Techno-economic investigation of solutions for decarbonizing the thermal management of the stand-still state of combined cycles

Thermochemical Power Group, DIME, University of Genoa, via Montallegro 1, 16145 Genova, Italy

^* Corresponding author: alessandro.sorce@unige.it

Abstract

In today’s RES-driven energy landscape, flexibility of Combined Cycle Gas Turbine (CCGT) power plants is essential for integrating more non-dispatchable sources while ensuring reliable power supply. CCGTs must adapt their market role and adopt new, flexible, yet cost-effective operational practices, even during part-load phases, with a focus on reducing emissions but augmenting the grid service potential. A key area of improvement is reducing start-up time and energy use by optimizing asset thermal management during stand-still periods. In particular, maintaining temperature in bottoming cycle components without relying heavily on gas-fired auxiliary boilers is crucial. Techniques like electric heat tracing or steam sparging are known but evaluated more on time reduction impact than on operative consumption. Their integration with decarbonization and electrification solutions, such as high-temperature heat pumps, and waste heat recovery, warrants further exploration. This paper analyses typical Start-Up types to determine which low-carbon technologies are most promising under different operating and market conditions. It considers technological constraints, energy efficiency indicators, emission reductions, and economic factors—particularly the potential to leverage low-cost electricity during downtime.