PSI - Issue 67

Jorge S. Dolado et al. / Procedia Structural Integrity 67 (2025) 23–29 Jorge S. Dolado/ Structural Integrity Procedia 00 (2024) 000–000

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1. Introduction Concrete, employed as a building material since ancient times by civilizations like the Egyptians and Romans, has traditionally served in the construction of buildings, roads, bridges, and various infrastructure projects. Yet, as the demand for sustainable energy grows, concrete is finding new roles in energy storage and harvesting. This marks a notable departure from conventional uses, reflecting a broader perspective on concrete's potential applications. The fundamental principle behind this emerging concept is the vast capacity of energy. Irrespective of the energy type in question, the substantial presence of cementitious structures may offset their initially perceived low energy density. One potential shift involves electrochemical energy. Materials like lithium, crucial for batteries, are scarce, unevenly distributed, and costly. Could we develop electrochemical batteries using abundant and inexpensive materials like those found in concrete? Could we conceive of a building acting as a colossal battery? Indeed, as evidenced by the groundbreaking research of Meng and Chung (2010), though significant advancements are necessary before such ideas become practical realities. Another instance lies in utilizing concrete for thermal energy storage. With its substantial thermal mass, concrete can effectively absorb and retain heat energy, making it ideal for regulating temperatures in buildings. Leveraging concrete as a thermal storage medium enables the storage of energy during off-peak periods when electricity costs are lower, subsequently releasing it during peak hours of demand. While this application is well-established in buildings, the thermal characteristics of concrete also prove advantageous for storing energy generated in Concentrated Solar Power (CSP) Plants. Indeed, the suitability and effectiveness of Ordinary Portland Cement (OPC) concrete for Thermal Energy Storage (TES) have been extensively examined and confirmed in first-generation Concentrated Solar Power (CSP) systems, as evidenced by studies such as those by Laing et al. (2006) and Hoivik et al. (2019). However, a challenge arises with the transition to second-generation CSPs, which operate at higher temperatures ranging from 500°C to 700°C, rendering the use of OPC-based TES modules considerably risky. This challenge intensifies with the advent of third-generation CSPs, expected to operate at temperatures between 700°C and 1000°C. Does this signify the end of concrete's utility in this application? Not necessarily. Rather, it suggests that OPC-based concretes may not be suitable. Alternative concrete formulations such as Calcium Aluminate (CA) concretes, as explored in recent studies like Boquera et al. (2022), or geopolymer-based concretes, as investigated by Rahjoo et al. (2022a), offer promising alternatives for this purpose, instilling optimism for the future of concrete in CSP systems. Another illustration involves utilizing concrete in photovoltaic energy harvesting systems. By embedding photovoltaic cells within concrete, it becomes capable of generating electricity from sunlight. This application is particularly advantageous in urban settings where space for traditional solar panels may be limited. Moreover, appropriately engineered concrete can effectively cool the embedded solar cells, as demonstrated by Cagnoni et al. (2022). Considering that the temperature significantly impacts the performance and lifespan of solar cells, the synergy between "cool" concretes and solar cells presents a mutually beneficial scenario. Recent advancements in cooling technologies, such as daytime radiative cooling materials introduced by Chu et al. (2017), have garnered considerable attention. These materials are designed to utilize the atmospheric transparency window (8-13 μm), known as the Atmospheric Window (AW), to passively dissipate heat from the Earth into outer space. Transforming concrete into a daytime radiative cooling material poses a significant challenge but offers promising implications for enhancing building energy efficiency and combating the urban heat island (UHI) effect, as discussed by Kousis and Pisello (2020). The current research for NICOM 2024 endeavors to showcase this innovative application of cement-based materials by (i) examining several noteworthy examples of cutting-edge rechargeable concrete batteries and (ii) providing a succinct overview of ongoing research conducted within my group concerning cementitious thermal energy storage devices for Concentrated Solar Power (CSP) systems, alongside the development of radiative cooling concretes.

2. Cement Batteries The concept of cement-based batteries gained traction following the groundbreaking research by Meng and Chung (2010). They utilized an Ordinary Portland Cement (OPC) paste infused with Zn and MnO 2 particles, achieving energy