slides

2. Renewable Energy ?
Renewable
energy is the
term used for
energy flows
occurring
naturally and
repeatedly at a
rate such that it
is replenished at
the same rate as
they are used.
Sun, Gravity,
Tidal, Biomass
etc.

3. Solar energy
The solar constant:- it is the rate at which energy is received from the
sun on a unit area perpendicular to the rays of the sun, at the mean
distance of earth from sun. Isc= 1367 w/m2

4. Motion of the earth around
sun

5. Definition of angles for solar
beam
1. Solar zenith angle (ΦZ):- angle b/w solar beam and normal to
horizontal plane.
2. Air mass ( AMR ):- it is the measure of path length of radiation
through the atmosphere. Secant ΦZ
3. Solar altitude (aa):- angle made by solar beam with the horizontal.
aa = 90 – ΦZ
4. solar azimuth angle :- this is the angle between projection of solar
beam on horizontal plane and the longitude meridian.
5. Hour angle :- The hour angle for any particular position p is the
angle through which earth has rotated since solar noon.
w = 15 ( tsolar – 12h )
Unit of solar Radiation :- 1 Langley = 1 cal/cm2
= 1.163*10-2 kWh/m2

6. Instrument used for measuring
solar Radiation and sunshine
 Pyranometer :- measure Global solar radiation.
 Pyrheliometer :-Measure direct( Beam ) Radiation.
 Campbell stokes sunshine Recorder :-
measure no. of insolation Hour. ( incident solar radiation for specific
period)
 Albedometer :- measure both global and reflected radiation.
1.Pyranometer
2. pyrheliometer
3. Sunshine Recorder 4. Albedometer

7. Application of Solar Thermal
Energy
 Water Heating
 Space Heating
 Space cooling and
Refrigeration
 Power Generation
 Distillation
 Drying
 cooking
Solar Distillation

8. Wind Energy
 The wind has
energy in the form
of kinetic energy
which can be
harnessed too
produce electric
energy.
 Tip speed ratio
Ration of the speed
of the blade tip to the
free stream velocity.
 Solidity
The ration of blade
area to frontal area of
the machine.

9. Tidal Energy
 Tidal energy is power produced by the surge of ocean waters during the rise and fall of
tides.
 Tidal Range:- it is difference between water level of consecutive high and low tides.
 Spring Tides:- when sun, Earth and moon are aligned in conjugation, the lunar and solar
tides are in phase and hence produces the maximum range.
 Neap tides:- when sun- Earth and Moon –Earth direction are perpendicular , the range of
tides is least. The corresponding tides are known as neap tides.

10. Question Session
I. Renewable energy Resources supply
a. Continuously energy
b. Intermittent energy
c. Replenish able energy
d. Non-replinshable energy
1. a & d 2. b & c 3. a & c 4. b & d ( b )
Q 2. which one of the following renewable energy resources have
maximum available energy flux.
a) Solar Radiation
b) Wind Power
c) Geothermal
d) Tidal Energy ( a )

11. 3.The maximum contribution in power production by renewable energy
sources comes from
a) Wind b) Solar c) Geothermal d) Biogas ( a )
4. Maximum and minimum declination of earth is observed on:
a) June 21 and September 21
b) June 21 and December 21
c) June 21 and March 21
d) March 21 and December 21 ( b )
5. Air mass Ration for solar noon is
a) Zero b) 1 c) infinite d) 2 ( b)
6. Solar altitude for solar noon as
a) Zero b) 90 c) 45 d) 60 ( b)
7. The unit of solar radiation flux is
a) Watt b) Samul c) Hertz d) Langley ( d)

12. 8. The instrument used to measure direct solar radiation
a) Pyranometer b) Pyrheliometer
c) Albedometer d) Sun shine Recorder ( b)
9. Tilt factor for flat collector is:-
a) 1 b) zero c) 0.5 d) 2 ( b)
Note ( tilt factor is the ration of beam radiation flux falling on a tilted
surface to that falling on a horizontal surface)
10. In case of solar thermal energy collector, the absorber casting are used
of high
a) Emissivity b) Reflectivity c) Transmissivity d) Absorptivity ( d)
11. Surfaces of absorber plate is coated by selective surfaces. Which of the
following is used
a) Black chrome b) Nickel Chrome c) Cermet d) All of them ( d)

13. 12. The power produced by PV cell array for open circuit voltage 0.5 v
and current 4 A is
a) 2 W b) 20 W c) zero d) 8W ( c )
13. The process by which saline water is converted into pure water by
using solar energy is known
a) Solar pond b) solar distillation
c) Solar cooking d) Solar Heating ( b )
14. Which of the following statement are true?
1. Band gap energy remains constant for homo junction solar PV cells
2. Band gap energy changes for hetro junction solar PV cells
3. A constant power is produced by hetro junction solar PV cells
4. A varying power is produced by homogeneous solar PV cells
a) 1 only b) 1 & 2 c) 1, 2 & 3 d) all of these ( c )

14. 15. The statistical distribution describing wind data with most accuracy is
a) Normal distribution
b) Student – t distribution
c) Poisson distribution
d) Weibull distribution ( d )
16. Gaseous fuel obtained as a result of biomass gasification is
a) Natural gas
b) Producer gas
c) Methane
d) All of these ( b )
17. The maximum power recoverable from the available wind power (p)
i) 0.59p ii) 0.49 p iii) 0.39 p iv) 0.29p (i)

15. 18. The main reason of generation of tidal is
a) Gravitational forces between sun and earth
b) Gravitational forces between moon and earth
c) Gravitational forces between sun and earth as well as moon and Earth
d) Revolution of Earth about its own axis. ( c )
19. The tidal Range is maximum for
a) Spring tides
b) Neap tides
c) ½ ( spring tides + neap tides)
d) None of the above ( a)
20. The variation of tidal curve with time is approximated by ------ curve.
a) Sinusoidal b) Elliptical
c) Cubical d) None of the above ( a )