Central Tower Receiver Using Heliostat Mirrors
- In case of central tower receiver collector, the receiver is located at the top of the tower. The system is equivalent to a very large paraboloidal reflector.
- It has large number of mirrors spread over a large area on the ground to focus the reflected solar radiation on to a receiver mounted on a tower. Each mirror used is called the heliostat.
- The mirrors are installed all around the central tower. The schematic diagram of such a system is shown in Figure.
- Each heliostat is rotated into two directions so as to track the sun. Heliostats together behave like a broken very large paraboloidal reflector.
- The solar radiations so reflected from heliostats are received by the receiver mounted on a high tower. A concentration ratio upto 3000 can be achieved with this type of system.
- It can generate directly the high pressure and high temperature of steam suitable for power generation in steam power plants. Alternately, the receiver can heat a liquid metal or a molten salt and this heat energy of the fluid can be used in a heat exchanger for generation of steam which can be used in a Rankine cycle for electric power generation.
- The design of such system is quite complicated and costly. It is estimated that the present cost of power generation is about Rs 5.6 crores per MW.