Energy, a term coined by Thomas Young in the 18th century, is the "ability to do work.
" The two
laws of thermodynamics govern how energy behaves:
The First Law: Energy cannot be created or destroyed, only converted from one form to another.
The Second Law: Some energy is always lost as heat, meaning no energy conversion is 100%
e cient.
All living organisms need energy for biochemical reactions. Around 99.8% of our energy comes
from the Sun, which plants use to create food and store energy as biomass. Energy use re ects
development, and there are large di erences in energy consumption across the world.
Renewable Energy
Renewable energy sources are those that can be naturally replenished and are considered more
sustainable compared to fossil fuels. Some common types of renewable energy include solar,
wind, hydroelectric, hydrogen, ocean, geothermal, and biomass energy. Below are their key
features, advantages, and disadvantages.
1. Solar Energy
Solar energy is the energy we receive from the Sun, primarily through nuclear fusion. The Earth
receives about 1.4 kJ/sec/m² of solar energy.
Advantages:
Renewable: Solar energy is constantly available.
Environmentally Friendly: It generates electricity without causing pollution.
Low Maintenance: Solar systems have a long lifespan (30-40 years) and require little upkeep.
Remote Areas: Solar energy can be used in places without a grid.
Versatile: Used in solar cookers, water heaters, and outdoor lighting.
Disadvantages:
Weather Dependent: Solar energy is less e ective on cloudy days and at night.
High Initial Cost: Solar panels and systems can be expensive to install.
Space Requirement: Large areas of land may be needed for solar farms.
Storage Issue: Energy must be stored in batteries for use at night.
2. Wind Energy
Wind energy is harnessed from the movement of air, typically using wind turbines. Wind farms are
large clusters of turbines that generate electricity.
Advantages:
Free & Clean: Wind is a natural, non-polluting energy source.
Remote Area Use: Wind turbines can be used in isolated regions.
Low Operating Cost: Once set up, wind energy has minimal recurring costs.
Dual Use of Land: The land beneath wind turbines can still be used for farming.
Disadvantages:
Unpredictable: Wind is not constant and can be unreliable.
High Initial Costs: Wind turbines are expensive to install and require large spaces.
Environmental Impact: Turbines can kill birds and disrupt local wildlife.
Noise: Wind farms can be noisy, disturbing nearby residents.
3. Hydroelectric Energy
Hydropower harnesses energy from falling or owing water to generate electricity, typically
through dams or water mills.
Advantages:
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Clean & Reliable: Hydroelectricity is a non-polluting and constant energy source.
Dual Purpose: Dams provide water for irrigation and ood control.
Long Lifespan: Hydroelectric plants have a long service life and low operating costs.
Disadvantages:
High Initial Investment: Building dams requires signi cant funding.
Environmental Impact: Dams can destroy ecosystems, displace people, and disrupt aquatic life.
Geographical Limitations: Suitable locations are limited to areas with signi cant water ow.
4. Hydrogen Energy
Hydrogen is a clean fuel that releases a large amount of energy when burned. It is used in fuel
cells to generate electricity.
Advantages:
Clean Fuel: Burning hydrogen only produces water, making it environmentally friendly.
Versatile: Can be used in various applications, including in spacecraft.
Energy Storage: Hydrogen can store energy for later use.
Disadvantages:
Explosive: Hydrogen is highly ammable and requires careful handling.
Storage & Transport: Hydrogen is di cult to store and transport safely.
5. Ocean Energy
The energy of the ocean can be harnessed from tides, waves, and temperature di erences.
Tidal Energy:
This uses the rise and fall of tides to generate electricity through turbines in a barrage system.
Wave Energy:
Harnesses the power of ocean waves to generate electricity using oscillating water columns.
Ocean Thermal Energy:
Exploits the temperature di erence between warm surface water and colder deep water to
generate electricity.
Advantages:
Free & Clean: Ocean energy is a renewable and non-polluting source.
Continuous: Tides and waves occur 24/7, ensuring a constant energy supply.
Disadvantages:
Environmental Impact: Tidal systems can disrupt marine life and habitats.
Location Speci c: E ective only in areas with strong tidal or wave activity.
High Costs: Building the necessary infrastructure is expensive.
6. Geothermal Energy
Geothermal energy is derived from the heat stored inside the Earth. It is used for heating and
generating electricity.
Advantages:
Sustainable: Geothermal energy is renewable and can be used continuously.
Low Emissions: It produces little to no greenhouse gases.
Reliable: Provides a steady source of energy.
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Disadvantages:
Geographic Limitations: Suitable locations are limited to areas with signi cant geothermal activity.
High Initial Cost: Drilling and setting up geothermal plants require a large investment.
7. Biomass Energy
Biomass energy comes from organic materials like wood, agricultural waste, and animal dung. It is
burned to produce heat or converted into biofuels.
Advantages:
Waste Utilization: Uses organic waste products for energy.
Renewable: Biomass is a renewable energy source.
Versatile: Can produce heat, electricity, and biofuels.
Disadvantages:
Emissions: Burning biomass can release pollutants into the air.
Land Use: Large-scale biomass production may compete with food production, causing
shortages.
Ine ciency: Traditional biomass stoves can be ine cient and produce harmful smoke.
Conclusion
Renewable energy sources o er a cleaner, more sustainable alternative to fossil fuels. Each type
has its advantages and challenges, but as technology improves, these sources are becoming
more viable and important for reducing our environmental impact.
Energy Content of Fossil Fuels and Biogas
1. Coal
Coal was formed millions of years ago during the Carboniferous period (255-350 million years
ago) from the remains of plants and animals in swampy regions. Over time, the organic material
was buried and compressed to form coal. Coal is the most abundant fossil fuel, with reserves of
about 6,000 billion tonnes globally, enough to last 200 years at current consumption rates.
However, if the consumption rate increases by 2% annually, the reserves may only last 65 years.
Readily available and cost-e ective.
High calori c value and capable of generating large amounts of electricity.
Extensive infrastructure for mining, transportation, and usage.
Disadvantages of Coal:
Overuse and depletion of reserves.
Emits pollutants like sulfur dioxide, leading to acid rain.
Contributes to global warming by releasing greenhouse gases.
Harmful environmental impacts from mining.
2. Petroleum
Petroleum, a major energy source, is primarily used for transportation and as raw material in
petrochemical industries. OPEC countries hold about 67% of the world’s petroleum reserves, with
Saudi Arabia holding the largest share (25%). If current consumption continues, global petroleum
reserves are expected to be exhausted in the next 40 years.
Oil Reserves in India:
Major oil elds are located in Assam, Gujarat, and Maharashtra, with the Bombay High eld being
signi cant.
3. Natural Gas
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Natural gas, mostly composed of methane (95%), is a cleaner fossil fuel and is used for domestic
heating, power generation, and as a raw material in industries. Major reserves are located in
Russia, Iran, and the USA, with new discoveries in India’s o shore and onshore elds.
Advantages of Natural Gas:
Clean-burning with fewer pollutants.
High calori c value and e cient for power generation.
Easily transported via pipelines.
4. Lique ed Petroleum Gas (LPG)
LPG is a clean fuel used mainly for domestic cooking. It’s produced by converting petroleum into
liquid form under pressure. LPG has lower emissions compared to diesel and petrol and is
considered a cleaner energy source.
5. Compressed Natural Gas (CNG)
CNG is a cleaner alternative to petrol and diesel used in vehicles. It is cheaper and produces
lower emissions, contributing to cleaner air in urban areas. It’s widely used in vehicles, such as
those in Delhi’s public transport system.
6. Nuclear Energy
Nuclear energy is generated through nuclear ssion or fusion, both of which release large
amounts of energy.
Nuclear Fission:
Involves splitting the nucleus of heavy elements (like Uranium-235) to release energy.
Example: Uranium-235 undergoes ssion when bombarded with neutrons, releasing energy and
more neutrons to continue the chain reaction.
Nuclear Fusion:
Involves merging lighter nuclei (like Hydrogen isotopes) to form heavier ones, releasing vast
amounts of energy.
Example: Deuterium + Deuterium → Helium + Energy.
Components of a Nuclear Reactor:
Moderator: Slows down neutrons (e.g., Heavy water, graphite).
Control Rods: Boron or cadmium rods to control the reaction.
Coolant: Removes heat produced and transfers it to turbines.
Shielding: Concrete walls to protect from radiation.
Fuel: Typically Uranium-235.
Advantages of Nuclear Energy:
Low greenhouse gas emissions.
High energy output from small amounts of fuel.
Cost-e ective once the plant is built.
Disadvantages of Nuclear Energy:
High initial construction and operational costs.
Risks, including accidents and long-lived radioactive waste.
Limited uranium supply (30-60 years).
Long construction periods and high expertise required.
Nuclear waste disposal is challenging, with spent fuel lasting 200-500 years.
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7. National Solar Mission
India’s National Solar Mission, launched in 2010 under the National Action Plan on Climate
Change (NAPCC), aims to establish India as a global leader in solar energy. The mission seeks to
harness solar energy to reduce reliance on depleting fossil fuels and promote sustainable growth.
Key Goals:
Achieve 1 lakh MW of grid-connected solar power by 2022.
Promote both centralized and decentralized solar energy solutions.
Ensure energy security and ecological sustainability.
Environmental Impact:
Solar energy is clean and produces no emissions during power generation.
It is renewable and available for long durations daily.
Solar power is suitable for remote areas without access to the grid.
Solar systems have a lifespan of 30-40 years, making them long-lasting.
This version breaks down the complex information into more digestible, easy-to-understand
sections with key points, making it more organized and easier to follow while maintaining
important details.
