High temperatures in line focusing systems: Dual loop cycle efficiency and heat losses

This paper analyses a concept for large parabolic trough power plants, in which a molten salt solar field acting as a live steam temperature booster is added to a thermal oil field. The potentially more expensive molten salt field, to which freeze protection has to be applied, can be kept small and the storage system can provide the same live steam properties during discharge as during solar field operation. The dual loop approach can reduce the levelized cost of electricity of a parabolic trough solar power plant. The capital expenditures are increased for such a system. In return a higher amount of energy is available for charging. The break even costs for the salt solar field are 1.3 times the costs of the thermal oil solar field for an optimized system design