No need to dig deep; just gather the falling rays

Concentrated Solar Technologies in India

India is full of sun energy. Technologies developed on use of this energy can help saving the fossil fuels in industrial, commercial and institutional establishments for various applications. A huge amount of fossil fuels especially the electricity and fuel oil are being consumed for thermal applications e.g. water /air heating, community cooking, process heat, space cooling etc. At most places the heat requirement in the form of steam/pressurized hot water/ air or oil is between 90 to 350 C. 

Solar water heating is already an established technology and is in promotion at large scale for providing hot water for various applications. This technology is, however, limited to temperatures below 90C. Concentrating solar technologies (CSTs) are now emerging fast in the country which can provide high temperatures in the range of 100 to 450 C or more even. These technologies basically focus the sunlight at receiver to achieve higher temperatures for various applications. Since these technologies can focus the direct radiation coming from the Sun, they need to be tracked alongwith the Sun. The technologies can be based on single axis (E-W) tracking as well as dual axis (E-W & N-S) tracking. Depending on their tracking arrangement, they can be put in the category of medium or high temperature applications.

Technology Status

Most of the CSTs have been developed and demonstrated in USA and Spain mainly for the purpose of power generation. Popular technologies for this purpose have been the Parabolic trough concentrators and Central tower receiver. Paraboloid dish and Linear Fresnel Reflector technologies have also been demonstrated at few places. These technologies, have, however, been hardly used for process heat, cooking or cooling applications. A couple of other technologies like Non-imaging concentrators and Heat pipes have also been developed abroad which find good applications for process heat and cooling applications in India .

In India mainly 3 types of concentrating solar technologies are presently in promotion. These are i) Manually tracked dish solar cookers to cook food for 10-40 people, ii) Fixed focus E-W automatically tracked elliptical dishes (Scheffler) for direct indoor cooking for about 50-100 people & for steam generation for the purpose of community cooking, laundry, space cooling etc. of any capacity (Figure-1) and  iii) Dual axis fully tracked Fresnel dishes (Arun) for all such applications .These technologies are in implementation for last few years with support from MNRE. A few other technologies e.g dual axis tracked paraboloid dishes, linear Fresnel reflectors, non-imaging concentrators have also been developed and are at demonstration stage.