Photovoltaic modules during sunny days can reach temperatures 35 °C above the ambient temperature, which strongly influences their performance and electrical efficiency as power losses can be up to −0.65%/°C. To minimize and control the PV panel temperature, the scientific community has proposed different strategies and innovative approaches, one of them through passive cooling with phase change materials (PCM). However, further investigation, including the effects of geometric shape, insulation, phase change temperature, ambient temperature, and solar radiation on the PV module power output and efficiency, needs further optimization and research. Therefore, the current work aims to investigate several system configurations and different PCMs (RT42, RT31, and RT25) and compare the system with and without insulation through computational fluid dynamic (CFD) tools. The final goal is to optimise and control the temperature of PV modules and evaluate their system efficiency and energy generation. The results showed that compared with a rectangular shape of the PCM container, the trapezoid-one exhibits a considerably better cooling performance with a negligible variation of the PV temperature, even when the melting temperature of the PCM was lower than the average ambient temperature. Moreover, the study showed that having insulation in the PCM container increases the amount of PCM needed, compared with no insulation case, and the increased amount depends on the PCM type. The newly proposed PV/PCM system configuration shows an efficiency and power generation enhancement of 17% and 14.6%, respectively, at peak times.

Thermochemical heat storage has attracted significant attention in recent years due to potential advantages associated with very high-energy density at the material scale and its suitability for long-duration energy storage because of almost zero loss during storage. Despite the potential, thermochemical heat storage technologies are still in the early stage of development and little has been reported on thermochemical reactors. In this paper, our recent work on the charging and discharging behavior of a fixed-bed thermochemical reactor is reported. Silica gels were used as the sorbent for the experimental work. An effective model was established to numerically study the effect of different charging conditions on the discharging behavior of the reactor, which was found to have a maximum deviation of 10.08% in terms of the root mean square error compared with the experimental results. The experimentally validated modelling also showed that the discharging temperature lift increased by 5.84 times by changing the flow direction of the air in the discharging process when the charging level was at 20%. At a charging termination temperature of 51.25 °C, the maximum discharging temperature was increased by 2.35 °C by reducing the charging flow velocity from 0.64 m/s to 0.21 m/s. An increase in the charging temperature and a decrease in the air humidity increased the maximum discharging outlet temperature lift by 3.37 and 1.89 times, respectively.

Liquid air energy storage (LAES) is one of the most promising large-scale energy storage technologies that are capable of providing different energy services to ensure the stability and flexibility of the grid with a high renewable penetration. Examples of such services include peak shaving, renewable firming and transmission constraint management. The LAES technology has several advantages relative to other energy storage technologies due to its high energy density, multi-functionalities, no geological constraints, environmental friendliness and scalability. However, the round-trip efficiency (RTE) of a standalone LAES system is around 50-60%, mainly due to the energy-intensive air liquefaction process (i.e., charging process), which, on average, consumes 0.22–0.7 kWh electricity to produce 1 kg liquid air. To reduce this electricity consumption, recycling high-grade cold energy from the liquid air regasification (power recovery) process has been utilized. However, this is not available in some cases, such as at the system start-up stage or when liquid air is used for black start applications. Additionally, partial loss of cold energy during storage, coupled with insufficient utilisation of compression heat, further reduces the RTE. In these cases, a back-up of liquid air produced in an energy-efficient way is need and to address this, we propose an air liquefaction system integrated with an organic Rankine cycle (ORC). This integrated system aims for utilisation of the compression heat by driving an ORC unit. Thermodynamic analyses indicate that the integrated systems allow the operation of air liquefaction unit at a much higher pressure up to 250 bar, leading to increased liquid air yield and reduced energy consumption by 25.36%.