Fibre-Reinforced Geopolymer Concretes for Sensible Heat Thermal Energy Storage: Simulations and Environmental Impact

Abstract

Power plants based on solar energy are spreading to accomplish the incoming green energy transition. Besides, affordable high-temperature sensible heat thermal energy storage (SHTES) is required. In this work, the temperature distribution and thermal performance of novel solid media for SHTES are investigated by finite element method (FEM) modelling. A geopolymer, with/without fibre reinforcement, is simulated during a transient charging/discharging cycle. A life cycle assessment (LCA) analysis is also carried out to investigate the environmental impact and sustainability of the proposed materials, analysing the embodied energy, the transport, and the production process. A Multi-Criteria Decision Making (MCDM) with the Analytical Hierarchy Process (AHP) approach, taking into account thermal/environmental performance, is used to select the most suitable material. The results show that the localized reinforcement with fibres increases thermal storage performance, depending on the type of fibre, creating curvatures in the temperature profile and accelerating the charge/discharge. High-strength, high-conductivity carbon fibres performed well, and the simulation approach can be applied to any fibre arrangement/material. On the contrary, the benefit of the fibres is not straightforward according to the three different scenarios developed for the LCA and MCDM analyses, due to the high impact of the fibre production processes. More investigations are needed to balance and optimize the coupling of the fibre material and the solid medium to obtain high thermal performance and low impacts.

Red Mud-Blast Furnace Slag-Based Alkali-Activated Materials

“…Based on the wide authors' experience on the preparation of alkali-activated mixes [26,27,29,32,33], a procedure was chosen which consisted in adding small quantities of RM powder to the alkaline activated solution under constant mixing. After the addition of RM, BFS powder was slowly added under 500 rpm frequency stirring.…”

“…The low percentage of silica and alumina in its composition makes RM unsuitable as the sole precursor, so other aluminosilicates must be added [25], but its intrinsic alkalinity promotes the activation. These materials have characteristics comparable to cement-based hydraulic binders; in fact, they present good compressive strength, good resistance to aggressive environments and could be used as thermal storage materials [26], lightweight at low environmental impact [27][28][29] catalyst support or as adsorbent material [30].…”

Alkali-Activated Red Mud and Construction and Demolition Waste-Based Components: Characterization and Environmental Assessment

“…It is worth noting that this estimation had little effect on the overall production impacts of each system, bordering on undetectable [19]. To be sure that the assumption made was verified, a simulation of the environmental impacts resulting from the shift of the red mud from the Podgorica site to the sand production site was also carried out, but the final environmental impact value increased by less than 5%, justifying the use of uniform transfer values for all materials used.…”

“…In this framework, the use of alternative low-energy and low-CO 2 binders, such as geopolymers and alkali-activated binders, is highly promising. Geopolymers have been proposed for a wide range of engineering applications, such as the production of geopolymer concrete [11]; the production of bricks and other non-structural elements starting from "poor" solid precursors [12]; hazardous waste stabilization/solidification [13,14]; fire-resistant binders [15,16]; and other functional applications [17][18][19].…”

Engineering Properties of Hybrid Fibre Reinforced Ternary Blend Geopolymer Concrete

“…In a hybrid fibre combination, the microfibres bridge the microcracks, whereas the macrofibres are more efficient in controlling the development of macrocracks in the concrete [14][15][16][17]. Geopolymer behaves comparably to conventional cement binders; hence the hybrid fibres can also be incorporated in geopolymer concrete to improve the mechanical properties [18][19][20][21][22][23]. Many researchers carried out many investigations on the properties of fibre reinforced unary and binary blend geopolymer concrete in the past [24,25].…”