Papers by Arvind Sastry
AIP Conference Proceedings, 2017
South Africa has implemented a 'time of day' tariff structure for concentrating solar power plant... more South Africa has implemented a 'time of day' tariff structure for concentrating solar power plants in the Renewable Energy Independent Power Producer Procurement Programme. It is hypothesised that payment allocation factors for the 'time of day' and the 'time of use' dispatch schedule influence the optimal heliostat field layout. SolarPILOT software is used to generate and optimize the heliostat field layout of a 100 MW e power tower plant in Upington, South Africa with 8 hours of thermal energy storage in the SunShot scenario with a high receiver thermal efficiency of 90%. A large size heliostat with a total area of 115.56 m 2 and an external cylindrical receiver are considered for the heliostat field layout. A subset of 12 days is simulated on an hourly basis to achieve convergence and to take seasonal, daily and hourly weather variability into account. During the optimization of a heliostat field layout, the heliostats are ranked and selected according to a performance metric. In this study, two field layouts are compared based on two different performance metrics, namely: power delivered to the receiver and the time of use weighted power. The optical performance is simulated using both the Hermite (analytical) and the Monte-Carlo Ray-Tracing methods.
The objective of this study is to investigate the effects of heliostat size on the levelized cost... more The objective of this study is to investigate the effects of heliostat size on the levelized cost of electricity (LCOE) for power tower plants. These effects are analyzed in a power tower with a net capacity of 100 MW e , 8 hours of thermal energy storage and a solar multiple of 1.8 in Upington, South Africa. A large, medium and a small size heliostat with a total area of 115.56 m 2 , 43.3 m 2 and 15.67 m 2 respectively are considered for comparison. A radial-staggered pattern and an external cylindrical receiver are considered for the heliostat field layouts. The optical performance of the optimized heliostat field layouts has been evaluated by the Hermite (analytical) method using SolarPILOT, a tool used for the generation and optimization of the heliostat field layout. The heliostat cost per unit is calculated separately for the three different heliostat sizes and the effects due to size scaling, learning curve benefits and the price index is included. The annual operation and maintenance (O&M) costs are estimated separately for the three heliostat fields, where the number of personnel required in the field is determined by the number of heliostats in the field. The LCOE values are used as a figure of merit to compare the different heliostat sizes. The results, which include the economic and the optical performance along with the annual O&M costs, indicate that lowest LCOE values are achieved by the medium size heliostat with an area of 43.3 m 2 for this configuration. This study will help power tower developers determine the optimal heliostat size for power tower plants currently in the development stage.
Heliostats of different sizes are often compared on a 'cost per square meter' basis. This approac... more Heliostats of different sizes are often compared on a 'cost per square meter' basis. This approach does not take into account other important factors like optical performance of the heliostat field, heliostat scaling and manufacturing volume effects, local weather conditions like wind speeds, possible structural deformation and the current price index. Currently, heliostats in operational power tower plants have sizes ranging from 1.14 m 2 to 150 m 2. This study aims to identify the optimum heliostat size range and aspect ratio (AR) for a hypothetical power tower plant with a net capacity of 100 MW e and 8 hours of thermal energy storage in South Africa. Levelized cost of electricity (LCOE) is used as a figure of merit to compare heliostats of different sizes since the heliostat field contributes substantially to the capital costs of such a plant. The results indicate that a lowest theoretical LCOE value of 0.1722 USD/kWh is achieved using a 36 m 2 medium sized heliostat. The lowest LCOE values are observed with heliostats in the range of 20-40 m 2 with an AR that is greater than one. This study will be useful for power tower developers to optimally size the heliostats for their power tower plants.
Conference Presentations by Arvind Sastry
South Africa has implemented a 'time of day' tariff structure for concentrating solar power plant... more South Africa has implemented a 'time of day' tariff structure for concentrating solar power plants in the Renewable Energy Independent Power Producer Procurement Programme. It is hypothesised that payment allocation factors for the 'time of day' and the 'time of use' dispatch schedule influence the optimal heliostat field layout. SolarPILOT software is used to generate and optimize the heliostat field layout of a 100 MW e power tower plant in Upington, South Africa with 8 hours of thermal energy storage in the SunShot scenario with a high receiver thermal efficiency of 90%. A large size heliostat with a total area of 115.56 m 2 and an external cylindrical receiver are considered for the heliostat field layout. A subset of 12 days is simulated on an hourly basis to achieve convergence and to take seasonal, daily and hourly weather variability into account. During the optimization of a heliostat field layout, the heliostats are ranked and selected according to a performance metric. In this study, two field layouts are compared based on two different performance metrics, namely: power delivered to the receiver and the time of use weighted power. The optical performance is simulated using both the Hermite (analytical) and the Monte-Carlo Ray-Tracing methods. By accounting for the TOU weighted power, it is found that the LCOE increases from 0.1831 $/kWh to 0.1870 $/kWh using the Hermite (analytical) method. Similarly, when MCRT techniques are used for the optical characterization, the LCOE value increases from 0.1781 $/kWh to 0.1832 $/kWh. It is recommended that payment allocation factors and the tariff structure for the time of day be included when comparing field layouts with other layout generation and optimization strategies. This study will be useful for power tower developers in identifying practices to be included in the optical characterization of their heliostat field layouts for better simulation results.
The objective of this study is to investigate the effects of heliostat size on the levelized cost... more The objective of this study is to investigate the effects of heliostat size on the levelized cost of electricity (LCOE) for power tower plants. These effects are analyzed in a power tower with a net capacity of 100 MW e , 8 hours of thermal energy storage and a solar multiple of 1.8 in Upington, South Africa. A large, medium and a small size heliostat with a total area of 115.56 m 2 , 43.3 m 2 and 15.67 m 2 respectively are considered for comparison. A radial-staggered pattern and an external cylindrical receiver are considered for the heliostat field layouts. The optical performance of the optimized heliostat field layouts has been evaluated by the Hermite (analytical) method using SolarPILOT, a tool used for the generation and optimization of the heliostat field layout. The heliostat cost per unit is calculated separately for the three different heliostat sizes and the effects due to size scaling, learning curve benefits and the price index is included. The annual operation and maintenance (O&M) costs are estimated separately for the three heliostat fields, where the number of personnel required in the field is determined by the number of heliostats in the field. The LCOE values are used as a figure of merit to compare the different heliostat sizes. The results, which include the economic and the optical performance along with the annual O&M costs, indicate that lowest LCOE values are achieved by the medium size heliostat with an area of 43.3 m 2 for this configuration. This study will help power tower developers determine the optimal heliostat size for power tower plants currently in the development stage.
LCOE reduction for parabolic trough CSP: Innovative solar receiver with improved performance at m... more LCOE reduction for parabolic trough CSP: Innovative solar receiver with improved performance at medium temperature AIP Conf.
MEng Thesis by Arvind Sastry
Heliostats typically contribute to about 40 % of the total installed costs in a concentrated sola... more Heliostats typically contribute to about 40 % of the total installed costs in a concentrated solar power (CSP) tower plant. The objective of this study is to investigate the effects of heliostat size on the levelized cost of electricity (LCOE). These effects are analysed in a power tower with a net capacity of 100 MWe with 8 hours of thermal energy storage in Upington, South Africa. A large, medium and a small sized heliostat with a total area of 115.56 m2, 43.33 m2 and 16.69 m2 respectively are considered for comparison. The heliostat cost per unit is calculated separately for the three different heliostat sizes and the effects due to size scaling, learning curve benefits and the price index is considered. The annual operation and maintenance (O&M) costs are estimated separately for the three heliostat fields, where the number of personnel required in the field is determined by the number of heliostats in the field. The LCOE values are used as a figure of merit to compare the different heliostat sizes. The lowest theoretical LCOE value of 0.1960 $/kWhe is achieved using the medium size heliostat with an area of 43.33 m2 for this power tower configuration.
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Papers by Arvind Sastry
Conference Presentations by Arvind Sastry
MEng Thesis by Arvind Sastry