" SOLAR THERMAL POWER PLANT• Introduction• Principles and operation• Types• Pros and cons• Introduction:• Sun is the primary source of energy. Solar has the greatest potential of all the sourcesof renewable energy.• Solar thermal power systems are emerging renewable energy technology and can bedeveloped as viable option for electricity generation in future.• This paper discusses the technology options, their current status, opportunities andchallenges in developing the solar thermal power plant. Solar energy potential and India’s power scenario:• India is located in the equatorial sun belt of the earth.• Sunny weather is about 250-300 days in a year.• The annual global radiation varies from 1600 to 2200KWh/sq.mt.• India’s current electricity insatalled capacity is 135401.63MW.Currently there is a peak power shortage of about 10% and over all power shortage of 7.5 Solar thermal power plants(STP’S):• Solar thermal power plant is one form of solar thermal utilization which uses solarthermal energy converted by solar radiation by concentrators and receivers to drivethe steam turbine to generate electricity according to thermal circuit.The mechanism of conversion of solar to electricity is fundamentally similar to the traditionalthermal power plant except use of solar energy as source of lightPrinciples of STP’S:• In the basic process of conversion of solar into heat energy,solar radiations arecollected and concentrated by solar collectors or mirrors and converted them to heat.This heat is transferred to heat transfer liquid(HTF).This HTF is used to generatesteam, which are then used to operate heat engine.• In this system efficiency of heat engine increases with increase in operatingtemperature • Among all the available systems the central receiver thermal electric power systemanddistributed solar thermal electric power system are suitable.• Advantages of central receiver thermal power system are:• Can be integrated into conventional thermal power plant• Have lowest cost for solar electricity• Have an energy payback time of 6-12 months. • Advantages of distributed power system:• High concentration ratio • High conversion efficiency• Remote operation• Backup heating of power package with fuel• Can be cheaper than PV plant• Low economic risk compared to bulk power production. Solar concentrating collectors:• These collectors increases amount of incident energy on absorber surface by makinguse of reflectors or refractors,which concentrate the solar radiations on to the suitableabsorber or receiver.• High temperature collectors are basically 3 types• Parabolic trough power system• Solar tower power plant• Parabolic dish power system.• Trough system uses mirrored surface of a linear parabolic to focus the solar radiationon the absorber pipe running along the focal line of parabola.• This process is economical and thermal efficiency ranges from 60-80%.• The overall efficiency from collector to grid is about 15%.Advantages of STP’S:• No fuel cost• Predictable• Eco-friendly• Requires less space• Plant can be quickly installed• Maintenance and lubrication cost is lower.• It can meet the sudden changes in load with out much difficult control operation. Disadvantages:• Over all capital investment is high• Large number of circuits make the design complex. • Limited locations• Technical difficulties."