Techno-economic evaluation of a full heat transfer fluid change-over in an existing parabolic trough power plant

Abstract

The efficiency of CSP plants is predominantly dependent on the operation temperatures of the heat transfer fluid (HTF). Increasing the maximum HTF operation temperature is expected to increase the power plant efficiency. However, the maximum operable temperature is determined by the material properties of the fluid itself. This thesis investigates the effects a change-over of the current HTF Dowtherm A to the new siliconebased HTF HELISOL_XLP has on an existing parabolic trough power plant. HELISOL_XLP has a higher operable temperature and furthermore a decreased hydrogen generation at higher temperature which reduces the likelihood of thermal losses within the solar collectors. The impact is analyzed on the existing parabolic trough power plant Central Termosolar de Morón (CT Morón) in Spain. The two main focus areas are the technical feasibility and the economic impact. Therefore, three exchange scenarios are defined: the first one looks at exchanging the HTF without changing the operation parameters, the second looks at an HTF change-over with increasing the temperature to 400 °C and the third scenario looks at the full potential of the new HTF and thus an increase to an operation temperature at 430 °C. All affected components are analyzed for their design conditions and compared against the changing operational conditions per scenario. Furthermore, the exchange scenarios are modeled in the software greenius and EPSILON Professional to simulate the energy flows and the electricity outputs. With this information, the cost and revenue structure are estimated and a cash flow analysis is performed. Capital budgeting metrics such as net present value, payback period, internal rate of return and return on investment are calculated and the profitability of each exchange scenario assessed.