Techno-Economic Optimization and Benchmarking of a Solar-Only Powered Combined Cycle with High-Temperature TES Upstream the Gas Turbine

Abstract

This work presents a techno-economic parametric study of an innovative central receiver solar thermal power plant layout that applies the combined cycle (CC) as thermodynamic power cycle and a multi-tower solar field configuration together with open volumetric air receivers (OVARs). The topping gas turbine (GT) is powered by an air-air heat exchanger (two heat exchanger trains in the case of reheat). In order to provide dispatchability, a high-temperature thermocline TES system is placed upstream the gas turbine. The aim is threefold, (i) investigating whether the multi-tower concept has a techno-economic advantage with respect to conventional single-tower central receiver plants, (ii) indicating the technoeconomic optimum power plant configuration, and (iii) benchmarking the technoeconomic optimum of the CC plant against that of a conventional single-cycle Rankine steam plant with the same receiver and TES technology. It is concluded that the multi-tower configuration has a techno-economic advantage with respect to the conventional single-tower arrangement above a total nominal solar power level of about 150 MW. However, the benchmarking of the CC against a Rankine single-cycle power plant layout shows that the CC configuration has despite its higher solar-to-electric conversion efficiency a higher LCOE. The gain in electricity yield is not enough to outweigh the higher investment costs of the more complex CC plant layout.

Techno-economic assessment of small-scale solar tower plants with modular billboard receivers and innovative power cycles

“…The cost of the towers for the solutions with modular fields, given their limited height (of 35 meters), are assumed according to the cost of small-scale steel-tubes wind turbines towers [30], where a cost of steel of 1.5 $/kg is considered. On the other hand, in case of the single tower plant, given the significant tower height (fixed at 65 meters) a cost function typical of concrete towers is considered [31]. The cost of the heliostats is taken from SAM [32], while the receivers costs was assumed proportional to the thermal input to the receiver [4], even if small scale receivers are not at a mature technological level and a high uncertainty on the costs of these components must be considered.…”