, environment, reliability. Know India's installed capacity rankings and key policies.

2.0 SOLAR ENERGY

2.1 Solar Radiation & Geometry

• Solar Constant: ~1367 W/m² (extraterrestrial radiation on a plane perpendicular to sun's rays at 1 AU).

• Key Angles:

  • Latitude (φ): Angular position north/south of equator.

  • Declination (δ): Angle between sun-Earth line & equatorial plane. $$\displaystyle \delta = 23.45^\circ \sin\left(\frac{360}{365}(284 + n)\right) $$, where $n$ = day number.

  • Hour Angle (ω): Angular displacement from solar noon: $$\displaystyle \omega = 15^\circ \times \text{time from solar noon} $$.

  • Altitude Angle (α): Angle between sun's rays & horizontal plane. $$\displaystyle \sin\alpha = \sin\phi\sin\delta + \cos\phi\cos\delta\cos\omega $$.

  • Azimuth Angle (γ): Angle of sun's rays projected on horizontal plane from south (northern hemisphere). $$\displaystyle \cos\gamma = \frac{\sin\phi\cos\alpha - \sin\delta}{\cos\phi\sin\alpha} $$.

• Measurement: Pyranometer (global radiation), Pyrheliometer (direct radiation), Sunshine recorder (sunshine hours).

2.2 Solar Thermal Energy Conversion

• Principle: Solar radiation absorbed → heat transfer to fluid → steam → turbine → electricity.

• Collector Classification:

  • Flat Plate Collectors: Absorber plate (black coated), glazing (glass, reduces convection loss), insulation (sides/back), housing. Used for low-temp (water heating, space heating).

  • Concentrating Collectors: Focus radiation to achieve high temp. Types:

    • Parabolic trough (linear focus, heat transfer fluid).

    • Parabolic dish (point focus, Stirling engine).

    • Solar tower (heliostats reflect to central receiver).

• Solar Thermal Power Plant Layout: Solar field → heat exchanger/steam generator → steam turbine → condenser → cooling tower → transformer. Often with thermal storage (molten salt).

• Performance Factors: Orientation (south in NH), tilt angle (≈ latitude), insulation quality, optical & thermal losses (conduction, convection, radiation).

2.3 Solar Photovoltaic (PV) Systems

• Principle: Photoelectric effect in p-n junction. Photons excite electrons → DC current.

• Key Elements:

  • Cell: Basic unit (Si, thin-film). Area ~100 cm², Voc ~0.5-0.6 V.

  • Module: Interconnected cells encapsulated.

  • Array: Series/parallel modules.

  • Inverter: DC-AC conversion.

  • BOS: Mounting, wiring, charge controller, batteries (if standalone), protection.

• I-V Characteristics:

  • Open Circuit Voltage ($$\displaystyle V_{oc} $$): Max voltage at I=0.

  • Short Circuit Current ($$\displaystyle I_{sc} $$): Max current at V=0.

  • Maximum Power Point (MPP): $$\displaystyle V_m $$, $$\displaystyle I_m $$ where $$\displaystyle P_{max} = V_m I_m $$.

  • Fill Factor (FF): $$\displaystyle \text{FF} = \frac{V_m I_m}{V_{oc} I_{sc}} $$ (typical 0.7-0.8).

  • Efficiency (η): $$\displaystyle \eta = \frac{P_{max}}{A \times G} \times 100\% $$, where $A$ = cell area, $G$ = irradiance (W/m²).

• Types of PV Systems:

  • Standalone: With battery storage (remote areas).

  • Grid-connected: No battery, feed into grid (net metering).

  • Hybrid: PV + diesel/generator + storage.

• Applications: Rooftop systems, solar farms, water pumping, street lights, space.

[!TIP]

Common Numerical: Calculate FF, efficiency from given $$\displaystyle V_{oc} $$, $$\displaystyle I_{sc} $$, $$\displaystyle V_m $$, $$\displaystyle I_m $$, area, irradiance. Remember $$\displaystyle P_{max} = V_m I_m $$.

3.0 WIND ENERGY

3.1 Principle of Wind Power Generation

• Kinetic Energy of Wind: $$\displaystyle P = \frac{1}{2} \rho A V^3 $$, where $\rho$ = air density (≈1.225 kg/m³ at STP), $$\displaystyle A = \pi R^2 $$ (swept area), $V$ = wind speed.

• Betz's Limit: Maximum power extractable is $$\displaystyle \frac{16}{27} \approx 59.3\% $$ of kinetic energy in wind. Power Coefficient $$\displaystyle C_p = \frac{P_{actual}}{P_{wind}} \leq 0.593 $$.

• Actual Power: $$\displaystyle P = \frac{1}{2} \rho A V^3 C_p \eta_g $$, where $$\displaystyle \eta_g $$ = generator efficiency.

3.2 Wind Energy Conversion Systems (WECS)

• Classification:

  • HAWT: Horizontal rotor shaft, needs yaw mechanism, higher efficiency, prevalent.

  • VAWT: Vertical rotor shaft, omnidirectional, lower efficiency (Darrieus, Savonius).

• Components of HAWT (Neat Diagram Required):

  • Rotor: Blades (aerofoil), hub.

  • Nacelle: Houses gearbox, generator, control systems.

  • Gearbox: Increases rotor speed (typically 20-50 rpm) to generator speed (1500 rpm).

  • Generator: Usually induction (squirrel cage) or synchronous. DFIG common for variable speed.

  • Tower: Steel/concrete, height 50-120 m.

  • Yaw Mechanism: Rotates nacelle to face wind.

  • Braking System: Aerodynamic (pitch), mechanical (disc), electrical.

• Types of Generators:

  • Fixed Speed: Directly coupled, constant rpm, poor efficiency at off-design.

  • Variable Speed: With power electronics (full converter), better efficiency, power quality.

  • Doubly-Fed Induction Generator (DFIG): Rotor connected via slip rings to converter, allows wide speed range, cost-effective.

3.3 Wind Characteristics & Performance

• Wind Speed Distribution: Modeled by Weibull Distribution: $$\displaystyle f(v) = \frac{k}{c} \left(\frac{v}{c}\right)^{k-1} e^{-(v/c)^k} $$, where $k$ = shape factor, $c$ = scale factor. Used for energy estimation.

• Wind Rose: Polar plot showing wind speed & direction frequency.

• Power Curve: Power output vs wind speed. Cut-in (3-4 m/s), rated (12-15 m/s), cut-out (25 m/s).

• Capacity Factor: $$\displaystyle \text{CF} = \frac{\text{Actual energy output}}{\text{Rated power} \times 8760 \text{ h}} $$ (typically 20-40%).

• Limitations: Intermittency, site-specific (needs avg speed >5-6 m/s), visual/noise impact, grid integration challenges.

3.4 Control Schemes for Wind Power

• Pitch Control: Blades rotate to adjust angle of attack, regulate power at high wind.

• Stall Control: Fixed pitch; beyond certain speed, aerodynamic stall limits power.

• Grid Integration: Use of power electronics for voltage/frequency control, fault ride-through, reactive power support.

3.5 Site Selection for Wind Power Plants

• Wind Resource: Avg speed >5 m/s at hub height, low turbulence intensity (<0.15), favorable wind rose.

• Topography: Smooth terrain, ridges, coastal areas; avoid complex terrain causing turbulence.

• Environmental: Avoid bird migration paths, protected areas.

• Grid Proximity: Near transmission lines to reduce evacuation cost.

• Other: Land availability, accessibility, social acceptance.

3.6 Safety & Environmental Aspects

• Bird Strike: Siting away from migratory paths; monitoring.

• Noise: Aerodynamic (blade) & mechanical (gearbox); setback distances.

• Visual Impact: Public perception; color, layout.

• Shadow Flicker: Rotating blades cast flickering shadows; siting & operational control.

• Safety Protocols: Lightning protection, fire suppression (nacelle), fall protection during maintenance.

[!TIP]

Key Formulas: $$\displaystyle P \propto V^3 $$ → small change in $V$ large change in $P$. Betz limit $$\displaystyle C_p \leq 0.593 $$. Capacity Factor < 1 because wind not always at rated speed.

4.0 BIOMASS ENERGY

4.1 Biomass Resources & Characteristics

• Types:

  • Agricultural residues (straw, husk, bagasse).

  • Forest residues (twigs, bark).

  • Energy crops (jatropha, switchgrass).

  • Animal waste (cattle dung).

  • Municipal solid waste (organic fraction).

• Environmental Problems: Open burning causes air pollution; unmanaged waste leads to methane emissions (GHG), water contamination, vector-borne diseases.

4.2 Biogas Generation

• Principle: Anaerobic digestion (four stages):

  1. Hydrolysis: Complex organics → simple sugars, amino acids.

  2. Acidogenesis: Sugars → volatile fatty acids, alcohols, CO₂, H₂.

  3. Acetogenesis: Acids → acetic acid, H₂, CO₂.

  4. Methanogenesis: Acetic acid/H₂+CO₂ → CH₄ (60-70%) + CO₂.

• Biogas Plant Types:

  • Deen Bandhu (KVIC) Model:

    • Floating Drum: Gas holder (drum) floats on slurry; simple, common.

    • Fixed Drum: Gas collected in fixed dome; no moving parts, but gas leakage issues.

  • Pragati Design: Improved fixed dome with water seal; better gas tightness.

  • Community Plants: Large scale; problems: feedstock consistency, maintenance, ownership disputes.

• Materials:

  • Feedstock: Cattle dung (most common), kitchen waste, crop residues (C/N ratio 20-30:1).

  • Inoculum: Seed slurry from existing biogas plant to introduce bacteria.

• Uses: Cooking, lighting (BG lamps), electricity (engine-generator), vehicle fuel (after purification).

• Digested Slurry: Rich in NPK, used as organic fertilizer, improves soil health.

4.3 Biomass Power Generation Technologies

• Direct Combustion: Burn biomass in boiler → steam → turbine (Rankine cycle). Simple, but ash handling, emissions.

• Gasification: Partial combustion at 600-1000°C → producer gas (CO, H₂, CH₄, N₂). Used in ICEs or gas turbines after cleaning (tars, particulates).

• Pyrolysis: Thermal decomposition in absence of air → bio-oil (liquid), charcoal (solid), gas. Small-scale units: feed → reactor (heater) → condensation → bio-oil collection.

4.4 Biomass Applications

• Thermal: Cooking (chulhas), industrial process heat, drying.

• Electrical: Cogeneration/CHP (sugar mills: bagasse for power & steam).

• Transportation: Biofuels: Ethanol (from sugarcane, corn), Biodiesel (from jatropha, waste cooking oil).

4.5 Advantages & Environmental Benefits

• Renewable, carbon neutral (CO₂ absorbed during growth).

• Waste management solution, rural employment.

• Reduces fossil fuel dependence.

• Digestate improves soil, reduces chemical fertilizer need.

[!TIP]

Biogas Plant Diagrams: Know floating drum vs fixed dome. Community plants face operational issues like regular feeding, slurry removal, maintenance.

5.0 OTHER RENEWABLE ENERGY SOURCES

5.1 Ocean Energy

• Tidal Energy:

  • Principle: Gravitational potential energy of tides (Moon/Sun). Tidal range = difference between high & low tide.

  • Tidal Power House Types:

    • Single Basin: One basin, turbine in barrage. Generation during ebb/flood.

    • Double Basin: Two basins at different levels; generation during both tides.

  • Site Selection: Tidal range > 4 m, suitable estuary/bay, minimal shipping disruption.

  • Generation Modes: Ebb generation (during outgoing tide), Flood generation (incoming), Two-way.

• Ocean Thermal Energy Conversion (OTEC):

  • Principle: Ocean temperature gradient (surface ~25°C, deep ~5°C, ΔT ≥ 20°C required).

  • Open Cycle: Warm seawater → flash evaporation → steam → turbine → condense with cold water → fresh water + power.

  • Closed Cycle: Working fluid (ammonia, low boiling point) evaporates in heat exchanger (warm seawater) → turbine → condense with cold seawater. Schematic: Pump → evaporator → turbine → condenser → pump.

  • Challenges: Low efficiency (3-4%), high capital cost, biofouling, pipe corrosion.

• Wave Energy:

  • Principle: Capture kinetic/potential energy of surface waves.

  • Devices: Oscillating Water Column (wave compresses air in chamber → turbine), Point Absorber (floater moves with waves), Overtopping device (wave fills reservoir → turbine).

5.2 Geothermal Energy

• Principle: Earth's internal heat (radioactive decay). High temperature reservoirs.

• Resource Types:

  • Hydrothermal: Hot water/steam (vapor-dominated like Geysers, USA; liquid-dominated).

  • Geo-pressured: Hot water under high pressure (contains methane).

  • Hot Dry Rock: Hot rock with fractures; water injected, returns as steam.

  • Magma: Molten rock (theoretical, very high temp).

• Power Plant Types:

  • Dry Steam: Direct use of geothermal steam (≥150°C) to drive turbine.

  • Flash Steam: High-pressure hot water flashed to steam in separator; steam drives turbine.

  • Binary Cycle: Geothermal fluid heats secondary fluid (butane, ammonia) in heat exchanger; secondary fluid vaporizes & drives turbine. Allows lower temp resources (100-150°C).

  • Hybrid Geothermal-Fossil: Combine with fossil fuel to boost output/temperature.

• Potential in India: Himalayas (tectonic zones), Gujarat (Cambay basin), Andhra Pradesh (Manikaran), Tamil Nadu (Bhavani). Moderate potential, exploratory stage.

• Advantages: Baseload, low emissions, small footprint, high capacity factor (90%).

5.3 Hydrogen & Fuel Cells

• Hydrogen Energy:

  • Production:

    • Electrolysis: $$\displaystyle 2H_2O \xrightarrow{electricity} 2H_2 + O_2 $$ (clean if renewable electricity).

    • Steam Reforming: $$\displaystyle CH_4 + H_2O \rightarrow CO + 3H_2 $$ (fossil-based, with CO₂).

    • Biomass Gasification: Biomass → syngas (CO+H₂) → shift reaction → H₂.

  • Storage Methods:

    | Method | Advantages | Disadvantages | |---------------------|-----------------------------------------|-------------------------------------------| | Compressed Gas | Simple, mature | Low energy density, high pressure (350-700 bar) | | Liquid Hydrogen | High density | High boil-off, energy-intensive liquefaction | | Metal Hydrides | Safe, moderate density | Heavy, slow kinetics | | Chemical Hydrides | High volumetric density | Complex chemistry, byproduct handling |

  • Advantages: Clean combustion (water), high energy per mass, versatile.

  • Disadvantages: Low volumetric density, production/storage cost, infrastructure lacking, safety (flammable, embrittlement).

• Fuel Cells:

  • Principle: Electrochemical conversion of H₂ + O₂ → electricity + water (no combustion). Anode: $$\displaystyle H_2 \rightarrow 2H^+ + 2e^- $$; Cathode: $$\displaystyle ½O_2 + 2H^+ + 2e^- \rightarrow H_2O $$.

  • Classification:

    • PEMFC (Polymer Electrolyte): Low temp (80°C), solid polymer electrolyte, quick start, transport applications.

    • AFC (Alkaline): High efficiency, space applications (NASA).

    • MCFC (Molten Carbonate): High temp (650°C), internal reforming, stationary power.

    • SOFC (Solid Oxide): Very high temp (1000°C), high efficiency, fuel flexible, stationary/APU.

  • Applications: Stationary (backup power), transport (fuel cell vehicles), portable (laptops, military).

5.4 Magneto-Hydro Dynamic (MHD) Generation

• Principle: Direct conversion of thermal to electrical energy. Hot ionized gas (plasma) flows through magnetic field → EMF induced across electrodes (Faraday's law: $$\displaystyle V = B l v $$).

• Schematic & Working: Combustor (air + fuel + seed (e.g., K₂CO₃) → plasma) → nozzle (accelerate) → channel (magnetic field perpendicular to flow) → electrodes collect DC → diffuser (slow down) → heat recovery → seed recovery → exhaust.

• Advantages: High theoretical efficiency (50-60%), no moving parts, fast start-up.

• Challenges: Material (high temp, corrosion), seed recovery, high capital cost, low proven efficiency (~30%).

[!TIP]

OTEC: Closed cycle uses ammonia (low boiling point). Tidal: single basin simplest, double basin allows generation on both tides. Fuel cells: PEMFC for cars, SOFC for stationary.

6.0 HYBRID & SPECIAL SYSTEMS

6.1 Concept of Hybrid Systems

• Definition: Integration of two or more renewable/ conventional sources with storage to overcome intermittency and improve reliability.

• Need: Smooth power output, reduce diesel backup, optimize component sizing.

• Common Combinations:

  • Solar-Wind: Complementary (wind at night, solar day).

  • Solar-Wind-Diesel: Diesel as backup.

  • PV-Diesel-Battery: PV + battery supply load, diesel for deficit.

• Configuration & Control: Energy management system (EMS) prioritizes renewables, controls battery charge/discharge, starts/stops diesel based on load & resource availability.

6.2 Cogeneration / Combined Heat and Power (CHP)

• Principle: Simultaneous generation of electricity & useful thermal energy (steam/heat) from same fuel. Captures waste heat from power generation.

• Applications: Industries with process heat需求: Sugar (bagasse cogeneration), paper, chemical, district heating.

• Advantages: Overall efficiency 70-90% (vs 30-40% for condensing plants), reduced fuel cost, lower emissions per unit energy.

6.3 Small-Scale & Distributed Generation

• Small Hydro Plants: Capacity 1-25 MW, run-of-river (no large dam), minimal storage. Compare with large hydro: lower environmental impact, faster construction.

• Micro-Hydro: <100 kW, for village/community.

• Pico-Hydro: <10 kW, for single household/small cluster.

• Rooftop Solar PV: Grid-connected or standalone, on residential/commercial buildings. Net metering, zero export policy in some states.

[!TIP]

Hybrid Systems: EMS critical for optimal operation. CHP: key for energy-intensive industries. Small hydro: important for remote hilly areas.

7.0 CONVENTIONAL POWER PLANTS (FOR COMPARISON & ECONOMICS)

7.1 Hydroelectric Power Plants

• Layout & Components:

  • Dam: Creates head, stores water.

  • Intake: Screens to prevent debris, gate control.

  • Penstock: Large pipe carries water to turbine.

  • Surge Tank: Pressure regulation, water hammer protection.

  • Turbine: Converts hydraulic to mechanical energy.

  • Generator: Converts mechanical to electrical.

  • Tailrace: Returns water to river.

  • Transformers: Step up voltage.

• Turbine Types:

  | Turbine | Head Range | Flow | Principle | Application | |-------------|------------------|---------------|---------------------|-----------------------| | Pelton | High (>300 m) | Low | Impulse (nozzle) | Mountainous regions | | Francis | Medium (30-300 m)| Medium | Reaction (pressure+velocity) | Common, medium head | | Kaplan | Low (<30 m) | High | Reaction (propeller)| Low-head rivers |

• Pumped Storage Plants: Reversible pump-turbine. Off-peak: pump water to upper reservoir. Peak: release to generate. Merits: Peak load, storage, frequency control. Demerits: High cost, evaporation losses, limited sites.

• Hydrograph: Flow (m³/s) vs time (daily/monthly).

• Flow Duration Curve: Flow exceedance curve (sorted descending). Used to estimate firm capacity.

• Power Duration Curve: Derived from hydrograph & head.

7.2 Thermal (Steam) Power Plants

• Layout of Modern Steam Plant:

  
  Coal handling → Pulverizer → Boiler (furnace, water walls, superheater) → Turbine → Condenser → Cooling tower → Feedwater pump → Economiser → Boiler.
  
  Chimney with ESP/FGD.
  
  

• Main Components & Functions:

  • Steam Turbine: Stages: impulse (nozzle, bucket) for high pressure; reaction (stator, rotor blades) for low pressure.

  • Economiser: Preheats feedwater using flue gas → improves boiler efficiency.

  • Air Preheater: Preheats combustion air using flue gas → reduces fuel needed.

  • Feed Water Heater: Open (direct contact with steam) or closed (shell & tube) → raises feedwater temp, reduces boiler load.

  • Cooling Towers: Natural Draft (hyperbolic, buoyancy), Mechanical Draft (fans). Recycle cooling water, reduce water consumption.

• Water Treatment Plant: Necessity: Prevent scaling (Ca/Mg salts), corrosion (dissolved O₂, CO₂), carryover. Process: Clarification → Filtration → Softening (lime-soda, ion exchange) → Deaeration (remove O₂, CO₂).

7.3 Gas Turbine Power Plants

• Layout of Simple Gas Turbine:

  
  Air → Compressor (axial/centrifugal) → Combustor (fuel injection, ignition) → Turbine (drives compressor & load) → Exhaust.
  
  

• Classification:

  • Open Cycle: Air from atmosphere, exhaust to atmosphere (common).

  • Closed Cycle: Working fluid (He, CO₂) recirculated, heat added externally.

  • Hybrid Cycles: Regenerative (heat exchanger preheats compressed air), Intercooled (cool between compressor stages), Reheated (heat between turbine stages).

• Efficiency Improvement:

  • Regeneration: Recovers exhaust heat → reduces fuel.

  • Intercooling: Reduces compressor work.

  • Reheating: Increases turbine work.

  • Combined Cycle: Gas turbine exhaust heat → steam cycle (HRSG → steam turbine) → overall efficiency 50-60%.

7.4 Diesel Power Plants

• Fuel System: Storage tank → filters → injection pump → injectors → engine.

• Exhaust System: Exhaust manifold → silencer → chimney.

• Applications: Peak load, standby, remote areas (no grid), small capacity (<100 MW). Quick start, high efficiency at part load.

7.5 Nuclear Power Plants

• Basic Nuclear Physics:

  • Fission: Heavy nucleus (U-235, Pu-239) splits → neutrons + energy + fission products (chain reaction).

  • Fusion: Light nuclei (H, He) combine → energy (sun, experimental).

• Reactor Components (Neat Diagram):

  • Core: Fuel rods (UO₂ pellets).

  • Moderator: Slows neutrons (Graphite, Heavy Water D₂O).

  • Control Rods: Absorb neutrons (Boron, Cadmium) → control reactivity.

  • Coolant: Removes heat (Light water, Heavy water, CO₂, Liquid Na).

  • Pressure Vessel: Contains core, coolant.

  • Shielding: Concrete, lead → protect from radiation.

• Reactor Types:

  • PWR (Pressurized Water Reactor): Primary loop (water under high pressure, no boiling) → steam generator → secondary loop (steam to turbine). Advantages: Separate radioactive/non-radioactive loops. Disadvantages: Complex, high pressure.

  • BWR (Boiling Water Reactor): Water boils in core → steam directly to turbine. Simpler, but turbine radioactive.

  • CANDU: Heavy water moderator & coolant, natural uranium fuel. Advantages: Use natural uranium, online refueling. Disadvantages: Heavy water expensive, large size.

• Nuclear Fuel Cycle (India):

  • Uranium: Jaduguda (Jharkhand), Tummalapalle (AP), Singhbhum (Jharkhand). Limited reserves.

  • Thorium: Kerala (Monazite sands), Odisha, Andhra Pradesh. Abundant, India's long-term strategy (three-stage program: PHWR → FBR → Thorium reactors).

• Radioactive Pollution: Accidents (Chernobyl, Fukushima), routine releases, waste. Effects: radiation sickness, cancer, genetic mutations.

• Nuclear Waste Management:

  • Types: Low-level (clothing, tools), Intermediate-level (resins, reactor components), High-level (spent fuel, highly radioactive).

  • Disposal Methods:

    • Near-surface (low-level).

    • Geological disposal (high-level): Deep geological repositories (e.g., Yucca Mountain), vitrification (immobilize in glass).

  • Safety Aspects: Multi-barrier approach (waste form, canister, buffer, geology), long-term monitoring.

[!TIP]

Hydro Plants: Know turbine applications (Pelton high head, Kaplan low head). Pumped storage: reversible pump-turbine. Thermal: economiser & air preheater recover waste heat. Nuclear: moderator slows neutrons; control rods absorb neutrons. India's thorium reserves key for future.

8.0 POWER SYSTEM ECONOMICS & PLANNING

8.1 Cost of Power Generation

• Fixed Costs (Independent of output):

  • Capital cost (land, plant, equipment).

  • Interest on loans.

  • Taxes, insurance.

  • Fixed O&M (salaries, routine maintenance).

• Operating Costs (Vary with output):

  • Variable O&M (repairs, maintenance proportional to use).

  • Fuel cost (major for thermal).

• Total Cost: $$\displaystyle C = C_f + C_v \times P $$ (simplified). Cost per unit: $$\displaystyle \text{Cost/kWh} = \frac{\text{Total annual cost}}{\text{Annual energy output}} $$.

8.2 Tariffs & Pricing

• Tariff: Rate charged per unit electricity (₹/kWh).

• Types:

  • Flat Rate: Fixed per kWh (simple, no demand charge).

  • Block Rate: Slab system (first 100 kWh @ ₹3, next 200 @ ₹4, etc.).

  • Two-Part Tariff: Fixed charge (based on max demand) + energy charge (per kWh). $$\displaystyle T = F + E \times \text{units} $$.

  • Three-Part Tariff: Fixed + semi-fixed (based on max demand) + energy charge.

  • Power Factor Tariff: Incentive/penalty based on PF (avoid low PF to reduce losses).

  • Seasonal Tariff: Different rates in peak/off-peak seasons.

  • Time-of-Day (TOD) Tariff: Different rates for peak, normal, off-peak hours (encourage load shifting).

• Peak Load Pricing: Higher tariff during peak hours to reflect higher generation cost & reduce peak demand.

8.3 Load Analysis & Forecasting

• Load Curve: Power (kW/MW) vs time (hourly/daily/monthly/yearly). Shows variation.

• Load Duration Curve: Load values sorted descending vs time (cumulative hours). Area = total energy.

• Integrated Load Duration Curve: Cumulative energy vs load.

• Key Factors:

  • Maximum Demand ($$\displaystyle P_{max} $$): Peak load.

  • Load Factor (LF): $$\displaystyle \text{LF} = \frac{\text{Average load}}{\text{Maximum demand}} $$. Always <1 because max demand occurs only for short periods.

  • Demand Factor (DF): $$\displaystyle \text{DF} = \frac{\text{Maximum demand}}{\text{Connected load}} $$. Always <1 because not all connected loads operate simultaneously.

  • Capacity Factor (CF): $$\displaystyle \text{CF} = \frac{\text{Actual energy output}}{\text{Rated capacity} \times \text{hours}} $$. Can be <1 (intermittent) or >1 (overloaded).

  • Utilization Factor (UF): Similar to CF, but based on time plant is in service.

  • Diversity Factor (DF): $$\displaystyle \text{DF} = \frac{\sum \text{individual max demands}}{\text{System max demand}} $$. >1 because peaks don't coincide.

• Relationship: Higher load factor → better utilization → lower cost per unit.

• Load Forecasting:

  • Short-term: Daily/weekly (unit commitment, economic dispatch).

  • Medium-term: Monthly/seasonal (maintenance scheduling, fuel procurement).

  • Long-term: Yearly/5-year (capacity expansion, planning).

  • Methods: Trend projection, regression analysis, econometric models, neural networks.

8.4 Economic Operation & Scheduling

• Economic Load Dispatch (ELD): Distribute total load among generating units to minimize total fuel cost.

• Incremental Fuel Cost (λ): $$\displaystyle \lambda = \frac{dC}{dP} $$ (₹/MWh). Equal Incremental Cost Criterion: For optimal dispatch, $$\displaystyle \lambda_1 = \lambda_2 = \cdots = \lambda_n $$ (neglecting losses).

• Including Transmission Losses: $$\displaystyle \lambda_i \times \text{Penalty Factor}_i = \lambda $$. Penalty factor $$\displaystyle = \frac{1}{1 - \frac{\partial P_L}{\partial P_i}} $$, where $$\displaystyle P_L $$ = transmission loss.

• Numerical Problems:

  • Given incremental cost curves $$\displaystyle \lambda_i = a_i P_i + b_i $$, solve $$\displaystyle \lambda_1 = \lambda_2 $$ with $$\displaystyle P_1 + P_2 = P_D + P_L $$.

  • Given fuel cost functions $$\displaystyle C_i = \alpha_i + \beta_i P_i + \gamma_i P_i^2 $$, find optimal $$\displaystyle P_1, P_2 $$ by equating incremental costs.

• Hydro-Thermal Scheduling: Hydro used for peak loads (low operating cost), thermal for base load. Coordination to minimize total cost over day/week.

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Formulas to Remember:

• Load Factor = Average Load / Max Demand < 1.

• Demand Factor = Max Demand / Connected Load < 1.

• Penalty Factor = $$\displaystyle 1/(1 - \partial P_L/\partial P_i) $$.

• ELD: $$\displaystyle \lambda_1 = \lambda_2 $$ (without losses).

Common Pitfall: Confuse load factor, demand factor, capacity factor. Load factor always <1 because max demand is short; demand factor <1 because not all loads on at once.

9.0 ENVIRONMENTAL, SAFETY & SUSTAINABILITY ASPECTS

9.1 Environmental Impact Assessment (EIA) for Power Plants

• Air Pollution:

  • SOx: From sulfur in coal → acid rain. Mitigation: Flue Gas Desulfurization (FGD, scrubbers).

  • NOx: High temp combustion → smog, ozone. Mitigation: Selective Catalytic Reduction (SCR), low-NOx burners.

  • Particulates: Fly ash, soot → respiratory issues. Mitigation: Electrostatic Precipitator (ESP), bag filters.

  • GHG (CO₂): Climate change. Mitigation: Carbon capture & storage (CCS), renewable shift.

• Water Pollution:

  • Thermal: Hot water discharge → aquatic life stress. Mitigation: Cooling towers, cooling ponds.

  • Chemical: Heavy metals, ash pond leachate. Mitigation: Ash pond liners, wastewater treatment.

• Land Use: Ash disposal (large area), deforestation for dams/mining. Mitigation: Ash utilization (cement, bricks), afforestation.

• Noise: From turbines, generators, cooling fans. Mitigation: Acoustic enclosures, barriers.

9.2 Safety Aspects

• Nuclear Power:

  • Radiation Shielding: Concrete, lead walls around reactor.

  • Containment: Steel-reinforced concrete dome to prevent radioactive release.

  • Emergency Core Cooling System (ECCS): Flood core with water during loss-of-coolant accident.

• Wind Turbines:

  • Safety Systems: Braking (pitch, mechanical), lightning protection (conductors), fire suppression (CO₂ in nacelle).

  • Working at Heights: Harnesses, training during maintenance.

• Solar PV:

  • Electrical Safety: Isolation, grounding, arc fault protection.

  • Working at Heights: Roof safety, fall arrest systems.

9.3 Sustainable Development & Energy Resources Reserve

• Reserve Capacity:

  • Hot Reserve: Plant running but not loaded (can pick up load quickly).

  • Cold Reserve: Plant shut down, can start in hours.

  • Spinning Reserve: Synchronized generator ready to serve load.

• Energy Security: Diversify sources (renewables, nuclear, imports), strategic reserves, reduce fossil dependence.

• Resource Availability: Fossil fuels finite, renewables abundant but intermittent. Sustainable mix needed.

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EIA Mitigation: ESP for particulates, FGD for SOx, SCR for NOx. Nuclear safety: containment, ECCS. Reserve capacity types: hot (running), cold (shutdown), spinning (synchronized).