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Parabolic trough collectors (PTCs) are still today the most mature technology in concentrating solar power. However, linear Fresnel collectors (LFCs) have been identified by many authors as a candidate to reduce the levelized cost of electricity, although with lower efficiencies. Within Fresnel technology, two possibilities appear for the receiver: multitube receiver and secondary reflector receiver. In the present work a developed Monte Carlo Ray Trace code is used in order to compare the energy effectiveness and flux intensity map at the receiver for different days of the year and different orientations in Almería, Spain, and in Aswan, Egypt. The optical annual energy and exergy efficiencies are also obtained for PTCs and LFCs, with multitube or secondary reflector receiver, where the concentration at each tube is used to weigh the exergy efficiency. It results that the maximum efficiency is obtained by PTCs, while the lowest one corresponds to LFCs with multitube receiver. Also, it is concluded that, while for PTCs NS orientation leads to clearly higher efficiencies, this is not the case for LFCs, where both orientations achieve similar efficiencies even when the solar field has been designed for NS orientation. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the influence of the solar multiple on the annual performance of parabolic trough solar thermal power plants with direct steam generation (DSG). The reference system selected is a 50MWe DSG power plant, with thermal storage and auxiliary natural gas-fired boiler. It is considered that both systems are necessary for an optimum coupling to the electricity grid. Although thermal storage is an opening issue for DSG technology, it gives an additional degree of freedom for plant performance optimization. Fossil hybridization is also a key element if a reliable electricity production must be guaranteed for a defined time span. Once the yearly parameters of the solar power plant are calculated, the economic analysis is performed, assessing the effect of the solar multiple in the levelized cost of electricity, as well as in the annual natural gas consumption. [Copyright &y& Elsevier]