1.
Limitations of non-conventional energy sources
• Non-conventional energy sources are intermittent and depend heavily on weather and
geographic location.
• They require high initial investments and advanced technology, which may not be
affordable everywhere.
• Energy storage solutions are still costly and less efficient, limiting continuous supply.
• Large land or space requirements can pose challenges for installation.
2. Greenhouse effect and its origin
The greenhouse effect is the warming of Earth’s surface due to the trapping of heat by
greenhouse gases like carbon dioxide, methane, and water vapor. These gases allow sunlight to
enter the atmosphere but prevent some of the heat from escaping back into space, acting like a
thermal blanket. This effect occurs naturally, but human activities such as burning fossil fuels
and deforestation increase the concentration of these gases, leading to enhanced warming. The
greenhouse effect contributes to global climate change and rising temperatures worldwide.
3. Prospects of fossil fuels in India
• Fossil fuels currently supply the majority of India’s energy demands, especially coal and
oil.
• Domestic reserves are limited, leading to increased imports and energy security concerns.
• Environmental concerns and international climate commitments push India towards
renewable energy sources.
• Despite growth in renewables, fossil fuels will remain significant in India’s energy mix
for the near future.
4. Operation of a heat pump
• A heat pump transfers heat from a low-temperature source to a higher temperature sink
using a refrigeration cycle.
• The main components include an evaporator, compressor, condenser, and expansion
valve.
• It absorbs heat from outside air or ground and releases it inside for heating or vice versa
for cooling.
• Heat pumps are energy efficient and widely used for heating buildings and water.
5. Heating value of fuel
• Heating value represents the amount of heat released when a unit quantity of fuel is
completely burned.
• It is classified into Higher Heating Value (HHV), including latent heat of vaporization,
and Lower Heating Value (LHV), excluding it.
• This value is critical for designing combustion systems and estimating energy content.
• Fuels with higher heating values provide more energy per unit mass or volume.
6. Operation of binary cycle power plant
• Binary cycle plants use moderate temperature geothermal water to heat a secondary
working fluid with a low boiling point.
• This working fluid vaporizes, drives a turbine connected to an electric generator, and then
condenses back to liquid.
• The geothermal water and working fluid remain in separate closed loops to prevent
contamination.
• Binary cycle plants are suitable for sites with low to moderate geothermal temperatures.
7. Working of solar water heater
• Solar radiation is absorbed by a collector plate, heating the fluid (usually water) inside
the tubes.
• Heated water naturally rises and is stored in an insulated tank for household use.
• Circulation can be passive (thermosiphon) or active (using pumps).
• The system provides an energy-efficient way to supply hot water using renewable energy.
8. Declination angle and its calculation on May 25
• Declination angle (δ) is the angle between the sun’s rays and the equatorial plane, varying
through the year.
• It is calculated using the formula δ = 23.45° × sin [360/365 × (284 + n)], where n is the
day number.
• May 25 is the 145th day of the year, so δ ≈ 23.45 × sin(360/365 × 429) ≈ 20.1°.
• This angle helps determine solar angles and radiation on a given date.
9. Difference between concentrating and solar Fresnel lens collectors
Aspect Concentrating Collectors Fresnel Lens Collectors
Use curved mirrors or lenses to focus Use flat, segmented lenses to
Principle
sunlight concentrate sunlight
Concentration
High (typically >10) Moderate (usually <10)
Ratio
Mechanically complex, requires
Complexity Simpler design, less expensive
precise tracking
Suitable for high-temperature power
Applications Used for medium-temperature heating
generation
10. Declination angle of beam radiation on PV array (Thane) – outline
• Calculate day’s declination δ using date (October 25).
• Find hour angle (ω) based on local time (10:30 LAT).
• Apply given cosine formula with latitude, slope, azimuthal angle, and time parameters.
• Determine angle of incidence θ to evaluate solar radiation on the PV surface.
11. Capital cost and life cycle cost (LCC) calculation for solar thermal plant
• Calculate total initial cost per kW by summing costs of components adjusted for their
lifespan.
• Apply capital recovery factor with 15% interest rate for annualized capital cost.
• Add maintenance cost as 2% of capital cost per year.
• LCC = Annualized capital cost + annual maintenance cost.
12. Low head hydro plant
• Operates with a low water head (below 30 meters) and high flow rates.
• Uses turbines like Kaplan or propeller designed for low head conditions.
• Suitable for river sites or canals with large water volumes.
• Cost-effective for areas where high-head sites are unavailable.
13. Peak load plants in hydro power
• Designed to meet the highest electricity demand during peak hours.
• Can start quickly and supply power on short notice.
• Usually operated during short durations for grid stability.
• Pumped storage plants often used as peak load plants.
14. Future prospects of renewable energy
• Renewable energy is expected to grow rapidly due to climate change mitigation efforts.
• Technology improvements and cost reductions make renewables competitive.
• Policy support and international agreements encourage renewable investments.
• Renewables will increasingly dominate global energy supply, reducing fossil fuel
dependence.
15. I-V characteristics of solar cell and fill factor
• I-V curve shows current decreasing as voltage increases until open circuit voltage.
• Maximum power point is where the product of current and voltage is maximum.
• Fill factor (FF) = (Vmp × Imp) / (Voc × Isc), indicating solar cell quality.
• Higher FF means better solar cell efficiency and performance.
16. Importance of MPPT in SPV system
• MPPT ensures solar panels operate at their maximum power output under changing
conditions.
• Maximizes energy harvest during variable sunlight and temperature.
• Improves overall system efficiency and electricity generation.
• Essential for stable and optimized photovoltaic operation.
17. Indirect solar energy
• Indirect solar energy is energy derived from solar-driven processes such as wind,
biomass, and hydro energy.
• Solar radiation heats the Earth’s surface, causing air movement and evaporation cycles.
• This drives wind currents, water cycles, and biological growth, producing usable energy.
• It relies on natural intermediaries rather than direct sunlight conversion.
18. Types of drive schemes used in wind turbines
• Direct drive: rotor directly connected to generator, reducing gearbox losses.
• Gearbox drive: uses gears to increase generator speed, common in large turbines.
• Hydraulic drive: uses hydraulic systems to transmit power.
• Hybrid drive: combines mechanical and hydraulic elements for optimized performance.
19. Yaw control method
• Yaw control aligns the turbine rotor to face the wind direction for maximum energy
capture.
• Active yaw uses motors controlled by wind direction sensors.
• Passive yaw uses a tail vane to orient the turbine naturally.
• Improves efficiency and reduces mechanical stress.
20. Offshore wind farm
• Wind turbines installed in sea or ocean environments to harness stronger and more
consistent winds.
• Higher installation and maintenance costs due to harsh marine conditions.
• Reduced land use conflicts and visual pollution.
• Potential for large-scale power generation with minimal social impact.
21. Power vs wind speed characteristics of wind turbine
• Power output starts at cut-in wind speed, increases rapidly with wind speed.
• Power grows approximately with the cube of wind speed until rated speed.
• At rated speed, power output is constant (rated power).
• Above cut-out speed, turbine shuts down for safety.
22. Stall control in wind turbines
• Controls the aerodynamic stall of blades to limit power at high wind speeds.
• Passive method with fixed blade angles causing stall when wind is too strong.
• Protects turbine from overload without complex controls.
• Less efficient than pitch control but simpler and cheaper.
23. Energy farming
• Cultivation of renewable energy sources such as wind, solar, and biomass at large scales.
• Combines energy production with agriculture or land use.
• Supports rural development and sustainable energy supply.
• Integrates natural resources management with energy generation.
24. Operation of oscillating water type wave device
• Uses oscillating water columns to convert wave motion into air pressure variations.
• Air pressure drives a turbine connected to a generator.
• Turbine designed to rotate with airflow in both directions.
• Captures wave energy to generate electricity.
25. Types of geothermal resources
• Hydrothermal: natural hot water or steam reservoirs near the surface.
• Geopressured: hot brine under pressure containing methane gas.
• Hot dry rock: deep, hot but dry rock formations requiring fluid injection.
• Magma resources: molten rock providing extremely high heat.
26. Tidal barrage and tidal basin
• Tidal barrage is a dam across estuaries, storing high tide water and releasing it to generate
power.
• Tidal basin is a reservoir filling and emptying with tides, used for power extraction.
• Barrages are large and costly but efficient; basins are simpler but less efficient.
• Both harness tidal energy to produce electricity.
27. Approximate concentration ratio of CPC collector
• Compound Parabolic Concentrator (CPC) collectors have a concentration ratio between 2
and 3.
• They concentrate sunlight moderately without needing tracking systems.
28. Collectors requiring one-axis sun tracking
• Parabolic trough collectors.
• Linear Fresnel reflectors.
• Heliostat fields with single-axis tracking.
29. Temperature range of paraboloidal dish collector
• Paraboloidal dish collectors can reach temperatures between 400°C and 1500°C.
• Suitable for high-temperature applications like power generation and industrial processes.
30. Power capacity of solar thermal power plant
• Typically ranges from a few MW (5-100 MW) in commercial installations.
• Larger plants require significant land and investment.
• Capacity depends on solar resource and technology type.
31. Heat pipe evacuated tube collector
• Consists of vacuum-sealed glass tubes with heat pipes inside.
• Heat pipe transfers absorbed solar heat to a fluid in the manifold.
• Vacuum reduces heat loss by conduction and convection.
• Highly efficient for hot water generation.
32. Applications of geothermal energy
• Electricity generation using geothermal steam.
• Direct heating for buildings and greenhouses.
• Industrial uses like drying, pasteurization, and aquaculture.
• Balneology (therapeutic baths) and spas.
33. Methods to extract energy from tidal currents
• Tidal stream turbines placed underwater convert kinetic energy of currents into
electricity.
• Oscillating hydrofoils that move with tidal flows.
• Underwater kite systems generating power from tidal movements.
34. Solar radiation spectrum and its approximate percentage
• Solar spectrum ranges from UV (5%), visible light (43%), to infrared (52%).
• Visible light constitutes the largest portion reaching Earth’s surface.
• Different solar collectors absorb specific spectrum parts.
35. Energy payback time of a solar PV system
• Time required to generate energy equal to the energy used to produce the system.
• Typically ranges between 1 to 4 years depending on technology and location.
• Shorter payback times indicate better sustainability.
36. Solar cell efficiency and factors affecting it
• Efficiency is the ratio of electrical power output to solar power input.
• Affected by material quality, temperature, shading, and angle of incidence.
• Higher temperatures reduce efficiency due to increased resistance.
• Manufacturing defects and impurities also decrease efficiency.
37. Types of solar cells
• Monocrystalline silicon cells with high efficiency.
• Polycrystalline silicon cells that are cheaper but less efficient.
• Thin-film cells made from materials like CdTe or CIGS with flexible applications.
• Emerging perovskite cells with potential for high efficiency and low cost.
38. Factors affecting the power output of solar cell
• Intensity of solar radiation.
• Temperature of the cell; higher temperatures reduce output.
• Angle of sunlight incidence relative to cell surface.
• Quality and age of the solar cell.
39. Classification of wind turbines
• Horizontal axis wind turbines (HAWT) with blades rotating around horizontal shaft.
• Vertical axis wind turbines (VAWT) with vertical shaft rotation.
• Based on power rating: small (<100 kW), medium, and large (>1 MW) turbines.
40. Power output from wind turbines
• Depends on air density, rotor swept area, and cube of wind speed.
• Captured by turbine blades and converted by generator.
• Maximum power limited by Betz limit (~59%).
• Power curve shows cut-in, rated, and cut-out speeds.
41. Applications of wind energy
• Electricity generation in wind farms.
• Water pumping in agriculture.
• Mechanical drives in mills and small industries.
• Remote power supply for telecom and off-grid areas.
42. Betz limit
• Theoretical maximum efficiency for wind energy extraction is 59.3%.
• Limits the amount of kinetic energy a wind turbine can convert into mechanical energy.
• Factors like blade design and wind conditions affect real efficiency.
• Provides a benchmark for turbine performance.
43. Offshore wind energy challenges
• High installation and maintenance costs due to marine environment.
• Corrosion and structural durability issues.
• Complex grid connection and transmission requirements.
• Environmental concerns for marine life.
44. Bio-energy resources
• Biomass like wood, agricultural residues, and animal waste.
• Biogas from anaerobic digestion of organic matter.
• Biofuels such as ethanol and biodiesel from crops.
• Algae and waste-to-energy technologies.
45. Combustion reaction of methane
• CH₄ + 2O₂ → CO₂ + 2H₂O + energy
• Releases a large amount of heat, making methane a valuable fuel.
• Complete combustion produces carbon dioxide and water.
• Incomplete combustion leads to CO and soot.
46. Properties of biogas
• Contains 50-70% methane, 30-50% CO₂, and trace gases.
• Renewable and clean-burning fuel.
• Lower energy content compared to natural gas.
• Odorless and colorless when purified.
47. Energy from biomass conversion
• Biomass can be converted thermochemically, biologically, or chemically.
• Thermochemical methods include combustion, pyrolysis, and gasification.
• Biological methods use anaerobic digestion or fermentation.
• Products include heat, electricity, biofuels, and biogas.
48. Bio-diesel production
• Transesterification of vegetable oils or animal fats with methanol or ethanol.
• Produces fatty acid methyl esters (biodiesel) and glycerol as byproduct.
• Renewable and biodegradable alternative to diesel.
• Can be used in existing diesel engines with minor modifications.
49. Advantages of biogas plants
• Provides clean and renewable energy for cooking and lighting.
• Reduces dependence on fossil fuels and deforestation.
• Treats organic waste, reducing pollution.
• Generates nutrient-rich slurry as fertilizer.
50. Types of biogas plants
• Fixed dome type with underground gas holder.
• Floating drum type with movable gas holder.
• Bag type made of flexible materials.
• Continuous and batch digesters based on feeding method.
51. Application of hydrogen energy
• Fuel for fuel cells producing electricity and water.
• Clean transportation fuel with zero emissions.
• Energy storage medium for renewable energy.
• Used in industrial processes like ammonia production.
52. Hydrogen storage methods
• Compressed gas cylinders storing hydrogen under high pressure.
• Cryogenic storage as liquid hydrogen at very low temperatures.
• Metal hydrides absorbing hydrogen in solid form.
• Chemical storage in hydrogen-rich compounds.
53. Fuel cell working principle
• Converts chemical energy of hydrogen and oxygen into electricity.
• Hydrogen oxidizes at anode releasing electrons and protons.
• Protons pass through electrolyte; electrons flow through external circuit.
• Oxygen combines with protons and electrons at cathode forming water.
54. Advantages of fuel cells
• High efficiency and low emissions.
• Quiet operation and modular design.
• Uses hydrogen as fuel producing only water as byproduct.
• Can provide continuous power with fuel supply.
55. Disadvantages of fuel cells
• High cost and complex manufacturing.
• Requires pure hydrogen fuel.
• Limited infrastructure for hydrogen distribution.
• Durability and lifespan concerns.
56. Sources of hydrogen
• Steam methane reforming from natural gas.
• Electrolysis of water using electricity.
• Biomass gasification.
• Photoelectrochemical and biological production.
57. Power plant layout and block diagram
• Includes fuel supply, boiler, turbine, generator, condenser, cooling tower, and control
system.
• Fuel burns to produce steam in the boiler.
• Steam drives turbine connected to the generator producing electricity.
• Condenser cools steam back to water; cooling tower dissipates heat.
58. Super-critical power plant
• Operates at pressure and temperature above the critical point of water.
• Higher efficiency due to better thermodynamic properties.
• Uses advanced materials to withstand high stress.
• Reduces fuel consumption and emissions.
59. Diesel power plant and its applications
• Uses diesel engines to drive generators for electricity production.
• Suitable for small to medium power requirements.
• Quick start-up and flexibility.
• Used in remote areas, emergency backup, and peak load plants.
60. Hydro power plant classification
• Based on head: high, medium, low.
• Based on operation: run-of-river or storage type.
• Based on construction: dam or diversion type.
• Based on turbine type used.
61. Run-of-river power plant
• Uses natural flow of river without large storage.
• Power generation varies with river flow.
• Minimal environmental impact compared to storage plants.
• Suitable for locations with consistent river flow.
62. Thermal power plant working
• Burns fossil fuel to produce steam in boiler.
• Steam drives turbine coupled to generator producing electricity.
• Exhaust steam condensed and recycled.
• Waste heat removed by cooling towers.
63. Steam power plant layout and block diagram
• Includes fuel handling, boiler, turbine, generator, condenser, cooling tower.
• Fuel combustion generates steam.
• Steam turbine converts thermal energy to mechanical energy.
• Generator converts mechanical to electrical energy.
64. Combined cycle power plant
• Combines gas turbine and steam turbine cycles.
• Exhaust heat from gas turbine used to produce steam for steam turbine.
• Higher overall efficiency (up to 60%).
• Uses natural gas as primary fuel.
65. Nuclear power plant working
• Uses nuclear fission to produce heat.
• Heat generates steam to drive turbine and generator.
• Uses uranium or plutonium as fuel.
• Requires shielding and safety systems.
66. Classification of nuclear reactors
• Pressurized Water Reactor (PWR).
• Boiling Water Reactor (BWR).
• Fast Breeder Reactor (FBR).
• Heavy Water Reactor (HWR).
67. Advantages of nuclear power plants
• Large power generation capacity.
• Low greenhouse gas emissions.
• Stable base load power supply.
• Efficient fuel usage.
68. Disadvantages of nuclear power plants
• Radioactive waste disposal problems.
• High capital costs and long construction time.
• Risk of nuclear accidents.
• Limited fuel availability.
69. Energy density
• Amount of energy stored per unit volume or mass.
• High energy density means more energy in less space.
• Important for fuel selection and storage design.
• Fossil fuels have high energy density compared to renewables.
70. Capacity factor
• Ratio of actual energy output to maximum possible output over a period.
• Indicates utilization efficiency of a power plant.
• Influenced by maintenance and resource availability.
• Higher capacity factor means better performance.
71. Load factor
• Ratio of average load to peak load in a system.
• Reflects efficiency in using installed capacity.
• Low load factor means underutilization.
• Important for economic operation of power plants.
72. Peak load and base load power plants
Aspect Peak Load Power Plants Base Load Power Plants
Operation Run during maximum demand periods Run continuously to meet constant demand
Startup time Fast start and stop Run continuously, slow startup
Cost Higher operational cost Lower operational cost
Examples Gas turbines, hydro peak plants Coal, nuclear power plants
73. Combined heat and power (CHP) system
• Produces both electricity and useful heat simultaneously.
• Improves overall energy efficiency up to 80%.
• Reduces fuel consumption and emissions.
• Used in industries, buildings, and district heating.
74. Types of energy storage
• Mechanical storage (pumped hydro, flywheels).
• Electrical storage (batteries, supercapacitors).
• Thermal storage (molten salts, ice storage).
• Chemical storage (hydrogen, synthetic fuels).
75. Battery storage system
• Stores electrical energy chemically for later use.
• Includes lead-acid, lithium-ion, and flow batteries.
• Used for grid stabilization and renewable integration.
• Limited by capacity, cost, and lifespan.
76. Importance of energy audit
• Identifies energy saving opportunities.
• Helps improve energy efficiency and reduce costs.
• Supports sustainable energy management.
• Enables compliance with regulations.
77. Load management
• Balances electricity demand to match supply.
• Includes peak shaving, load shifting, and demand response.
• Improves grid stability and reduces operational costs.
• Enables efficient utilization of power plants.
78. Environmental impacts of energy production
• Air pollution from fossil fuel combustion.
• Water pollution and thermal pollution from power plants.
• Habitat disruption and land use changes.
• Greenhouse gas emissions causing climate change.
79. Global warming
Global warming refers to the long-term increase in Earth's average surface temperature due to
human activities, mainly the emission of greenhouse gases like carbon dioxide and methane.
These gases trap heat in the atmosphere, enhancing the natural greenhouse effect and leading to
climate changes such as melting glaciers, rising sea levels, and more frequent extreme weather
events. The consequences threaten ecosystems, agriculture, and human health, making mitigation
and adaptation critical global priorities.
