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Solar technologies in India: An overview
Hence, it is important to understand the market readiness of different CSP technologies, the investment opportunities which these technologies are likely to create and the overall market development scenario. TERI was entrusted to undertake a comparative analysis of the different CSP technologies. The study also covered sub-technologies/components which by themselves are an important market segment and also addresses the cost benefit and investment opportunities in solar power projects.
The government took a major step in promoting solar power in India by announcing the Jawaharlal Nehru National Solar Mission (JNNSM) in November 2009. The objective is to establish India a global leader in solar power generation. The mission also aims to achieve grid parity by 2022 and parity with coal-based thermal power by 2030 and feed 20000 MW of solar power by 2022. While in the first phase (2010-13) it targets 1000 MW of grid-connected solar power, and promotes different decentralized applications including off-grid systems to serve populations without access to commercial energy; in the second (2013-17) and third (2017-22) phases, the power generation capacity will be aggressively ramped up to create conditions for up-scaled and competitive solar energy penetration. Targets include ramping up capacity of grid-connected solar power generation through the solar-specific renewable purchase obligations for utilities, backed with a preferential tariff.
The parabolic trough technology is currently the most proven CSP technology and, therefore, the most developed and standardized. The parabolic trough projects, currently in operation, are between 14 and 80 MWe in size, and existing plants produce well over 500 MW of electrical capacity.
Central receiver technology is also well proven. Central receiver systems use a field of distributed mirrors i.e. heliostats which individually track the sun and focus the sunlight on the top of a tower. Such systems can achieve up to 35% peak and 25% annual solar electric efficiency when coupled to a combined cycle power plant. Over 300 MW capacity CST power projects have been announced by various companies in the coming decade.
The compact linear fresnel reflector system is similar to the parabolic trough collector system. It consists of an array of nearly-flat reflectors which concentrates solar radiation onto an elevated inverted linear receiver. Water flows through the receiver and is converted into steam. This system is line-concentrating, similar to a parabolic trough, with the advantages of low cost for structural support and reflectors, fixed fluid joints, a receiver separated from the reflector system, and long focal lengths that allow the use of flat mirrors. The technology is seen as a potentially low-cost alternative to trough technology for the production of solar process heat.
The parabolic dish-shaped reflector concentrates sunlight on to a receiver located at the focal point of the dish. The concentrated beam radiation is absorbed into a receiver to heat a fluid or gas (air) to approximately 750°C. This fluid or gas is then used to generate electricity in a small piston or Stirling engine or a micro turbine, attached to the receiver. The dishes are usually designed to track the Sun along two axis to get reflect the sun beam on point of focus.
A cost break-up of the trough and power tower technologies was undertaken. The solar PTC-based solar thermal power plant was estimated to cost Rs 2,02,150/kW and power tower-based solar thermal power plant Rs 2,35,877/kW.
The study also estimated the market for CSP technologies under three scenarios – the solar mission scenario, the optimistic scenario, and the conservative scenario. The solar mission scenario is the result of the government’s policy following the JNNSM. The optimistic scenario is based on the efforts of governments and other initiatives to promote the technologies. The conservative scenario assumes that the development of CSP technology will take place in a sluggish manner. The projected market development indicates that the CSP market can reach about 15.2 GW by 2022 under the optimistic scenario where as under conservative scenario only about 5.7GW market is likely to be developed by 2022. It observed that while the government is taking steps to encourage the development of CSP technologies; much will depend on the implementation of these policies and the impetus from the private sector.
It is a method by which dispersed sunlight is concentrated through the use of low-cost mirrors to generate electricity. This is done in two ways – Concentrating Solar Thermal (CST) and Concentrating Photovoltaic (CPV) technologies.
The concentrated solar power technology is a globally proven technology. India’s vast solar resource potential can be tapped through these technologies for energy generation. There is a need for great focus on the promotion and implementation of these technologies. With the indigenization of the technology, the CSP power generation may soon achieve grid parity.
The findings of the study are:
- Parabolic trough collector (PTC) will be the most dominating CSP technology by 2020.
- Maximum Integrated Solar Combined Cycle (ISCC) projects will be of PTC Technology.
- Parabolic Dish sterling might find space in manufacture of small capacities and no-water design.
- There are two prime movers of cost reduction of CSP
- Improvement of efficiencies of the components:
- i. Reflectors through coatings and new materials;
- ii. Receivers through new materials of higher optical efficiencies;
- iii. Tracking and control.
- Indigenization of various components:
- i Balance of system of solar field;
- ii Turbines and boilers;
- iii Power evacuation system.
- Low labor costs in India will make the projects financially attractive.
- Drivers like JNNSM will accelerate the implementation mechanism.