Energetic Comparison of Linear Fresnel and Parabolic Trough Collector Systems

Abstract

Within the last years, Linear Fresnel (LF) collector systems have been developed as a technical alternative to parabolic trough collector (PT) systems. In the past, LF systems focused on low- and medium temperature applications. Nowadays, LF systems equipped with vacuum receivers can be operated at the same temperatures as PT systems. Papers about the technical and economical comparison of specific PT and LF systems have already been published, [1–3]. However, the present paper focuses on the systematic differences in optical and thermodynamic performance and the impact on the economic figures. In a first step the optical performance of typical PT and LF solar fields has been examined, showing the differences during the course of the day and annually. Furthermore, the thermodynamic performance, depending on the operating temperature, has been compared. In a second step, the annual electricity yield of typical PT and LF plants are examined. Solar Salt has been chosen as heat transfer fluid. Both systems utilize the same power block and storage type. Solar field size, storage capacity, and power block electrical power are variable, while all examined configurations achieve the same annual electricity yield. As expected for molten salt systems, both systems are the most cost-effective with large storage capacities. The lower thermodynamic performance of the LF system requires a larger solar field and lower specific costs in order to be competitive. Assuming specific PT field costs of 300 €/m2 aperture, the break-even costs of the LF system with Solar Salt range between 202 and 235 €/m2, depending on the site and storage capacity.