Unit-I: Introduction to NCES & Solar Energy

Sipna College of Engineering and Technology, Amravati.

Department of Mechanical Engineering
Non-Conventional Energy System (Open Elective –II)6ME05

INTRODUCTION:
Energy is one of the major inputs for the economic development of any country. In the case of the
developing countries, the energy sector assumes a critical importance in view of the ever - increasing
energy needs requiring huge investments to meet them.
Energy can be classified into several types based on the following criteria:
 Primary and Secondary energy
 Commercial and Non commercial energy
 Renewable and Non-Renewable energy

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

Primary energy sources are costly converted in industrial utilities into secondary energy sources;
for example coal, oil or gas converted into steam and electricity

Commercial Energy and Non Commercial Energy

The energy sources that are available in the market for a definite price are known as commercial energy. By
far the most important forms of commercial energy are electricity, coal and refined petroleum products.

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 and
agricultural wastes.

Renewable and Non-Renewable energy

Renewable Energy Sources:
 The resources that are continuously replenished by natural processes and cannot be exhausted even
after continuous utilization are termed as renewable energy sources also known as non-conventional
energy sources. For example, solar energy, wind energy, bio-energy, hydropower, tidal energy etc., are
some of the examples of renewable energy sources.
 A renewable energy system converts the energy found in sunlight, wind, falling-water, sea waves,
geothermal heat, or biomass into a form, we can use such as heat or electricity. Most of the renewable
energy comes either directly or indirectly from sun and wind and can never be exhausted, and therefore
they are called renewable

Various forms of renewable energy:

 Solar energy from the sun.
 Geothermal energy from heat inside the earth.
 Wind energy.
 Biomass from plants.
 Hydro energy, i.e. Hydropower from flowing water.

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Merits:
 Available in nature free of cost
 Zero Carbon Emissions: there are no greenhouse gasses or other pollutants created during the process.
 Environment friendly
 Inexhaustible
Demerits:
 Energy is available in dilute form
 Energy Storage Is a Challenge
 Availability is uncertain
 Difficulty in transporting such form of energy
Non-Renewable Energy Sources:
 The energy sources which can be exhausted and cannot be used again.
 Eg: Coal, Petroleum, Natural gases, etc.

Merits:
 Affordable
 Easily accessible more compatible
 Easy to store

Demerits:
 Cannot be replaced once sources is used up
 Its byproducts causes environmental damages

Global Primary Energy Reserves:

Coal
The proven global coal reserve was estimated to be 9,84,453 million tonnes by end
of 2003. The USA had the largest share of the global reserve (25.4%) followed by
Russia (15.9%), China (11.6%). India was 4th in the list with 8.6%.

Oil
The global proven oil reserve was estimated to be 1147 billion barrels by the end of 2003. Saudi Arabia had
the largest share of the reserve with almost 23%.
(One barrel of oil is approximately 160 litres)

Gas
The global proven gas reserve was estimated to be 176 trillion cubic metres by the end of
2003. The Russian Federation had the largest share of the reserve with almost 27%.
(*Source: BP Statistical Review of World Energy, June 2004)

World oil and gas reserves are estimated at just 45 years and 65
years respectively. Coal is likely to last a little over 200 years

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Global Primary Energy Consumption
The global primary energy consumption at the end of 2003 was equivalent to 9741 million tonnes of oil
equivalent (Mtoe).

The primary energy consumption for few of the developed and developing countries are shownin Table 1.1.
It may be seen that India's absolute primary energy consumption is only 1/29th of the world, 1/7th of USA,
1/1.6th time of Japan but 1.1, 1.3, 1.5 times that of Canada, France and U.K respectively.

TABLE 1.1 PRIMARY ENERGY CONSUMPTION BY FUEL, 2003

In Million tonnes oil equivalent

Oil Natural Coal Nuclear Hydro Total
Country Gas Energy electric
USA 914.3 566.8 573.9 181.9 60.9 2297.8
Canada 96.4 78.7 31.0 16.8 68.6 291.4
France 94.2 39.4 12.4 99.8 14.8 260.6
Russian Federation 124.7 365.2 111.3 34.0 35.6 670.8
United Kingdom 76.8 85.7 39.1 20.1 1.3 223.2
China 275.2 29.5 799.7 9.8 64.0 1178.3
India 113.3 27.1 185.3 4.1 15.6 345.3
Japan 248.7 68.9 112.2 52.2 22.8 504.8
Malaysia 23.9 25.6 3.2 - 1.7 54.4
Pakistan 17.0 19.0 2.7 0.4 5.6 44.8
Singapore 34.1 4.8 - - - 38.9
TOTAL WORLD 3636.6 2331.9 2578.4 598.8 595.4 9741.1

Indian Energy Scenario:

Coal dominates the energy mix in India, contributing to 55% of the total primary energy pro- duction. Over
the years, there has been a marked increase in the share of natural gas in prima- ry energy production from
10% in 1994 to 13% in 1999. There has been a decline in the share of oil in primary energy production from
20% to 17% during the same period.

Energy Supply

Coal Supply
India has huge coal reserves, at least 84,396 million tonnes of proven recoverable reserves (at the end of
2003). This amount to almost 8.6% of the world reserves and it may last for about 230 years at the current
Reserve to Production (R/P) ratio. In contrast, the world's proven coal reserves are expected to last only for
192 years at the current R/P ratio.
Reserves/Production (R/P) ratio- If the reserves remaining at the end of the year are divided by the
production in that year, the result is the length of time that the remaining reserves would last if production
were to continue at that level.
India is the fourth largest producer of coal and lignite in the world. Coal production is con- centrated in these
states (Andhra Pradesh, Uttar Pradesh, Bihar, Madhya Pradesh, Maharashtra, Orissa, Jharkhand, West
Bengal).

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Oil Supply
Oil accounts for about 36 % of India's total energy
consumption. India today is one of the top ten oil-
guzzling nations in the world and will soon overtake
Korea as the third largest consumer of oil in Asia
after China and Japan. The country's annual crude
oil production is peaked at about 32 million tonne as
against the current peak demand of about 110
million tonne. In the current scenario, India's oil
consumption by end of 2007 is expected to reach
136 million
tonne(MT), of which domestic production will be only 34 MT. In terms of sector wise petroleum product
consumption, transport accounts for 42% followed by domestic and industry with 24% and 24%
respectively. India spent more than Rs.1,10,000 croreon oil imports at the end of 2004.
Natural Gas Supply
Natural gas accounts for about 8.9 per cent of energy consumption in the country. The current demand for
natural gas is about 96 million cubic metres per day (mcmd) as against availability of 67 mcmd. By 2007, the
demand is expected to be around 200 mcmd. Natural gas reserves are estimated at 660 billion cubic meters.

Electrical Energy Supply

The all India installed capacity of electric power generating sta- tions under utilities was 1,12,581 MW as on
31st May 2004, consisting of 28,860 MW- hydro, 77,931 MW - thermal and 2,720 MW- nuclear and 1,869
MW- wind (Ministry of Power).

Nuclear Power Supply

Nuclear Power contributes to about 2.4 per cent of electricity generated in India.

Hydro Power Supply

India is endowed with a vast and viable hydro potential for power generation of which only 15% has been
harnessed so far..

Final Energy Consumption

Final energy consumption is the actual energy demand at the user end. This is the difference between
primary energy consumption and the losses that takes place in transport, transmission & distribution and
refinement. The actual final energy consumption (past and projected) is given in Table 1.2.

TABLE 1.2 DEMAND FOR COMMERCIAL ENERGY FOR FINAL

CONSUMPTION (BAU SCENARIO)

Source Units 1994-95 2001-02 2006-07 2011-12

Electricity Billion Units 289.36 480.08 712.67 1067.88

Coal Million Tonnes 76.67 109.01 134.99 173.47

Lignite Million Tonnes 4.85 11.69 16.02 19.70

Natural Gas Million Cubic Meters 9880 15730 18291 20853

Oil Products Million Tonnes 63.55 99.89 139.95 196.47

Source: Planning Commission BAU:_Business As Usual

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Sector Wise Energy Consumption in India
The major commercial energy consuming sectors in the country are
classified as shown in the Figure 1.5. As seen from the figure, industry
remains the biggest consumer of commercial energy and its share in the
overall consumption is 49%. (Reference year: 1999/2000)

Solar radiation at the Earth’s Surface:

Solar radiation, often called the solar resource or just sunlight, is a general term for the electromagnetic
radiation emitted by the sun. Solar radiation can be captured and turned into useful forms of energy, such as
heat and electricity, using a variety of technologies.

Diffuse and direct solar radiation:

As sunlight passes through the atmosphere, some of it is absorbed, scattered, and reflected by:
 Air molecules
 Water vapor
 Clouds
 Dust
 Pollutants
 Forest fires
 Volcanoes.
This is called diffuse solar radiation.
The solar radiation that reaches the Earth's surface without being diffused is called direct beam solar
radiation. The sum of the diffuse and direct solar radiation is called global solar radiation.

Attenuation of Solar Radiations:

Attenuation of solar radiations is due to absorption and scattering in atmosphere.
The intensity of solar radiation keeps on attenuating as it moving away from the earth surface,
keeping wavelength remains unchanged.
Absorption:
As solar radiation passes through the earth’s atmosphere, short wave (Ultra violet rays) absorbed by
Ozone.
Whereas long wave (infrared rays) are absorbed by carbon dioxide and moisture in the atmosphere.
Scattering:
As solar radiation passes through the earth’s atmosphere, the components of atmosphere such as,
water vapor, dust scatters a portion of radiation.
Some part of scattered radiation is lost in the space and remaining is directed towards earth’s surface
in different direction as diffuse radiation.

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Factors affecting attenuation of Solar radiations:
Time of the day
Distance from the sun
Cloud cover
Pollution
Intensity of the sun, it varies slightly

Extra Terrestrial & Terrestrial Radiations:

 Solar radiations incident on the outer atmosphere of the earth is known as Extra terrestrial radiation.
 Extra terrestrial radiations is not affected by change in atmospheric condition while passing through
the atmosphere.
 It is subjected to mechanism of atmospheric absorption & Scattering.
 The solar radiation that reaches to earth’s surface after passing through earth atmosphere is known as
Terrestrial radiation.

Fig. Extra terrestrial & Terrestrial radiation

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Solar Radiation:
The Sun is a large sphere of very hot gases, the heat being generated by various kinds of fusion
reactions, i.e. four hydrogen atoms combines to form one helium atom, the mass of one helium is less
than four hydrogen atoms, the difference in mass is being converted into energy.
4(H)→2He4 + 26.7 MeV
The diameter of sun is 1.39 x 106 km, while that of earth is 1.27 x 104 km. The mean distance between
Sun & Earth is 1.496 x 10 8 km.
The Sun radiates energy uniformly in all directions in the form of Electromagnetic waves.
These radiations can be converted directly or indirectly into other forms of energy such as heat &
electricity.
Energy is radiated in the form of electromagnetic wave in which 99% have wavelength in the range of
0.2 to 0.4 μm. {1 micrometer = 10 -6 meter}. It consists of
8% - U.V. radiations (λ < 0.39) { λ= wavelength}
46%- Visible light (0.39 < λ < 0.78)
46%- Infrared radiation (λ > 0.78)
The output of the sun is 2.8 x 1023 kW-hr/year and energy reaching to the earth is 1.5 x 10 18 kW-
hr/year.

Solar Constant (Isc):

The amount of energy received in unit time on a unit area perpendicular to the Sun’s direction at the
mean distance of the earth from the sun.
According to NASA standard value for the solar constant is taken as,1.353 kilowatts per square meter
or 1353 watt per square meter.
i.e. Isc = 1353 w/m2
The Extraterrestrial radiation emitted, deviates from solar constant valve is given by,

Solar Radiation Geometry:

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1. Latitude and Longitude:

A geographic coordinate that describes the north–south position of a place on the Earth's surface above or
below the Equator, measured from the center of the Earth. is known as latitude. It is measured with 180
imaginary lines that form circles around the Earth east-west, parallel to the Equator. These lines are known as
parallels.

Longitude is a geographic coordinate that describes the east–west location of a location on the Earth's surface or
a celestial body's surface. It is an angular measurement represented by the Greek letter lambda and generally
represented in degrees.

Lines of longitude, also called meridians, are imaginary lines that divide the Earth. They run north to south
from pole to pole, but they measure the distance east or west.
Lines of latitude, also called parallels, are imaginary lines that divide the Earth. They run east to west, but
measure your distance north or south. From the equator, latitude increases as you travel north or south.

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The hour angle is the angular displacement of the sun east or west of the local meridian due to rotation of
the earth on its axis at 15° per hour with morning being negative and afternoon being positive
Or
The Hour Angle (ω) in decimal degrees. We represent the apparent displacement of the sun away from
solar noon, either as a negative or positive angle. An ω of zero indicates that the sun is at its highest point
for that given day.

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Slope or Tilt Angle: In this case, for the solar panels to get their best performance, a steep angle of 60° is
best. During the spring the best angle is 45° and during the summer when the sun is high in the sky it's best to
have a low tilt at 20°

What is optimum tilt angle ?

The optimal tilt angle is the angle where the solar radiation will arrive perpendicularly upon the surface.
The optimum tilt angle is calculated by adding 15 degrees to your latitude during winter, and subtracting
15 degrees from your latitude during summer. For instance, if your latitude is 34°, the optimum tilt angle for
your solar panels during winter will be 34 + 15 = 49°.

Celestial Sphere: Used to describe the position of objects in the sky, the celestial sphere is a fictitious
sphere centred on the Earth upon which all celestial bodies can be projected and It is also the imaginary
spherical shell formed by the sky, usually represented as an infinite sphere, the center of which is a given
observer's position.

Poles of the earth: Earth has two geographic poles: the North Pole and the South Pole. They are the places on
Earth's surface that Earth's imaginary spin axis passes through. Our planet also has two magnetic poles: the
North Magnetic Pole and the South Magnetic Pole.
The North Pole is at the northernmost point of the Earth, while the South Pole is at the southernmost point on
the Earth. The area around the North and South Poles is very cold but the area around the equator is very warm.

Earth equator: The Equator is an imaginary line around the middle of the Earth. It is halfway between the
North and South Poles, and divides the Earth into the Northern and Southern Hemispheres.

Declination angle: The declination angle, denoted by δ, varies seasonally due to the tilt of the Earth on its axis
of rotation and the rotation of the Earth around the sun. The declination of the sun is the angle between the
equator and a line drawn from the centre of the Earth to the centre of the sun.

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Slope: The slope of a line is the measure of the steepness and the direction of the line. slope is calculated
as "rise over run" (change in y divided by change in x).

Solar Radiation Measurement:

Measurement of solar radiation are important because of the increasing no. of solar heating and cooling
application.
It require accurate data to predict performance.
In order to assess the availability of solar energy arriving on the earth, measurement of solar radiation
at same location is essential.

Types of instrument for solar radiation Measurement:

1) Pyrheliometer
It is an instrument for measurement of direct solar radiation flux as normal incidence.
2) Pyranometer
It is an instrument for measurement of direct & diffuse irradiance arriving from the whole atmosphere.

Pyrheliometer:
Measures direct solar radiation
Points at the sun and is perpendicular to solar beam

Classification of Pyrheliometer:
Angstrom Electrical Compensation Pyrheliometer
Abbot Silver-Disc Pyrheliometer
Eppley Pyrheliometer
Bimetallic Pyrheliometer

Moll Gorczynski Pyrheliometer

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1. Angstrom electrical compensation pyrheliometer:

Figure shows the schematic of Angstrom electrical compensation pyrheliometer.

In this pyrheliometer, a thin blackened shaded maganin strip (20*2*0.1mm) is used.
This strip heated electrically untill it is at the same temperature as a similar strip which is exposed to
solar radiation.
Under steady state condition (both strips at identical temperature).
The energy used for heating is equal to the absorbed solar energy.
The thermocouples on the the back of each strip, connected in opposition through a sensitive
galvanometer are used to test for the equality of temperature.
The energy H of direct radiation is calculated by means of formula
HDN = Ki2
Where,
HDN= Direct radiation incident on an area normal to sun’s rays
i = Heating current
K = instrument constant
K = R/Wα
Where,
R= Resistance per unit length of absorbing strip
W= Width of absorbing strip

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2. Abbot Silver-Disc Pyrheliometer:

The sensing element is a silver disk measuring 28 mm in diameter with a thickness of 7 mm that is painted
black on its radiation-receiving side.
It has a hole from the periphery toward the center to allow insertion of the bulb of a high-precision
mercury-in-glass thermometer.
To maintain good thermal contact between the disk and the bulb, the hole is filled with a small amount
of mercury.
It is enclosed outside by a heat-insulating wooden container.
The stem of the thermometer is bent in a right angle outside the wooden container and supported in a
metallic protective tube.
A cylinder with diaphragms inside is fitted in the wooden container to let direct solar radiation fall
onto the silver disk.
There is a metallic-plate shutter at the top end of the cylinder to block or allow the passage of solar
radiation to the disk.
During the measurement phase, the disk is heated by solar radiation and its temperature rises.
When radiation is allowed to fall on the plate for a short period & when it is compared to the thermal
time constant, the temperature rise of the plate is proportional to the intensity of the incoming radiation.
Stability of this instrument is very good.

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Classification of Pyranometer:
Eppley 180° Pyranometer
Yellot Solarimeter (photo-voltaic solar cell)
Moll-Gorczynski solarimeter
Bimetallic Actiono graph of the Rabitzsch type
Velochme pyranometer
Thermoletric pyranometer etc.

1. Eppley 180° Pyranometer:

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The pyranometer manufactured by Eppley laboratories.

Instrument was first developed in 1923 by Kim-ball and Hobbs of the US weather bureau and is known
as Eppley pyranometer.
The receiver surface of this instrument consist of two of two concentric silver rings.
Inner one is coated with parson optical black lacquer and outer one with magnesium oxide.
The temperature difference between the two rings is measured with thermopile of gold-palladium &
platinum-rhodium alloy.
The whole assembly is hermetically sealed inside specially blown spherical lamp bulb.
The spherical lamp bulb is 76 mm in diameter and made of soda lime glass of about 0.6 mm of
thickness filled with dry air.
The temperature difference between the rings gives rise to a thermal e.m.f.

2. Moll-Gorczynski Solarimeter:

This instrument uses a thermopile designed by Dr. W. J. Moll & moll thermopile was used by Dr. L.
Gorczynski.
The thermopile consist of 14 very thin (0.005mm) blackened strips of manganese constantan junction.
Half of which are exposed to the sun while other half are completely shaded.
The narrow metallic ribbon which form the thermopile are arranged in the form of rectangle
(12*11mm).
The exposed junction are coated with dull black lacquer.
It is protected by two hemispherical glass domes which can be removed for inspection & cleaning.
Condensation of moisture on the inside of the dome is prevented by the enclosed space being connected
through a tube to a bottle which normally contains silica gel.
Sensitivity of the instrument is 8 to 9mv/cal cm -2 min-1.

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Campbell Stokes Sunshine Recorder:

🞂 This instrument was invented by “Campbell” & modified by “Stokes”

🞂 The duration of bright sun-shine in a day is measured by means of sunshine recorder.
🞂 Sun rays are focused by a glass-shape dome to a point on a card strip held in a groove of spherical
bowl.
🞂 This spherical bowl is mounted with sphere concentrically.
🞂 Whenever, there is a bright sunshine, the image formed is intense enough to burn a spot on card strip.
🞂 Throughout the day, the sun moves across the sky, the image moves along the strip.
🞂 Thus a brunt space whose length is proportional to duration of sunshine is obtained on a strip.

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Problems:

Type-I: Estimating Monthly Avg. of Daily Global Radiation on Horizontal Surface

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Type-II: Calculation of Angle Made by Beam Radiation with normal to L.F.P.C (θi)

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Type-III: Calculation of Local Solar Time

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