Q1: (A) Difference between Conventional and Renewable Energy Sources
| Conventional Energy | Renewable Energy |
|---|---|
| Comes from fossil fuels like coal, oil, and natural gas. | Comes from natural sources like sun, wind, water, biomass. |
| Limited in quantity and non-renewable. | Naturally replenished and unlimited. |
| Causes pollution and greenhouse gases. | Eco-friendly and clean energy source. |
| Expensive and difficult to extract as resources deplete. | Cheaper in long-term and sustainable. |
(B) Availability of Renewable Energy Sources in India
Solar Energy: Abundant in Rajasthan, Gujarat, Tamil Nadu, etc.
Wind Energy: High potential in coastal areas like Tamil Nadu, Gujarat, Maharashtra.
Hydro Energy: Available in Himalayan and Western Ghats regions.
Biomass Energy: Found in rural areas with agricultural waste.
Geothermal Energy: Limited spots in Ladakh, Himachal Pradesh.
Tidal Energy: Potential in coastal states like Gujarat and West Bengal.
Q2: (A) Difference between Beam Radiation and Diffuse Radiation
| Beam Radiation | Diffuse Radiation |
|---|---|
| Direct sunlight reaching the surface without scattering. | Sunlight scattered by clouds, dust, or atmosphere. |
| Strong and focused, used in solar concentrators. | Weak and spread, used in flat plate collectors. |
| Available on clear sunny days. | Available even on cloudy days. |
(B) Principle of Pyrheliometer with Neat Sketch
A Pyrheliometer measures beam solar radiation.
It has a collimating tube to allow only direct sunlight.
A blackened thermopile at the end absorbs solar energy.
The temperature difference is converted to an electrical signal.
(Draw a simple sketch showing collimator, thermopile, and sun rays.)
Q3: (A) Principle of Fresnel Lens Collector
Fresnel lens is a flat, thin lens that focuses sunlight.
It concentrates solar rays onto a small receiver or pipe.
Used in solar thermal systems to generate high temperature.
Made of concentric grooves to reduce weight and cost.
(B) Principle of Solar Flat Plate Collector
A flat plate collector absorbs both beam and diffuse radiation.
It consists of:
Absorber plate (black coated),
Transparent glass cover,
Insulated casing.
Water flows through pipes attached to absorber and gets heated.
Used for solar water heating in homes and industries.
Q4: (A) Components of Wind Energy Conversion System (WECS)
Typical wind turbine components:
- Rotor blades – capture wind energy.
Nacelle – houses gearbox and generator.
Gearbox – increases rotation speed.
Generator – converts mechanical to electrical energy.
Tower – supports turbine at high altitude.
Yaw mechanism – aligns rotor with wind direction.
Controller – monitors operation and safety.
(B) Factors Affecting Site Selection for WECS
Wind Speed and consistency.
Open land without obstructions.
Accessibility for transport and maintenance.
Grid connection availability.
Environmental impact.
Land ownership and government regulations.
Q5: (A) Methods of Obtaining Energy from Biomass
Direct Combustion – Burning wood or waste for heat.
Gasification – Converting biomass to producer gas.
Anaerobic Digestion – Producing biogas from organic waste.
Fermentation – Producing ethanol from sugar crops.
Pyrolysis – Heating biomass in absence of oxygen to produce oil, gas, and char.
(B) Factors Affecting Biogas Production
Temperature – Optimal range is 35–40°C.
pH Level – Should be neutral (6.8 to 7.4).
Feedstock type – Cow dung, kitchen waste, etc.
Retention time – How long waste stays in digester.
Mixing and agitation – For uniform digestion.
Carbon to Nitrogen ratio – Ideal C:N is about 25–30:1.
Q6: Write Brief Notes on Any Two
(A) Open Cycle MHD Generator
MHD = Magneto-Hydro-Dynamics.
Converts hot ionized gas (plasma) into electricity using a magnetic field.
No moving parts, high efficiency.
Used in high-temperature power plants.
(B) Floating Drum Type Biogas Plant
Made of two parts:
Digester tank (fixed underground),
Floating gas holder (moves with gas level).
Organic waste is added and digested anaerobically.
Biogas collects in the drum for use in cooking or power.
(C) Thermoelectric Power Converter
Works on Seebeck effect.
Converts temperature difference into electric voltage.
No moving parts, reliable for remote power.
Used in spacecraft and remote sensors.
Electrifying Trends Shaping the Future
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