Concentrated Solar Power

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EC02107 CONCENTRATED SOLAR POWER Rohima Bhavani email id:[email protected] Hitech college of engineering & technology

Renewable energy
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Biofuels Biomass Hydro power Geothermal power Solar power Tidal power Wave power Wind power

Solar power (also known as solar energy) uses Solar Radiation emitted from our sun. Solar power, a renewable energy source, has been used in many traditional technologies for centuries, and is in widespread use where other power supplies are absent, such as in remote locations and in space. Solar energy is currently used in a number of applications:
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Heat (hot water, building heat, cooking) Electricity generation (photovoltaics, heat engines) Transportation (solar car) Desalination of seawater Photosynthesis by plants

Contents
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1.10 Solar desa1.7.1 Power towers 1.7.2 Parabolic troughs

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1.7.3 Concentrating collector with steam engine 1.7.4 Concentrating collector with Stirling engine 1.7.5 Solar updraft tower

1.7.6 Energy towerlination 2 3.1 Advantages 3.2 Disadvantages

Solar thermal electric power plants

Solar Two, a concentrating solar power tower (an example of solar thermal energy applied to electrical power production). can be focused on a heat exchanger, and converted in a heat engine to produce electric power or applied to other industrial processes. Power towers The solar heat coming from the sun is reflected off the mirrors and is concentrated on the top of the tower where it will heat water or oil to boiling point. After the water or oil is heated it will be transferred to the power plant where it will make steam to turn a turbine to generate electricity. Parabolic troughs A long row of parabolic mirrors concentrates sunlight on a tube filled with a heat transfer fluid (usually oil). As with the power tower, this heated oil is used to power a conventional steam turbine, or stored for nighttime use. The largest operating solar power plant, as of 2007, is one of the SEGS parabolic trough systems in the Mojave Desert in California, USA (see Solar power plants in the Mojave Desert).

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Concentrating collector with steam engine Solar energy converted to heat in a concentrating collector can be used to boil water into steam (as is done in nuclear and coal power plants) to drive a steam engine or steam turbine. The concentrating collector can be a trough collector, parabolic collector, or power tower. Concentrating collector with Stirling engine

A parabolic solar collector concentrating the sun's rays on the heating element of a Stirling engine. The entire unit acts as a solar tracker. Solar energy converted to heat in a concentrating (dish or trough parabolic) collector can be used to drive a Stirling engine, a type of heat engine which uses a sealed working gas (i.e. a closed cycle) and does not require a water supply. Until recently, a solar Stirling system held the record for converting solar energy into electricity (30% at 1,000 watts per square meter).[25] Such concentrating systems produce little or no power in overcast conditions and incorporate a solar tracker to point the device directly at the sun. That record has been broken by a so-called concentrator solar cell produced by Boeing-Spectrolab which claims a conversion efficiency of 40.7 percent.[26] Solar updraft tower A solar updraft tower (also known as a solar chimney, but this term is avoided by many proponents due to its association with fossil fuels) is a relatively low-tech solar thermal power plant where air passes under a very large agricultural glass house (between 2 and 8 km in diameter), is heated by the sun and channeled upwards towards a convection tower. It then rises naturally and is used to drive turbines, which generate electricity.

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Photovoltaic cells produce electricity directly from sunlight


lgeological past, but they would not normally be classed as solar energy.

Concentrating or non-concentrating

A large parabolic reflector solar furnace is located in the Pyrenees at Odeillo, French Cerdagne. It is used for various research purposes.[34] Concentrating solar power (CSP) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam capable of producing high temperatures and correspondingly high thermodynamic efficiencies. Concentrating solar is generally associated with solar thermal applications but concentrating photovoltaic (CPV) applications exist as well and these technologies also exhibit improved efficiencies. CSP systems require direct insolation to operate properly.[35] Concentrating solar power systems vary in the way they track the sun and focus light.


Line focus/Single-axis
o

A solar trough consists of a linear parabolic reflector which concentrates light on a receiver positioned along the reflector's focal line. These systems use single-axis tracking to follow the sun. A working fluid (oil, water) flows through the receiver and is heated up to 400 °C before transferring its heat to a distillation or power generation system.[36][37] Trough systems are the most developed CSP technology. The Solar Electric Generating System (SEGS) plants in California and Plataforma Solar de Almería's SSPS-DCS plant in Spain are representatives of this technology.[38]



Point focus/Dual-axis

A power tower consists of an array of flat reflectors (heliostats) which concentrate light on a central receiver located on a tower. These systems use dual-axis tracking to follow the sun. A working fluid (air, water, molten salt) flows through the receiver where it is heated up to 1000 °C before transferring its heat to a power generation or energy storage syst] Advantages


The 89 petawatts of sunlight reaching the earth's surface is plentiful compared to the 15 terawatts of average power consumed by humans.[41] Additionally, solar electric generation has the highest power density (global mean of 170 W/m2) among renewable energies.[41] Solar power is pollution free during use. Production end wastes and emissions are manageable using existing pollution controls. End-of-use recycling technologies are under development.[42]



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Facilities can operate with little maintenance or intervention after initial setup. Solar electric generation is economically competitive where grid connection or fuel transport is difficult, costly or impossible. Examples include satellites, island communities, remote locations and ocean vessels. When grid-connected, solar electric generation can displace the highest cost electricity during times of peak demand (in most climatic regions), can reduce grid loading, and can eliminate the need for local battery power for use in times of darkness and high local demand; such application is encouraged by net metering. Time-of-use net metering can be highly favorable to small photovoltaic systems. Grid-connected solar electricity can be used locally thus minimizing transmission/distribution losses (approximately 7.2%).[43] Once the initial capital cost of building a solar power plant has been spent, operating costs are low compared to existing power technologies.







Disadvantages


Solar electricity can currently be more expensive than electricity generated by other sources. Solar heat and electricity are not available at night and may be unavailable due to weather conditions; therefore, a storage or complementary power system is required for most applications. Limited power density: Average daily insolation in the contiguous U.S. is 1-2 kW·h/m2 usable by 7-19.7% efficient solar panels.[44][45][46] Solar cells produce DC which must be converted to AC (using a grid tie inverter) when used in currently existing distribution grids. This incurs an energy loss of 4-12%.[47]







Availability of solar energy

The Sun. There is no shortage of solar-derived energy on Earth. Indeed the storages and flows of energy on the planet are very large relative to human needs.


The amount of solar energy intercepted by the Earth every minute is greater than the amount of energy the world uses in fossil fuels each year.[48]

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Tropical oceans absorb 560 trillion gigajoules (GJ) of solar energy each year, equivalent to 1,600 times the world’s annual energy use.[49]em. ability of solar e Energy storage Main article: Grid energy storage For a stand-alone system, some means must be employed to store the collected energy for use during hours of darkness or cloud cover. The following list includes both mature and immature techniques:
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Using traditional batteries Thermal mass Pumped-storage hydroelectricity Flow batteries Molten salt[53] Cryogenic liquid air or nitrogen Compressed air in cylinders and in caverns Flywheel energy storage Hydrogen produced by electrolysis Hydraulic accumulator Superconducting magnetic energy storages Vegetable oil economy

Storage always has an extra stage of energy conversion, with consequent energy losses, increasing the total capital costs. One way around this is to export excess power to the power grid, drawing it back when needed. This appears to use the power grid as a battery but in fact is relying on conventional energy production through the grid during the night. However, since the grid always has a positive outflow, the result is exactly the same. Electric power costs are highly dependent on the consumption per time of day, since plants must be built for peak power (not average power). Expensive gas-fired "peaking generators" must be used when base capacity is insufficient. Fortunately for solar, solar capacity parallels energy demand; since much of the electricity is for removing heat produced by too much solar energy (using conditioners). This is less true in the winter when the peak energy use is in the early evening when food is being prepared and lighting, heating, and entertainment equipment loads are higher. Winter heating loads can be time shifted by storing thermal energy in bulk materials such as rock, water, or thermal phase transistion materials such as glauber's salt] or wax, provided solar ilumination is sufficient. Wind power complements solar power since it can produce energy when there is no sunlight but this advantage is highly dependant upon local and seasonal wind availability.

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[edit] References 1. ^ Solar Spectra: Standard Air Mass Zero. NREL Renewable Resource Data Center (200610-17). Retrieved on 2006-10-17. 2. ^ Earth Radiation Budget Earth Radiation Budget. NASA Langley Research Center (200610-17). Retrieved on 2006-10-17. 3. ^ Earth Radiation Budget 4. ^ NREL: Dynamic Maps, GIS Data, and Analysis Tools - Solar Maps 5. ^ us_pv_annual_may2004.jpg. National Renewable Energy Laboratory, US. Retrieved on 2006-09-04. 6. ^ International Energy Agency - Homepage 7. ^ Liepert, B. G. (2002-05-02). Observed Reductions in Surface Solar Radiation in the United States and Worldwide from 1961 to 1990. GEOPHYSICAL RESEARCH LETTERS, VOL. 29, NO. 10, 1421. Retrieved on 2006-09-04. 8. ^ NREL - Solar Hot Water 9. ^ Solar Hot Water Heating History 10. ^ EERE - Indirect Gain (Trombe Walls) 11. ^ NREL - Transpired Air Collectors (Ventilation Preheating) 12. ^ Horace de Saussure and his Hot Boxes of the 1700s. Retrieved on 2006-09-04. 13. ^ Solar Cooking Plans. Retrieved on 2006-09-04. 14. ^ IEA - Daylighting HVAC Interaction (pg 85) 15. ^ DOE - Daylighting 16. ^ ORNL - Solar Technologies Program 17. ^ Adrienne Kandel; Daryl Metz (2001). "Effects of daylight saving time on California electricity use" (PDF). P400-01-013. California Energy Commission. Retrieved on 2007-0624. 18. ^ Ryan Kellogg; Hendrik Wolff (2007). "Does extending daylight saving time save energy? Evidence from an Australian experiment". CSEMWP 163. Center for the Study of Energy Markets. Retrieved on 2007-05-16. 19. ^ Installed PV power 20. ^ Regional Renewables.org Retrieved 28 November 2006

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21. ^ World Sales of Solar Cells Jump 32 PercentViviana Jiménez, 2004 Earth Policy Institute. Retrieved 4 September 2006. 22. ^ Sun King Russell Flannery 27 March 2006. Retrieved 4 September 2006. 23. ^ Silicon Shortage Stalls Solar John Gartner, Wired News, 28 March 2005. Retrieved 4 September 2006. 24. ^ 2005 Solar Year-end Review & 2006 Solar Industry Forecast Jesse W. Pichel and Ming Yang, Research Analysts, Piper Jaffray, 11 January 2006. Retrieved 4 September 2006. 25. ^ Solar Stirling system ready for production. Retrieved on 2006-09-06. 26. ^ U.S. Department of Energy (2006-12-05). New World Record Achieved in Solar Cell Technology. Press release. Retrieved on 2006-12-06. 27. ^ Solar pond in Gujarat 28. ^ Solar pond at University of Texas El Paso 29. ^ K. Lovegrove, A. Luzzi, I. Soldiani and H. Kreetz "Developing Ammonia Based Thermochemical Energy Storage for Dish Power Plants." Solar Energy, 2003. http://engnet.anu.edu.au/DEresearch/solarthermal/pages/pubs/SolarEAmmonia4.pdf or http://dx.doi.org/10.1016/j.solener.2003.07.020 30. ^ IsraCast: ZINC POWDER WILL DRIVE YOUR HYDROGEN CAR, Wired News: Sunlight to Fuel Hydrogen Future and Solar Technology Laboratory: SynMet 31. ^ New Scientist issue 2577, 13 November 2006 Take a leaf out of nature's book to tap solar power by Duncan Graham-Rowe Accessed Nov 2006 32. ^ J Murray. Investigation of Opportunities for High-Temperature Solar Energy in the Aluminum Industry, National Renewable Energy Laboratory report NREL/SR-550-39819 (USA). 33. ^ NREL - Ocean Energy Basics 34. ^ Les Fours solaires 35. ^ DOE - Solar Basics 36. ^ Plataforma Solar de Almería Concentrator Facilities 37. ^ Sandia - Concentrating Solar Power Overview 38. ^ Plataforma Solar de Almería - Linear-focusing Concentrator Facilities 39. ^ a b c Quaschning, Volker (June 2003). "Technology Fundamentals: Solar thermal power plants" (Reprint). Renewable Energy World: 109-113. Retrieved on 2006-12-7. 40. ^ Sandia - Concentrating Solar Power Overview

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41. ^ a b Vaclav Smil - Energy at the Crossroads 42. ^ Environmental Aspects of PV Power Systems ^ U.S. Climate Change Technology Program - Transmission and Distribution TechnologiesnergyClassifications of solar power technology presented by P.ROHIMA K.BHAVANI ECE ‘A’ HITECH ENGG COLEGE

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