Energy Storage and Applications

Demand for new solutions to emerging issues faced by the electricity generation, demand and supply industries continues to increase with the introduction of increasing proportions of variable renewable energy and changing system demands. Energy storage systems represent a key part of the solution as stakeholders attempt to move towards a ‘net zero’ system. Within research, studies into the techno-economic optimisation of varied energy storage technologies for different applications continue to play a significant role in this changing landscape. A key aspect of this research is the modelling and simulation of such systems, often with the goal of optimising their parameters for deploying in specific roles and services. This paper presents an extensive analysis of the current economic outlook for five major energy storage technologies, highlighting the significant variation in quoted costs within the literature. It presents a unique and novel perspective by considering economic and optimisation modelling from both a technology and application-centric approach. It explores the different approaches available for performing economic analysis on energy storage systems, providing a novel overview of the advantages of various approaches along with examples from the literature on how these studies are implemented. Finally, the paper explores optimisation studies, giving an in-depth explanation of different approaches used in the optimisation of energy storage systems and reviewing prominent uses within the literature. The paper concludes with a consideration of the main challenges that face the field of techno-economic energy storage studies and provides recommendations on areas that require further research.

Pure calcium hydroxide, Ca(OH)₂, and magnesium hydroxide, Mg(OH)₂, are limited in their applicability for the storage of medium-temperature heat due to their high dehydration temperatures. Modification of the hydroxides by doping with appropriate materials is a viable method for solving this problem. In this work, samples of Ca(OH)₂ and Mg(OH)₂ have been doped with various proportions of boron nitride (BN) and potassium nitrate (KNO₃) to reduce their dehydration temperatures. The results showed that the doping processes were successfully achieved as desired, but there was a reduction in their surface areas and porosity, which could impact their thermodynamic behavior. However, the thermal analysis on the samples revealed that the KNO₃ had a more positive effect on the Mg(OH)₂ material than Ca(OH)₂. For instance, a reduction of 23 °C in the dehydration temperature and an increase of 6% in heat storage capacity were achieved with 5 wt% KNO₃-doped Mg(OH)₂, thus making it applicable for heat storage in the temperature range of 293–400 °C. Thermodynamic and kinetic studies on this composite material are therefore encouraged to establish its full potential.

Hydrogen storage is vital to the development of renewables, especially in low-infrastructure countries. Metal hydrides offer a small but safe solid-state candidate for hydrogen storage at medium pressures and near-ambient temperature, yet large-scale applications face heat-management challenges. In this article, we numerically analyze examples of two large-scale lanthanum pentanickel (LaNi₅)-based metal hydride reactor configurations with shell-and-tube heat exchangers. This research studies two large-scale shell-and-tube metal hydride reactor configurations: a tube-side cooling reactor with hydride powder packed in the shell and coolant flowing through internal tubes, and a shell-side cooling reactor using annular hydride pellets with coolant circulating through the shell. The thermal and kinetic performance of these large-scale reactors was simulated using COMSOL Multiphysics (version 6.1) and analyzed under different geometries and operating conditions typical of industrial scales. The tube-side solution provided 90% hydrogen absorption in 1500–2000 s at 30 bar, while the shell-side solution reached the same level of absorption in 430 s at 10 bar. Results show that tube-side cooling has higher storage, while shell-side cooling improves heat removal and kinetics. For energy and maritime transport applications, these findings reveal optimization insights for large-scale, efficient hydrogen storage systems.