Selection of Reflective Mirror
In almost all of the STSs plane mirrors
are used. The reason is that the cost of manufacturing curved mirrors is
enormous which results in an increased amount of capital required to install
the plant.
Despite the higher cost, curved mirrors
were selected for this project due to following reasons
1. Through
literature survey we came to know that in terms of “Levelized Cost of
Electricity” (LCOE) reduction, a design improvement that results in 1% performance
improvement is equivalent to a design improvement that reduces solar field cost
by about 2.3% i.e. the leverage of performance vs. cost on LCOE is better by a
factor of about 2.3x
The exact improvement in
efficiency due to this decision is unknown at this stage & it is possible
that this improvement might not be able to balance out the increase in capital
cost. Any and all results will be reported at the end of the project including
the impact of this decision.
2. There
is another factor that inspired us to use curved mirrors. As the distance from
the solar tower increases, the effect of scattering from dust particles becomes
more and more pronounced. Thus the advantage of using a converging beam of
light become more evident as this kind of reflected beam will be able to
transfer a considerably more amount energy to the solar tower even after scattering.
3. As
the beam is converging therefore the area of the “wave front” formed at the
receiver will be of small size. This enables us to design a receiver of smaller
size which will reduce cost.
4. Higher
concentration of light due to converging beam will result in increased
temperature which will result in increased efficiency of the system.
5. Very
high precision tracking is usually not feasible. The decreased wave front area
of the reflected beam gives us an increased margin of tolerable error in our
tracking.
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