solar thermal in india

Solar Thermal

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Solar thermal systems harness solar energy by utilising solar radiations to generate heat- as hot water, hot air, steam etc. that can be deployed for meeting numerous applications in different sectors such as power generation on a large scale, space heating, space cooling, community cooking, process heating etc. These applications make use of solar energy collectors as heat exchangers that transform solar radiation energy to internal energy of the transport medium (or heat transfer fluid, usually air, water, or oil). The solar energy thus collected is carried from the circulating fluid either directly to the hot water or space conditioning equipment, or to a thermal energy storage tank from which can be drawn for use at night and/or cloudy days. Solar thermal systems can be either non-concentrating or concentrating types. They may also be either stationary or with sun-tracking mechanisms, depending on the application, temperatures required and economic viability.

Concentrated Solar Thermal Power

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Concentrating Solar Power (CSP) technologies use systems of mirrored concentrators to focus direct beam solar radiation to receivers that convert the energy to high temperature for power generation. There are four main configurations that are commercially available- Parabolic Trough, Linear Fresnel Reflector, Parabolic Dish and Central Receiver Tower – with Parabolic Trough being the most prevalent.

Typically, this heat is transformed to mechanical energy through a steam turbine and then to electricity. CSP has advantages compared to photovoltaic as it can readily incorporate thermal energy storage and/or hybridization to provide dispatchable power. The use of relatively ‘low tech’ manufacturing methods for solar collector fields, together with the use of available steam turbine technologies, makes the prospect of CSP capacity quite feasible to get rapidly scaled up. 

SECI plans to undertake the following activities to further the progress of the CSP technology. 

Implementation of CSP Pilot projects:

Out of the 500 MW of capacity addition through solar thermal targeted by JNNSM Phase-I, projects worth 470 MW have been allotted and are due to be commissioned by end of 2013.

SECI is developing Pilot Concentrated Solar Power Projects to establish new technologies on commercial scale. Two CSP Plants, of 50 MW each, are being developed with the following parameters:

Project 1: 50 MW capacity project on Parabolic Trough technology with hybrid cooling and 3 hours Thermal storage, using up to 15% auxiliary fuel. It would reduce water consumption to 25% of a conventional CSP plant. 

Project 2: 50MW capacity project on Solar tower technology with a provision of high (>470 deg. C) operating temperature and 3 hours Thermal storage, using up to 15% auxiliary fuel.

These CSP projects of various configurations and storage types/capacities would demonstrate the efficacy and scalability of such plants for large scale installation in the country.

Title: Concentrating Solar Power Plant using Central Receiver Tower technology

Solar Thermal applications

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Solar Thermal systems have the flexibility of being used for off-grid applications too. Industrial process heat (IPH) applications below 250°C, for example, contribute to about 15 to 20% of India’s total oil consumption (almost 80%-90% of which is imported). 

SECI envisages tremendous potential in the field of off-grid solar thermal application and is in the process of drawing specific plans for implementation and facilitation of projects throughout the country. Such decentralized systems not only empower the customers by granting energy-independence but also have immense potential of scalability. Commissioning of Decentralized Solar Thermal applications is, therefore, going to be a prominent strategy towards achievement of these targets.

Other significant off-grid applications include solar water heaters (using both Flat Plate Collectors and Evacuation Tube Collectors), solar mass cooking and comfort cooling applications 

Installation of Solar Water heating systems:

A solar water heater consists of a collector to trap the heat energy of sun rays by use of selective coating. The heat is transferred to riser pipes or tubes so that water through the tubes gets heated and is delivered to storage tank. The total system with solar collector, storage tank and pipelines is called Solar Water Heating System. The hot water temperature can be raised up to 800 C by re-circulation of same water through collector. 

The mission is setting an ambitious target for encouraging solar thermal applications in domestic and industrial segment. The key strategy is 

• to make solar heaters mandatory, through building bye-laws and incorporation in the National Building Codes 
• to ensure effective mechanism for certification/rating of manufacturers
• To promote such thermal applications through local agencies/power utilities, and 
• To support the upgrading of technologies and manufacturing capacities through concessional funding. 

SECI would be supporting the above mission objectives and is planning to implement the installationof Solar Water Heating Systems for schools, colleges, industries etc. through empanelled agencies.

Title: 50,000 LPD systems in Gurgaon

Courtesy: MNRE

Installation of Solar Air Heating Systems:

Solar Air Heating Systems consist of collectors which have an airtight and insulated metal frame and a high transmittance solar glazing for absorbing sunrays and heat the air in the collector.  An electrically powered fan moves air through the collectors and then blows back to the building using conventional, HVAC ducting and air handling equipment. 

Courtesy: www.greenoptions.com