Introduction to Energy

Types of Energy Sources

Solar Energy

Wind Energy

Tidal Energy

Hydro Energy

Biomass Energy

Geothermal Energy

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Definition of Energy: Energy can be defined as the ability (or) capacity to do work

Energy can be basically divided into Potential & Kinetic Energies:•Potential Energy is the energy that something has

due to its position or because of its arrangement of parts. It can also be called stored energyExamples: A coiled spring, Chemicals in batteries etc.•Kinetic Energy is the energy possessed by any

object in motion. Examples: energy in a ball thrown upward, wind etc.

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The Other types of energy: Energy can be obtained in number of way. It may

be in the form of

(1) Chemical energy -due to chemical reaction (2) Electrical energy -due to flow of electron (3) Heat energy - due to thermal vibration(4) Light energy - due to radiation of light

(5) Mechanical energy – due to moving parts(6) Nuclear energy - due to nuclear

reaction(7) Sound Energy - due to vibration of

solids, liquids and gasesThe SI unit of energy is Joule (or) Nm.

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Law of conservation of energy

According to law of conservation of energy, Energy can neither be created nor destroyed. But, one form of energy can be converted to another form.

Example: A battery generates electrons from chemical

reactions, which are used to make electrical energy.

A heater convert electrical energy into heat energy. The human leg converts the chemical energy stored in the muscles into mechanical energy when you pedal a bicycle.

Energy ChainsMost of the energy in nature needs to be converted from one form to another before being used.On the basis of availability they can also be classifies as

• Primary energy resources • Secondary energy resourcesThere is also intermediate energy, which is a stage between the other two

Primary energy: All energy originating from natural sources such as coal, solar, wind, hydro are called primary energy resources.

Secondary energy: The energy converted from primary energy sources. For example, the solar energy can be converted into electricity

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Types of Energy sources1. Conventional energy sources (or) Non-renewable energy

sources2. Non-Conventional energy sources (or) Renewable energy

sources

• Generally, non-renewable energy sources come out of the ground as liquids, gases and solids.

Examples: The conventional (or) Non-renewable energy sources are Oil, Coal, Petroleum and natural gas, Nuclear energy

(1) Conventional energy (or) Non-renewable energyConventional (or) Non-renewable energy sources are those, which cannot be replaced continuously.

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Conventional Energy sources

Fossil Fuels – Fuels formed from plant and animal remains over millennia

1.Solid Fuels –Coal is formed from decay of plant matter. Forms include peat, lignite etc.

2. Liquid Fuels – Petroleum is formed due to decay of marine and extinct spices of life. Forms include petrol, diesel, kerosene etc.

3. Gaseous Fuels – Natural has was also formed due to decay of vegetable matter.

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We can obtain renewable energy from the sun, from the water, from the wind, from crop residues and waste  

The types of Non-conventional (or) Renewable energies are

Solar energy Tidal energy

Wind energy Hydro energyBiomass energy BiofuelsGeothermal Wave Power

Non-Conventional energy (or)Renewable energy

Renewable energy is a source of energy that can never be exhausted and can be replaced continuously

Earth Receives 1018kwh of solar energy every year

The surface of the earth receives about 1014 kW from sun

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It is not constantly available on earth. Thus some form of storage is needed to sustain solar energy through the night and during rainy season

Solar energy is diffused.

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Flat plate collector Parabolic or concentrating

collector

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The absorber plate is metallic.

It is usually coated black to absorb more heat energy.

Tubes, passages or channels integral with the collector carry water or other working fluid.

Insulation should be provided at the back and at the sides to minimize the heat losses.

Usually glass wool is used as insulation material.

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The reflector will have a parabolic shape so that the sun rays striking the profile will be reflected on its focal point.

If a tube carrying a fluid is kept along the focal line, the fluid will be heated to a very high temperature.

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This system uses a flat plate collector, which can heat water up to about 800C only.

Water is circulated through the flat plate collector.

Heat exchanger is used to vaporize a low boiling fluid (butane) and the butane vapor will run the turbine

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A receiver is mounted on the tower which is 100 to 500m high

reflecting mirrors are known as heliostat. The heliostat are arranged in such a way that they direct the solar energy on the receiver throughout the day.

The receiver is designed and positioned in such a way to intercept, absorb and transfer maximum heat to working fluid.

The temperature achieved is 15000C to 17000C

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Photovoltaic systemPhotovoltaic system

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Photovoltaic conversion Photovoltaic conversion Stand alone systemGrid-interface system

Stand alone systems are for low level application

Grid interfaced systems are for the high level and greater power requirement

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Stand alone systemStand alone system

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Grid interfaced systemGrid interfaced system

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Steps involved in selection Steps involved in selection of PV systemof PV systemCalculation of electrical loadSize of PV systemPV sub systems(inverters, charge

controllers, wiring)Panel mountingStorage( Batteries)Type of PV

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Advantages Advantages Renewable source of energy Pollution free After the capital cost, the cost of

power generation is quite low Wide range of applications,

powering street lights to satellites

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DisadvantagesDisadvantages Capital cost is very high Large area of land is required Large number of solar panels

are required Affected by seasons.

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Bio Mass EnergyBio Mass EnergyCan be obtained for biomass

(organic matter)Cheaper for operating the thermal

power plants used along with coal.Includes bio mass crops such as hay

of paddy, wheat, and corn ,bran, animal wastes.

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Bio PowerBio PowerFrom the organic matter when

burnt .Gasification of bio mass (animal

wastes, other organic matter)

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Bio FuelsBio FuelsEthanol (as gasoline)E85 ( ethanol (85%) and petrol

(15%))Bio diesel - alkyl monoesters of

fatty acids Jatropha and soya bean Vegetable oils and animal fats

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AdvantagesAdvantagesTheoretically in exhaustible fuelLess environmental impactClean burning fuels

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DisadvantagesDisadvantagesCan cause particulate pollution Expensive production Available on small scale

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Wind EnergyWind EnergyElectrical energy can be

generated by wind energy by utilizing the kinetic energy of wind

Wind mills are classified into two types

Horizontal axis wind turbine Vertical axis wind turbine

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Horizontal Axis Wind Horizontal Axis Wind TurbineTurbine

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Vertical Axis Wind Vertical Axis Wind TurbineTurbineVertical axis wind

turbine can be classified into two types

Darrieus type Savonius type

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AdvantagesAdvantages Wind Is Renewable And Free Of

Cost Pollution free Can be installed in remote

villages, thus reducing costly transmission lines

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DisadvantagesDisadvantages Capital cost is very high Large area of land is required Very diffused source. maintenance cost is very high Winds direction have an impact

on production High speed directional winds

and cyclones(hurricanes) may ruin the equipment

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Tidal EnergyTidal Energy The large scale up and down

movement of sea water represents an unlimited source of energy.

The main feature of the tidal cycle is the difference in water surface elevations at the high tide and at the low tide.

If the differential head could be utilized in operating a hydraulic turbine, the tidal energy could be converted into electrical energy by means of an attached generator.

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Tidal Power PlantTidal Power Plant

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AdvantagesAdvantages It is inexhaustible source of

energy No problem of pollution After the capital cost, the cost of

power generation is quite low High output can be obtained

compared to solar or wind energy

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DisadvantagesDisadvantages Capital cost is very high As the head is not constant,

variable output is obtained As the head is low, large amount

of water is necessary for the turbine

It will not operate when the available head is less than 0.5m

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Active geothermal places on Active geothermal places on EarthEarth

Geothermal EnergyGeothermal EnergyGeothermal power plants derive energy

from the heat of the earth’s interior. The average increase in temperature

with depth of the earth is 10C for every 30-40m. At a depth of 10-15km, the earth’s interior is as hot as 1000-12000C.

In certain areas of our planet, the underground heat has raised the temperature of water to over 2000C which bursts out as hot steam through the cracks in the earth’s crust. This steam can be utilized for power production.

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Geothermal energyGeothermal energySteam generation is of two kindsMagmatic steamMeteoritic steam

Depending up on the type of source

Vapour dominated Liquid dominated systems

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Geothermal Power PlantsGeothermal Power PlantsGeothermal wells are

drilled at suitable locations.

Water vaporized into steam comes out of the earth’s surface in a dry condition at around 2000C and 8 bar.

This steam will run the turbine coupled with a generator.

Steam is condensed in a condenser and re injected back into the ground by a rejection well

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AdvantagesAdvantages Geothermal energy is cheaper Used as space heating for

buildings Used as industrial process heat Geothermal energy is

inexhaustible

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DisadvantagesDisadvantages Low overall power production

efficiency (about 15%) Drilling operation is noisy Large areas are needed for

exploitation of geothermal energy

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Ocean Thermal Energy Ocean Thermal Energy ConversionConversion

OTEC uses the temperature difference of the sea water at different depths to generate electricity

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Ocean Thermal Energy Ocean Thermal Energy ConversionConversion

OTEC utilizes the temperature difference that exists between the surface waters heated by the sun and the colder deep (up to 1000m) waters to run a heat engine. This source and sink provides a temperature difference of 200 c in ocean areas within 20 of the equator.

Such a small temperature difference makes energy extraction difficult and expensive.

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Merits and DemeritsMerits and DemeritsAvailable throughout yearNo special equipment required for

energy conversion

Less efficiency 3%Large tubing requiredChances of temperature leak outImpact on coral life

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Nuclear Energy Nuclear Energy Fission and fusion reactions causes

enormous energy which can be used in production of electricity

Uranium dioxidePlutonium dioxide

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Merits and DemeritsMerits and DemeritsLess fuel can cause plenty of heat energySuitable for large scale energy productionCompact in size

High installation cost and expertise Disposal of wastes Maintenance cost is very high Highly skilled professionals required Risk involved in radiation

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Nuclear power plant Nuclear power plant

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