Solar STIG Cycle Annual Analysis

The Steam Injection Gas turbine (STIG) cycle offers a way to use solar steam at a low temperature and pressure, generated by low-cost concentrators, in order to augment the power output of the turbine. In conventional STIG, the steam is generated from the gas turbine exhaust and injected into the combustion chamber. In previous work we proposed the solar augmentation of a STIG cycle, using solar concentrators to generate steam in much larger amounts compared to the natural limit of heat recovery in the conventional STIG. In the current work, an annual analysis of the Solar STIG cycle is presented for two sites with moderate and high annual DNI, under two scenarios: constant power with a varying Solar Fraction (SF), and variable power with a nearly constant SF. Results show typical annual SF in the range of 20–30%, and solar to electricity efficiency of around 15%, similar to the annual efficiency of current parabolic trough plants that operate at much higher pressure and temperature. The variable power scenario improves the SF with only a minor decrease in efficiency.