Work

Slags as Thermal Energy Storage Media for Concentrated Solar Power and Renewable Energy Integration

Year: 2025

Type: article

Abstract: ABSTRACT The growing demand for low‐cost, high‐performance thermal energy storage (TES) materials has prompted interest in repurposing metallurgical slags in concentrated solar power (CSP) systems. This review critically evaluates the potential of various steel, copper, and aluminum slags as high‐temperature TES media in packed‐bed configurations. Emphasis is placed on the thermophysical properties of steel slags, for example, with reported thermal conductivities ranging from 1.6 to 1.9 W/m K and specific heat capacities of up to 1.5 J/g K, making them competitive with conventional materials, such as molten salts. The review also explores numerical modeling approaches such as the Schumann model, local thermal non‐equilibrium (LTNE), and continuous solid‐phase frameworks to capture heat transfer behavior in slag‐based TES systems. Additionally, system‐level integration strategies, particularly direct and indirect packed‐bed designs, are compared to conventional two‐tank molten salt systems in terms of performance, cost, and environmental benefits. Notably, steel slags offer thermal stability above 1000°C, economic savings of up to 40% over commercial fillers, and significant CO 2 reductions through circular material reuse. Case studies and simulations validate slag's long‐term performance and scalability in CSP and industrial waste heat recovery applications. The review identifies research gaps in slag characterization, compatibility with heat transfer fluids, and modeling fidelity. This work contributes a comprehensive roadmap for advancing slag‐based TES technologies, providing insights for research in designing next‐generation, cost‐effective CSP systems.

Source: Energy Storage

DOI: 10.1002/est2.70274

Authors: Michael Enemuo, Ngozi Enemuo, Arash Dahi Taleghani, Olumide Ogunmodimu

Institutions: Pennsylvania State University, University of Johannesburg

Language: English

Topic: Solar Thermal and Photovoltaic Systems

Subfield: Renewable Energy, Sustainability and the Environment

Field: Energy

Domain: Physical Sciences

SDGs: Affordable and clean energy, Responsible consumption and production, Climate action

Open Access status: hybrid

Estimated APC paid: $3,460