Theoretical Investigation of Aspect Ratio of Heliostat to Minimize Capital Cost of Solar Tower Plant

摘要

Electricity generation with solar energy using solar tower integrated with thermal energy storage is a promising technology over solar PV system which needs expensive and non-ecofriendly battery for electricity storage. However, the capital cost of the solar tower plant is quite high. In an effort to bring down the cost, this paper presents theoretical investigation of aspect ratio of heliostats which carry substantial cost of the total solar tower plant. It is known fact that heliostat design is influenced significantly by the wind loads. Several researchers have shown that optimum area of a heliostat is determined by the design wind speed considering a square heliostat. This paper looks at the aspect ratio as an important variable to be considered for optimizing the cost/m~2 of a heliostat. It is established that appropriate aspect ratio coupled with the optimum area has a significant impact on the cost/m~2 of a heliostat and the influence of aspect ratio increases with increase in design wind speed. It is observed that at design wind speed of 6 m/s, the cost/m~2 gets reduced by 2.8%, while it is 5.08% for 12 m/s. It is estimated that for a 20 MW PT plant with 150000 m~2 heliostat field and a design wind speed of 12 m/s, the reduction in capital cost will be about US$ 0.8 million.