Abstract
•CSP Fresnel with CO2 as heat transfer fluid new possibilities in the power block.•Multi-tube Fresnel receiver increases freedom degrees in the optimization process.•Coherent thermal design opens the way for a reduction of the CSP electricity cost.
Results from a systematic research on the coherence (and inefficiencies) of current and alternative ways to exploit solar thermal energy are reported in this paper, intended to analyze forth and back the energy conversion chain from solar radiation to electricity. This exercise pointed out the pivotal role of the heat transfer fluid for an effective integration of said energy chain, and CO2 was selected for that role, because it is a gas without practical limitations in maximum temperature, and very adequate values of critical temperature and pressure. Optimum operating conditions were attainable in multi-tube receivers illuminated by advanced Linear Fresnel Reflectors with moderate values of radiation concentration factors; and the architecture of the full solar field system could be simplified in modular lattices leading to minimum values of mass requirements of the relevant materials, from glass to concrete. The specific investment cost for this new kind of power plant was evaluated in terms of said mass accountancy, and it was found that solar thermal power could be competitive with fossil fuel power plants in the near future.