RENEWABLE ENERGY 69 have done so and thus the Trustee’s of Ashram have started a section 25 company in name of “MSA Renewtech Foundation” to offer solutions to industries, societies and others to share its experience, expertise and offer consultancy and tun-key projects too. Success of Scheffler solar concentrator in India has encouraged development of many indigenous solar concentrators. Most of the companies are working on making the system more efficient and to achieve the same they went bigger and bigger in size. Even Gadhia Solar had pursued these path and over years and kept on increasing the size of Scheffler Concentrator. When it started the first systems ( at Brahma Kumari’s Mt. Abu) the size of dish was 7.4 m2 each. The system at Tirupati Temple was with 10 m2 sized dishes. The 100 ton solar air-conditioning system was with 12.5 m2 sized dishes and the system at Shirdi is with 16 m2 sized dishes. They had also installed a system with 32 m2 dish each for waste water evaporation. The solar crematorium at Ashram in making has 50 m2 Scheffler dish. Brahma Kumaris are installing a 3 MW Solar Power Plant with 750 Scheffler dishes each of 60 m2. The dishes installed by Mega Watt Solution for Process heating in Universal Medicap Limited through MSA Renewtech Foundation have 16 dishes of 90 m2 each. A company in Mumbai called Clique Solar offers energetica INDIA · SEP | OCT15 Solar Concentrator of 160 m2. The logic was larger the size of the dish more efficiency it would achieve and cheaper will be the cost of energy. If one reduces the area (foot print) needed it reduces the number of receivers (heat ex-changers that receive the heat from concentrators) and trackers which keeps on moving the dish synchronized with movement of Sun. A company in Mumbai called EnerSun Power tech Pvt. Ltd. took exactly the opposite path. It has got a solar concentrator developed through and with help of Prof Joshi and Prof Panse of ICT (Institute of Chemical Technology), Mumbai (Previously known as UDCT- University Department of Chemical Technology). They have worked innovatively and differently and have come out with very unique solutions to overcome the problems faced by parabolic dish concentrators and parabolic trough concentrators. To overcome the wind-load problems that every solar concentrator faces (larger the area more the wind-load) they took the route of developing Fresnel based concentrator. They arranged the mirrors in such a way that the wind passes in between. Parabolic trough concentrator needed curved mirrors, which added to the cost, and thus by using the flat strips of mirrors they overcame that problem too. In Fresnel Type flat mirrors are placed in such a way that they act as a parabola. Normally parabolic solar dishes require a receiver that is evacuated (vacuum) making it expensive and needed to be imported. The professors used a receiver which has secondary reflector at back and a glass cover in front and the back cover has air cavity so there is no need for extra insulation to reduce the radiation losses as air cavity acts as insulation. To test and demonstrate the system a 34 m2 Joshi- Panse EnerSun CLF Concentrating System has been installed at Muni Seva Ashram on its terrace of kitchen of Athithi Mandir (Guest House) and the heat generated is used in form of hot water above 100 degree Celsius for cooking. Besides working on solar concentrators; Professor Joshi and Professor Panse are also working on solar cooking vessels. Conventionally solar steam is generated and injected into the cooking vessel filled with rice/ dal/ vegetables and water or the steam is circulated in an outside jacket of vessel and the rice/ dal/ veg immersed in water gets cooked. What Professor Joshi and Prof Panse did was that they have been able to develop is a continuous rice cooking system in which one can cook with hot water and not steam thus reducing the energy consumption by as much as 50-60 %. Another advantage of being able to cook with hot water is that it is easier to store heat inhot water unlike steam which condenses and thus the problem of storing of heat to cook in non-sun-shine hours like evenings and next day early morning got resolved. The biggest advantage is that it is continuous cooker where rice is fed into hopper and it is carried to cooking vessel by a screw feeder where solar hot water is injected and on the other end comes out cooked rice. This reduces the man-power. The system has been successfully installed and operated and yesterday the first potential clients visited the Ashram to see for themselves and left very excited. The solar concentrators are also tested and approved by School of Energy Studies, SPPU – PUNE having a National Testing Facility for Concentrating Thermal Technologies (CST’s) with an average operating efficiency of 52% & with maximum efficiency of 57% ! For all those wondering & confused between solar thermal & solar pv technologies, all we can say is that each one has its own benefit/advantages & disadvantages along with unique applications. >> FROM PAGE 68 Figure 2: New Rice Cooking System at Green Ashram.
Energética India | September / October 2015
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