Enhancing the Profitability of Solar Tower Power Plants through Thermoeconomic Analysis Based on Multi-objective Optimization
Solar tower power plants with integrated thermal energy storage units represent one of the most promising technologies for enhancing the economic viability of concentrating solar power in the short term. Tower systems allow higher concentration ratios to be achieved, which in turn means higher fluid operating temperatures and thus higher power cycle efficiencies. Moreover, the integration of storage allows power production to be shifted from times where there is low demand to periods where
... periods where electricity prices are higher, potentially enhancing the profitability of the plant despite representing an additional upfront cost. The variable nature of the solar resource and the myriad potential roles that storage can assume, together with the complexity of enhancing the synergies between the three blocks: the solar field, the storage block and power block, make the design of these power plants a challenging process. This paper introduces a comprehensive methodology for designing solar tower power plants based on a thermoeconomic approach that allows the true optimum trade-off curves between cost, profitability and investment to be identified while simultaneously considering several operating strategies as well as varying critical design parameters in each of the aforementioned blocks. The methodology is presented by means of analyzing the design of a power plant for the region of Seville. For this location, results show that similar profits, measured in terms of the internal rate of return, can be achieved from different power plant configurations in terms of sizing and operating strategy, each associated to different investments. In particular, optimum configurations found corresponded to larger power blocks with medium-to-large solar field and storage blocks that allow the plants to operate continuously throughout the day and be shut down during midnight. Moreover, it is shown that for a fixed power block size it can also be economically interesting to consider smaller storage units and adopt instead a peaking strategy, as this can still be profitable whilst representing a lower investment, thus lower risk.