Concentrated Solar Thermal Downstream of the Solar Field: Design and Optimization of the Associated Power Generation Cycle

Abstract

While major design efforts are dedicated to the development and improvement of solar energy collection technologies, the downstream power generation cycle is often considered a straightforward exercise. The diverse nature of the heat sources and their cyclic behavior make the design of the turbo-machinery and associated balance-of-plant equipment for solar plants quite different from the design for use in conventional fired power plants. The high capital cost of these renewable energy facilities and the limited hours of operation are powerful drivers to increase equipment efficiency and reduce the startup time. This paper reviews the state of the art regarding hardware selection and design considerations for tower, trough, and Fresnel solar thermal technologies from an engineering, procurement, and construction (EPC) contractor’s perspective. It also describes the benefits and limitations of each method and the impact of flow and temperature on cycle efficiency. In particular, it addresses the turbine design challenges for repeated fast startups and plant size optimization. Special emphasis is given to heat sink design in consideration of water scarcity. In conclusion, the paper provides recommendations for achieving a balance between the economics of generation and cost of equipment and reliability for the downstream power generation system.