Sustainable or Renewable energy generation and use of waste heat discarged from conventional power plant

1. Solar updraft power plants and
efficiency enhancement
(Sustainable energy generation)
Presented by:-
Name:- Govind Kumar Mishra
Roll No.:- 14/ME/32
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2. Content:
1. Introduction
2. Types of solar power plants
3. Solar chimney power plant
I. Parts of SCPP
II. Working principle of SCPP
III. Wind action on Solar chimney
IV. Suitable locations for SCPP
4. Efficiency enhancement by waste heat
5. Thermal /CFD analysis of combined cycle
6. Conclusions
7. References
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3. Introduction
 Why renewable energy ?
 By the year 2050 the total world energy demand is
estimated to increase at least 50%, combined with
an expected reduction in fossil fuel energy
technologies.
 There is no balance between the fuel consumption
and discovery of new fossil reserves around the
world .
 Most importantly, the consumption of fossil fuels,
which accounts for 60% of the global greenhouse
gas emissions , has negative impacts on both
environment and human health.
 Every year thousands of premature deaths and
various diseases such as allergies and asthma due to
air pollution are reported worldwide.
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5. Solar power plants:
 There are different types of solar energy
systems as:
 Flat plate collector like photovoltaic (PV)
 Focusing collector like concentrating solar
power technology (CSP)
 Solar chimney power plant (SCPP)
 SCPP cycle combined with other primary power
plant cycles.
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6. Solar chimney power plant(SCPP):
 It is best among all solar energy systems because
others have some practical disadvantages:
• All present renewable-technologies have life-
durations of 20– 35 years, which are rather short
compared to service-lives of classical power plants
(>60 years) for fossil or nuclear.
• CSP-technologies exploit only the direct (beam)
fraction of the solar irradiation and waste the
diffuse light (>10%).
• CSP require water for steam production and re-
condensation, which rarely exists in deserts with
optimal solar irradiance.
• PV is the most expensive solar technology, with the
largest CO2-footprint due to water-production and
the shortest life service.
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7.  However SCPP removes all these
limitations:
1. Except for glass cleaning – no water during
power generation is reqired.
2. It possesses a natural storage capacity for low-
temperature heat, which can be extended towards
base-load energy supply. Thus it also uses diffused
rediation.
3.Design targets for solar updraft power plants
(SUPPs) are 100–120 years of life-duration.
4.Even the large land areas required for SUPPs are no
disadvantage if built in deserts.
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9. Parts of SCPP:
 It is also known by the name ‘Solar updraft power
plant’. It has mainly three parts
 Solar chimney(SC)
 Collector area(CA)
 Power conversion unit (Turbine and Generator)
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10. Source of this centered air-flow is the buoyancy (updraft)
of the warm air in the huge SC, creating as a plant-engine
a pressure sink at the PCUs’ outlet. This updraft draws
permanently fresh cold air from the collector’s rim into
the plant, forming a continuous flow-process. In the
PCUs, the kinetic energy of this permanent airflow is
partly transformed into electric power.
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11. Wind action on chimney:
 Wind flow characteristics varies with increase in
height .It is divided into 2 layers mainly.
1. Prandtl Layer:- The wind flow close to the ground
(Ground distance<100m) is characterized by a
constant shear and high turbulence intensity.
2. Ekman Layer:- The wind shear decreases
continuously, the wind flow becomes more
uniform, and the intensity of turbulence
diminishes to about 5% at 1500 m above ground.
Thus, wind buffeting reduces as the towers
become higher.
Note:- Typical values are 39 m/s at 10 m and about
70 m/s at a height of 1500 m .
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12.  Design process or procedure of solar chimney is not
similar to that of cooling tower due to its height. Its
height is comparatively higher than cooling tower which
is shown below.
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13.  The distribution of the wind pressures around the
circumference of a circular cylinder is controlled by the
REYNOLDS number and by the surface roughness as
shown below.
 With a smooth surface, the suction in the flanks is high
and the drag force is small; with a rough surface the
opposite is true.
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14.  For the beam-like structural behavior of a slender
tower, the wind stresses are proportional to the overall
wind force.
 Therefore, a smooth surface leading to a small drag
coefficient is appropriate for SCs of SUPPs as long as
adequate ring stiffness of the cross-sections is ensured.
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15. Suitable locations:
 SUPPs are designed to operate efficiently in
locations with yearly solar irradiation of more than
2.0 MW h/m2 a, like in the deserts of the earth’s
sun-belt between the tropics.
 The efficiency of SUPPs depends on the intensity G
of the irradiation, the size of the CA (air
temperature) and the height of the SC (air
buoyancy).
 For example, plants with CA diameter of 7000 m
and SC height of 1000 m, like in Fig. 1, will deliver
an electric power output of 200 MW, at noon in
summer time. An annual energy production of 650
GW h/a can be expected.
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17. Efficiency enhancement of SCPP:
 The efficiency of SCPP is extremely low, ranging from 0.5
to 10% of the solar energy input. So several efforts have
been made to enhance the efficiency of SCPP.
1. During night time, an SCPP cannot work as efficiently
as during the daytime.The concept of water-filled
tubes/tanks under the collector roof to increase the
thermal storage capacity. This idea helps to smooth
out the generation of warm air to drive the turbine
and improve the power output after sunset.
2. By combining the solar chimney tower system with a
nuclear power plant, the overall thermal efficiency
will increase because of the extra electrical power
produced by the turbine in the SCPP.
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18. To apply waste heat from nuclear power plant to SCPP cooling
tower is removed and heat is transferred to air in collector
through pressurised water.
Conventional Nuclear power
plant
Nuclear power plant with
SCPP
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19. Thermal analysis of combined
cycle:
 After CFD/thermal analysis of combines cycle it is
observed that overall efficiency of nuclear power plant
increases from 30-35% to 42% .
 the overall thermal efficiency will increase because of
the extra electrical power produced by the turbine in the
SCPP.
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20. Other results obtained in simulation:
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21. Conclusions:
 Solar chimney power plant is the best solar system among
all other solar systems .Its efficiency ranges from ( 0.5% -
10 %).
 Overall efficiency of SCPP combined with conventional
power plant increases for both and it is approaximately to
42%. It is overall increase of 8-9% in conventional cycle.
 Utilizing the harvestable power increases the output
power of the SCPP up to 150% annually .
 Combined cycle does not require a body of water to
provide cooling, and thus can be better suited for arid
environments.
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22. References:
1. Solar updraft power plants: Engineering structures
for sustainable energy generation by Reinhard Harte
, Rüdiger Höffer , Wilfried B. Krätzig and others.
2. Efficiency enhancement of solar chimney power
plant by use of waste heat from nuclear power plant
by Nima Fathi a, Patrick McDaniel and others.
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23. Thank You
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