Thermochemical energy storage materials and reactors have been reviewed for a range of temperature applications. For low-temperature applications, magnesium chloride is found to be a suitable candidate at temperatures up to 100 °C, whereas calcium hydroxide is identified to be appropriate for medium-temperature storage applications, ranging from 400 °C up to 650 °C. For the high-temperature range (750–1050 °C), oxides of cobalt, manganese, and copper are found to have the redox behaviour required for thermochemical heat storage. However, some of these materials suffer from low thermal conductivities, agglomeration, and low cyclability and, therefore, require further improvements. The concept of enhancing thermal conductivities through additives such as nanomaterials has been encouraging. From an operational point of view, fluidized-bed reactors perform better than fixed- and moving-bed reactors due to better particle interactions. There is, however, a need for the reaction bed to be further developed toward achieving optimum heat and mass transfers. Agitated fluidized-bed reactors have shown encouraging results and are suggested for further exploration. A combination of appropriate computational tools can facilitate an in-depth understanding of bed dynamics.

The amount of waste heat generated annually in the UK exceeds the total annual electricity demand. Hence, it is crucial to effectively harness all available sources of waste heat based on their varying temperatures. Through suitable technologies, a substantial portion of this waste heat has the potential to be recovered for reutilization. Thermochemical energy storage (TCES) provides the best opportunities to recover waste heat at various temperatures for long-term storage and application. The potential of TCES with magnesium hydroxide, Mg(OH)₂, has been established, but it has a relatively high dehydration temperature, thus limiting its potential for medium-temperature heat storage applications, which account for a vast proportion of industrial waste heat. To this end, samples of doped Mg(OH)₂ with varying proportions (5, 10, 15, and 20 wt%) of potassium nitrate (KNO₃) have been developed and characterized for evaluation. The results showed that the Mg(OH)₂ sample with 5 wt% KNO₃ achieved the best outcome and was able to lower the dehydration temperature of the pure Mg(OH)₂ from about 317 °C to 293 °C with an increase in the energy storage capacity from 1246 J/g to 1317 J/g. It also showed a monodisperse surface topology and thermal stability in the non-isothermal test conducted on the sample and therefore appears to have the potential for medium heat storage applications ranging from 293 °C to 400 °C.

Magnesium hydroxide, Mg(OH)₂, is recognized as a promising material for medium-temperature heat storage, but its low thermal conductivity limits its full potential application. In this study, thermal enhancement of a developed magnesium hydroxide-potassium nitrate (Mg(OH)₂-KNO₃) material was carried out with aluminum oxide (Al₂O₃) nanomaterials. The theoretical results obtained through a molecular dynamics (MD) simulation approach showed an enhancement of about 12.9% in thermal conductivity with an optimal 15 wt% of Al₂O₃. There was also close agreement with the experimental results within an error of ≤10%, thus confirming the reliability of the theoretical approach and the potential of the developed Mg(OH)₂-KNO₃ as a medium heat storage material. Further investigation is, however, encouraged to establish the long-term recyclability of the material towards achieving a more efficient energy storage process.

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.

Ensuring access to clean and potable water is a global challenge, especially in regions like Nigeria where it is a pressing concern. Understanding the hydrogeological conditions, particularly the depth of the water table, is crucial for sustainable water resource management. In this study, we employed the direct current (DC) resistivity method to investigate the depth of the water table at the University of Calabar, Nigeria. Our approach involved measuring the electrical resistivity of subsurface materials to delineate the water table depth. The DC resistivity method emerged as a reliable and efficient tool for estimating the water table depth in our study area. By constructing a resistivity profile of the university campus, we uncovered valuable information about the subsurface hydrogeological conditions. Utilizing a multi-electrode resistivity system, we collected data at various depths and locations within the campus. These measurements were then processed using inversion techniques to produce a 2D resistivity image of the subsurface. This image revealed intriguing variations in subsurface resistivity, indicative of changes in composition and saturation of underground materials. Most importantly, our findings shed light on the depth of the water table, which ranged between 5.5m and 34.5m below the mean sea level. This information not only enhances our understanding of the University of Calabar’s hydrogeology but also contributes to broader efforts in sustainable water management and development strategies.

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 behaviour. 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 ℃ 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 ℃. Thermodynamic and kinetic studies on this composite material are therefore encouraged to establish its full potential.