basics of energy and classification

CC102-ENERGY AND

ENVIRONMENTAL ENGINEERING

V.DHINAKARANFACULTY

DEPRTMENT OF MECHANICAL

ENGINEERING

1

What is Energy?

• Any physical activity in this world, whether carried

out by human beings or by nature, is cause due to

flow of energy in one form or the other.

• The energy of a body is its capacity to do work. It is

measured the total amount of work that the body can

do.

• Energy is the primary and most universal measure of

all kinds work by human beings and nature.

2

Classifications of energy

• Primary and Secondary energy

• Commercial and Non commercial energy

• Renewable and Non-Renewable energy

• Conventional and Non-conventional energy

3

Primary and Secondary Energy

• Primary energy sources are those that are either

found or stored in nature.

• Common primary energy sources are coal, oil, natural

gas, and biomass (such as wood).

• Other primary energy sources available include

nuclear energy from radioactive substances, thermal

energy stored in earth's interior, and potential energy

due to earth's gravity.

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Primary and Secondary Energy

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Commercial Energy and Non

Commercial Energy

• The energy sources that are available in the market

for a definite price are known as commercial energy..

• Examples: Electricity, lignite, coal, oil, natural gas

etc.

• Commercial energy forms the basis of industrial,

agricultural, transport and commercial development

in the modern world. In the industrialized countries,

commercialized fuels are predominant source not

only for economic production, but also for many

household tasks of general population..6

Non Commercial Energy

• The energy sources that are not available in the

commercial market for a price are classified as non-

commercial energy.

• Non-commercial energy sources include fuels such as

firewood, cattle dung a nd agricultural wastes, which

are traditionally gathered, and not bought at a price

used especially in rural households.

• Firewood, agro waste in rural areas; solar energy for

water heating, electricity generation, for drying grain,

fish and fruits; animal power for transport, lifting

water for irrigation, crushing sugarcane; wind energy

for lifting water and electricity generation7

Renewable Energy &Non-

Renewable Energy

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Renewable Energy &Non-

Renewable Energy • Renewable energy is generally defined as energy that

is collected from resources which are naturally

replenished on a human timescale, such as sunlight,

wind, rain, tides, waves, and geothermal

• The most important feature of renewable energy is

that it can be harnessed without the release of harmful

pollutants.

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Conventional energy Energy

&Non- Conventional energy • Conventional energy resources which are being

traditionally used for many decades and were in

common use around oil crisis of 1973.

• Conventional energy sources includes oil, gas and

coal. These conventional sources are usually fossil

fuels

• Their use leads to increased greenhouse gas emissions

and other environmental damage.

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Conventional energy&Non-

Conventional energy

• Non-conventional energy resources which are

considered for large –scale use after oil crisis of 1973,

• Solar Energy, tidal energy, geo-thermal energy, wind

energy

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Conventional Power generation

• The sources of energy which have been in use for a

long time, e.g., coal, petroleum, natural gas and water

power.

• They are exhaustable except water.

• They cause pollution when used, as they emit smoke

and ash.

• They are very expensive to be maintained, stored and

transmitted as they are carried over long distance

through transmission grid and lines.

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Non- Conventional Power

generation

• The resources which are yet in the process of

development over the past few years. It includes

solar, wind, tidal, biogas, and biomass, geothermal.

• They are inexhaustible.

• They are generally pollution free.

• Less expensive due to local use and easy to maintain.

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Conventional Power plants

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Coal-fired Power plant

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Natural gas or Oil Power plant

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Gas Turbine Power plant

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Combined cycle Power plant

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Hydro Power plant

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Non-Conventional Power plants

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GeoThermal Power plant

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Advantages and Disadvantages

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• One of the most abundant energy sources

• Versatile; can be burned directly, transformed into

liquid, gas, or feedstock

• Inexpensive compared to other energy sources

• Good for recreational use (charcoal for barbequing,

drawing)

• Can be used to produce ultra-clean fuel

• Can lower overall amount of greenhouse gases

(liquification or gasification)

• Leading source of electricity today

• Reduces dependence on foreign oil By-product of

burning (ash) can be used for concrete and roadways23

COAL-Advantages

COAL-Dis advantages

• Source of pollution: emits waste, SO2 , Nitrogen

Oxide, ash

• Coal mining mars the landscape

• Liquification, gasification require large amounts of

water

• Physical transport is difficult

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COAL-Dis advantages

• Technology to process to liquid or gas is not fully

developed

• Solid is more difficult to burn than liquid or gases

• Not renewable in this millennium

• High water content reduces heating value

• Dirty industry—leads to health problems

• Dirty coal creates more pollution and emissions

25

Natural Gas-Advantages

• Burns clean compared to cola, oil (less polluting)

• 70% less carbon dioxide compared to other fossil

fuelshelps improve quality of air and water (not a

pollutant)

• does not produce ashes after energy release

• has high heating value of 24,000 Btu per pound

• inexpensive compared to coal

• no odor until added

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Natural Gas-Disadvantages

• not a renewable source

• finite resource trapped in the earth (some experts

disagree)

• inability to recover all in-place gas from a producible

deposit because of

• unfavorable economics and lack of technology (It

costs more to recover the remaining natural gas

because of flow, access, etc.)

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Renewable energy

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Renewable energy

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Indian Energy Scenario

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Growth of Electricity Consumption in India

Indian Energy Scenario

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Growth of Installed Capacity in India

Tidel Power plants

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Wind Energy

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•Estimated:20,000 MW

•Installed: 732 MW

Solar Energy

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•IIT Mumbai

•BHEL Hyderabad

•NPL ,New Delhi

•NAL,Bangaloore

Nuclear Energy

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What is SOLAR Energy?

• Energy from the sun

• from nuclear fusion reaction that takes place deep in

the sun

• Hydrogen nucleus fuse into helium nucleus

• radiant energy

• light infrared rays. Ultra violet rays, and X- Rays

• All life on the earth depends on solar energy

• Photosynthesis

• Life cycle and food cycle

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What is SOLAR Energy?

• The solar energy that falls on India in one minute is

enough to supply the energy needs of our country for

one day.

• Man has made very little use of this enormous

amount of solar energy that reaches the earth.

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Radiation Spectrum

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Solar Radiation

• The earth surface receives most of the energy in short

wave form

• The energy received by the earth is known as

incoming energy or insolation.

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Variability of insolation

• (i)the rotation of earth on its axis;

• (ii) the angle of inclination of the sun’s rays;

• (iii) the length of the day;

• (iv) the transparency of the atmosphere;

• (v)the configuration of land in terms of its aspect.

40

Terrestrial Radiation

• The insolation received by the earth is in short waves

forms and heats up its surface. The earth after being

heated itself becomes a radiating body and it radiates

energy to the atmosphere in long wave form. This

energy heats up the atmosphere from below. This

process is known as terrestrial radiation

• The long wave radiation is absorbed by the

atmospheric gases particularly by carbon dioxide and

the other green house gases. Thus,the atmosphere is

indirectly heated by the earth’s radiation.

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Terrestrial Radiation

• The atmosphere in turn radiates and transmits heat to

the space. Finally the amount of heat received from

the sun is returned to space, thereby maintaining

constant temperature at the earth’s surface and in the

atmosphere.

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Solar constant

• The solar constant is the amount of energy that

normally falls on a unit area (1 m2) of the earth's

atmosphere per second when the earth is at its mean

distance from the sun. The value of the solar

constant is found experimentally to be 1.35 kW m-2.

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Heat Budget of the Planet Earth

• The earth as a whole does not accumulate or loose

heat.

• This can happen only if the amount of heat received

in the form of insolation equals the amount lost by the

earth through terrestrial radiation.

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Heat Budget of the Planet Earth

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MEASUREMENT OF SOLAR

RADIATION

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Radiation Components

• Solar radiation reaching earth is classified into two

components : Beam & Diffuse radiation.

• Beam radiation(Iь) – Direct Sunlight.

• Diffuse radiation (Id) – solar radiation scattered by

aerosols, dust and molecules.

• Total radiation (It) – (Iь+Id) also known as global

radiation..

49

Solar radiation data

• To design a solar system or to evaluate potential of

any solar application ,it is necessary to have

•Monthly average

• Hourly variation

• Radiation received per day

• Sunshine hours per day

•Daily solar radiation data on a horizontal

surface consisting of both global and diffuse

radiation

•Daily solar radiation with certain tilt angle

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51Solar radiation map(kWh/sq.m/day)


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Pyranometer

• global or diffuse Radiation

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Pyranometer

• Thermopile sensitive surface

• Black body absorbs all wavelengths

• Cold junction of thermopile is completely shaded

• Sensing element is covered by two concentric

hemispherical class domes

• Three leveling screws

• Voltage range 9 micro volt

• Hourly basis and pyrnogram

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Pyranometer

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Pyranometer-Advanatages

• Very small temperature coefficient

• Calibrated to ISO standards

• More accurate measurements of performanceindex and performance ratio

• Longer response time than a photovoltaic cell

• Integrated measurement of the total availableshort-wave solar energy under all conditions.

56

Pyranometer-Application

• Predicting insulation requirements for buildingstructures

• Establishment of greenhouse locations

• Designing photovoltaic systems

• Meteorological and climatological studies

• Measurement of solar intensity data.

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Pyrheliometer

• A pyrheliometer is an instrument formeasurement of direct beam solar irradiance.Sunlight enters the instrument through awindow and is directed onto a thermopile whichconverts heat to an electrical signal that can berecorded.

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Pyrheliometer

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Pyrheliometer

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Pyrheliometer

• Wire wound thermopile of 8 micro volt and 200om impedance

• Tube is sealed with try air-silica gel to avoid anyabsorption of beam radiation the presence owingto moister in the air

• Tracker is provided –continuously face the sunrays

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Pyrheliometer -Types

• Angstrom compensation pyrheliometer

• Abbot silver disc pyrheliometer

• Eppley pyrheliometer

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Angstrom compensation pyrheliometer

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Angstrom compensation pyrheliometer

• Thermocouples on the back of strips measure thetemperature of the strips.

• One strip exposed to the Sun.

• One strip heated by an electric current until it isthe same temperature as the strip exposed to thesun.

• When balanced, the energy absorbed by stripfrom Sun is equal to the energy absorbed by stripfrom electric current.

• Accuracy: ±1.0 to 1.5%64

Sunshine recorder

• The duration of bright sun shine in a day ismeasured by means of a sunshine recorder

• The sun’s Rays are focussed by a glass sphere to apoint on a card strip held in a groove in a sphericalbowl mounted concentrically with the sphere.

• Whenever there is bright sunshine, the imageformed is intense enough to burn a spot on thecord strip.

• Though the day as the sun moves across the sky,the image moves alone the strip.

• Thus, a burnt trace whose length is proportional tothe duration of sunshine is obtained on the strip.

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Sunshine recorder

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Sunshine recorder

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What is Solar Energy?Solar energy can be sued in two ways

• directly as thermal energy

• indirectly using solar photovoltaic cells to convert it

to electricity

In cold climate region or other regions in winter, a large

amount of thermal energy is required to heat air to

maintain comfort conditions in space and to heat water

for washing, cleaning and drying, both for domestic and

industrial needs. Solar energy collectors are the devices

similar to heat converter which are used to obtain

thermal energy from solar energy.

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What is Solar Energy?• 5–7.5 kWh/m2

• Indian Renewable Energy Development Agency and

the Ministry of Non-Conventional Energy Sources

• (i) domestic lighting, (ii) solar water heating, (iii)

street lighting, (iv) village electrification, (v) railway

signals, (vi) desalination of saline water, (vii) water

pumping, (viii) space heating, (ix) solar cooking, (x)

space cooling, (xi) solar greenhouse and (xii)

powering of remote telecommunication stations.

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Solar CollectorA solar collector is a device

• to collect and absorb solar radiation and

• to transfer the absorbed heat energy to the fluid

(generally air or water) in contact or passing through

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Features of Solar Collector

• Collector efficiency

• Concentrating ratio (CR)

• Temperature range

71

Flat Plate Collector

Principle of conversion

a + r + t = 1

a · HG = Î s T 4

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The characteristic features of a flat plate collector

• It absorbs both direct and diffuse solar radiation

• It does not need any sun tracking system. Hence, it is

mechanically stronger than other collectors which

require tracking system.

• It has simple construction requiring a little

maintenance.

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Modified Flat Plate Collector

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increase the acceptanceBooster mirror

Compound Parabolic Concentrator

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Linear Fresnel Lens Collector

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The Fresnel lens consists of fine and linear

grooves formed on one of the surfaces of

some refracting materials sheet while its other surface is flat.

Linear Fresnel Lens Collector

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The Fresnel lens consists of fine and linear

grooves formed on one of the surfaces of

some refracting materials sheet while its other surface is flat.

Paraboloidal Dish Collector

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• This type of collectors can have concentration ratio

ranging from 10 to 1000 which helps to produce

temperature up to 3000°C.

• In order to ensure proper incidence of radiation, the

parabolic dish collector should be provided with two

axes tracking: (i) by rotating the support structure

about the vertical axis for dish alignment and (ii) the

dish is rotated about a horizontal axis for elevation

tracking

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Central Tower Receiver Collector

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In this type of collectors, the receiver is located at the top of a tower and

solar radiation is reflected on it from a large number of independently

controlled flat mirrors called heliostats. The heliostats can be moved

independently about two axes so that the reflected solar radiation isalways directed towards the absorber mounted on the tower

Comparison between Flat and

Focussing Collectors

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Collector Performance Testing

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Collector Performance Testing

87

SOLAR ENERGY STORAGE

88

• Thermal energy storage system

• Chemical energy storage system

• Electrical energy storage system

• Hydrogen energy storage system

• Electromagnetic energy storage system

• Biological storage system

SOLAR ENERGY STORAGE

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• Thermal energy storage system

• Chemical energy storage system

• Electrical energy storage system

• Hydrogen energy storage system

• Electromagnetic energy storage system

• Biological storage system

Sensible heat storage

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91

• It is abundantly available.

• It is inexpensive.

• It has high specific heat which enables to store

more heat per unit mass.

• It has low viscosity requiring less energy to

pump through the pipe system.

• It can be used for both storage and working

medium.

• It is stable.

• It has no harmful effect.


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• It has limited temperature range of 0–100°C.

• It results in the corrosion of pipes.

• It can leak easily as it has low surface tension..

Solid media storage or packed

media storage

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• Stones or pebbles are abundantly available

• Low cost

• Non-combustible

• Easy to handle

• Possibility of high storage temperature

• No freezing point during heat removal

• No corrosion problem

• No requirement of heat exchanger..


95

• The size of the storage container should be large

• Simultaneously charging and discharging of energy

is impossible

• Large pressure drop needs high capacity air blower

basics of energy and classification

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