This study presents a theoretical model to simulate the temperatures and productivity of a single-slope, single-basin solar still when an external solar enhancement is used. Experiments were performed in the New Mexico region (32.3199° N, 106.7637° W) to validate the numerical model. A point focusing Fresnel lens was used in the experiments to enhance the solar input. It was found that a significant rise in the productivity of the still was achieved with the Fresnel lens. Parametric study by varying the water depth showed the Fresnel lens was more effective for larger water depths. In addition, the Fresnel lens can aid in improving the overall efficiency of the solar still.

The production of freshwater from desalinating abundant saline water on the planet is increasingly considered a climate change adaptation measure. Yet, there are challenges associated with the high cost, intensive energy demand, and environmental implications of desalination. Effective integration of solar energy generation and freshwater production can address both issues. This review article highlights recent key advances in such integration achieved in a joint-research university-national laboratory partnership under the auspices of the United States Department of Energy and parallel efforts worldwide. First, an overview of current and emerging desalination technologies and associated pretreatment, brine treatment, and valorization technologies that together can result in zero-liquid-discharge systems is presented, and their technological readiness levels are evaluated. Then, advanced modeling techniques and new software platforms that enable optimization of solar-desalination applications with the dual objective of cost and environmental impact minimization are discussed.

Effective pretreatment is essential for achieving long-term stable operation and high water recovery during the desalination of alternative waters. This study developed a process modeling approach for technical, economic, energetic, and environmental assessments of pretreatment technologies to identify the impacts of each technology treating brackish water desalination brine with high scaling propensity. The model simulations evaluated individual pretreatment technologies, including chemical softening (CS), chemical coagulation (CC), electrocoagulation (EC), and ion exchange (IX). In addition, combinations of these pretreatment technologies aiming at the effective reduction of key scaling constituents such as hardness and silica were investigated. The three evaluation parameters in this assessment consist of levelized cost of water (LCOW, $/m³), specific energy consumption and cumulative energy demand (SEC|CED, kWh/m³), and carbon dioxide emissions (CO₂, kg CO_2-eq/m³). The case study evaluated in this work was the desalination brine from the Kay Bailey Hutchison Desalination Plant (KBHDP) with a total dissolved solids (TDS) concentration of 11,000 mg/L and rich in hardness and silica. The evaluation of individual pretreatment units from the highest to lowest LCOW, SEC|CED, and CO₂ emissions in the KBHDP brine was IX > CS > EC > CC, CS > IX > EC > CC, and CC > CS > EC > IX, respectively. In the case of pretreatment combinations for the KBHDP, the EC + IX treatment combination was shown to be the best in terms of the LCOW and CO₂ emissions. The modeling and evaluation of these pretreatment units provide valuable guidance on the selection of cost-effective, energy-efficient, and environmentally sustainable pretreatment technologies tailored to desalination brine applications for minimal- or zero-liquid discharge.

A safe and efficient method for storing hydrogen is solid state storage through a chemical reaction in metal hydrides. A good amount of research has been conducted on hydrogenation properties of metal hydrides and possible methods to improve them. Background research shows that heat transfer is one of the reaction rate controlling parameters in a metal hydride hydrogen storage system. Considering that some very well-known hydrides like lanthanum nickel (LaNi₅) and magnesium hydride (MgH₂) are paramagnetic materials, the effect of an external magnetic field on heat conduction and reaction kinetics in a metal hydride storage system with such materials needs to be studied. In the current paper, hydrogenation properties of lanthanum nickel under magnetism were studied. The properties which were under consideration include reaction kinetics, hydrogen absorption capacity, and hydrogenation time. Experimentation has proven the positive effect of applying magnetic fields on the heat conduction, reaction kinetics, and hydrogenation time of a lanthanum nickel bed. However, magnetism did not increase the hydrogenation capacity of lanthanum nickel, which is evidence to prove that elevated hydrogenation characteristics result from enhanced heat transfer in the bed.