Session: 09-04 Techno-Economic Analysis and System Integration of Energy Storage

Submission Number: 178373

Steam Cycle Analysis for Concrete-Based Thermal Energy Storage Integrated Power System 

According to global reports such as the IEA Electricity 2025, the power sector remains the largest source of CO₂ emissions, and the growing share of variable renewables highlights the need for flexible and reliable generation technologies. Pressurized water reactor (PWR) technology, with its proven safety and maturity, and Steam power plants, including small modular reactors (SMRs) and modern coal-fired units, is increasingly recognized as a viable option for load-following operation. This study suggests a steam power cycle system integrated with a concrete-based thermal energy storage (TES) unit to enhance load-following capability. During low-demand periods, a portion of the steam flow is extracted to charge the TES, whereas during high-demand periods, the stored heat is discharged to preheat the feedwater, thereby adjusting the net electric output without significant changes in the boiler or reactor heat generation rate.
The TES is modeled as a concrete block with embedded heat transfer fluid (HTF) channels, and its design parameters—such as the number, diameter, length, and spacing of channels—are optimized based on round-trip efficiency (ηRTE) and steady discharge time within a ΔT band, representing overall thermal efficiency and discharge stability. The power conversion system is simulated under constant thermal power input, with cycle behavior reflecting TES-induced variations through a quasi-steady-state modeling approach. The impact of TES integration is analyzed by evaluating different steam extraction and merge locations, and the resulting changes in system performance are quantified. Each configuration modifies thermodynamic state of the cycle, influencing turbine efficiency while maintaining the terminal temperature difference (TTD) and drain cooler approach (DCA) of the feedwater heaters to reflect off-design operation characteristics.
The results demonstrate that the optimal TES connection strategy can improve both system flexibility and cycle efficiency while preserving thermal margins. This study provides a practical framework for integrating TES with steam power plants, contributing to the development of flexible, low-carbon thermal power systems capable of supporting renewable-dominant power grids.
 

Presenting Author: Takhyun Chun KAIST

Presenting Author Biography: Takhyun Chun is a Ph.D. candidate in the Department of Nuclear and Quantum Engineering at KAIST, Republic of Korea. He received his B.S. and M.S. degrees in Mechanical Engineering from Korea University, where he conducted CFD-based thermal–fluid analysis on phase change material (PCM) energy storage and radiative heating systems. His current research focuses on system-level modeling and optimization of small modular reactor (SMR) power conversion systems, particularly the integration of concrete-based thermal energy storage (TES) for flexible load-following operation.

Authors:

Takhyun Chun KAIST
Gyudong Kim KAIST
Yong Jae Chae KAIST
Jeong Ik Lee KAIST