Distributed Generation (Technology) Lectures.ppt

Solar related

1. Distributed Generation
Technology

2. Technologies
Introduction
Solar Energy
Wind Energy
Fuel Cell

3. Introduction
Renewable Energy is recognized by several
names:
Soft Energy
Appropriate Energy
Green Energy
Renewable Energy
Alternative Energy

4. ENERGY NEEDS
he world population rose from 2000 million to 4000 million since the
turn of the century and will increase to 6000 million by the year 2000.
World energy demand is increasing rapidly
Due to which Gas and Oil deposits will be running low by the next
century.
This puts extra pressure on coal.
Also the unequal distribution of fuel e.g. USA being 1/6 of the world
population but it consumes 1/3 of the worlds fuel.
The unequal distribution of physical resources.
Environmental constraints on the exploration of non-renewable
energy resources; e.g. green house effects, high temperatures,
which melts ice on the poles,resulting in floods.

5. Renewable Energy
Energy Resource Origin
Solar Energy: Mother of all energy resources
Wind Energy: Due to Difference in
temperature
Biomass: Organic substance
Geothermal Energy: Heat Energy under earth
Wave Energy: Wind Energy
Tidal Energy: Gravitational force between
earth and moon
Fuel Cell: man Made process

6. RESOURCES FORM OF
DELIVERED
ENERGY
CURRENT
DISTRIBUTE
ON
REMARKS/ COMMENTS
1. SOLAR Total solar
radiation absorbed by
the earth and its
atmosphere is
3.8x 10
24
J/Y
Low Temp heat
(space heating)
Low temp heat
(water heating)
Electricity
LARGE
SMALL
NEGLIGIBLE
The Sun maintains ambient
temperature of the planet at 200-
300 Celsius degrees above absolute
zero in addition passive solar gains
through windows and .walls meet a
large fraction of world space
heating demand. In UK 15-20 % of
domestic heating is obtained from
solar energy 10-15 M\V of solar
cells are installed. 1-2 M\V of
Power towers are in operation.
2. WIND
The kinetic energy
available in the
atmosphere circulation
is
7.5 x10
22
j
ELECTRICITY NEGLIGIBLE Several Multi MW wind turbines
are in operation, e.g. 4 MW
machines for wind farm iii Hawaii.
There are about one million wind
pumps in use. The total capacity is
I GegaWatt. Sailing ships have
traditionally been used for in shore
and off shore shipping.

7. 3. BIOMASS
The total solar radiation
absorbed by the planet
is 1.3x lO
21
J/Yr The
worlds standing
biomass has an energy
constant of about 1.5x
lO
22
J
High Temp
Heating
Biogas
Alcohol
SIGNIFICANT
SMALL
NEGLIGIBLE
Biomass principally wood. It accounts
for about 15% of the world’s fuel
consumption. It provides 80% of
the energy need of many
developing countries.
4. GEOTHERMAL
The heat Flux from the
earth's interior
through the surface is
9.5x10
20
j/yr
Low Temp Heat
(Bathing)
Low Temp Heating
(space & water
heating)
Electricity
SMALL
SMALL
NHGL1GIBLI
Geothermal energy supplies 5350 MW
of heat for use in bathing,
principally in Japan but in 1
Hungary and Iceland about 100000
houses are supplied with heat from
geothermal wells. The installed
electricity capacity is 2500 MW
and is expected to increase more
than 7 folds by the year 2000.
5. HYDRO: Hydro by
annual precipitation
over
Land amounts to 1.1x10
7 Kg

of water. Taking the
average elevation of
the land area as 840
M the annually
accumulated potential
energy would be 9x
10
20
J.
Electricity S1GN1NCAN T Large Hydro schemes provide about 1/4
of the world’s total electricity and
more than 40% of the electricity
used in developing countries. The
installed capacity is 363 Gega
Watts.

8. 6. TIDAL: Energy
dissipation in
connection with
slowing down the earth
ns a result of tidal
action is around lO
20

J/Yr.
Electricity NEGLIGIBLE Only one large tidal barrage is in
operation in France. There are also
small schemes in Russia and
China. Total installed capacity is
240 MW.
7. WAVES: The
amount of energy
stored as kinetic and
potential energy in
waves may be of the
order of lO
ix
J.
Electricity NEGLIGIBLE The Japanese wave energy
research vessel has an installed
capacity of 1 M\V. There are in
addition several hundred wave
powered navigational setups.

9. SOLAR PROSPECTS
 1. The Sun is the potential source of energy that can replace oil, gas and coal. It is basically a
fusion reactor.
 2. Incoming energy absorbed by earth and its atmosphere in one year is 3.8X1024 J, which is 15
to 20 times the amount of energy stored in all of the worlds resources of renewable hydrocarbons.
 3. Unlike capital energy resources, renewable can not be exhausted only limitation is the rate at
which they are used.
 4. Renewable already supply major parts of the worlds energy needs.
 BIOMASS accounts for l/7th of all the fuel consumed and supplies 90% of energy needs of the third
world countries.
 Hydro generates l/4th of the world electricity and 2/3rd of that is used in 35 Countries.
 Sun contributes directly to space heating in virtually all the buildings, through walls and windows.
 Renewable energy technology is in many ways more attractive than the conventional energy technology.
 They can be matched in scale to the need and can be built close to the site where it is required thus
minimizing the cost.
 They can be produced in large number and introduced quickly. Rapid planning and construction lowers
unit cost.
 Diversity of systems available also increases flexibility and security of supply.
 Comparing to other non renewable resources they are less hazardous.Misconception about renewable
energy technologies is that it can be done by DIY (Do it your self).

10. PAKISTAN'S ENERGY OPTIONS IN A
CHANGING WORLD
1. While rest of the world is striving, to reduce its dependence on fossil fuels, our
dependence on these fuels is continuously on the rise.
2. According to the national power plan project, current Hydro share is 38.4% and
it will decrease to 26% at the end of the year 2018 while it's current share of oil
based generation will grow from 29.7% to 42%. The emission of the green
house and dependence on imported fuel is obvious.
3. This means 10 fold rise in oil consumption in power sector, expenditure on oil
imports will increase from $261 MILLION at present to over 1.5 BILLION by the
year 2018.
4. The waste and polluted gases increases to10 times their current values. This is
high lime to go for solar technologies and then integration with grid.
5. Data gathered from five main and thirty two small observations indicate that with
the exception of extreme northern regions, the country on the whole exhibits an
excellent solar climate available for solar energy conversion throughout the
year.
6. The average radiation level exceeds 9.5 MJ/m2-day. The country receives over
it's land 1.5 quadrillion KWH of solar energy per year.
7. For perspective our current annual electricity production from all sources is
50,640 GWH, which represents only about 0.003% of this i.e. solar potential.

11. 8. There can be many different ways in which solar energy can be harnessed to
replace oil based generation in power sector.
a) Utilizes passive solar technologies in power sector which can be built into the
architectural design of the buildings to satisfy heat, cold, light and ventilation
loads.
b) Utilizes active solar technologies to meet some of the space and water heating
demands on buildings.
9. Studies and experiences in other parts of the world suggest that 30 to 80% of
the electricity requirements in the residential sector can be avoided by passive
or active solar technologies.
10.At present, residential consumers proportionate share in electricity consumption
in Pakistan is 37% and is expected to be about 35% by 2018. By employing
alternative resources, 30% saving can be achieved which means demand
avoidance of about 28500 GWH by 2018 or about 10.5% of the annual
electricity demand.
The above applications represent a total contribution of about 55000 GWH by the
year 2018.
 Assuming that this energy from solar applications replaces energy that would be
otherwise be generated from oil fired capacity, it means an annual reduction in
the emission in CO2 of over 41 million ton's. An oil fired plant contributes about
762 ton's of CO2 per GWH and solar technologies produce an average of below
5 ton's per GWH. This means annual reduction in CO2 emission from the power
sector of about 255 ton's.
12.In terms of annual fuels related expenditure it means annual saving of the order
of 31.78 million ton's of oil products and over 1 to 1.5 billion dollars in foreign
exchange.

12. SOLAR ENERGY
It is inexhaustible source.
One hour of energy on earth equals one years fuel energy consumed.
One months supply equals total worlds exploitable fossil fuels.
It is silent and nonpolluting has following potentials:

13. NATURE OF SOLAR ENERGY
Sun is fueled by thermo nuclear fusion and radiates at the rate of 4x lO
25
Watts.
30%) of the radiation is reflected / scattered into space.
23% is consumed in evaporation, convection and precipitation of water
(Hydrological cycle)
47% is absorbed by atmosphere, land surface and oceans.
Total energy consumed over the year by earth atmosphere and hydrological
cycle is 3.8x lO
24
J.
The intensity of in coming solar radiation at any point on earth surface depends
on its position in sky i.e. time of the day, latitude, season, could cover,
atmosphere pollution and height above the sea level.
It is possible to capture and convert up to 60% of the solar energy on the
surface to heat by solar collectors and 20% in electricity by solar cells.
On cloudy days, there may be 300 w/m
2
of defused light following on a
horizontal flat surface which can be collected by advanced collectors.

14. ACTIVE SOLAR GAINS
SOLAR COLLECTORS
Solar collectors exist in wide variety of
shapes and sizes and can deliver heat
across a broad temperature range.
They are grouped to the following operating
temperature range:
Low temperature heat i.e. (<90 degree Centigrade):
Does not focus the rays and can not track the Sun.
Medium temperature heat i.e. (90 Degree to 300
Degree Centigrade):
They carry more concentrating ling focus-arrangements.
High temperature heat i.e. (>300 Degree Centigrade):
Uses strong focusing system of mirrors and lenses to
concentrate on to a point absorber.

15. SOLAR COLLECTORS
LOW TEMPERATURE HEAT
i.Flat Plate Collector
(a) Water Collector
(b) Air Collector
ii.Roof space Collector.
iii. Solar Ponds.
 It provides low temperature heat for swimming pools, space and
water heating.
 Water and Air can be used as heat exchangers.
 Average collectors have conversion efficiency = 30%. High
quality collectors can have 60% efficiency.
 Most of the collectors provide heat in the range of 40 Degree
to 50 Degree Centigrade.

16. SOLAR COLLECTORS
LOW TEMPERATURE HEAT

17. i (a) WATER COLLECTORS
Blackened absorber plate capturing solar radiation into heat. Copper,
Steel or Aluminum is used.
Plastic can also be used for low heat arrangements.
Heat transfer fluid usually water or anti-freeze circulates through
tubes.
Rear side is insulated; front side layer is of glass or transparent plastic.
Vast majority of water collectors are active systems involving pumps to
force heat transfer fluid through collectors.

18. i (a) WATER COLLECTORS
The pumps are activated by heat sensors and operate only when there is
sufficient heat collected.
They can be mounted on roofs.
Should withstand the stress associated with repeatedly being heated or
cooled.
Freezing should be avoided by using antifreeze in indirect system or "fail"
safe and drain automatically".
Thermal diode collectors are also available in which diode will only
transmit heat in one direction. They have an entirely sealed system that
only operates when the panels temperature is sufficient to cause non-
freezing fluid to vaporize and carry heat over to the heat exchanger.

19. i (a) WATER COLLECTORS
Air is sucked through rows of holes in the surface of the panel.
It is cheaper and easier to manufacture
There is no danger of leaks or corrosion.
The disadvantage is that they require electricity to dive fans that
circulates air.
Its principle of operation is the same as water collector only
difference is that air is used as heat transfer fluid.
In it air is drawn through collectors and delivered into the living
space via ducts.

20. (i b) Air Collector
South facing roof can be
converted into solar
collector by replacing roof
tiles with glass or
transparent plastic
Internal surface is sheeting
and blackened internal
surface to absorb the Sun’s
heated air trapped in the
roof
(ii) Roof Space Collectors
Air can be sucked down to
the building using a fan or a
distributed through ducts.

21. (iii) Solar Pond

22. (iii) SOLAR POND
It is usually 2-3 meter deep having conical sides and a flat
blackened bottom.
It is filled with layers of brine of increasing concentration with
most dense layer as the bottom.
20% of the sun light which is not reflected by the surface of
the salt pond is transmitted through the brine, yielding bottom
temperature as high as 100 C where it is retained.

23. MEDIUM TEMPERATURE HEAT
Vacuum Tube
Collectors:
•Uses vacuum between the inner
and outer service of tube.
•Provides more insulation from
dissipation of heat
i (a) Owens Illinois Collector
•Consists of vacuum tube
arranged in an array on a hard
base
•The base has reflecting surface
for trapping sun light among
tubes for absorption of solar
heat

24. MEDIUM TEMPERATURE HEAT
Vacuum Tube Collectors:
ii (b) Phillips Collectors:
It consists of a hollow tube
containing small quantity of
liquid.
For more efficiency the tube is
encased in an evacuated glass
jacket.
They have tilt adjustment.
When the tube is heated and the
liquid evaporates the hot vapors
rise up the tube and condenses
in the cooled cap releasing heat.
Condensed liquid flows back
down the pipe under gravity to
repeat the evaporation /
condensation process.

25. MEDIUM TEMPERATURE HEAT
Line Focus Collector:
 It uses mirrors and lenses to focus sun light.
 They operate at over the range of 100 to 300 Degree Centigrade.
 They tracking system is activated by a computer or a small solar sensor.
 A small panel of solar cells will provide sufficient power to drive a light weight
reflector.
 Following are the various types of tubes under this category:
(a) Hot Line Solar Collector:
(b) Compound Parabolic Collector:
(c) Parabolic Trough Collector:
(d) Segmented Mirror Collector:
(e) Fresnel Lens:
 It consists of rows of parallel grooves embossed on a thin plastic sheet each
groove acts an a tiny prism focusing incident light on a receiver

26. (a) Hot Line Solar Collector:

27. (b) Compound Parabolic Collector:

28. (c) Parabolic Trough Collector:

29. (d) Segmented Mirror Collector:

31. HIGH TEMPERATURE HEAT
Greater than 300 Degree Centigrade
It uses point focus collectors, which are of two types.
a.Parabolic Dish Collectors (Temp: up to 900 degree
Centigrade can be achieved).
b.Central Receiver System, which uses thousands of
sun tracking reflectors (Heliostats) to focus sun light.
(Temp: up to 1400 Degree Centigrade is achieved).
To achieve high concentration of heat, it requires high
level of optical precision and complex guidance
systems capable of tracking the sun's motion along
two axis the dish must turn both East to West and tilt
up and down to keep the beam focused on the point
receiver.

36. THE APPLICATION OF SOLAR COLLECTORS
1. Solar Space Heating:
•First house to rely on flat plate collector for its requirement was
built in 1939 in MIT, USA.
•Since World War II, it became more and more popular.
•Active space heating systems are far more promising for large
buildings or to supply groups of houses.
2.Solar Water Heaters:
•There are Four million solar heaters in use in various countries,
•Three Million are in Japan, 200,000 in Israel, 100,000 in
Australia, over 100,000 in USA, and 20,000 in UK.
•A typical four person family requires 4-5m
2
of collector which will
provide 30 to 40% of average hot water requirements.
•Vacuum tube collectors are more effective than flat plate
collectors but are more expensive.
3.Medium High Temp:
Current designs of vacuum tube collectors have temperature
between 50 degree to 140 degree Centigrade, which makes it
suitable for a wide range of industrial application such as in
dyeing process in furnace etc.

37. SOLAR ELECTRIC
Electricity can be generated in two ways
i.Solar Thermal Electric
•Solar heat is used to drive heat engines, which
can be coupled to a generator to produce
electricity.
ii.Solar Photo Electric
•Sun rays can be converted directly to electricity
using Semi-Conductors Semi Conducting
photovoltaic cells i.e. Solar Cell

38. THERMAL ELECTRIC
a.Among different ways to convert heat into electricity, Rankle cycle
is more popular i.e. pressure steam is produced in boilers by
burning fossil fuel or fussioning Uranium.
b.This is expanded through a turbine which drives a generator.
c.The exhausted steam is condensed back to water and returned to
the boiler to repeat the cycle.
b.The same principle is used in solar power stations in modified
form
c.using low boiling point organic working fluid instead of water i.e.
using more volatile working fluid below 100 degree Centigrade
boiling temperature e.g. Freon, Toluene, Isobutene.
c.Over 40 such cycle engines in the range of 1 to 25 KW stations
are working in Africa to power water pumps.
d.Large generators generating thousands of KW are also
operational, e.g. in Israel.
d.Conversion efficiency is about 35 to 40%

39. THERMAL ELECTRIC
Use of Solar Energy for Electric Power
There are two types of solar power stations
i.Distributed Solar Collector
a.Distributed solar collector system or solar farms
use arrays of line focus or point focus solar
collectors to produce high temperature heat to
generate steam and drive a turbo generator.
b.Heat is conveyed to central heat store using heat
transfer fluids, e.g. High pressure water, oil, molten
salt or liquid metal.
c.This store provides buffer against passing clouds
or can allow over night generation.
d.Example: l MW in Japan, 500 KW in Spain, 150
KW in Arizona, 100 KW in Kuwait and Australia.

40. THERMAL ELECTRIC
Use of Solar Energy for Electric Power
Central Receiver System
•It employs thousands of Sun tracking mirrors to focus
light into central receiver, mounted on top of a tower.
b.The receptor cavity is lined with blackened pipes
which carry heat exchanger fluid having temperature
of 500 Degree to 700 Degree Centigrade to generate
electricity.
c.Example are 5KW in Mexico, 2 KW in France, 1 MW
in Japan and Italy, 500 KV in Spain.
c.The biggest is in California which has 90,000 m
2

heliostats (i.e. tracking reflectors) and occupies 100
acres of land. Capacity is 10 MW.
d.Biggest potential size is 20-30 MW, beyond this,
problem in optical precision with mirrors occur.
e.They are potentially promising to replace Oil/Gas fired
stations.

44. PHOTO ELECTRIC
a.Solar cells convert Sun light into electricity.
b.They are ideal source of energy.
c.They are clean, safe and have no moving
parts,
d.Requires little attention once installed.
d.They can be manufactured from silicon, the
second abundant element on earth, which
could provide virtually all energy that is
required around the world.

45. Photo Electric
DEVELOPMENT OF SOLAR CELL
They are used in Satellites for highly reliable features.
They can be made by Cadmium Sulphide, Gallium Arsenide but
Silicon is far more popular.
Pure Silicon is mixed with impurities of Phosphorus, Baron or
Arsenic to form Semi Conductor material.
Large cylinders of such materials are made and then sliced into
thin wafers.
A second chemical impurity is added on to the surface of wafer.
When light strikes the Semi Conductor it dislodges loosely held
electrons and these flow through the wafer, generating an electric
current.
The wafer is sandwiched between two contacts, the whole
assembly is enclosed in a plastic or glass.
It was first produced in USA Bell Lab in 1954.

46. Solar Cell

47. Photo Electric
Specification SOLAR CELL
a.Electrical output from cell is measured in terms of
peak Watts or KW.
b.A standard of 9 cm diameter silicon cell develops
peak power output equal to 0.75 Watts in bright
sun light or slightly less under defused light.
c.The output from an array of cells will depend on
the way in which it is interconnected, various
combinations of series and parallel produces
output with varying current -voltage.
d.Higher output can be achieved by focusing direct
sun light on to the surface of the cell. (E.g. Point
Focus Lenses).

48. Photo Electric
Specification SOLAR CELL
e.With high concentration ratio output can be
increased to around 20W/c m2.
f.This requires solar tracking, and cooling system
which also increases the cost.
f.Reflectors and lenses are cheaper than all.
g.Another option is to use lummesent concentrator.
h.It consists of glass or plastic impregnated with dye
which first absorbs the sun light falling on the plate
and then radiates it.
i.Most of the re-radiated light trapped with in the
pane by internal reflection, which is focused on to a
strip of cells which are mounted along the edges.
(Potentially this sort of arrangement can be built on
the windows

49. Photo Electric
Specification SOLAR CELL
CONVERSION EFFICIENCY
a.Solar cell can convert up to l/6 of the energy in incident light into
electrical energy.
b.Efficiency can be increased by stacking different types of cells
on top of each other.
c.Efficiency varies, depending on type of cells, temperature of
operation and nature of incident sun light.
d.Silicon efficiency is 15%, GaAs is 18%
e.Efficiency falls as temperature increases for silicon, it may half if
temperatures rise from 20 Degree to 100 Degree Centigrade.
f.GaAs is less effected by temperature variations.
g.Manufacture of solar cells requires considerable amount of
energy and with technology improving, its manufacture has now
reduced from 6 years to 12 months.

50. Solar Electric Application
Solar Challenger was the first to cross the English Channel.
It crossed 180 miles in 1981 and was airborne for five and half
hours.
The planes power came from 16000 solar cells glued on top of
the wings, tail and other parts.
Its total output was 2.7 KW, sufficient to drive a small electric
motor and propeller and also to achieve a speed of 48 km/hr i.e.
30 MPH. Its weight was 93 kg.
Satellites and space vehicles also use solar energy for their
operation.
It carries millions of solar cells to absorb solar energy and to
convert in into useful electrical energy.
The Satellites have banks of batteries to cater for electrical
energy during dark zones where the satellite is not exposed to
sun light.

51. WIND ENERGY(Planetary)
Winds can be broadly classified as planetary
and local.
Greater solar heating of the earth surface
near the equator than near the northern or
southern poles causes planetary winds.
This causes warm tropical air to rise and flow
through the upper atmosphere towards the
poles and cold air from the poles to flow back
to the equator near to the earth surface.

52. Wind Energy (Local Winds)
Local winds are caused by 2 mechanisms.
The first is differential heating of land and water.
The land mass becomes hotter than the water, which causes the
air above the land to heat up and become warmer than the air
above the water.
The warmer lighter air above land rises and the cooler heavier air
above the water moves in to replace it. This is the mechanism of
share breezes.
At night the direction of breeze is riverside because the land
mass cools to the sky more rapidly than the water assuming the
clear sky.
The second mechanism of local wind is caused by the hills and
mountains sides. The air above the slopes heat up during the
day and cools down at night, more rapidly than the air above low
lands. This causes heated air during the day to rise along the
slopes and relatively cool heavy air to flow down at night.

53. Wind Energy (Importance)
it has been estimated that 2% of the solar radiation
falling on the face of the earth is converted to kinetic
energy in the atmosphere and 30% of the kinetic
energy occurs in the lowest location of elevation.
It is then said that the total kinetic energy of the wind in
the lowest kilometer if harnessed can satisfy more than
3 times the energy demand of U.S.
History of wind power : earliest preference in wind mill
appeared in Arab writing from the 9th century A.D that
describe mill that operated on the boarder of Persia
and Afghanistan some two countries earlier.

54. VERTICAL AXIS WIND MILLS:
These early machines sometimes referred to
Persian wind mills near vertical axis
machines.
They were used for grinding or evaporating
sea water for the production of salt (used by
China in 13th century A.D and latter in
Europe and US)

55. HORIZONTAL AXIS WIND MILL:
Horizontal Axis Mills It was used in place of vertical
axis.
Wind mills, after the idea of wind mills reached Europe
they were used for grinding grains, drainage, pumping.
In Netherlands, where very large areas or below sea
land and constantly threaten with flooding.
Wind mills were widely used to pump water out of the
field and into clouds which took it back to the sea.
Nowadays only a few romantic mills remain and
pumping relies mostly on electric grains.
the first windmill to drive an electrical generator was
built in 19th century.

57. Power of Wind Stream
The total power of wind stream is equal to:
P (total) = 1/2gc ρAV
i
3
The Maximum power of wind stream is equal to:
P (max) = 8/27gc ρAV
i
3
Where,
P (total) = total power
ρ = incoming wind density
A = cross sectional area of stream
g
c = conversion factor
V
i
= incoming velocity

58. Maximum Theoretical Efficiency
The ideal or maximum theoretical efficiency (also called the
power coefficient) of a wind turbine is the ratio of the maximum
power obtained from the wind to the total power of the wind.
Maximum Efficiency:

ƞ
max = P(max)/P(total) = 8/27gc X 2gc = 16/27 = 0.5926.
In other words a wind turbine is capable of converting no more
than 60% of the total power of a wind to a useful power.
The maximum efficiency (on power ceoff.) is the ideal efficiency.
Wind turbine blades experience changes in velocity dependent
on the blade inlet angle and blade velocity.
A rigorous treatment of the power extracted from the wind by a
propeller-type wind turbine shows that the power coeff. is
strongly dependent on blade to speed ratio, that it reaches to its
maximum value of about 0.6 angle when the maximum blade
speed (i.e. the blade speed at the tip) is sometimes 6 or 7 times
the wind speed.

59. Maximum Theoretical
Efficiency
Because a wind turbine wheel cannot be completely
closed, and because of spillage and other effects,
practical turbine achieve 50-70% of idea efficiency
(looses in gear box, transmission system and
generator or pump).
The relation of power for wind turbine shows that
these strong dependence of power produced on
wheel diameter, wind speed being proportional to
turbine wheel area i.e. the sequence of its diameter
and to the cube of wind velocity.

60. FLAT RATING
It is more cost
effective to design a
wind mill to produce
rated power at less
than the maximum
prevailing velocity,
using a smaller
turbine and
generator, and to
maintain a constant
output at wind speed
above rating. This is
called flat rating.

61. Wind Turbine Ratings
Because of the source loss in efficiency and power as
low wind velocities, a wind turbine is also designed to
come into operation and wind speed, called the Cut-in
Speed and to Cut-off Speed if damaged against any
high velocity, it is designed to stop operation at a
certain velocity.
Wind turbine ratings are usually gathered for a wind
velocity occurring at a height usually 30 ft (9.1 m) with
an availability factor usually 90%,
The availability factor is defined as the fraction of time,
during a given period that the turbine is actually on line.
The over all load factor is typically 30-40%.

62. Wind Turbine Ratings
Considering an average load factor of 1/3, a wind power
plant of a particular rating would have to be nearly 2.5
time as large as a conventional power plant of same
rating, for a wind power plant would have to multiplied at
about 2.5 to yield a more realistic cost
This is one of the economic burden of wind power.
Small machines are those of less than 100 kw (used for
local purpose, also called SWECs “small wind energy
conversion system”
Large machines are those of those of more than 100 KW
(used at larger scale which is connected to grid)

64. Aero Electric Plant
Uses flow up a tower that looks much like a
cooling tower
Its walls are heated by solar radiation.
Because the walls are circular, the suns rays
need not to be tracked as it changes position in
the sky during the day
The heated walls in turn heat the inside air and
flow up the tower is established
This air flow is made to drive a number of air
turbines located near the the top of the tower
The turbines in turn drive the generators

65. Aero Electric Plant

66. Wind Energy: Other Considerations
Environmental Effects
Noise of Blades
Threat to Birds
TV Interference
Visual Intrusion
Economics
Negligible operating Cost (1% of Capital Cost)
Breakdown Chances far less
Short Construction Time
Quick Return of capital
Cost of Standby Capacity Small

67. Fuel Cell
Where did fuel cell come from?
The 1st fuel cell was built in 1839 by sir
William .G. serious interested in the fuel cell
as practical generators did not begin until this
1960.

68. Fuel Cells
In principle, a fuel cell operates like a battery.
Unlike a battery, a fuel cell does not run down
or require recharging.
It will produce energy in the form of electricity
and heat as long as fuel is supplied.
A fuel cell consists of two electrodes
sandwiched around an electrolyte.
Oxygen passes over one electrode and
hydrogen over the other, generating electricity,
water and heat.

69. Diagram

70. Contd.
Hydrogen fuel is fed into the "anode" of the fuel cell.
Oxygen (or air) enters the fuel cell through the
cathode.
Encouraged by a catalyst, the hydrogen atom splits
into a proton and an electron, which take different
paths to the cathode.
The proton passes through the electrolyte.
The electrons create a separate current that can be
utilized before they return to the cathode, to be
reunited with the hydrogen and oxygen in a
molecule of water.

71. Contd.
A fuel cell system which includes a "fuel
reformer" can utilize the hydrogen from any
hydrocarbon fuel - from natural gas to
methanol, and even gasoline.
Since the fuel cell relies on chemistry and not
combustion, emissions from this type of a
system would still be much smaller than
emissions from the cleanest fuel combustion
processes.

72. What is a fuel cell?
In principle, a fuel cell operates like a battery.
Unlike a battery a fuel cell doesn’t run down or
require recharging.
It will produce energy in the form of electricity
and heat as long as fuel is supplied.
A fuel cell consists of two electrodes, sandwich
around and electrolyte.
Oxygen passes over one electrode and
hydrogen over the other, generating electricity,
water and heat.

73. Contd.
Hydrogen fuel is feed into the” anode” of the fuel cell.
Oxygen (or air) enters the fuel cell through the
cathode encouraged by the catalyst the hydrogen
splits into a proton and electron, which takes different
path to the cathode.
The proton passes through the electrolyte; the
electrons create a separate current that can be
utilized before they return to the cathode to be ruined
with the hydrogen and oxygen in the molecule of
water.

74. Contd.
A fuel cell system which include a fuel
reformer can utilize the hydrogen from any
hydrocarbon fuel from natural gases to
methanol, and even a gasoline, since the fuel
cell relies on chemistry and not combustion,
emission from this type of a system which
would still be much smaller than emission
from the end of fuel cell.

75. TYPES OF FUEL CELL
1- Phosphoric acid
2- Proton exchange membrane or solid
polymers.
3- Molten carbonate.
4- Solid oxide
5- Alkaline
6- Other fuel cell

76. Phosphoric acid:
This is the most commercial develop type of fuel cell.
It is already being used in such diverse applications as hospital,
nursing homes, hotels, office buildings, utility power and air port
terminal.
Phosphoric acid fuel generates more than 40% efficiency and
nearly 85% of steam this fuel cell produces is used for CO
generation compared to 30% for the most efficient internal
combustion engine.
Operating temperature is in the range of 400 degree F.
These fuel cell also can be used in larger vehicles such as busses
locomotives proton exchange membrane.
These cells operates at relatively low temperature about 200
degree F, have high power density, can vary their output quickly to
meet shifts in power demand and are suited for applications such
as in automobile where quick start up is required, according to the
us department of energy there is a primary candidate for light
vehicles, for building and for potentially much smaller applications
such as replacements for rechargeable batteries in video cameras.

77. Molten carbonate
These cells promise high fuel to electricity
efficiency and the ability to consume cold
based fuels.
This cell operates at about 1200 degree F.
the first full scale molten carbonate stack has
been tested and demonstration unite are
being readied for testing in California in 1996.

78. Solid Oxide:
Another highly promising fuel cell the solid oxide fuel cell could be
used in big, high power application including industrial in large
scale in central electricity generating station.
Some developer also sees solid oxide used in motor vehicles.
A 100 kw test has been readied in Europe too small in 25 kw are
already online in Japan.
A solid oxide system usually uses a hard ceramic material instead
of a liquid electrolytes allowing operating temperature 1800
degree F.
Power generating efficiency could reach in 50 second uses an
array of meter long tube.
Other variation includes a compressed disk that resembles the top
of soup can alkaline. Long used by NASA on space mission these
cells can be achieved power generation efficiency up to 70%.
They use alkaline potassium hydroxide as the electrolytes until
recently. They were too costly for commercial applications but
several companies are examining weight to reduce cost and
improve operating flexibility.

79. Other fuel cells:
Direct methanol fuel cell DMFC are relatively
new member of the fuel cell family.
These cells are similar to the PEM cells.
However in the DMFC the anode catalyst itself
draws the hydrogen from the liquid methanol
efficiency of about 40% are expected with this
type of fuel cell which would typically operate at
a temperature b/w 120-190 degree F.
Higher efficiency are achieved at a high
frequency.

80. REGENERATING FUEL CELLS:
Still a very young member of the fuel cell family.
It would be attracted as closed loop form of
power generation.
Water is separated into hydrogen and oxygen
by a solar power electrolyser.
The water is then recalculated back to the solar
power electrolysers and the process begins
again.
These types of fuel cells are currently being
researched by NASA and other world wide.

81. BENEFITS of fuel cells:
New markets. Fuel cell power system market could
exceed $10 billion world wide by 2020 according to a
recent report.
A mere 1 % of the global vehicles market 450, 000
vehicles would mean another $ 2 billions or more.
If just 20% of cars used fuel cells they would cut oil
imports by 1.5 million barrels every day.
If every new vehicles sold in the US in coming years
was occupied with a 60% kw fuel cell.
10,000 fuel cell vehicles running on non petroleum fuel
would reduce fuel consumption by 6.98 million gallons
per year

82. CLEAN AND EFFICIENT
Fuel cells could dramatically reduce urban air
pollution, decrease oil imports and produces
American job.
The US departments of the energy projects
that if the mere 10% of automobiles nation
wide were powered by fuel cells regulated air
pollutant would be cut by 1 million ton per
year and 60 million tons of the green house
gas carbon dioxide would be eliminated.

83. FUEL CELL EMISSION:
Fuel cell running on derived from a reliable
source would be nothing but water vapour
fuel cell can create new market for steel
electronics electrical control industries
suppliers.
They could provide tens of thousands of high
quality jobs the consultant’s estimates that
each 1 thousand mega volt will create 5000
jobs.

84. What sort of fuel can be used in
a fuel cell?
Fuel cells can promote energy diversity and a
transition to renewable energy sources.
Hydrogen can be used directly.
Fuel cell today are running on many different
fuel even gas in land field and waste water
treatment plants.

85. How much do fuel cells cost?
One company commercially offers fuel cell
power plants for about $ 3000 power kw
At that price the units are competitive in high
value,” NICHE” markets, and in areas where
electricity price is high and natural gas price is
low.
Fuel cell will have too be much cheaper to
become commercially in vehicles.
More research is needed to bring the cost of
fuels cell down to that level.

86. What is U.S government doing
now?
The U.S government owns and operates 30
fuel cell cogeneration units, the world’s
largest fleet of fuel cell. T
he U.S department of energy spends the
most i.e. 50 million on research in molten
carbonate and solid oxide fuel cell and more
then 30 million dollar on transportation
application.

87. Why should government support the
fuel cell development?
 Fuel cell can provide major environmental,
energy and economic benefits.
Developments and optimization of energy
technologies has always been a partnership
between governments and private sector.

88. What are other countries doing?
Canada, Japan and Germany aggressively promoting fuel
cell development with text credits, low interest loans and
grants to support purchases and drive down costs.
Toyota has been investing heavily in fuel cells vehicles
research. Show casing a methanol fuel cells version of its
RAV4.
Sport utility vehicles in 1997 while Chrysler recently invested
CAN$450 million in cash.
The latest been a hydrogen fuel cell passenger vehicles
based on company A class car.
The company has a fuel cell buss Ballard also has fuel cell
buses running both in Canada and on the other streets of
Chicago.
Almost all other automakers researching fuel cell cars are
incorporating Ballard fuel cell engine.

89. What more should be done to
spur development of fuel cell?
There are three steps to help commercialize fuel cells.
major increase are needed in research in development
budget
the federal government should also take the lead to
purchase early power unit and vehicles
the government should continue to expand the
program to help buy down the costs of early unit install
around the country
To put cost into perspective we pay more than $5
billion for imported oil each month.
A smaller fraction of the amount could fully
commercialized fuel cells within five years and creates
tens of thousands of jobs.