Retrofitting of existing parabolic trough collector power plants with molten salt tower systems

Abstract

Existing thermal oil based parabolic trough collector (PTC) power plants have been commercially deployed since 2008. Parabolic trough technology dominates by ca. 90 % the global market of all operational commercial concentrated solar power (CSP) plants. Worldwide over 32 % of these PTC power plants have an indirect salt thermal storage system that enables night operation [1, 2]. Since existing parabolic trough power plants with thermal oil are limited regarding their maximum operating temperature, the addition and integration with a molten salt tower systems (MSTS) could be an attractive option to increase the temperature level of the thermal storage and steam cycle and thus the overall efficiency of the plant. This paper describes the conception, investigation and techno-economic evaluation for retrofitting an existing Andasol type parabolic trough power plant. The most promising out of five coupling configurations has been analyzed and evaluated for three different retrofitting concepts using greenius and EBSILON®Professional simulation tools. The analysis shows that retrofitting concepts based on the addition of a MSTS are only economically attractive, if the capital expenditure for the power block modification does not exceed 440 $/kW. The retrofitting of existing PTCs with a MSTS is economically unviable.