Application of Reflector Antenna Theory to Solar Concentrators

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Application of Reflector Antenna Theory to Solar
Concentrators

• Nipun Dave (04d07023)
• Nikhil Pande (04d07026)

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Dying Planet

• Fossil fuels are being depleted 10000 times
  faster than they are formed
• 16 million tonnes of CO2 emitted every 24 hours
  by human activities
• 4ºC rise in global temperature by 2100
• Sea levels could rise by 6m by 2100

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OUTLINE

• Why Solar Energy ?
• Solar Reflectors and Antenna Theory
• Solar One Project
• Conclusions
• Questions?

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Why Solar Energy ?

• Most Abundant source of Energy
• Per capita electricity power consumption in India
  
• Expected rise 1200 KW-Hours / year by 2012
• 3.3 KW energy per day
• Over the day average
• Mumbai 4 KW-hour /m2 Day
• Rajasthan 7 KW-hour/m2 Day
• 0.3 land in Rajasthan is enough to satisfy
  electricity demand of entire nation by 2012.

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Why Solar Energy?

• Clean Source of Energy
• India 4th largest producer of CO2
• Contribution of CO2 1,342,962 metric tonnes
  every year
• No residues. No harmful radiations.
• No global warming gases.

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Solar Cooker
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Solar Water Heater
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Public Lighting
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Space Missions
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Aim Harnessing Solar Energy for all purposes
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Two Main Issues

• Generation only during day time. Intensity
  variation over the day. Storage is required.
• Not a Concentrated Source of Energy. Huge amount
  of space and Infrastructure required.

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Requirements

• Better Storage Devices
• Scheduling of distribution of power in the grid
  along with Conventional Power Plants
• Desired Materials Higher Power rated
  photovoltaic cells
• Design Aspects Solar Concentrators

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Design Aspects
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Solar Cell Vs Antenna

• Bandwidth Depends on band gap
• Gain Area of Active Aperture
• Acceptance Angle
• Ground Plane Reflective surface

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Concentrator PV

• Inexpensive optics such as lenses or mirrors used
  to focus light
• Require trackers to follow the sun
• Concentrators reduce requirement of PV material
  by 100-1000 times
• More expensive higher efficiency cells

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Cassegrainian Reflector

• Concentration 500 suns
• Triple Junction Cell
• Cell Size 1mm2
• 26 Efficiency
• Tile size 28cm43cm
• 30W output

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Another Cassegrainian Reflector

• Multi-junction cells
• Two separate cells
• Dichroism for separating wavelengths
• Size 25cm25cm
• 33 Efficiency
• Power Output 17 W
• Concentration ratio of 1200 suns

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Another Cassegrainian Reflector

• 25cm25cm primarymirror
• Dichroic secondary mirror
• InGaP/GaAs cellarea 0.5cm2
• GaSb IR cell of area1cm2
• Height 15cm

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Slat-Array Concentrator

• Concave Reflective slats
• Active aperture 2.7m2
• Concentration 20 suns
• Power 500 W
• 19 Efficiency
• Effectively deflects strong winds

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Solar Thermal Power Plants

• Power production similar to conventional power
  plants
• 1 of Sahara desert sufficient to supply power to
  entire world
• 1 sq.km. of land can generate 1GWh of power per
  year

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Solar Thermal Power Plants

• Types of Solar Thermal plants
• Solar Trough
• Solar Power Tower
• Parabolic Dish

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Solar trough

• Linear ParabolicReflector
• Single Axis Tracking
• Fluid flowing through receiver heated to 400ºC

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Solar Power Tower

• Array of flat reflectors (heliostats)
• Dual-axis tracking
• Air, water / moltensalt heated to 1000ºC
• Higher efficiency,better energy storage
  capability

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Parabolic Dish

• Parabolic reflector
• Dual-axis tracking
• Hydrogen, Helium, air heated to 1500ºC
• Highest Solar to electric efficiency

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Solar One

• The steam side, it is not rocket science. It has
  existed for more than 100 years. The solar side,
  we know it is going to work,"
• Gilbert Cohen, Senior Vice President of Acciona
  Solar Power

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SOLAR ONE

• One of the biggest solar Thermal Projects
• 400 Hectare Land
• 1,84,000 parabolic mirrors
• 15000 US house holds
• 3 Million kgs of Aluminum
• 64 MW capacity

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Solar One

• Practicalities considered while choosing the site
• Lake 18.5 miles. Water easily available
• 3 Electrical Substations are within 3 Km radius
  as the rate to connect to an substation/ grid is
  1.5 Million per mile
• Desert region ? sunlight 365 days

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Solar One

• Parabolic Reflectors/Mirrors
• Molten Salts and Oil in Reflector tube (76 Km of
  tubing)
• Coating on Receiver tubes 96 efficiency
• The panels rotate along with the sun

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Solar One

• Advantages
• 40 efficiency
• Molten Salt can hold heat up to 4 hours
• Disadvantages
• Require dry and sunny locations .
• Dust may reduce the efficiency by 10
  ?Maintenance
• Costs
• Installation and running cost 250 million
• Expensive15 to 17 cents/KW (Other sources 7
  cents/KW)
• By 2020 at par with running costs of coal power
  plants

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Conclusions

• Sun Energy source for the Future
• Solar Concentrators economically viable
• Solar One Just the Beginning !
• Solar Thermal Industry profitable in near future !

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References

• www.wikipedia.org
• Demonstration of a 33 Efficient Cassegrainian
  Solar Module by L.Fraas, et al, JX Crystals Inc.
• A Solid 500 Sun Compound Concentrator Design PV
  Design by Stephen Horne et al PARC
• Solar Concentrators by Scott Elrod, PARC

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Thank You!!Questions?