Concentrated Solar Power Technology

CONCENTRATED SOLAR POWER (CSP) TECHNOLOGY

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INDIA’S ENERGY SCENARIO
 The energy policy of India - country's burgeoning energy deficit & increased focus on developing alternative sources of energy, particularly nuclear, solar and wind energy  Due to rapid economic expansion, India is expected to be the second-largest contributor to the increase in global energy demand by 2035, accounting for 18% of the rise in global energy consumption  The country has five nuclear reactors under construction (third highest in the world) and plans to construct 18 additional nuclear reactors (second highest in the world) by 2025  India got plans to add about 20GW of solar power capacity by 2022  India has the world's fifth largest wind power market  It suffers from a major shortage of electricity generation capacity ; it is the world's fourth largest energy consumer after US, China and Russia  The electricity sector in India had an installed capacity of 210.936 GW as of November 2012, the world's fifth largest  Over 300 million people in India have no access to electricity. Of those who do, almost all find electricity supply intermittent and unreliable
Source Coal Hydroelectricity Renewable source Gas Nuclear Oil Total Total Capacity (MW) 120,103.38 39,291.40 24,998.46 18,903.05 4780 1,199.75 2,09,276.04 Percentage 57.38 18.77 11.94 9.03 0.57 2.28 2/18

SOLAR POWER IN INDIA
 With about 300 clear, sunny days in a year, India's theoretical solar power reception, on only its land area, is about 5000 Petawatt-hours per year (PWh/yr) (i.e. 5000 trillion kWh/yr or about 600 TW)  India has high solar insolation around 4 to 7 kWh/m2 with about 1500–2000 sunshine hours per year, which is far more than current total energy consumption  Thar Desert alone has a potential to generate 700 GW to 2100 GW  The amount of solar energy produced in India in 2007 was less than 1% of the total energy demand  The grid-interactive solar power as of December 2010 was merely 10 MW; 468.3 MW in 2011; By July 2012 the installed grid connected PV had increased to 1040.67 MW; expecting 10GW by 2017 and a total of 20GW by 2022

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SOLAR ENERGY POWER PLANTS
Two ways to use Solar Energy to generate Electricity:  Photovoltaic : The direct conversion of Sunlight to Electricity  Thermal/CSP : The use of heat to generate electricity
A Photovoltaic Solar PP contains:  Solar Arrays  Inverter  transformer PV Cell uses 250nm-1100nm bandwidth only A Thermal/CSP Plant Contains:  Collector Field  Heat Storage Tank  Heat engine/Turbine  Generator  Cooling Tower  Transformer Thermal Band 100nm-14000nm 4/18

Limitations of Photovoltaic Conversion
     It generates DC Power (4-12% loss in DC to AC conversion) Power not available at night or in bad weather Much More expensive than conventional Toxic chemicals are used like Cadmium and arsenic. (Environmental hazard in disposing off) Can be used for low volume power generation

INTRODUCTION
 Solar thermal energy (STE) is a technology for harnessing solar energy for thermal energy (heat)  Solar thermal collectors are classified by the United States Energy Information Administration as low, medium or high-temperature collectors  High temperature collector is also called as CSP collectors - use mirrors to reflect & concentrate sunlight onto receivers that collect solar energy & convert it to heat  This thermal energy can then be used to produce electricity via a steam turbine/heat engine that drives a generator  More efficient than photovoltaics  Heat storage is possible. With current technology, storage of heat is much cheaper & more efficient than storage of electricity. In this way, the CSP plant can produce electricity day and night  With reliability, unused desert, no pollution, and no fuel costs, the obstacles for large deployment for CSP are cost, aesthetics & land use  Development is underway for CSP projects for around 14,000MW

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VARIETIES
 Cylindrical Parabolic Collector (Parabolic Trough)  Compound Parabolic Collector  Dish/Engine technology  Fresnel Lens Collector  Central Tower Concept

FOSSIL-FIRED BACKUP SYSTEM Solar Thermal Energy

SOLAR RADIATION

CONCENTRATOR

RECEIVER

Concentrated Solar Radiation POWER CONVERSION SYSTEM

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Schematic Diagram for Solar Thermal PP

CYLINDRICAL PARABOLIC COLLECTORS (Also known as Parabolic Troughs
or Linear Parabolic Collector)

Most matured Technology as on date Basic Elements
Absorber tube located at trough’s focal axis Concentric transparent cover Parabolic Concentrator

Most optimum orientation – Focal Axis is N-S & horizontal Tilting of trough in E-W direction needed to absorb the sun’s radiation Heat transfer fluid(Synthetic thermal oil) circulates in tube, temp reaches about 400oC Passed through a series of Heat Exchangers to produce superheated steam Steam runs the conventional Steam turbine to produce Electricity. Better for large capacity power plant The overall efficiency from collector to grid is about 15%, similar to PV Cells but less than Stirling dish concentrators Can be used in Hybrid concept Heat storage feasible for electricity generation when there is no Sun. 20+ Power plants established so far worldwide. Largest – SEGS plant with 5 collector fields with 354MW generation capacity @ Kramer Junction, California, USA 7/18 45+ Under construction/Announced

SCHEMATIC OF CYLINDRICAL PARABOLIC COLLECTORS (also known
as parabolic troughs or linear parabolic collector)

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ANDASOL (SPAIN) Parabolic Trough (50 MW) using thermal oil heat transfer fluid and molten salt storage (7 h)

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PARABOLIC DISH-STIRLING TECHNOLOGY
Parabolic Dish Reflector Focuses incoming sunlight onto a stirling cycle engine Engine/generator uses the Stirling Thermodynamic cycle to produce electricity Two axis tracking Produces high temperature (700-800oC) in the fluid receiving the focused solar energy One Parabolic dish- stirling engine unit produces 3 to 25 kW By using many units in an array power can be produced in MW High efficiency – solar to electricity – 30% Can be used for relatively small distributed power source Minimal water requirement Disadvantage - No thermal energy storage. No sun- No electricity Plants i) Maricopa Solar, Arizona USA – 1.5 MW – 2010 ii) Renovalia, Albacete Spain – 1 MW

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SCHEMATIC OF PARABOLIC DISH-STIRLING TECHNOLOGY

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SES (STIRLING ENERGY SYSTEMS) STRILING POWER UNITS

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LINEAR FRESNEL REFLECTOR SYSTEM
Flat or slightly curved mirrors mounted on trackers on ground are configured to reflect sunlight onto a receiver tube fixed in space above the mirrors A small parabolic mirror is sometimes added atop the receiver to further focus the sunlight Lower overall costs-sharing a receiver between different mirrors

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SOLAR CENTRAL POWER TOWER 2nd most matured Technology as on date (2 sq mile) Circular/Rectangular Array of Heliostats (Flat Mirrors) Central Receiver mounted on Tower Parabolic Concentrator 2 axis Tracking Heat Transfer Fluid (HTF) HTF temp reaches about 1000o F (538ᵒC) Passed through a series of Heat Exchanger to produce superheated steam Steam runs the conventional Steam turbine to produce Electricity. Better for large capacity power plant Can be used in Hybrid concept Heat storage feasible for electricity generation when there is no Sun. 5+ Power plants established so far worldwide. Biggest - 20 MW Spain Seville 10+ Under Construction/Announced 200 MW California, Mojave
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10 MW POWER PLANT AT BARSTOW, CALIFORNIA

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MATURITY LEVEL OF CSP TECHNOLOGIES

CSP Technology type

Installed capacity (MW)

Appropriate capacity under construction and proposed (MW) > 10,000 > 3,000 > 1000 > 500

Parabolic trough Central Receiver

1150 93

Parabolic Dish-Stirling 2.5 Linear Fresnel Reflector (LFR) 11

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CONCLUSION
Of all of these technologies the solar dish/Stirling engine has the highest energy efficiency. (A single solar dish-Stirling engine installed at Sandia National Laboratories National Solar Thermal Test Facility (NSTTF) produces as much as 25 kW of electricity, with a conversion efficiency of 31.25%) Solar parabolic trough plants have been built with efficiencies of about 20% Fresnel reflectors have an efficiency that is slightly lower (but this is compensated by the denser packing) Since a solar power plant does not use any fuel, the cost consists primarily of capital cost with minor operational and maintenance cost. If the lifetime of the plant and the interest rate is known, the cost per kWh can be calculated. This is called the levelised energy cost The first step in the calculation is to determining the investment for the production of 1 kWh in a year. Example, the fact sheet of the Andasol 1 project shows a total investment of 310 million euros for a production of 179 GWh a year. Since 179 GWh is 179 million kWh, the investment per kWh a year production is 310 / 179 = 1.73 euro A study done by Greenpeace International shows that by 2050, CSP technologies could account for around 25% of world’s energy demands

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