The document discusses solar tower technology for solar thermal power generation. It describes how solar towers work using a central receiver system with a tower and heliostat field. The heliostats reflect sunlight onto the receiver at the top of the tower to heat a fluid. This thermal energy is then used to generate electricity. Key components discussed include the heliostat field design and technology, receiver types, heat transfer fluids, thermal energy storage, and operational commercial solar tower plants around the world. Economics and the potential for solar towers in India are also summarized.

2. FLOW OF PRESENTATION
 Solar Thermal Technologies
 Solar Tower & its Working
 Technical Aspects
 Solar Tower Projects
 Economical Aspects
 Grid Connectivity
 Advantages & Disadvantages

3. SOLAR THERMAL POWER GENERATION
 Concentrating Solar Technology(CST)
 Concentrates Solar Radiations to heat up a
fluid.
 Heated fluid as heat source for power plant

5. Solar towers generate
electric power from
sunlight by focusing
concentrated solar
radiation on a tower-
mounted heat
exchanger (receiver).
Central Receiver
System(CRS).
SOLAR TOWER

6. CENTRAL RECEIVER SYSTEM
 All of the solar energy to be collected in the
entire field, is transmitted optically to a small
central collection region rather than being
piped around a field as hot fluid.
 Because of this characteristic, central
receiver systems are characterized by large
power levels (1 to 500 MW) and high
temperatures (540 to 1500°C).

7. BASIC WORKING

9. COMPONENTS OF CRS
 Heliostat Field
 Receiver Tower
 Storage System

10. Heliostat
 Heliostats are mirrors
Solar tracking on two
axes.
Concentrates the
reflected solar radiation
on a focal point located at
the top of a tower in
which the receiver
element is placed

12. HELIOSTAT TECHNOLOGY
 Tracking Controls
 Target Focusing Controls
 Heliostat Field Arrangement
 Heliostat Protection

13. TRACKING CONTROLS
 Real Time Analysis
 Actuators-DC Stepper Motors
 Input From various sensors and satellite
 Processing-Digital Computers.
 Latest advances-SCADA system.

15. TARGET FOCUSING
 Achieved by calibration.
 Individual calibration of each heliostat.
 Making focus on Beam Characteristic
Targets by manual control.
 Program stores angle values and gets
calibrated.

17. ADVANCES IN TARGET FOCUSING
 Use image processing.
 Auto calibration.
 Increases Efficiency
 Costly Technique

18. HELIOSTAT FIELD DESIGN
 Cosine Effect
 Shadowing and Blocking
 Attenuation
 Power Level of Plant

20. COSINE EFFICIENCY
 Tells Positioning of Heliostats.
 North Field has max Efficiency.

22. SHADOWING AND BLOCKING

23. SHADOWING AND BLOCKING
 Function of the heliostat spacing, tower
height, and sun angle.
 Ray tracing techniques using computer
analysis.
 Suggests Radial Spacing.

24. ATTENUATION
 Reflected Beam
attenuates as it travels
from heliostat to
receiver.
 Puts a limit to size of
heliostat field for a
particular tower.

25. POWER LEVEL OF PLANT
 Determines size of heliostat field and
number of towers.
 Small level plants have only north field
heliostat fields or two such fields with two
towers.
 Large level plants have heliostat field all
around the tower.

26. FINAL FIELD DESIGN
 Should be radial to minimize shading and
blocking.
 Maximum heliostats on north side to reduce
cosine effect.

29. RECEIVER
 Consists of a large number of metal tubes that
contain a flowing fluid.
 The outer surface of the tubes are black to assure
maximum light absorption.
Thermal Energy
Converts into
Receives concentrated solar
Radiation
Thermal Energy

31. TYPES OF RECEIVERS
 External type:
 These normally consist of panels of many small
(20-56 mm)vertical tubes welded side by side to
approximate a cylinder.
 The bottoms and tops of the vertical tubes are
connected to headers that supply heat transfer fluid
to the bottom of each tube and collect the heated
fluid from the top of the tubes

33. TYPES OF RECEIVERS
 Cavity Type
 Flux absorbing surface placed inside of an
insulated cavity, thereby reducing the convective
heat losses from the absorber.
 The flux from the heliostat field is reflected through
an aperture onto absorbing surfaces forming the
walls of the cavity.

34. TYPES OF RECEIVERS
 Typical designs have an aperture area of about
one-third to one-half of the internal absorbing
surface area.
 Cavity receivers are limited to an acceptance angle
of 60 to 120 degrees. Therefore, either multiple
cavities are placed adjacent to each other

35. Cavity Type Receiver

36. TOWER DESIGN
Height of Tower Depends on:
Weight of the
receiver
Wind age area of
the receiver
Seismic
considerations

37. TOWER DESIGN
 The weight and size of a receiver are affected by
the fluid choice and heliostat field size.
 Typical weights for a 380 MW receiver range from
250,000 kg for an external receiver using liquid
sodium to 2,500,000 kg for a cavity air receiver.
 These would be placed at the top of a 140 to 170 m
tower

38. TOWER DESIGN
 Material for Tower Construction
 Proposed tower designs are of either steel frame
construction, using oil derrick design techniques, or
concrete, using smokestack design techniques.
 Cost analyses indicate that steel frame towers are
less expensive at heights of less than about 120 m
and that concrete towers are less expensive for
higher towers .

40. HEAT TRANSFER FLUIDS
 Five Types
Heat
transfer Oils
Steam
Nitrate Salts
Liquid
Sodium
Air Or
Helium

41. STORAGE SYSTEM
 A storage system makes
it possible to run the
steam turbine under
constant conditions even
during periods of varying
insolation (clouds) or after
sunset.
 It consists of two main
parts which are hot and
cold storage tanks.

42. ENERGY COLLECTION EFFICIENCY

43. RECEIVER LOSSES

44. EFFICIENCY OF GEMASOLAR PLANT(20MW)

45. PILOT PROJECTS-SOLAR ONE
 Built in 1982 and kept operational for six
years.
 Water was used as heat transfer fluid.
 Heliostat field consisted of 1818 heliostats
of 39.2m2 area each.
 3 hour storage.

46. PILOT PROJECTS-SOLAR TWO
 Started in 1996
 Improvement of Solar One
 Added 108 More Heliostats
 Used Molten salt as fluid(nitrate salt)
 Area-82750m2

47. SOLAR TOWERS ACROSS THE WORLD
432 MW plants operating
commercially.
About 1100 MW under construction
and proposal process.

48. OPERATIONAL COMMERCIAL SOLAR TOWER
PLANTS
 PS 10/20
 Seville (Spain)
 10 + 20MW,
 1h storage
 2400 crores
 1255-115m
624-165m

49. COMMERCIAL SOLAR TOWERS
 Gemasolar
 near Seville (Spain)
 20MW,
110MWh/year
 15h storage
 2650 heliostats
 6500 hours per year
 2500 crores

50. COMMERCIAL SOLAR TOWERS
 Ivanpah
 Las Vegas(USA)
 377MW
 no storage

51. COMMERCIAL SOLAR TOWERS
 Sierra SunTower
 Lancaster (USA)
 5MW,
 no storage

52. PLANT ECONOMICS

53. PLANT ECONOMICS
 About 50% cost is of receiver and heliostat
field.
 These two factors are main factors to
control plant economics.
 Main points of plant economics
Levelized Electricity Cost
Payback period

54. PLANT ECONOMICS
 Includes thermo-economic analysis.
 Improved efficiency rate and improved plant
economics rate are not equal.
 So we have to do agreement between costs
and efficiency.

56. ECONOMICS OF GEMASOLAR PLANT
 2500 crores of investment.
 Used government ,private funds and loans.
 Provides electricity at Rs.14.7/unit
 10years payback period.

59. SOLAR TOWER IN INDIA
Estimated medium-term (2032) potential and cumulative achievements as on 31-09.2008.
No. Sources/Systems
Estimated
Potential (MW)
Cumulative
Achievements (MW)
1 Biomass Power (Agro residues & Plantations) 61,000 656
2 Wind Power 100000 * 9521
3 Small Hydro Power (up to 25 MW) 15,000 2290
4 Cogeneration (bagasse) 5,000 993
5 Waste to Energy 2700 55
6 Solar Thermal Power (CSP) 200000** Nil
7 Solar PV and CPV 200000** 2.12
Total 5,83,700 13,450
* Industry estimate
** Assuming only 4% of Indian desert area of ~ 2,00,000 sq. km
(Guj, Raj)

60. SOLAR TOWER IN INDIA
 1 MW Pilot project
 Allotted to Sun Borne Energy
 50-50 funding by MNRE and Sun Borne
Energy
 Site selection process going on.

61. 0 6 12 18 24
SOLAR TOWER GRID CONNECTIVITY
Generation
w/ Thermal
Storage
Solar Resource Hourly Load

62. SOLAR TOWER GRID CONNECTIVITY
 Solar Towers can provide base load power to grids.

63. COST REDUCTION
 Initial Stage.
 Cost reduction by increasing business in
this field.
 Huge potential of cost reduction by
technological advancement of heliostats.
 Recent studies and technological
achievements promises to provide electricity
at Rs.4/unit

64. ADVANTAGES
 Solar-Clean fuel.
 Use barren and wasteland.
 Carbon Emission Reduction
 PS 20-12000 tons of CO2 Emission reduced yearly
 Permanent jobs creation.
 Works in Night and cloudy days.

65. DISADVANTAGES
 High Initial Investment
 Huge Land Required
 Environmental Issue-Bird Killer