Assessment of the Overall Efficiency of Gas Turbine-driven CSP Plants Using Small Particle Solar Receivers

Abstract

While current commercial Concentrated Solar Power (CSP) plants utilize Rankine steam cycles in the power block, there is a goal to develop higher-efficiency plants based on Brayton cycles or on combined cycles. In this paper, we present an assessment of a gas turbine-driven CSP plant using small particle solar receivers. In particular, a recuperated, single-shaft gas turbine engine and a Small Particle Heat Exchange Receiver –a high temperature receiver for solar tower power plants developed in the framework of the U.S. DOE's SunShot Program– are the technologies employed for the gas turbine and the receiver, respectively. The curves of the solar receiver and the gas turbine engine were first obtained using in-house codes, and then coupled together. A backup combustor fueled with natural is used to compensate the variable nature of the solar resource. For a more flexible and optimum operation, the guide vane angle of the compressor is allowed to vary, and so is the position of the valves of the receiver and combustor bypasses. Two different operational strategies were analyzed: maximizing the overall efficiency of the plant and maximizing the net output power. Hence, the overall efficiency of a gas turbine-driven CSP plant based on a Small Particle Heat Exchange Receiver is estimated, and the potential to generate electricity is assessed. This analysis reveals the strengths of small particle receivers with respect to molten salt tubular receivers due to the much higher temperatures that can be achieved while maintaining (or even increasing) the receiver efficiency.